The gastroprotective efficacy of two extracts of St. John's wort (dry extract standardised to 0.3% of hypericin and ethanolic extract containing hypericin 2.5 mg/100 cm3) was studied in male Wistar rats (200-250 g) by using a model of ethanol-induced stress ulcer. The both extracts were given per os 60 minutes before absolute ethanol (1ml/rat) in doses of 200-800 mg/kg (dry extract) and 0.5-2 ml/kg (ethanolic extract). Intensity of gastric lesions was estimated 60 minutes after administration of ethanol.
Results showed that both tested extracts of St. John's wort produced dose-dependent and significant gastroprotective effect implying their potential use as antiulcer agents.
St. John's wort has been used in herbal healing for more than 2000 years. It is one of the most popular herbal remedies in folk medicine that is used in the treatment of various conditions ranging from insomnia to haemorrhoids. Its external use for relieving inflammation and promoting wound healing is particularly valued. Today St. John's wort is widely used as an effective nerve tonic, useful in cases of anxiety, depression and unrest (1,2,3).
The aim of this study was to investigate antiulcer potency of St. John's wort extracts by using a model of ethanol-induced stress ulcer in rats.
Two extracts of St. John's wort were used: dry extract standardised to 0.3% of hypericin (Institute for Medicinal Plant Research "Dr Josif Pančić", Belgrade, Yugoslavia) and commercially available ethanolic extract containing hypericin 2.5 mg/100 cm3 (Biosenzalâ drops, "Zdravlje", Leskovac, Yugoslavia). The gastric lesions had been induced by absolute ethanol (1 ml/rat) given to 24hr-starved male Wistar rats (200-250 g) through the gastric tube. In order to study the gastroprotective efficacy of above-mentioned extracts they were administered per os 60 minutes before ethanol. In this purpose the dry extract was suspended in distilled water and given in doses of 200, 400, 600 and 800 mg/kg, while the ethanolic extract was given directly from original flask in doses of 0.5, 1.0 and 2.0 ml/kg. The control animals were given saline (1 ml/kg per os) at the same time before ethanol. Each experimental group was consisted of 8 animals.
Sixty minutes after ethanol the animals were sacrificed, their stomachs were opened and intensity of gastric lesions was estimated by using a modified scale of Szabo et al. (4):
0 - no lesions; 0.5 - mild hyperaemia; 1 - stronger hyperaemia or < 10 small petechiae; 1.5 - > 10 petechiae; 2 - petechiae and one erosion < 4 mm; 2.5 - two and more erosions < 4 mm; 3 - erosions > 4 mm.
Two independent investigators who did not know anything about the treatment used always performed the estimation of gastric lesion intensity.
Statistical analysis was performed by using Mann-Whitney U-test. Differences where p < 0.05 were considered statistically significant.
Results showed that both tested extracts of St. John's wort produced dose-dependent and significant gastroprotective effect (Table 1).
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| Saline (control)1 |
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| Biosenzalâ drops1 |
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| Dry extract2 |
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Having in mind the quantity of applied extracts in relation to the content of hypericin declared by manufacturers it seems that the commercially available ethanolic extract, known under trade name Biosenzalâ, has a stronger antiulcer potential than that of the dry extract. This might be the consequence of better gastrointestinal resorption of active principles from the extract applied in the form of BIOSENZALâ drops where ethanol is used as the solvent. The dry extract was not dissolved, but just suspended in distilled water, and this is most probably the reason why the higher dose of the extract (calculated to the content of hypericin) was given for achieving the gastroprotective effect comparable to that of BIOSENZALâ drops.
St. John's wort contains a number of active principles of which are most important: naphthodiantrones (hypericin, pseudohypericin, protohypericin, protopseudohypericin, cyclopseudohypericin), hyperforin, flavonoids and flavonoid derivatives (e.g. rutin and hyperin), xanthone derivatives, a volatile oil and tannins (1, 3). Having in mind known facts about pathophysiological mechanisms included in the ethanol-induced stress ulcer (free-radical production, vasoconstriction, ischaemia, decrease of prostaglandin synthesis, decrease of concentration of nonprotein and protein sulfhydryls, etc.) (4), it might be supposed that due to a strong antioxidant and cytoprotective action flavonoids could be considered as the key carriers of gastroprotective efficacy of the extracts of St. John's wort (5). Tannins also may exert some ulcer-healing effects through their astringent and protein-precipitating action. However, which active principles of St. John's wort are really responsible for observed effects and the exact mechanism of their gastroprotective action just should be established in the future.
It could be concluded that both tested extracts of St. John's wort produced dose-dependent and significant gastroprotective effect implying their potential use as antiulcer agents.
Tyler V.E. (1993): St. John's wort, In: The honest herbal, 3rd ed., Pharmaceutical Products Press, New York-Norwood, 275-276.
Tyler V.E. (1994): Herbs of choice, Pharmaceutical Products Press, New York-Norwood, 122-124.
Schulz V., Hänsel R., Tyler V.E. (1998): Rational phytotherapy, Springer, Berlin-Heilderberg, 50-65.
Szabo S., Trier J.S., Frankel P.W. (1981): Sulfhydryl compounds may mediated gastric cytoprotection, Science 214, 200-202.
Mimica-Dukić N. (1997): In vivo and in vitro study of antioxidant activity of plant extracts, Arh. Farm. 47, 475-493 (in Serbian, Abstract in English).