A potential source for new lipoxygenase inhibitors is undoubtedly provided by the abundance of medicinal plants used in traditional medicine. As part of screening programme for biologically active plants, 20 extracts of different parts of 10 Malaysian medicinal plants belonging to four families were evaluated for their inhibitory activity on soybean 15-lipoxygenase (15-sLo). The leaves of Peronema canescens Jack. (Verbenaceae) were shown to be the most potent inhibitor with an IC ₅₀ value of 25.64 μg/ml. While the extracts of P. canescens stem and Stereospermum fibricatum DC. (Bignonaceae) leaves were found to possess profound inhibitory activity with IC ₅₀ values of 33.65 and 39.41 μg/ml, respectively. The methanol extracts obtained from Stenolobium stans (L.) D. Don (Bignonaceae) leaves and stems, Piper ribesioides Wall. (Piperaceae) stems and S. fibricatum stems were moderately active with IC ₅₀ values ranging from 40 to 60 μg/ml. While the remaining samples showed low lipoxygenase inhibitory activity at concentration of 100 μg/ml.

The aim of this study was to evaluate the diuretic potential of Sri Lankan black tea (Camellia sinensis L.). This was assessed in rats using high grown Dust grade No: 1 tea, which is consumed widely by the tea drinkers worldwide. Different doses of hot black tea brew (BTB) (84, 167, 501 or 1336 mg/ml respectively equivalent to 1.5, 3, 9 and 24 cups) were made and orally administered to previously starved (24 h) but subsequently hydrated (with 15 ml of isotonic saline) rats and their urinary output was monitored cumulatively at hourly intervals for 6h. The reference drug used was frusemide (13 mg/kg). The results showed that BTB induced significant (P < 0.05), mild to moderate and dose- dependent diuresis (starting from 167 mg/ml). This diuretic activity had a fairly rapid onset (within 2 h) and relatively short duration of action (3 h). BTB also significantly (P < 0.05) increased the overall urinary frequency. Further, the diuretic activity of BTB was less potent to frusemide (by 45%). Decaffeination of black tea almost completely abolished the diuresis. The diuresis of the BTB was solely due to increased (by 55 %) urinary Na ⁺ excretion (with no urinary K ⁺ loss). Further, the chronic daily administration of the BTB did not develop tolerance or induce toxicity (general, renal and hepatic). It is concluded that BTB made from Sri Lankan high grown Dust grade No :1 tea has safe, mild to moderate diuretic activity with rapid onset and relatively short duration of action. Further, this study supports the claim made by Sri Lankan indigenous physicians that it is a diuretic.

This study examined the anti-inflammatory potential of Sri Lankan black tea (Camellia sinensis L. Family: Theaceae) using both acute (carrageenan-induced paw oedema) and chronic (formaldehyde-induced paw oedema and cotton pellet granuloma test) rat inflammatory models. Three dose of black tea brew (BTB) [84 mg/ml, equivalent to 1.5 cups; 168 mg/ml, equivalent to 3 cups; and 501 mg/ml, equivalent to 9 cups] were made using high grown unblend Dust grade No: 1 black tea samples and was orally administed to rats (n = 6-9/ dose/ test). The results showed that Sri Lankan BTB possesses marked and significant (P < 0.05) oral anti-inflammatory activity against both acute and chronic inflammation. This anti-inflammatory activity was dose-dependent in the carrageenan-induced paw oedema test and cotton pellet granuloma test. Further, in the carrageenan paw oedema model, the anti-inflammatory activity of BTB was almost identical to green tea brew of both Chinese and Japanese types. Further, the BTB had significant antihistamine activity (in terms of wheal test) phagocytic cell migration inhibitory activity (in terms carrageenan-induced leucocyte peritoneal infiltration test), nitric oxide production inhibitory activity, antioxidant activity (DPPH method) and prostaglandin synthesis inhibition activity (in terms of rat enteropooling test). It is concluded that Sri Lankan black tea has marked anti-inflammatory potential against both acute and chronic inflammation which is mediated via multiple mechanisms.

The composition of the essential oil obtained from the dried flowering aerial parts of Artemisia annua L. (Compositae) was analysed by GC and GC/MS. Thirty-two components were identified in the essential oil of A. annua L. with campher (48.00%), 1,8-cineole (9.39%), camphene (6.98%) and spathulenol (4.89%) as major components. The essential oil was evaluated for antibacterial and antifungal activities . The activity was more pronounced against fungal organisms than against Gram-positive and Gram-negative bacteria.

The present study was aimed at investigating the effect of the various fractions of hydromethanol extract of the leaves of Coccinia grandis (Cucurbitaceae) against ethanol-induced cerebral oxidative stress in rats. The leaves of this species is used in traditional medicine for treating jaundice, bronchitis, skin eruptions, burns, rheumatism, syphilis, gonorrhoea, etc. Cerebral oxidative stress was induced in rats by the administration of 20% ethanol (5 ml/100 g b.w.) for 28 days. The pet-ether (PEF), chloroform (CF), ethylacetate (EAF) and residual (RF) fractions at a dose of 200 mg/kg b.w. were simultaneously administered with ethanol orally for 28 days. Vitamin E at a dose of 100 mg/kg orally was used as the standard. Administration of ethanol resulted in a significant increase in the activities of serum transaminases, alkaline phosphatase, uric acid and lipid levels. In addition, there was a significant elevation in the levels of malondialdehyde and lipid hydroperoxides and a reduction in the activities of enzymatic and non-enzymatic antioxidants in the brain. Simultaneous administration of the fractions prevented the enzymatic leakage and the rise in uric acid and lipid levels. All the fractions (except the residual fraction) prevented the peroxidative damage caused by ethanol, which is evidenced from the improved antioxidant potential. Further, histopathological examination of the brain tissue revealed that the fractions offered significant protection against ethanol toxicity. Among the fractions tested, the chloroform fraction exhibited appreciable antioxidant property, which was almost comparable with the standard Vitamin E. These results suggest that the leaves of Coccinia grandis exhibit significant antioxidant activity in ethanol-treated rats.