Monograph Quercus
The Quercus genus comprises many species widespread in Europe, Asia and America. The genus contains about 400 species. The most popular are, in central and northern Europe: Quercus robur, Quercus pedunculata and Quercus petraea; in southern Europe and in the Middle East: Quercus infectoria, Quercus ilex, Quercus pubescens and Quercus brantii; in the Mediterranean region: Quercus cerris and Quercus coccifera; in North America: Quercus alba, Quercus havardii, Quercus breviloba, Quercus gambelli and Quercus douglassi, in the Far East (China, Japan and Korea): Quercus acuta, Quercus acutissima, Quercus aliena, Quercus ogilva, Quercus glauca, Quercus salicina, Quercus serrata and Quercus dentate. Several Quercus species were tested as described in non-clinical part. Further data derive from accidental animal poisoning. Furthermore, Quercus infectoria and Quercus ilex species were examined due to their common therapeutical use in southern Europe.
Oak bark has been traditionally used as a tanning material in Europe since medieval times (Smout 2007). For commercial purposes, the timber and bark of Quercus pedunculata Ehrh. and Quercus sessiflora Salisb. are not differentiated. Quercus was mentioned in the writings of Dioskurides, Hieronimus Bock 1565, Matthiolus (1626), Haller (1755), Hecker (1814), Clarus (1860), Rademacher (1851), Kissel (1863), (according to Madaus“ Lehrbuch der Biologischen Heilmittel”, 1938), Spencer (1832) and Schimpfky (1900). Its cultivation in Europe dates back to ancient and medieval times. The oak tree was held sacred by the ancient Greeks and Romans and in the rest of Europe. The origin of its name is said to be derived from the Celtic quer (fine) and cuez (tree). The astringent effects of oak bark or nutgalls are known for centuries. Oak bark was applied topically to burns and wounds, or applied orally in gastritis or diarrhoea. After precipitation of superficial proteins, a protective coat is formed to protect healing of the damaged tissues. Assessment report on Quercus robur L., Quercus petraea (Matt.) Liebl., Quercus pubescens Willd., cortex EMA/HMPC/3206/2009 Page 6/23
Especially valuable oak bark was used to tan leather. An infusion formed a dye, which was used in rural regions to dye wool. Records of the bark use in folk medicine are found in many countries to counter diarrhoea, infusions for gargle for sore throat and for adding to a hot bath for sore or excessively perspiring feet or sprained ankle. The infusions were also used for treatment of ulcers, toothache, neuralgia and rheumatism (Allen and Hatfield, 2004). Oak bark powder of Quercus robur is used for prophylaxis of diarrhoea in cattle, horses, pigs, sheep and chicken (EMEA Committee for Veterinary Medicinal Products 1997).
Description of the herbal substance(s), herbal preparation(s) or combinations thereof Herbal substance(s) The herbal substance is mentioned in several well known handbooks such as Madaus (1938), Martindale (2007), Bisset and Wichtl (1994), PDR for Herbal Medicines (2000; 2004), German Comission E Monograph and European Pharmacopoeia 6.0, Duke’s Handbook of Medicinal Herbs (2002), Mills and Bone (2000), Schulz et al. 1998, Wagner and Wiesenauer 1995; Weiss and Fintelman (1999).
In the European Pharmacopoeia, it is described as the cut and dried bark of young branches and the lateral shoots of Quercus robur, Quercus petraea and/or Quercus pubescens. It contains a minimal amount of 3% of tannins, expressed as pyrogallol, calculated with reference to the dried herbal substance. The plant belongs to the family Fagacae, subfamily Quercoideae, genus Quercus. Oak bark is harvested in spring from March to April.
The oak bark contains highly variable amount of tannins (8-20%). The tannin content depends on the time of the harvest, age of the branches and on the method of assay used. Tannins are polyphenolic secondary metabolites of higher plants. They comprise either: galloyl esters and their derivatives (gallotannins, ellagitannins and complex tannins) or they are oligomeric and polymeric proanthocyanidins and can possess different interflavanyl coupling and substitution patterns (condensed tannins) (Okuda et al. 1993; 2005). The oak bark contains both hydrolyzable and condensed tannins (Ahn and Gstirner 1971; 1973; Bate-Smith 1972; Bruneton 1995; Chen 1970; Evans 2009; Glasl 1983; Grundhöfer et al. 2001; Haddock et al. 1982; Haslam 2007; Haslam and Cai 1994; Herve du Penhoat et al. 1991a, 1991b; Ikram and Nowshad 1977; Ishimaru et al. 1987; Khanbabaee and van Ree 2001; König et al. 1994; Mämmelä et al. 2000; Niemetz and Gross 2005; Pallenbach et al. 1991, 1993; Roux and Evelyn 1958; Salminen et al. 2004; Scalbert et al. 1988; 1989, 1990; Schofield et al. 2001; Vivas et al. 1995; Vovk et al. 2003; Yoshida 1984).
Hydrolysable tannins They are previously known as pyrogallol tannins. Principal types of hydrolysable tannins are gallotannins and elagitannins. They are polyesters of glucose and can be hydrolysed by acids or enzymes sych as tannase. They release sugar upon hydrolysis and either gallic acid or hexahydroxydiphenic acid. Phenolic acids: gallic acid is present in gallotannins or hexahydroxydiphenic acid in ellagitannins. The latter undergoes lactonization to produce ellagic acid (Okuda et al. 1989). Gallotannins are the simplest hydrolysable tannins, containing a polyphenolic and a polyol residue (mostly derived from D-glucose). Tannic acid is a polymer of about eight monomers of gallic acid and glucose.
Ellagitannins (formed from the gallotannins by the oxidative coupling of at least two galloyl units, yielding an axially chiral hexahydroxydiphenoyl (HHDP) unit) grandinin, castalagin, pedmolagin, pedunculagin, roburin A-E, vescalin, vescalagin, 2,3-(S)-hexahydroxy diphenoyl glucose (Bate-Smith 1972; Feldman 2005; Herve du Penhoat et al. 1991a; 1991b; Mämmelä et al. 2000; Peng et al. 1991; Vivas et al. 1995). Assessment report on Quercus robur L., Quercus petraea (Matt.) Liebl., Quercus pubescens Willd., cortex EMA/HMPC/3206/2009 Page 3/23
Flavano-ellagitannins: acutissimins A an B, eugenigrandin A, guajavin B, stenophyllanin C (Khanbabaee and van Ree 2001). Procyanidinoellagitannin: mongolicanin. Ellagitannins are instable and hydrolysed over time with formation of free ellagic acid and decrease of their solubility (Charrier et al. 1992; Klumpers et al. 1994; König and Scholz 1994; Mämmelä et al. 2000; Simon et al. 1999). Present data suggest, that the pyrogallol phenols (+)-gallocatechin and leucodelphinidin, which are formed in oak leves, are oxidated by polyphenoloxidases in the heartwood and leaves to phlobatannin and are translocated to the bark. The increase in tannin concentration suggests a downward movement of phenolic metabolites from the leaves to the phloem (Hathway 1958; 1959). Condensed tannins (proanthocyanidins) More than 20 compounds (catechins and low-molecular-mass, oligomeric, and polymeric proanthocyanidins) have been isolated from the bark of Quercus robur.
Monomers: ( _ )-epicatechin, ( _ )-epicatechin gallate, (+)-catechin, (+)-catechin gallate, (+)- gallocatechin, ( _ )-epigalloatechin, and ( _ )-epigallocatechin gallate; dimeric proanthocyanidins: (+)-catechin-(4α-8)-(+)-catechin, 3-galloyl-(+)-catechin-(4α-8)-3-0-galloyl-(+)catechin, 3-)- galloyl-(+)-gallocatechin-(4β-8)-(+)-gallocatechin, ( _ )-epicatechin-(4β-8)-3-0-galloyl-( _ )- epigallocatechin, 3-)-galloyl-( _ )-epigallocatechin-(4β-8)-(+)-catechin. Oligomeric proanthocyanidins: D14-D19 (Kuliev et al. 1997; Matthews et al. 1997; Thompson et al. 1972). Condensed tannins are not very stable; they can be oxidized into soluble phlobaphens, which have no tanning properties anymore. Triterpenes: friedelin, friedelinol, 3-friedelanol (Castola et al. 2002, Coquet et al. 2008; Kohlmünzer 2000; Scalbert and Haslam 1987, Sousa et al. 2006) Insoluble lipid polyesters: suberins (Graça and Santos 2007; Holloway 1983) Volatile acids: acetic and formic acid (Balaban and Uçar 2003) Herbal preparation(s) (Hänsel et al. 1994, PDR for Herbal Medicines 2000, 2004, Matindale 2007) Comminuted herbal substance (12 – 16% tannins)
Decoctions: 20 g/L of water
Infusions: 5 g/L of water
Extracts: dry extract (5.0-6.5:1), extraction solvent: ethanol 50% V/V
Combinations of herbal substance(s) and/or herbal preparation(s) including a description of vitamin(s) and/or mineral(s) as ingredients of traditional combination herbal medicinal products assessed, where applicable The herbal substance is also available in combination products. Main plants used in combination are: Glycyrrhiza glabra, Triticum repens, Juglans regia, Potentilla erecta, Bistorta polygonum, Fucus
vesiculosus, Althea officinalis, Foeniculum vulgare, Mentha piperita, Achillea millefolium, Salvia officinalis and Thymus vulgaris
Historical data on medicinal use
The Quercus genus comprises many species widespread in Europe, Asia and America. The genus contains about 400 species. The most popular are, in central and northern Europe: Quercus robur, Quercus pedunculata and Quercus petraea; in southern Europe and in the Middle East: Quercus infectoria, Quercus ilex, Quercus pubescens and Quercus brantii; in the Mediterranean region: Quercus cerris and Quercus coccifera; in North America: Quercus alba, Quercus havardii, Quercus breviloba, Quercus gambelli and Quercus douglassi, in the Far East (China, Japan and Korea): Quercus acuta, Quercus acutissima, Quercus aliena, Quercus ogilva, Quercus glauca, Quercus salicina, Quercus serrata and Quercus dentate. Several Quercus species were tested as described in non-clinical part. Further data derive from accidental animal poisoning. Furthermore, Quercus infectoria and Quercus ilex species were examined due to their common therapeutical use in southern Europe. Oak bark has been traditionally used as a tanning material in Europe since medieval times (Smout 2007). For commercial purposes, the timber and bark of Quercus pedunculata Ehrh. and Quercus sessiflora Salisb. are not differentiated. Quercus was mentioned in the writings of Dioskurides, Hieronimus Bock 1565, Matthiolus (1626), Haller (1755), Hecker (1814), Clarus (1860), Rademacher (1851), Kissel (1863), (according to Madaus“ Lehrbuch der Biologischen Heilmittel”, 1938), Spencer (1832) and Schimpfky (1900). Its cultivation in Europe dates back to ancient and medieval times. The oak tree was held sacred by the ancient Greeks and Romans and in the rest of Europe. The origin of its name is said to be derived from the Celtic quer (fine) and cuez (tree). The astringent effects of oak bark or nutgalls are known for centuries. Oak bark was applied topically to burns and wounds, or applied orally in gastritis or diarrhoea. After precipitation of superficial proteins, a protective coat is formed to protect healing of the damaged tissues. Assessment report on Quercus robur L., Quercus petraea (Matt.) Liebl., Quercus pubescens Willd., cortex EMA/HMPC/3206/2009 Page 6/23
Especially valuable oak bark was used to tan leather. An infusion formed a dye, which was used in rural regions to dye wool. Records of the bark use in folk medicine are found in many countries to counter diarrhoea, infusions for gargle for sore throat and for adding to a hot bath for sore or excessively perspiring feet or sprained ankle. The infusions were also used for treatment of ulcers, toothache, neuralgia and rheumatism (Allen and Hatfield, 2004). Oak bark powder of Quercus robur is used for prophylaxis of diarrhoea in cattle, horses, pigs, sheep and chicken (EMEA Committee for Veterinary Medicinal Products 1997).
Specified strength/posology/route of administration/duration of use for relevant preparations and indications
PDR for Herbal Medicines (2000, 2004) Comminuted herbal substance: 3 g/day. Tea: 1 g of comminuted oak bark is put to cold water, rapidly boiled and strained after some time (1 teaspoon corresponds to 3 g of drug). Daily dosage: internally 3 g of oak bark, tea: 1 cup (250 ml) 3 times daily. Externally: rinses/gargles: boil 2 dessert spoons finely cut drug with 3 cups water. Bath additive: 5 g of oak bark is boiled with 1 L water and added to the full or hip bath. Bath additive – duration: 20 minutes at 32 – 37 0 C. Hänsel et al. (1994) Internal use: Comminuted oak bark: Tea: 1 g comminuted oak bark is put to cold water, rapidly boiled and strained after some time. Daily dose: 3 g of oak bark. Duration of use: 3 – 4 days. External use: For external use: 0.1 g of tannins/liter of water. Rinses/gargles: boil 20 g of finely cut oak bark in 1 L of water. Bath: 5g of oak bark is boiled with 1 L of water and added to the full or hip bath. Bath temperature: 32 – 37 0 C, duration: 20 minutes, 2 – 3 times per week, no longer than 2 – weeks. Assessment report on Quercus robur L., Quercus petraea (Matt.) Liebl., Quercus pubescens Willd., cortex EMA/HMPC/3206/2009 Page 10/23
(Bundesanzeiger No 22a. 01.02.1990) Quercus cortex Internal use: Comminuted oak bark, 3g daily. Preparations adequately. External use: Rinses/gargles: 20 g of finely cut oak bark in 1 L of boiled water. Baths: complete and partial: 5g of oak bark in 1 L of water. Duration of use: If diarrhoea lasts longer than 3-4 days, qualified advice is required. External use: no longer than 2 – 3 weeks.
Overview of available pharmacological data regarding the herbal substance(s), herbal preparation(s) and relevant constituents thereof Pharmacodynamics
Tannins are supposed to contribute to the therapeutic effect. Oak bark is used against chillblains, mouth sores, haemorrhoids and indigestion. Tannins occurring in oak bark are reported to have various activities: antisecretolytic, antiirritant, antimicrobial and antiparasitic. Traditionally oak bark was used to treat nonspecific diarrhoea, inflammation of mouth and throat and slightly injured skin (Madaus (1938), Martindale (2007), Bisset and Wichtl (1994), Mills and Bone (2000) and Weiss and Fintelman (1999).
Astringent actions
The astringency of the extracts of Quercus bark is mainly due to its content of oligomeric proanthocyanidins. By hydrogen binding the available polyhydroxyphenolic groups are crosslinking with proteins. This effect is also involved in the process of leather tanning. The phenolic groups of tannins may interact with proteins of saliva, mucus, gastric contents and epithelial cells of the gastrointestinal tract. The presence of tannins in food may limit digestion and is recognized as a feeling of dryness in the palate, a feeling of roughness, dryness, constriction and loss of lubrication. Tannins are reported to repel predators by their strongly astringent taste (Prinz and Lucas 2000).
Salivary proteins in saliva (proline-rich proteins and histatins) are precipitators of tannins (Bacon and Rhodes 2000; Bennick 2002; Charlton et al. 1996; Fickel et al. 1999; Hu et al. 2007; Luck et al. 1994; Murray et al. 1994; Schenkels et al. 1995). The astringency – characteristics of wine, tea etc. is associated specifically with the interaction polyphenols with proline rich proteins. They have high affinity for tannins and can act as postingestive countermeasures against dietary tannins. Proteins secreted in saliva can bind to dietary tannins in oral cavity in the first stage of digestion. Proline rich proteins form approximately 70% of the protein content of saliva (Helmerhorst and Oppenheim 2007; Henson et al. 2004; Lawless et al. 1994; Lu and Bennick 1998; Luck et al. 1994).
Polyphenols inhibit digestive enzymes, stabilize collagen, block several receptors and channels and reduce bioavailability of iron as potential metal chelators (Baxter et al. 1997; Kim and Miller 2005; Madhan et al. 2005; Zhu et al. 1997). Multivalent cross-linking leads to astringency – reduction of the lubricating power of saliva by precipitating salivary proteins and dewetting of the mucosal surface. Astringency increases with repeated use (Cai et al. 2006, Cai and Bennick 2006; Charlton et al. 1996, 2002; He et al. 2006; Jöbstl et al. 2006; Shimada 2006; Skopec et al. 2004).
It was shown, that the affinity for tannins is inversely related to the size of the polymer, and peptides with less than six residues interact very weakly with tannin. The specificity of interaction depends on size, conformation and charge of the protein molecules. Tightly coiled globular proteins like ribonuclease A, cytochrome C, lysozyme and myoglobin have much lower affinities for tannin than conformationally loose proteins like bovine serum albumine and histone F1. Proanthocyanidins may precipitate one protein in the presence of a large excess of another protein. The high affinity interactions between proanthocyanidins and some proteins may protect the plant from pathogens or predators (Dawra et al. 1988; Hagerman and Butler 1981). Kandra et al. (2004) have shown that tannin (gallotannin) inhibited human salivary α-amylase. For this reason, tannin is suggested to be tested for the prevention of dental caries as some reports suggested that tea consumption reduces dental caries in experimental animals and humans.
The antidiarrhoeal effect of tannins: tri-0-galloyl-β-D-glucopyranose and penta-0-galloyl βD- glucopyranose was tested on isolated colon of guinea pigs in a model of experimental diarrhoea with water secretion stimulated by rhein perfusion (Verhaeren and Lemli 1986). Both tested tannins in a concentration of 0.1% completely inhibited the secretory effect of rhein. The antidiarrhoeal activity of gallotannins is attributed to the astringent action on mucosal proteins resulting in the formation of a protective layer (Verhaeren and Lemli 1986). Comparison of astringency of ellegitannins and complex tannins from Quercus petrea bark has shown that relative potency of the oak bark ellagitannins (pedunculagin, vescalagin, stenophyllanin C, acutissimin A, eugenigrandin A, guajavin B) is rather low in the range of 0.45 % of the astringency of the bark (König et al. 1994). This weak activity can be explained by their rigid and inflexible structures and limited ability to complex with proteins. The astringency of the crude herbal substance is mainly due to its content of oligomeric proanthocyanidins (Pallenbach et al. 1993).
Gastroprotective activity
The mucosal cells are able to resist damage against exogenous and endogenous factors and epithelium acts as a barrier to the passive diffusion of harmful substances (Martin and Wallace 2006). Tannic and phenolic acids are reported to protect the stomach mucosa against toxicants and can prevent gastrointestinal inflammation. Using an experimental model of ethanol induced gastric damage in rats Gharzouli et al. (1999) have shown that an aqueous extract of Quercus ilex root bark or tannic acid may be gastroprotective. When given orally to rats (3.62 mg/ml total polyphenols, n=9-10) Quercus ilex root bark extract induced a reduction on lesion number compared to water (n=9-10) control (7.3 1.4 vs. 16.3 1.7, p<0.05) and ulcer index (35.3 9.4 vs. 67.7 7.3, p<0.05). Plant extracts (5 ml/kg) were given orally 60 min before administration of 50% ethanol and rats were killed 15 min after ethanol treatment. Lesions were photographed at about 2.3 magnifications and the ulcer index was determined according to a 6 grade scoring scale.
Khennouf et al. (2003) reported gastroprotective effects of 25, 50 and 100 mg/kg of 70% acetone extracts of Quercus suber and Quercus coccifera leaves and of tannins (50 mg/kg of pedunculagin, castalgin, phillyraeoidin A and acutissimin B) given orally in the mouse ethanol-induced gastric ulcer model (n=8-10). Extracts and tannins were suspended in 5% carboxymethyl cellulose (CMC) and administered by gavage 1 h before 40% of ethanol. The control group (n=8-10) received CMC only. Lesions were delimited manually using an image tool program and the number and total area of the lesions were determined. The average number of lesions in the control group was 45.0 13.9 on area of 12.1 3.0 mm 2 of mucosa. Both extracts tested diminished the number of lesions (pooled mean: 11.7 3.6 and reduced area of lesions (pooled mean areas of the lesions were 3.1 1.5 mm 2 for the Q. coccifera and 2.5 1.6 mm 2 for Q suber extract (p<0.05). The protection varied between 68 -91% and neither extract produced dose-dependent protection.
Purified tannins (50 mg/kg) were also protective and the percent protection varied between 66 to 83%. Castalgin was most potent, but there were no significant differences between tannins tested (p>0.05). Authors conclude, that the gastroprotective properties of Quercus extracts and isolated tannins might be related to their strong antiperoxidant activity. However, a dose-response relationship was not investigated. Antiulcer activity of ethanolic extracts of several Jordanian plants was tested by Alkofahi and Atta (1999) on a gastric ulcer ethanol model in rats. All extracts were given orally in a dose of 400 mg/kg, twice in a day preceding the experiment and a third time 90 min before induction of gastric ulceration with ethanol 50% (10 ml/kg). The control rats received distilled water. The strongest antiulcer activity was found with use of Quercus coccifera L. (curative ratio 99.5%) and with Quercus aegilops L. (curative ratio of 97.4%)
Antiviral activity
The antiviral effect of octyl gallate against influenza and other RNA viruses were studied in vitro by Yamasaki et al. (2007). They tested three different types of viruses: vesicular stomatitis virus VSV (Rhabdoviridiae family), influenza virus (Orthomyxoviridiae family) and poliovirus (Picornoviridiae family). The infected cells were incubated overnight in medium containing varying concentrations of octyl gallate. At the end of infection, the amounts of infectious progeny viruses were counted and were normalized to the virus yield in the absence of the octyl gallate. Octyl gallate inhibited multiplication of all tested viruses and in addition exhibited virucidal activity against enveloped viruses. The VSV virus yield was less than one hundredth of that in the absence of octyl gallate at concentration 4 g/ml, for this effect 20 g/ml concentration was required for influenza virus and poliovirus. The addition of octyl gallate at 2 h post infection almost completely abolished the formation. of the progeny viruses of influenza. Octyl gallate also suppressed the multiplication of HSV-1 at early stages within 6 h p.i. in the infected Hep-2 or Vero cells. Moreover it induced inhibition of the multiplication of RNA viruses, such as VSV and poliovirus (Uozaki et al. 2007).
Several tannins exhibit significant HIV-reversal transcriptase inhibition in vitro. It is suggested, that their antiviral activity is rather due to interference with virus-cell adhesion. However comprehensive study on HIV and reverse transcriptase inhibition showed that activity of tannins in cell cultures is due to their toxic features. It was concluded, that relevance of tannins as anti HIV prospective treatment is greatly limited by their toxicity (Matthée et al. 1999). Plausibility of several plants, Quercus infectoria included, was tested in vitro against HCV protease and significant inhibiting activity was reported (Jassim and Naji 2003). Assessment report on Quercus robur L., Quercus petraea (Matt.) Liebl., Quercus pubescens Willd., cortex
Antibacterial activity
Tannins have been traditionally used as antimicrobial agents and their antibacterial activity and antiseptic treatment has long been recognized (Cowan 1999; Haslam 2007). Their mode of antimicrobial action may depend on inactivation of microbial adhesins, enzymes and cell envelope transport proteins. They may also form complexes with polysaccharide molecules. According to comprehensive review (Scalbert 1991) tannins can be toxic also to fungi and yeasts. Tannic acid was proposed as a protein precipitating agent in genomic and plasmid DNA bacterial preparations. Tannic acid as the prototypical gallotannin was chosen as a model system. It is environmentally friendly and biodegradable (Van Huynh 2008). Antimicrobial and oxidative activity of a methanol extract of Quercus robur bark (80% (v/v) methanol solution in water) were tested using agar diffusion method on Staphylococcus aureus, Enterobacter aerogenes and Candida albicans (Andrenšek et al. 2004).
Extracts were prepared using a stepwise- gradient for preparative separation. Extracts of the oak bark were prepared by performing the extraction three times with each extraction solvent successively before the extraction solvent of higher polarity was applied. The total extractable dry matter from the bark was 8%. The substance related to the activity of the fractions was screened simultaneously by thin layer chromatography (TLC) and estimation of antioxidant activity. Extracts 10 and 12 [50% (v/v) MeOH in ethyl acetate] and extracts 16 and 18 [75% (v/v) MeOH in water] were bactericidal for Staphylococcus aureus. The less polar extracts (75% ethyl acetate in n-hexane, 100% ethyl acetate and 5% MeOH in ethyl acetate; extracts 1-9) and 5% were bacteriostatic against Gram negative Enterobacter aerogenes and the yeast Candida albicans. Extract 10 (95%MeOH in ethyl acetate) was bacteriostatic against Enterobacter aerogenes.
The active substances against Staphylococcus aureus and against Enterobacter aerogenes and Candida albicans were in lipophilic extracts. Kolodziej et al. (1999) studied in vitro antimicrobial potency of 27 pure tannins and related compounds. The chemotherapeutic activity was evaluated against Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, Psedomonas aeruginosa, Proteus mirabilis and yeasts: Candida albicans and Cryptococcus neoformans. Only weak to moderate antibacterial activity of tested tannins was detected, but the activity against Cryptococcus neoformans was found quite potent for gallic acid: MIC (minimal inhibitory concentration) = 250 g/ml) and hydrolyzable tannins: corilagin (MIC = 250 g/ml) and phyllantusiin C (MIC = 125 g/ml). The antimicrobial activities of Quercus ilex L. extracts were tested in vitro (Güllüce et al. 2004). Quercus ilex is an evergreen Mediterranean plant species used as a folk remedy to treat haemorrhages, chronic diarhoea and dysentery. A total of 55 human and plant bacteria, one yeast and four fungi were used in this study. The dried plant extracts were dissolved in methanol to a final concentration of 30 μg/ml.
The extracts of Quercus ilex showed antibacterial effects against 35 bacterial strains tested on disc diffusion method: Brucella, Enterobacter, Escherichia, Neisseria, Pseudomonas and Bacillus and Candida albicans. Quite potent antibacterial effects were shown against Escherichia coli (MIC – 16 μg/ml). Negative control with methanol did not show any influence on diameter of inhibition zone. Molochko et al. (1990) examined antistaphylococcal properties of plant extracts against several strains of Staphylococcus aureus, Staphylococcus epidermidis and Staphylococcus saprophyticus. The most active was a water/alcohol extract of oak bark.
Berahou et al. (2007) examined antibacterial activity of extracts of Quercus ilex L. bark. Plant material was extracted with methanol (35.97%, w/w), dissolved in hot distilled water and successively extracted with n-hexane, dichloromethane, ethyl acetate and n-butanol. Each extract was dried under sodium sulphate and reduced to give: hexane extract (1.74%, w/w), ethyl acetate extract (1.5%, Assessment report on Quercus robur L., Quercus petraea (Matt.) Liebl., Quercus pubescens Willd., cortex w/w), butanol extract (16.05%, w/w) and final aqueous layer (16.36%, w/w). Evident antibacterial activity was reported against all tested strains for ethyl acetate, n-butanol, and final aqueous extracts with MIC ranging from 128 to 512 μg/ml. The tested reference bacteria strains were: Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Staphylococcus epidermidis, Proteus mirabilis, Klebsiella pneumoniae, Bacillus subtilis, Salmonella typhimurium, Vibrio cholerae, Streptococcus pyogenes and Streptococcus agalactiae. Akiyama et al. (2001) performed studies on the antibacterial action of several tannins against Staphylococcus aureus.
They examined influence of tannins on plasma coagulation by Staphylococcus aureus and the effect of conventional chemotherapy combined with tannic acid below the MIC. All tannins inhibited coagulation below the MIC. Coagulation was significantly inhibited in plasma containing tannic acid (100 mg/l, gallic acid (5000 mg/l), ellagic acid (5000 mg/l), (-)-epicatechin (1500 mg/l), (-)-epicatechin gallate (500 mg/l) or (-)-epigallocatechin gallate (200 mg/l) after incubation for 24 h. Also the MICs of oxacillin and cefdinir for Staphylococcus aureus were reduced to 0.06 mg/l with tannic acid (100 mg/l) at a concentration below MIC. These results indicate the possibility of treatment of Staphylococcus aureus skin infections with tannic acid as adjuvant agent in addition to beta-lactam antibiotics. Tannic acid at a sub-MIC concentration presents useful topical application in in vivo conditions. Voravuthikunchai and Kitpit (2005a; 2005b) investigated antibacterial effects of aqueous and ethanolic extracts of several plants including Quercus infectoria against hospital isolates of methicillin-resistant Staphylococcus aureus (MRSA ATCC 25923). Aqueous and ethanolic extracts of Quercus infectoria showed activity against all MRSA isolates, with MICs of 0.2 – 0.4 mg/ml. It should be investigated if Quercus infectoria extracts might provide a new treatment effective against multiresistant Staphylococcus aureus infections. Voravuthikunchai et al. (2006) tested the effects of ethanolic extracts of Punica granatum and Quercus infectoria on 10 clinically isolated Helicobacter pylori strains. Both extracts were strongly effective against Helicobacter pylori in the range of MIC from 0.78 to 6.25 and 3.12 to 6.25 mg/ml respectively. There was no resistance to these extracts found in any isolates, irrespective of their antibiotic resistance.
Aqueous and ethanolic extracts of 38 medicinal plants were used against enterohaemorrhagic Escherichia coli 0157:H7 (Voravuthikunchai et al. 2004). The greatest inhibition zone was produced from the ethanolic extract of Quercus infectoria with the MIC values of 0.09 mg/ml and MBC (minimal bactericidal concentration) values of 0.78 mg/ml. Limsuvan et al. (2005) tested an ethanolic extract of Quercus infectoria with E. coli 0157:H7 strain with MIC values of 0.09 to 0.78 ng/ml. However no correlation was found between MIC and cell aggregation. Park et al. (2006) examined extracts from nine types of Korean oak trees (Castanopsis cuspidata var. sieboldii, Quercus acuta, Quercus acutissima, Quercus aliena, Quercus dentata, Quercus ogilva, Quercus glauca, Quercus salicina and Quercus serrata) to determine their antibacterial activity against Microcystis aeruginosa. The most potent extracts of Quercus: salicina, acuta, gilva and acutissima, inhibited the growth of M. aeruginosa by approximately 50% at 20 mg/l.
Antiprotozoan activity
Gallic acid was shown to have trypanocidal effects in vitro both against the bloodstream forms and procyclic forms of Trypanosoma brucei (Koide et al. 1998). LD 50 values of gallic acid are 46.96 1.28 μM for bloodstream forms and 30.02 3.49 for procyclic forms. The authors suggest that the pyrogallol moiety could be responsible for this activity. Assessment report on Quercus robur L., Quercus petraea (Matt.) Liebl., Quercus pubescens Willd., cortex
Antifungal activity
Hwang et al. (2001) reported the inhibitory activity for chitin synthase II from Saccharomyces cerevisiae by tannins and related compounds. Seven tannins and related compounds identified as gallic acid, methyl gallate and others inhibited chitin synthase II, with most potent activity of 3-O-galloyl-(-)- shikimic acid (IC 50 value of 18 μM). Gallic acid, methyl gallate and ellagic acid have had IC 50 values 206, 87 and 149 μM, respectively. Fungicidal activity of oils obtained by oak bark pyrolysis at temperature 400 – 450 o C were tested against brown rot fungus (Gleophyllum trabeum) and white-rot fungus (Trametes versicolor) (Mohan et al. 2008). The pyrolytic lignin-rich fractions consisted mainly of phenols and neutrals. The lignin-rich fractions showed stronger fungal inhibition (45 – 58 kg/m 3 ) than whole bio-oils for an impregnation solution of 10% concentration level.
Antiparasitic activity
Extracts of several plants including Quercus robur were tested in vivo by Paolini et al. (2004) against nematodes living in small ruminants: Teladorsagia circumcinta, Haemonchus contortus and Trichostrongylus colubriformis. Crushed oak bark (5 g) was extracted by 100 ml of water at 90 0 C for 2 h. The filtrate was concentrated to obtain dried powdered sample. Powders were dissolved in phosphate-buffered saline and serially diluted immediately prior to incubation. T. circumcinta and T. colubriformis extracts of oak bark significantly reduced migration of the larvae (1200 g/ml, p<0.01). After incubation with oak bark extract (1200 g/ml) significant reduction of motility was only noted for adult worms of T. colubriformis (p<0.01). Results confirmed that tannins were the source of inhibition of motility of the 3 rd -stage larvae and adult worms and could represent an alternative choice to chemotherapy.
Antioxidant activity
Chen et al. (2007) showed protective activity of tannic acid, gallic acid, ellagic acid and propyl gallate against reactive oxygen species (ROS) using human lung fibroblast IMR-90 cells model. All compounds were incubated at concentration of 10 g/ml and alleviated H 2 O 2 -induced lipid peroxidation. Compounds were also tested against the depletion of intracellular glutathione. When IMR-90 cells were pretreated with 10 g/ml propyl gallate, it was demonstrated to be the only compound successfully preventing depletion of GSH. Results of the study suggested, that tested compounds can protect cells from oxidative stress. Anticancer activity Pan et al. (1999) showed induction of apoptosis by penta-O-galloyl-β-D-glucose through activation of caspase-3 in human leukemia HL-60 cells. Penta-O-galloyl-β-D-glucose induced apoptosis in a concentration and time dependent manner. HL-60 cells were incubated with different doses (5, 10, 20, 30, 40, 50 and 100 M) of penta-O-galloyl-β-D-glucose. The percentage of apoptotic HL-60 cells was 2.89%, 2.47%, 2.86%, 8.25%, 46.99% and 64.08% after 0, 3, 6, 12, 18 and 24 h of incubation with penta-O-galloyl-β-D-glucose (50 M), respectively. The apoptosis potency of penta-O-galloyl-β-D- glucose is correlated to its cancer chemopreventive efficacy in animal models.
Sehrawat et al. (2006) reported preventive effects of tannic acid on 2-acetylaminofluorene (2-AAF) mediated hepatic oxidative stress and cell proliferation in rats. Treatment of rats with tannic acid (125 and 250 mg/kg bw) resulted in significant increase of glutathione hepatic levels, increase of antioxidant activity and phase-II metabolizing enzymes as compared to saline treated control. Inhibition of electrophilic species – significant decrease in lipid peroxidation, xanthine oxidase and hydrogen peroxide generation was also reported. The tumor promotor markers parameters (ornithine decarboxylase activity and DNA synthesis) were dose-dependently decreased. Assessment report on Quercus robur L., Quercus petraea (Matt.) Liebl., Quercus pubescens Willd., cortex EMA
Influence on Angiotensin Converting Enzyme Activity (ACE)
Uchida et al. (1987) examined the effects of condensed tannins on angiotensin converting enzyme activity. Procyanidin B-5 3.3’-di-O-gallate and procyanidin C-1 3.3’- di-O-gallate strongly inhibited activity of the ACE enzyme. The IC 50 values for procyanidin B-5 3.3’-di-O-gallate and procyanidin C-1 3.3’- di-O-gallate were 1.3 and 1.7 x 10 -6 respectively. For inhibition of other proteases: trypsin, chymotrypsin, leucine aminopeptidase, carboxypeptidase A and urinary kallikrein over one hundred times the concentration was required. Influence on the nervous system
The effects on central nervous activity of extracts of galls of Quercus infectoria were studied by Dar et al. (1976) and Dar and Ikram (1979). The methanolic fraction of galls which has been identified as syringic acid exhibited significant local anaesthetic (1 2% solution), analgesic and central depressive activity in mice (doses of 250 and 500 mg/kg). Galls of Quercus infectoria are reported to contain also ellagic acid and gallotannins. The effects of tannic acid were shown by Takahashi et al. (1986). Tannic acid dose dependently (10 - 100 mg/kg) reduced abdominal constrictions in mice (writhing analgesic model induced by i.p. injection of 0.6% acetic acid), increased nociceptive threshold measures by the hot-plate test and potentiated pentobarbital sleeping time. Tannic acid (100 mg/kg) significantly inhibited locomotor activity in mice.
Overall conclusions
The available data are sufficient to include the traditional use of specified preparations of oak bark in a Community herbal monograph. Oak bark fullfils the requirement of therapeutic use for at least 30 years (15 years within the European Union, Directive 2004/24/EC).
Indications for treatment:
1) Traditional herbal medicinal product for symptomatic treatment of mild diarrhoea,
2) Traditional herbal medicinal product for symptomatic treatment of minor inflammation of the oral mucosa or skin.
3) Traditional herbal medicinal product for symptomatic relief of itching and burning associated with haemorrhoids after serious conditions have been excluded by a medical doctor.
The HMPC concluded that prior to using oak bark in symptomatic self-medication by haemorrhoid patients, serious conditions should be excluded by a medical doctor. Hemorrhoids are a common chronic condition with symptoms that include rectal bleeding, protrusion, and itching. Because other conditions (diverticulitis, vascular ectasias, colorectal cancer, colitis and megacolon) can lead to identical symptoms, a professional careful rectal examination and proctosigmoidoscopy is justified for any patient who reports hemorrhoids. Only medical doctors, gastroenterologists and surgeons are qualified to accurately diagnose hemorrhoids and offer a consequent, competent treatment plan.
Due to the lack of data on acute and chronic toxicity, repeated dose toxicity, mutagenicity, carcinogenicity, reproductive and developmental toxicity, a list entry for Quercus cortex can not be recommended. Benefit/risk assessment Oak bark is a subject of a European Pharmacopoeia monograph. There are no concerns about serious side effects or interactions with oak bark preparations. There are reported side effects concerning gastrointestinal reactions and allergic reactions due to the oak bark preparations used. No serious adverse events with a therapeutic posology of the herbal preparations are reported.
Despite limited toxicological data, levels of exposure associated with the use of oak bark, either by oral or topical route of administration for limited times; most probably do not result in any significant risk to human health. It can be concluded that the benefit/risk assessment for oak bark preparations is positive for use in therapeutical dosages in specific conditions of mild diarrhoea, in minor inflammatory conditions of the oral mucosa or skin and in conditions of medically diagnosed haemorrhoids before anorectal use.
http://www.theodora.com/drugs/eu/quercus_cortex_herbal.html
Bereiding: Eikeltjesmeel
Kijk de eikels goed na op beschadigingen of gaatjes. Gebruik alleen de gave exemplaren. Rooster ze eerst in een oven op 200 graden gedurende 10 minuten. Laat ze vervoelgens afkoelen en zet ze dan op in een pan met ruim water. Gooi na 5 minuten koken het kookwater weg en kook ze weer 5 minuten. Gooi dan weer het kooskwater weg en zet ze nogmaals op en kook ze nu 10 minuten. Giet dan het water weer af en leg ze tot de volgende dag in vers koud water.
Giet de volgende dag de eikels af en droog ze af. Pel de eikels, wat nu gemakkelijk gaat. Soms heb je gaat dat mesje nodig, maar meestal niet. Haal ook de vliesjes van de eikels af, maar meestal gaat dat vanzelf.
Het kan ook gebeuren dat na de eerste keer in de oven roosteren de eikels al open gebarsten zijn. Haal dan de vruchthulsjes en de vliesjes gelijk er af, maar ga dan gewoon wel net de ontgiften van de eikels door, door ze op de te zetten en 5 minuten te koken en zo voorts.
Gebruik ook nu weer alleen mooie exemplaren. Rooster de eikels nu weer 10 minuten in de oven op 200 graden. Laat ze helemaal afkoelen en maal vervolgens de eikels tot meel. Je kan ze eerst grof hakken in een blender om ze vervolgens in een koffiemolen of graanmolen fijn te malen. Leg het meel in de afkoelende oven tot dat die helemaal koud is geworden ( dus minstens 3 uur) . Zet wel de deur van de oven op een kiertje open opdat het vocht kan ontsnappen.
Bewaar het meel in een af te sluiten bus. Het is slim tijdens het maalproces de geroosterde en gemalen eikels eerst te zeven, zo houdt men gelijk de al fijn genoeg gemalen eikels apart. De grove delen kan men vervolgens nog wat meer aandrogen en dan later weer malen. Blijven er nog grove stukjes over, dan kan men die ook zo door het deeg mengen. Of gebruiken om er eikeltjes koffie van te maken en ze veel donkerder te roosteren. Natuurlijk kan men ze net geroosterd ook over de sla of bij een stamppot geven. Door brooddeeg gemengd is het effect vergelijkbaar met als men gemalen noten door het brooddeeg mengt.
Er werd traditioneel van alleen dit meel brood gebakken , beter is brood van 1/3 eikeltjesmeel, 1/3 tarwebloem en 1/3 roggemeel. Dit geeft erg lekker brood op. ( vanwege de waarschijnlijk nog steeds aanwezige looizuur in het eikeltjes meel, moet men niet elke dag dit brood eten. Maar 1 keer per drie dagen levert dit brood geen enkele probleem voor iemands gezondheid op. Maar er zijn in het verleden bevolkingsgroepen geweest waarvan eikeltjesbrood de belangrijkste voedingsbron was ). Zowel als je zuurdesembrood maakt, als je het met gist laat rijzen krijg je goed voedzaam brood. Maakt men het brood op gistbasis, dus voegt men naast gist , wat suiker, zout en een scheut koolzaadolie en natuurlijk ongeveer 1/3 liter lauw water op ½ kilo meelmengsel toe. Verder het brood maken volgens een gewoon broodrecept.
Dodonaeus Cruijdeboeck deel 6 capitel 65, bladzijde 795-796
Naem
[796] 1 Die Eyckenboom wordt gheheeten in Griecx Drys/ In Latijn Quercus/ In Hoochduytsch Eichbaum/ In Franchois Chesne.
2 Die vrucht wordt ghenaemt in Griecx Balanos/ In Latijn Glans/ In Hoochduytsch ein Eichel/ Hier te lande een Eeckel/ In Franchois ung Gland.
3 Dat ront Appelken dat op die bladeren groeyet es ghenaemt in Griecx Cecis/ In Latijn Galla/ In Hoochduytsch Eichopffel/ und Galopffel/ Hier te lande Eycken appel/ ende Galnoten/ In Franchois Noix de galle.
4 Die scaelkens daer die Eeckelen in hanghen worden gheheeten in Latijn Calices glandium/ In die Apoteke Cupulae glandium.
Natuere
Die bladeren ende scorssen van den Eycken/ ende die scaelkens van den Eeckelen sijn verdrooghende tot in den derden graedt ende tsamen treckende. Ende van ghelijcke natuere sijn oock schier die Eeckelen/ maer meer werm ende min tsamen treckende.
Die Galnoten sijn cout ende drooghe tot in den derden graedt/ ende seer tsamen treckende.
Cracht ende werckinghe
A Die bladeren scorssen ende scaelkens van den Eycken ende Eeckelen stelpen ende ghenesen dat bloetspouwen/ bloetpissen/ ende alle bloetganck/ ende dijsghelijcx oock dat root melizoe ende die loop des buycx in water oft rooden wijn ghesoden ende ghedroncken.
B Die bladeren van Eycken cleyn ghestooten ghenesen ende heylen die versche wonden ende stelpen dat bloeyen der selver daer op gheleyt.
C Die scorssen van den Eycken ghepoedert es goet tseghen die wormen van den kinderen/ ende tseghen den loop des buycx ende overvloedighe camerganck.
D Die scaelkens van den Eeckelen ende scorssen van den boomen/ sijn oock goet vermenght in alle medecijnen/ salven/ olien/ plaesteren/ die goet sijn om te stelpen eenighe vloet ende loop van bloede oft van andere humoren.
2
E Die Eeckelen sijn schier den bladeren ende scorssen van crachten ghelijck/ nochtans niet soo seer stoppende/ sy doen water maken/ ende wederstaen alle fenijn ende vergiftheyt/ ende sijn sonderlinghe goet tot die beten ende steken van die fenijnnighe ghedierten in melck ghesoden ende ghedroncken.
F Eeckelen cleyn ghestooten sijn oock goet gheleyt op die versche heete gheswillen/ ende als sy met ghesouten verckens smout vermenght sijn/ zoo ghenesen sy die quade voortsetende sweeringhen ende ulceratien.
3
G Die Galnoten stoppen oock seer ende sijn goet tot alle bloetganck/ ende tot die loop des buycx in alder manieren/ het sy van binnen inghegheven/ oft in eenighe olien salven plaesteren vermenght/ ende van buyten ghebruyckt.
H Galnoten sijn oock goet tot die vochticheyt ende gheswil van dat tantvleesch/ ende tot alle swillinghen van den amandelen ende keele/ ende dijsghelijcx oock tot die puysten van den mont.
I Item Galnoten stelpen den vloet van den vrouwen ende doen die moeder die gesoncken es in huer plaetse keeren/ alsmen in dwater sidt daer sy in ghesoden sijn.
K Galnoten met azijn oft water gheweyckt maken dat hayr swert/ ende doen dat overvloedich vleesch verdwijnen/ daer mede bestreken.
L Galnoten ghebrant ende met azijn oft wijn gheblust/ stoppen alle vloet ende loop van den bloede.