Stained chestnut tree leaves

Stained chestnut tree leaves

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The leaves of the chestnut tree in our back yard have, for a while, developed these stains on them:

… which don't appear to be a normal feature of this tree's leaves, at least according to the pictures on Wikipedia (I'm no botanist).

Also, the grass at the bottom of & around the tree does not (no longer?) grows around its root:

Its fruit, on the other hand, appear to me to be healthy:

We've only moved here for a few months, so am not sure whether it has always been like this or whether the tree only got infested in the last period.

Does the leaves' degradation + non-fertile ground around its root, signal that the tree is sick? If so, is there some "medicine" I can get for it myself, or would I have to speak to the administrators of the garden? Thanks in advance for any thoughts!

This looks like Horse Chestnut Leaf Miner ( It is very common, and infects most of the horse chestnut trees around here. Some years are worse than others. It has been spreading for the past few years. It doesn't seem to seriously harm the tree, but there is no cure I have heard of. The link I posted from the RHS offers some ideas about collecting the leaves and composting them in sealed bags, until the moth larvae have died. Occasionally, trees have been found that are genetically resistant to the disease.

Don't worry about the grass, the tree needs the light and water from that bit of soil, but you could try some bark mulch around the trunk to cover the soil, and keep the moisture in.

Stained chestnut tree leaves - Biology

The caterpillar population explodes.
(Jodie Ellis, Purdue University)

Voracious Feeders

Gypsy moth caterpillars consume as much leaf tissue as they can, as quickly as they can, to obtain nourishment to become reproducing adults. Since the caterpillars' feeding period lasts seven to ten weeks through spring and summer, they can do a lot of damage to young tree leaves. If a tree loses more than 50% of its leaves for more than two years in a row, it will certainly be weakened and may not survive.

A single gypsy moth caterpillar can consume 11 square feet of vegetation during its lifetime so the presence of millions of caterpillars can severly affect trees and forests.

Although gypsy moths are capable of feeding on over 500 different species of trees and plants, they prefer oak trees.

Gypsy moth caterpillars feed during an outbreak.

Aftermath of a gypsy moth outbreak.
(Vince Burkle, Indiana IDNR)


Although gypsy moths can exist at relatively low population levels for years at a time, sometimes their populations explode. This occurs for various reasons (favorable weather conditions or a lack of predators, for example). This rapid swelling of population size is called an "outbreak".

During large outbreaks, trees are virtually stripped of their leaves by hungry caterpillars within a few days. Although most trees will re-grow new leaves before summer's end, the process stresses the tree and drains its reserves.

Copyright © 2009, Purdue University, all rights reserved, site authors Cliff Sadof
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Oak, Chestnut Quercus prinus

The bold aspects of the Chestnut Oak make it an attractive choice for shade tree use in large areas. Glossy, dark greenish-yellow leaves that are 4"-6" long turn an orange-yellow to yellowish-brown in the fall. Produces acorns that are a deep-toned brown and are favored by many types of wildlife. The bark of the Chestnut Oak is dark brown to black with deep ridges and is quite a handsome sight. Grows 60'-70' high with a similar, rounded spread. Prefers moist, well-drained and acidic soils and full sun.

Try this tree in your yard:

Zones 4 - 8

Hardiness Zones: Zones 4 - 8
The Chestnut Oak can be expected to grow in the zones shown in color in the zone map. VIEW MAP

Shade Tree

60' - 70' High

Mature Height:
The Chestnut Oak grows to be 60' - 70' feet in height.

60' - 70' Spread

Medium Growth

Full Sun

Various Soils

The Chestnut Oak grows in acidic, drought tolerant, loamy, moist, rich, sandy, silty loam, well drained soils.

Rounded Shape

More Info

The bold aspects of the Chestnut Oak make it an attractive choice for shade tree use in large areas. Glossy, dark greenish-yellow leaves that are 4"-6" long turn an orange-yellow to yellowish-brown in the fall. Produces acorns that are a deep-toned brown and are favored by many types of wildlife. The bark of the Chestnut Oak is dark brown to black with deep ridges and is quite a handsome sight. Grows 60'-70' high with a similar, rounded spread. Prefers moist, well-drained and acidic soils and full sun.

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Chestnut has a long association with appetites. From the staple made of ground nuts called polenta that fed Caesar's legions, to chestnuts roasting by a yuletide fire, the tree's fame has spread by story and song.

Introduced to northern Europe and Great Britain by the invading Romans, the European variety of the chestnut tree has been cultivated not only for its nuts but for its durrable, decay-resistant wood. In the United States, the native American chestnut once dominated the eastern hardwood forests. Growing to a girth greater than most oaks, the chestnut provided the country's pioneers with wood for every imaginable use.

Then, in the early part of this century, a severe blight swept the chestnut, reducing it to a nearly extinct species. Today, the available chestnut lumber and veneer comes from blight victims or from European trees.

Sighting full-grown chestnut trees in Europe is commonplace. Castanea sativa, the European species, remains hearty. In the U.S., the experience could be historic.

However, there's a ray of hope for the American chestnut (Castanea dentata). Researchers at the American Chestnut Foundation have found a thriving stand of chestnut trees at an undisclosed site. And, according to a spokesman for the National Arboretum, foresters have discovered a new, harmless strain of the original chestnut blight fungus.

When it reproduced unhampered, American chestnut grew best on the lighter soils in a range from southern Maine to North Carolina, Tennessee and west to Indiana and Michigan. At maturity, these burly trees stood 60-80' tall and measured 5-6' around the trunk. Deeply furrowed bark formed broad, flat ridges spiraling up the tree.

Early July brought blooms among chestnut's long, thin, toothed leaves, followed by small, prickly burrs. By the end of August, the hard-shelled burrs yielded nuts.

Chestnut has a tiny band of light-colored sapwood. The biscuit-colored heartwood, slightly lighter in weight than maple, resists decay. In color and grain, chestnut strongly resembles oak. Pinworm infestation of the heartwood results in highly-valued "wormy" chestnut with tiny holes.

Due to its coarseness, chestnut does not turn as well as oak. However, it works easily with other hand and power tools. Lumber from downed wood tends to be brittle, so, use fasteners and glue.

You can sand chestnut glass-smooth without difficulty, and the wood responds well to any finish. And, in service, you'll find chestnut one of the most stable woods.

From colonial times, chestnut has been made into anything destined to last: shingles, siding, fence rails and posts, railroad ties, and furniture. It was prized as casket stock.

Today, woodworkers select chestnut veneer for custom cabinets, and solid stock for clocks, chests, and furniture. And, antique furniture restorers demand chestnut for replacement parts.

You can purchase solid (from American and European trees) and wormy chestnut (from American trees) as lumber in up to 3" thickness. However, you'll find it primarily on the East Coast, and in limited quantities. At about $10 per board foot, you'll also pay dearly. More readily available than chestnut lumber, veneer sells for about $4 per square foot.


This work was supported by grants from the National Natural Science Foundation of China (No. 31201488) and the Fundamental Research Funds for Environment and Plant Protection Institute, CATAS (No. 1630042019017). The authors would like to thank Jiatao Xie, Heng Kang, and Chaoxi Luo, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China, for kindly assisting with the cloning experiments, endophyte studies, and generously contributing the GFP plasmid, respectively. We also thank Robert H. A. Coutts for assistance with the English language and helpful discussions.


Isolation of a highly bioactive fraction: 224C-F2

Fractionation of the crude Castanea sativa leaf extract (224) was guided by measures of bioactivity, selecting for fractions that exhibited quorum quenching with little to no growth inhibitory activity, Fig 2. This was measured through use of reporter strains for agr types I-IV. To create fractions for testing, extract 224 was suspended in water and partitioned in succession using hexane, ethyl acetate and butanol. The ethyl acetate partition (224C) was determined to be the most bioactive under these testing parameters and was selected for further fractionation with a flash chromatography system using a gradient of hexane, ethyl acetate and methanol. The most active fraction (224C-F2) was selected for further testing and chemical characterization, described below.

224C-F2 inhibits S. aureus quorum sensing across the diversity of agr alleles

A number of in vitro assays were employed to guide fractionation of the natural product composition and to evaluate efficacy in blocking S. aureus quorum sensing mediated virulence. Growth inhibitory impact of the extracts was assessed with traditional static MIC assays (Table 2) growth inhibition was also tracked in the fluorescent reporter assays for agr activity (Fig 3). A slightly higher level of growth inhibition was observed in the static MIC assays over that observed in the super-aerated reporter assay, but in all reporter strains, the MIC remained >100 μg mL -1 for 224C-F2. Limited biofilm inhibitory activity of the extracts was noted (Table 2).

Minimum inhibitory concentrations (MIC) were determined for extracts 224, 224C, 224C-F2 and control antibiotics (Ampicillin and Kanamycin) against Staphylococcus aureus strains. Minimum biofilm inhibiting concentration (MBIC) determination is also presented, and compared to control extract 220D-F2. All MIC and MBIC values are represented in μg mL -1 .

S. aureus agr reporter strains were treated with extracts 224, 224C, and 224C-F2 at a dose range of 0.05–100 μg mL -1 . Bioactivity guided sequential fractionation resulted in increased quenching of all 4 agr alleles in a manner independent of growth inhibition. Optical density of the culture is represented by solid black symbols fluorescence in the agr reporters is indicated by the open symbols. The IC50 and IC90 for quorum quenching impact of each extract are reported in Table 3. (A) agr I, AH1677 (B) agr II, AH430 (C) agr III, AH1747 (D) agr IV, AH1872.

Quorum quenching effects for 224C-F2 were observed at IC50 values of 1.56–25 μg mL -1 , depending upon the strain tested (Table 3). The most potent quorum quenching activity was observed for agr III (IC50 of 1.56 μg mL -1 ), and the least for agr IV (IC50 of 25 μg mL -1 ). Significant inhibition of agr was observed for all agr alleles at sub-inhibitory concentrations for growth, indicating that the quorum-quenching activity is due to specific interference with agr, and not simply the result of a false positive due to growth inhibition.

All tests were performed at sub-MIC50 concentrations to avoid data skewing from potential growth inhibition effects. All IC values are represented in μg mL -1 .

To verify the observed quorum quenching activity, downstream translational products of the quorum sensing system were assessed. HPLC quantification of δ-toxin (Fig 4A) from the supernatant of a heavy producer of exotoxins (NRS385, a USA 500, agr I, HA-MRSA isolate) revealed significant reduction (p<0.01) in production of δ-toxin in 224C-F2 treated cultures at doses as low as 0.25 μg mL -1 (Fig 4B).

(A) 224C-F2 demonstrates a dose-dependent effect in inhibition of de-formylated and formylated delta toxin, as illustrated in this HPLC chromatogram. (B) Quantification of delta-toxin confirmed the dose-dependent inhibitory activity of extracts, and the increased activity of the refined fraction 224C-F2 over 224 and 224C. (C) Extracts quench the hemolytic activity of both the S. aureus wild type and Δhla mutant, demonstrating that in addition to preventing production of α-hemolysin (responsible for the major share of hemolytic activity), that extracts also inhibit PSM production, responsible for the observable hemolytic activity in hla mutant strains. All treated groups are significant in comparison to the vehicle control (p<0.001). (D) USA300 (Δspa) was exposed to increasing doses of 224, 224C, 224C-F2, and vehicle control for 8 hrs. Western blot for α-hemolysin on supernatants demonstrated a dose-dependent decline in protein levels. Significant differences between treatment and vehicle are represented as: *: p<0.05 ‡: p<0.01 †: p<0.001.

To verify the block in production of additional exotoxins, cultures of strain LAC (AH1263, a USA300, agr I, CA-MRSA isolate) and its isogenic agr (AH1292) and hla (AH1589) mutants were grown in the presence of the extracts and their supernatants were examined in a rabbit red blood cell lysis assay. In this assay, the majority of RBC lysis is attributed to the presence of α-hemolysin in the culture supernatant. The presence of some lytic activity in the Δhla vehicle control suggests that some additional hemolytic activity (

18%) may be due to additional toxins in the supernatant, phenol soluble modulins (PSMs), in particular. Treatment of wild type with 224C-F2 resulted in significant (p<0.001) reduction in hemolytic activity in wild type strain at 6.25 μg mL -1 , and almost total loss of hemolytic activity at the concentration of 100 μg mL -1 . Treatment of the Δhla mutant demonstrated nearly total loss of hemolytic activity at 6.25 μg mL -1 (Fig 4C). Similar to the hemolysis assessment, when USA300 is exposed to increasing doses of all extracts (224, 224C, and 224C-F2), the level of α-hemolysin protein production is markedly attenuated, with the most potent activity exhibited by 224C-F2 (Fig 4D).

224C-F2 blocks S. aureus damage to human keratinocytes

In addition to monitoring the activity of each agr allele and detecting specific downstream products (e.g. α-hemolysin and δ-toxin), we also broadened our scope to capture virulence impact data on any other exotoxins that could be produced through this system. To do this, we exposed HaCaT cells to the sterile-filtered supernatants of treated and control cultures. The difference in cytotoxicity as detected by LDH assay was very clear (p<0.001) for all extracts (224, 224C, and 224C-F2) in comparison to control, and this was evident at doses as low as 0.25 μg mL -1 (Fig 5A). Likewise, images of the HaCaT cells following exposure to the supernatants reaffirmed the lack of exotoxins in the supernatants in 224C-F2 treated cultures (Fig 5B).

(A) Supernatants were applied to HaCaT cells (20% v/v for 24 hrs) to measure the lytic capacity (determined by LDH assay) of a full suite of S. aureus exotoxins. Supernatants from 224C-F2-treated cultures were non-toxic to the mammalian cells, confirming inhibition of exotoxin production. (B) Following exposure to supernatants (14% v/v for 3 hrs) or staurosporine (7.1 μM for 3 hrs), HaCaT cells were imaged by fluorescent microscopy to examine cell integrity. Green cells are live, red are dead. Black regions are indicative of dead cells that have detached from the slide. Significant differences between treatment and vehicle are represented as: *: p<0.05 ‡: p<0.01 †: p<0.001.

224C-F2 does not inhibit the growth of common skin bacteria

We investigated the potential of 224C-F2 to create a state of dysbiosis by inhibiting the growth of specific members of the normal skin microflora. While our studies were restricted to assessing the MICs of Actinobacteria and Firmicutes, we did find that 224C-F2 has little to no growth inhibitory activity against the Actinobacteria (Corynebacterium amycolatum, C. striatum, Micrococcus luteus, and Propionibacterium acnes) and Firmicutes (Staphylococcus epidermidis, S. haemolyticus, S. warneri, Streptococcus mitis, and S. pyogenes) tested (Table 4) at the concentrations required for quorum quenching activity in S. aureus. Of these species, S. warneri was the most sensitive, with an MIC50 of 32 μg mL -1 the MIC90 was not detectable at the range tested (4–512 μg mL -1 ).

Minimum inhibitory concentration (MIC) determination for 224C-F2 and antibiotic controls (ampicillin, erythromycin, clindamycin and kanamycin) against bacterial skin microflora. All MIC values are represented in μg mL -1 .

Repeated exposure to 224C-F2 does not lead to resistance

Antibiotic resistance is a major concern in any anti-infective drug discovery initiative. Here, we hypothesized that targeting bacterial virulence with a multi-component botanical therapy—potentially containing multiple actives acting on multiple targets–would not be very likely to generate resistance. As reporter strains can lose their effectiveness in tracking activity over multiple passaging days (e.g. due to loss of the plasmid), we chose to design a new method for tracking the quorum quenching efficacy of our lead composition (224C-F2). This was achieved through use of a high toxin output strain (NRS385) that has been shown to consistently produce high levels of δ-toxin in the supernatant. Bacterial growth was monitored by OD600 and δ-toxin was quantified by HPLC. Data for total peak area measured by HPLC (Fig 6A) and area adjusted for slight differences in daily OD (Fig 6B) both reflect significant differences between the levels of δ-toxin produced by the treated versus control cultures for 15 days of passaging. Moreover, no trends in the shift of this observation towards resistance were noted.

Cultures of USA500 isolate NRS385 (agr group I) were passaged for 15 consecutive days in the presence of 16 μg mL -1 of 224C-F2. (A) The sum total peak area of de-formylated and formylated delta toxin was quantified for the mock vehicle control (DMSO) and treated group. A significant difference (p<0.05) was evident for all treatment days. (B) 224C-F2 inhibited delta-toxin production over the length of the passaging experiment in the absence of growth inhibition. Significant differences between treatment and vehicle are represented as: *: p<0.05 ‡: p<0.01 †: p<0.001.

224C-F2 is nontoxic to HaCaT cells and mouse skin

To investigate the potential for cytotoxic or irritant effects of C. sativa leaf extracts, we treated immortalized human keratinocyte cells with up to 512 μg mL -1 of each extract. In all cases (224, 224C, 224C-F2), cytotoxicity (>30%) was only observed at doses at 8–10 times greater than the dose range necessary for quorum quenching activity, and which also corresponded with the rise in toxicity of vehicle treatment alone (DMSO), with no significant difference in cytotoxicity between the vehicle and extracts (Fig 7A). With regards to the potential for irritant or necrotic effects on murine skin, mice were injected intradermally with either 5 μg or 50 μg and monitored for any visible changes in the skin morphology and weight loss. No changes were noted any day at up to 6 days of post-injection follow-up (Fig 7B).

(A) Immortalized human keratinocytes (HaCaT cells) were treated with up to 512 μg mL -1 of extract fractions (24 hrs). The LD50 for 224C-F2 could not be determined at this test range, indicating that it is well above the active dose for quorum quenching activity (IC50 = 1.56–25 μg mL -1 , depending on strain). (B) Uninfected mice received an intradermal injection of 5 or 50 μg 224C-F2. No gross alterations in skin appearance were observed.

224C-F2 attenuates MRSA-induced illness in an in vivo skin infection model

The agr quorum sensing system controls staphylococcal virulence factor expression and is required for necrotic skin lesion formation following cutaneous challenge [29, 35, 37]. Having demonstrated the quorum sensing inhibiting activity of 224C-F2 in vitro (Figs 3–6), we next assessed the efficacy of this composition in a mouse model of S. aureus skin infection. When delivered at the time of infection, 224C-F2 decreased the area of resultant ulcers in a dose-dependent manner (Fig 8A and 8B). In addition, 224C-F2 administration significantly attenuated infection-induced morbidity (assessed by weight loss) compared to vehicle treated controls (Fig 8C). Importantly, mice receiving intradermal injection of 224C-F2 alone did not exhibit any overt signs of dermal irritation or clinical illness e.g., weight loss, malaise, hunching, coat ruffling (Fig 7B and data not shown). Together these data corroborate the in vitro findings and suggest that 224C-F2 impairs MRSA pathogenesis without manifesting local or systemic toxicity.

C5Bl/6 mice were intradermally injected with 1x10 8 CFUs of LAC (USA 300 isolate, AH1263) or its agr deletion mutant (AH1292). Mice received a single dose of 224C-F2 (at 5 or 50 μg) or the vehicle control (DMSO) at the time of infection. Significant differences between treatment and vehicle are represented as: *: p<0.05 ‡: p<0.01. (A) Images of abscesses and ulcers on days 2 and 6 post-infection (scale in cm). (B) 224C-F2 attenuates dermatopathology with a single dose of either 5 or 50 μg. (C) 224C-F2 reduces morbidity and mice do not lose weight.

Chemical characterization of 224C-F2

The percent yield of extract from the dry leaves was 43.98% for extract 224, 2.716% for 224C and 1.155% for 224C-F2 (Fig 2). LC-FTMS analysis of 224C-F2 revealed the presence of at least 94 compounds (Table 5). The greatest quorum quenching effects of 224C-F2 were observed in the retention time region of 21–49 min (Fig 9), suggesting the presence of several distinct quorum quenching compounds (data not shown). Specifically, there are 22 compounds found in this region, 10 present at >1% relative abundance. These correspond to peak numbers, predicted formulas, and relative abundances of: 35 C57H24O2 (2.67%), 36 C27H50O6 (2.65%), 42 C31H50O6 (1.43%), 43 C30H46O7 (1.86%), 46 and 47 C57H23O2N3 (1.64% and 3.13%, respectively), 48 and 49 C59H25O3 (1.45 and 1.07%, respectively), 50 C41H33O16 (1.20%) and 51 C30H47O5 (5.96%). Putative structures for 7 peaks were determined to be pentacyclic triterpenes (specifically, oleanene and ursene derivatives) based on accurate mass analysis, fragmentation patterns, and comparison with natural product databases (Fig 10), and these collectively represent 16.37% in relative abundance. Of note, while present at relative abundance levels of <1% each, the putative structures of gallotannins (32, 33, 34) and ellagitannins (39) were also identified in the most active region of 224C-F2 (Fig 11).

The corresponding chromatogram is reported in Fig 9 putative structures in Figs 10 and 11.

All peaks correspond to data presented in Table 5. Putative structures are reported in Fig 10.

Compounds are listed by Peak number, corresponding to Table 5. Peak 31 was determined to be C39H59O8 or C38H55O9 with a relative abundance of 0.34%. Putative structural matches include: (31a) escigenin tetraacetate (6CI) (31b) tetraacetate (7CI, 8CI) 16α, 21α- epoxy-olean- 9(11)—ene- 3β, 22β, 24, 28- tetrol (31c) tetraacetate aescigenin (31d) triacetate (8CI) cyclic 16, 22- acetal-olean- 12- ene- 3β, 16α, 21β, 22α, 28- pentol (31e) triacetate (8CI) cyclic 22, 28- acetal-olean- 12- ene- 3β, 16α, 21β, 22α, 28- pentol. Peak 32 was determined to be C35H59O6 with a relative abundance of 0.30%. Putative structural matches include: (32a) stigmastane (Fig 11) and (32b) (3β, 4β, 16α, 21β, 22α) -16, 21, 22, 23, 28- pentamethoxy (9CI) olean- 12- en- 3- ol. Peak 42 was determined to be C31H49O6 with a relative abundance of 1.43%. Putative structural matches included (42) amirinic acid. Peak 52 was determined to be C32H51O7 with a relative abundance of 0.48%. Putative structural matches include: (52a) 21-acetate protoescigenin, (52b) 16-acetate protoescigenin, (52c) 22-acetate protoescigenin and (52d) 28-acetate protoescigenin. Peak 55 was determined to be C30H48O5, with a relative abundance of 4.11%. Putative structural matches include: (55a) 16,21-epoxy-(3β,4β,16α,21α,22β)-olean-12-ene-3,22,24,28-tetrol (9CI) (55b) asiatic acid (55c) arjunolic acid (55d) isoescigenin. Peak 60 was determined to be C30H48O6, with a relative abundance of 6.80%. Putative structural matches include: (60a) camelliagenin E (60b) brahmic acid (60c) sericic acid (60d) belleric acid and (60e) 2,3,23,24-tetrahydroxy-(2α,3β)-urs-12-en-28-oic acid. Peak 64 was determined to be C30H45O5, with a relative abundance of 2.91%. The putative structural match is (64) ouillaic acid.

Compounds are listed by Peak number, corresponding to Table 5. Peak 32 was determined to be C35H59O6 with a relative abundance of 0.30%. Putative structural matches include: (32a) stigmastane and (32b) (3β, 4β, 16α, 21β, 22α) -16, 21, 22, 23, 28- pentamethoxy (9CI) olean- 12- en- 3- ol (Fig 10). Peak 33 was determined to be C27H23O18 with a relative abundance of 0.16%. Putative structural matches include: (33a) 1,3,6-tri-O-galloylglucose (33b) 1,2,6-tri-galloyl-β-D-glucose (33c) 1,2,3-tri-O-galloylglucose (33d) 1,2,3-tri-O-galloyl-β-D-glucopyranose (33e) 2',3,5-tri-O-galloyl-D-hamamelose (33f) 2- C- [[(3, 4, 5- trihydroxybenzoyl) oxy] methyl]- 1, 5- bis(3, 4, 5- trihydroxybenzoate) D- Ribofuranose (33g) kurigalin (33h) 3,4,6-tri-O-galloyl-D-glucose. Peak 34 was determined to be C39H31O15 with a relative abundance of 0.65%. Putative structural matches include: (34) castanoside B. Peak 39 was determined to be C17H11O8 or C20H11O4N2 with a relative abundance of 0.72%. Putative structural matches include: (39a) 3,4,3'-tri-O-methylellagic acid and (39b) 3,3',4'-tri-O-methylellagic acid. Peak 44 was determined to be C34H29O15 with a relative abundance of 0.26%. Putative structural matches included (44) norbadione A.

224C-F2 was also examined by HPLC-DAD and LC-FTMS for the presence of 5 compounds reported to be found in crude C. sativa leaf extracts [42], and it was determined that 224C-F2 does not contain chlorogenic acid, ellagic acid, hyperoside, isoquercitrin, or rutin.


There are three major classes of tannins: Shown below are the base unit or monomer of the tannin. Particularly in the flavone-derived tannins, the base shown must be (additionally) heavily hydroxylated and polymerized in order to give the high molecular weight polyphenol motif that characterizes tannins. Typically, tannin molecules require at least 12 hydroxyl groups and at least five phenyl groups to function as protein binders. [4]

Base Unit:
Gallic acid


Flavan-3-ol's scaffold
Class/Polymer: Hydrolyzable tannins Phlorotannins Condensed tannins and
Phlobatannins (C-ring
isomerized condensed tannins) [5]
Sources Plants Brown algae Plants (former), tree heartwood (latter)

Oligostilbenoids (oligo- or polystilbenes) are oligomeric forms of stilbenoids and constitute a class of tannins. [6]

Pseudo tannins Edit

Pseudo tannins are low molecular weight compounds associated with other compounds. They do not change color during the Goldbeater's skin test, unlike hydrolysable and condensed tannins, and cannot be used as tanning compounds. [4] Some examples of pseudo tannins and their sources are: [7]

Pseudo tannin Source(s)
Gallic acid Rhubarb
Flavan-3-ols (Catechins) Tea, acacia, catechu, cocoa, guarana
Chlorogenic acid Nux-vomica, coffee, mate
Ipecacuanhic acid Carapichea ipecacuanha

Ellagic acid, gallic acid, and pyrogallic acid were first discovered by chemist Henri Braconnot in 1831. [8] : 20 Julius Löwe was the first person to synthesize ellagic acid by heating gallic acid with arsenic acid or silver oxide. [8] : 20 [9]

Maximilian Nierenstein studied natural phenols and tannins [10] found in different plant species. Working with Arthur George Perkin, he prepared ellagic acid from algarobilla and certain other fruits in 1905. [11] He suggested its formation from galloyl-glycine by Penicillium in 1915. [12] Tannase is an enzyme that Nierenstein used to produce m-digallic acid from gallotannins. [13] He proved the presence of catechin in cocoa beans in 1931. [14] He showed in 1945 that luteic acid, a molecule present in the myrobalanitannin, a tannin found in the fruit of Terminalia chebula, is an intermediary compound in the synthesis of ellagic acid. [15]

At these times, molecule formulas were determined through combustion analysis. The discovery in 1943 by Martin and Synge of paper chromatography provided for the first time the means of surveying the phenolic constituents of plants and for their separation and identification. There was an explosion of activity in this field after 1945, including prominent work by Edgar Charles Bate-Smith and Tony Swain at Cambridge University. [16]

In 1966, Edwin Haslam proposed a first comprehensive definition of plant polyphenols based on the earlier proposals of Bate-Smith, Swain and Theodore White, which includes specific structural characteristics common to all phenolics having a tanning property. It is referred to as the White–Bate-Smith–Swain–Haslam (WBSSH) definition. [17] [ self-published source? ]

Tannins are distributed in species throughout the plant kingdom. They are commonly found in both gymnosperms and angiosperms. Mole studied the distribution of tannin in 180 families of dicotyledons and 44 families of monocotyledons (Cronquist). Most families of dicot contain tannin-free species (tested by their ability to precipitate proteins). The best known families of which all species tested contain tannin are: Aceraceae, Actinidiaceae, Anacardiaceae, Bixaceae, Burseraceae, Combretaceae, Dipterocarpaceae, Ericaceae, Grossulariaceae, Myricaceae for dicot and Najadaceae and Typhaceae in Monocot. To the family of the oak, Fagaceae, 73% of the species tested (N = 22) contain tannin. For those of acacias, Mimosaceae, only 39% of the species tested (N = 28) contain tannin, among Solanaceae rate drops to 6% and 4% for the Asteraceae. Some families like the Boraginaceae, Cucurbitaceae, Papaveraceae contain no tannin-rich species. [18]

The most abundant polyphenols are the condensed tannins, found in virtually all families of plants, and comprising up to 50% of the dry weight of leaves. Tannins of tropical woods tend to be of a cathetic nature rather than of the gallic type present in temperate woods. [19]

There may be a loss in the bio-availability of still other tannins in plants due to birds, pests, and other pathogens. [20]

Localization in plant organs Edit

Tannins are found in leaf, bud, seed, root, and stem tissues. An example of the location of the tannins in stem tissue is that they are often found in the growth areas of trees, such as the secondary phloem and xylem and the layer between the cortex and epidermis. Tannins may help regulate the growth of these tissues.

Cellular localization Edit

In all vascular plants studied so far, tannins are manufactured by a chloroplast-derived organelle, the tannosome. [21] Tannins are mainly physically located in the vacuoles or surface wax of plants. These storage sites keep tannins active against plant predators, but also keep some tannins from affecting plant metabolism while the plant tissue is alive it is only after cell breakdown and death that the tannins are active in metabolic effects. [ citation needed ]

Tannins are classified as ergastic substances, i.e., non-protoplasm materials found in cells. Tannins, by definition, precipitate proteins. In this condition, they must be stored in organelles able to withstand the protein precipitation process. Idioblasts are isolated plant cells which differ from neighboring tissues and contain non-living substances. They have various functions such as storage of reserves, excretory materials, pigments, and minerals. They could contain oil, latex, gum, resin or pigments etc. They also can contain tannins. In Japanese persimmon (Diospyros kaki) fruits, tannin is accumulated in the vacuole of tannin cells, which are idioblasts of parenchyma cells in the flesh. [22]

Presence in soils Edit

The convergent evolution of tannin-rich plant communities has occurred on nutrient-poor acidic soils throughout the world. Tannins were once believed to function as anti-herbivore defenses, but more and more ecologists now recognize them as important controllers of decomposition and nitrogen cycling processes. As concern grows about global warming, there is great interest to better understand the role of polyphenols as regulators of carbon cycling, in particular in northern boreal forests. [23]

Leaf litter and other decaying parts of kauri (Agathis australis), a tree species found in New Zealand, decompose much more slowly than those of most other species. Besides its acidity, the plant also bears substances such as waxes and phenols, most notably tannins, that are harmful to microorganisms. [24]

Presence in water and wood Edit

The leaching of highly water soluble tannins from decaying vegetation and leaves along a stream may produce what is known as a blackwater river. Water flowing out of bogs has a characteristic brown color from dissolved peat tannins. The presence of tannins (or humic acid) in well water can make it smell bad or taste bitter, but this does not make it unsafe to drink. [25]

Tannins leaching from an unprepared driftwood decoration in an aquarium can cause pH lowering and coloring of the water to a tea-like tinge. A way to avoid this is to boil the wood in water several times, discarding the water each time. Using peat as an aquarium substrate can have the same effect. Many hours of boiling the driftwood may need to be followed by many weeks or months of constant soaking and many water changes before the water will stay clear. Adding baking soda to the water to raise its pH level will accelerate the process of leaching, as the more alkaline solution can draw out tannic acid from the wood faster than the pH-neutral water. [26]

Softwoods, while in general much lower in tannins than hardwoods, [27] are usually not recommended for use in an aquarium [28] so using a hardwood with a very light color, indicating a low tannin content, can be an easy way to avoid tannins. Tannic acid is brown in color, so in general white woods have a low tannin content. Woods with a lot of yellow, red, or brown coloration to them (like cedar, redwood, red oak, etc.) tend to contain a lot of tannin. [29]

Tannin-rich fresh water draining into Cox Bight from Freney Lagoon, Southwest Conservation Area, Tasmania, Australia

Bog-wood (similar to, but not, driftwood) in an aquarium, turning the water a tea-like brown

Upper Tahquamenon falls Panoramic view

The tannin-rich Oparara River in the West Coast region of New Zealand

There is no single protocol for extracting tannins from all plant material. The procedures used for tannins are widely variable. [30] It may be that acetone in the extraction solvent increases the total yield by inhibiting interactions between tannins and proteins during extraction [30] or even by breaking hydrogen bonds between tannin-protein complexes. [31]

There are three groups of methods for the analysis of tannins: precipitation of proteins or alkaloids, reaction with phenolic rings, and depolymerization. [32]

Alkaloid precipitation Edit

Alkaloids such as caffeine, cinchonine, quinine or strychnine, precipitates polyphenols and tannins. This property can be used in a quantitation method. [33]

Goldbeater's skin test Edit

When goldbeater's skin or ox skin is dipped in HCl, rinsed in water, soaked in the tannin solution for 5 minutes, washed in water, and then treated with 1% FeSO4 solution, it gives a blue black color if tannin was present. [ citation needed ]

Ferric chloride test Edit

Use of ferric chloride (FeCl3) tests for phenolics in general. Powdered plant leaves of the test plant (1.0 g) are weighed into a beaker and 10 ml of distilled water are added. The mixture is boiled for five minutes. Two drops of 5% FeCl3 are then added. Production of a greenish precipitate is an indication of the presence of tannins. [34] Alternatively, a portion of the water extract is diluted with distilled water in a ratio of 1:4 and few drops of 10% ferric chloride solution is added. A blue or green color indicates the presence of tannins (Evans, 1989). [35]

Other methods Edit

The hide-powder method is used in tannin analysis for leather tannin and the Stiasny method for wood adhesives. [36] [37] Statistical analysis reveals that there is no significant relationship between the results from the hide-powder and the Stiasny methods. [38] [39]

400 mg of sample tannins are dissolved in 100 ml of distilled water. 3 g of slightly chromated hide-powder previously dried in vacuum for 24h over CaCl2 are added and the mixture stirred for 1 h at ambient temperature. The suspension is filtered without vacuum through a sintered glass filter. The weight gain of the hide-powder expressed as a percentage of the weight of the starting material is equated to the percentage of tannin in the sample.

100 mg of sample tannins are dissolved in 10 ml distilled water. 1 ml of 10M HCl and 2 ml of 37% formaldehyde are added and the mixture heated under reflux for 30 min. The reaction mixture is filtered while hot through a sintered glass filter. The precipitate is washed with hot water (5× 10 ml) and dried over CaCl2. The yield of tannin is expressed as a percentage of the weight of the starting material.

Reaction with phenolic rings Edit

The bark tannins of Commiphora angolensis have been revealed by the usual color and precipitation reactions and by quantitative determination by the methods of Löwenthal-Procter and of Deijs [40] (formalin-hydrochloric acid method). [41]

Colorimetric methods have existed such as the Neubauer-Löwenthal method which uses potassium permanganate as an oxidizing agent and indigo sulfate as an indicator, originally proposed by Löwenthal in 1877. [42] The difficulty is that the establishing of a titer for tannin is not always convenient since it is extremely difficult to obtain the pure tannin. Neubauer proposed to remove this difficulty by establishing the titer not with regard to the tannin but with regard to crystallised oxalic acid, whereby he found that 83 g oxalic acid correspond to 41.20 g tannin. Löwenthal's method has been criticized. For instance, the amount of indigo used is not sufficient to retard noticeably the oxidation of the non-tannins substances. The results obtained by this method are therefore only comparative. [43] [44] A modified method, proposed in 1903 for the quantification of tannins in wine, Feldmann's method, is making use of calcium hypochlorite, instead of potassium permanganate, and indigo sulfate. [45]

Pomegranates Edit

Accessory fruits Edit

Strawberries contain both hydrolyzable and condensed tannins. [46]

Berries Edit

Most berries, such as cranberries, [47] and blueberries, [48] contain both hydrolyzable and condensed tannins.

Nuts Edit

Nuts vary in the amount of tannins they contain. Some species of acorns of oak contain large amounts. For example, acorns of Quercus robur and Quercus petraea in Poland were found to contain 2.4–5.2% and 2.6–4.8% tannins as a proportion of dry matter, [49] but the tannins can be removed by leaching in water so that the acorns become edible. [50] Other nuts – such as hazelnuts, walnuts, pecans, and almonds – contain lower amounts. Tannin concentration in the crude extract of these nuts did not directly translate to the same relationships for the condensed fraction. [51]

Herbs and spices Edit

Legumes Edit

Most legumes contain tannins. Red-colored beans contain the most tannins, and white-colored beans have the least. Peanuts without shells have a very low tannin content. Chickpeas (garbanzo beans) have a smaller amount of tannins. [52]

Chocolate Edit

Drinks with tannins Edit

Principal human dietary sources of tannins are tea and coffee. [54] Most wines aged in charred oak barrels possess tannins absorbed from the wood. [55] Soils high in clay also contribute to tannins in wine grapes. [56] This concentration gives wine its signature astringency. [57]

Coffee pulp has been found to contain low to trace amounts of tannins. [58]

Fruit juices Edit

Although citrus fruits do not contain tannins, orange-colored juices often contain tannins from food colouring. Apple, grape and berry juices all contain high amounts of tannins. Sometimes tannins are even added to juices and ciders to create a more astringent feel to the taste. [59]

Beer Edit

In addition to the alpha acids extracted from hops to provide bitterness in beer, condensed tannins are also present. These originate both from malt and hops. Trained brewmasters, particularly those in Germany, consider the presence of tannins to be a flaw [ citation needed ] . However, in some styles, the presence of this astringency is acceptable or even desired, as, for example, in a Flanders red ale. [60]

In lager type beers, the tannins can form a precipitate with specific haze-forming proteins in the beer resulting in turbidity at low temperature. This chill haze can be prevented by removing part of the tannins or part of the haze-forming proteins. Tannins are removed using PVPP, haze-forming proteins by using silica or tannic acid. [61]

Tannins have traditionally been considered antinutritional, but it is now known that their beneficial or antinutritional properties depend upon their chemical structure and dosage. The new technologies used to analyze molecular and chemical structures have shown that a division into condensed and hydrolyzable tannins is too simplistic. [62] Recent studies have demonstrated that products containing chestnut tannins included at low dosages (0.15–0.2%) in the diet of chickens may be beneficial. [63]

Some studies suggest that chestnut tannins have positive effects on silage quality in the round bale silages, in particular reducing NPNs (non-protein nitrogen) in the lowest wilting level. [64]

Improved fermentability of soya meal nitrogen in the rumen may occur. [65] Studies conducted in 2002 on in vitro ammonia release and dry matter degradation of soybean meal comparing three different types of tannins (quebracho, acacia and chestnut) demonstrated that chestnut tannins are more efficient in protecting soybean meal from in vitro degradation by rumen bacteria. [66]

Condensed tannins inhibit herbivore digestion by binding to consumed plant proteins and making them more difficult for animals to digest, and by interfering with protein absorption and digestive enzymes (for more on that topic, see plant defense against herbivory). Many tannin-consuming animals secrete a tannin-binding protein (mucin) in their saliva. Tannin-binding capacity of salivary mucin is directly related to its proline content. Salivary proline-rich proteins (PRPs) are sometimes used to inactivate tannins. One reason is that they inactivate tannins to a greater extent than do dietary proteins resulting in reduced fecal nitrogen losses. PRPs additionally contain non-specific nitrogen and non-essential amino acids making them more convenient than valuable dietary protein. [ citation needed ]

Histatins, another type of salivary proteins, also precipitate tannins from solution, thus preventing alimentary adsorption. [67]

Tannin production began at the beginning of the 19th century with the industrial revolution, to produce tanning material for the need for more leather. Before that time, processes used plant material and were long (up to six months). [ citation needed ]

There was a collapse in the vegetable tannin market in the 1950s–1960s, due to the appearance of synthetic tannins, which were invented in response to a scarcity of vegetable tannins during World War II. At that time, many small tannin industry sites closed. [68] Vegetable tannins are estimated to be used for the production of 10–20% of the global leather production. [ citation needed ]

The cost of the final product depends on the method used to extract the tannins, in particular the use of solvents, alkali and other chemicals used (for instance glycerin). For large quantities, the most cost-effective method is hot water extraction.

Tannic acid is used worldwide as clarifying agent in alcoholic drinks and as aroma ingredient in both alcoholic and soft drinks or juices. Tannins from different botanical origins also find extensive uses in the wine industry. [ citation needed ]

Uses Edit

Tannins are an important ingredient in the process of tanning leather. Tanbark from oak, mimosa, chestnut and quebracho tree has traditionally been the primary source of tannery tannin, though inorganic tanning agents are also in use today and account for 90% of the world's leather production. [69]

Tannins produce different colors with ferric chloride (either blue, blue black, or green to greenish-black) according to the type of tannin. Iron gall ink is produced by treating a solution of tannins with iron(II) sulfate. [70]

Tannins can also be used as a mordant, and is especially useful in natural dyeing of cellulose fibers such as cotton. [71] The type of tannin used may or may not have an impact on the final color of the fiber.

Tannin is a component in a type of industrial particleboard adhesive developed jointly by the Tanzania Industrial Research and Development Organization and Forintek Labs Canada. [72] Pinus radiata tannins has been investigated for the production of wood adhesives. [73]

Condensed tannins, e.g., quebracho tannin, and Hydrolyzable tannins, e.g., chestnut tannin, appear to be able to substitute a high proportion of synthetic phenol in phenol-formaldehyde resins for wood particleboard. [ citation needed ]

Tannins can be used for production of anti-corrosive primer, sold under brand-name "Nox Primer" for treatment of rusted steel surfaces prior to painting, rust converter to transform oxidized steel into a smooth sealed surface and rust inhibitor. [ citation needed ]

The use of resins made of tannins has been investigated to remove mercury and methylmercury from solution. [74] Immobilized tannins have been tested to recover uranium from seawater. [75]

Nutriproteomics survey of sweet chestnut (Castanea sativa Miller) genetic resources in Portugal

Sweet chestnut (Castanea sativa Miller) is a tree species whose edible fruit was a staple food for many centuries until the emergence of potato and cereal crops. Once of great importance for the survival of rural populations, at present there is a renewed interest in this fruit as a nutritious food, partly due being gluten-free. Portugal is one of the major sweet chestnut producing countries and is an important natural habitat for native European chestnut species. In a nutriproteomics approach, the main objective was to describe and evaluate the sweet chestnut germplasm present in Portugal. Globulins of 22 Portuguese sweet chestnut varieties were used as markers of genetic diversity. This characterization showed significant diversity (h = 0.334) among the varieties tested, but also a homonymy problem in varietal identification. Two-dimensional electrophoresis and mass spectrometry were then used to further investigate the chestnut proteome. Most of the proteins were assigned as having functions in nutritional storage activity. The photorespiration protein Rubisco, normally present in photosynthesizing plant parts was also present in the fruit which suggests that the catabolism of this protein is unusual in C. sativa species. Furthermore, the Portuguese varieties have been shown to be good sources of essential amino acids, and particularly the ‘Bária’ variety showed a balanced profile that meets the recommended dietary requirements of older children, adolescents, and adults.

USGS Woodland and Rock Garden Walks

The National Center site (105 acres) provides habitat for many native and migratory birds, insects, and large and small mammals. Visitors are invited to enjoy these surroundings by exploring the USGS Woodland and Rock Garden Walks.

Woodland Walk

The Woodland Walk (green path on map) winds through the forested area north of the main entrance to the Powell Federal Building. Along the walk and elsewhere on the grounds, indigenous trees have been labeled with their scientific and common names. On the map, colored dots provide a generalized identification key: green for conifers, blue for deciduous, and red for flowering deciduous trees. See how many of the following trees you can find!

  • Oak: Many native species occur along the walk,including black, chestnut, southern red, scarlet, and white oaks. (Other oak species that can be found on the USGS site include the blackjack, swamp white, willow, and post oaks.)
  • Red Maple: The name is derived from red budsthat appear in February or March, heralding thecoming of spring.
  • Pignut or Broom Hickory: This spindly hardwoodthrives in deep shade and poorly drained soil.Virginia Pine: This tall slender conifer with two-needle bundles quickly invades abandonedfields, preventing loss of topsoil.
  • Black Tupelo: This dark-barked tree has small,round, dark-blue fruit resembling gum balls.
  • Flowering Dogwood: The dogwood is a decora-tive tree, whose white blossoms brighten the early spring.
  • Tulip Tree or Yellow Poplar: This softwood treewith broad palmate leaves produces large yellowflowers. It forms much of the forest canopy of theNational Center site.
  • Sassafras: This low, scrubby tree, used in colonialtimes to make fenceposts and small boats, has aromatic leaves and roots that can be used to prepare a tea.

Rock Garden Walk

Large rock specimens have been placed on gravel pads around the USGS site to show examples of some nearby rock units in the Triassic Lowland and in the Maryland and Virginia Piedmont. The rocks exhibit striking sedimentary, structural, mineralogic, and weathering features.

How to Identify Hickory Trees

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Hickory - belonging to a section of the walnut family - is a canopy tree that is prevalent in eastern North America, although other species of hickory have been known to exist in Europe, Africa and Asia. The hickory tree produces a dense, strong, and shock-resistant wood that is commonly used to make tool handles, furniture, and decorative architectural elements. [1] X Research source In addition, many types of hickory are sought for use in the content and preparation of food, and can be useful in survival situations. These guidelines will help you identify any hickory tree, so you can get to work on whatever you may need it for.


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