Journal/Magazine Articles
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This collection contains original research articles, review articles and case reports published in local and international peer reviewed journals by the staff members of the Faculty of Medicine
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Item A Pilot study on palmyrah pinattu (dried fruit pulp) as an anti-diabetic food component(International Formulae Group (IFG), 2007) Uluwaduge, D.I.; Perera, A.N.S.; Jansz, E.R.; Thabrew, M.I.The fruit pulp of palmyrah (Borassus flabellifer L.) has been shown to inhibit intestinal glucose uptake in mice, the active principle being a steroidal saponin, flabelliferin-II which inhibits intestinal ATPase in mice at 5x 10"5M level. Palmyrah fruit pulp (PFP) is widely used to manufacture many food products including dried PFP (pinattu), which has been consumed in North-East Sri Lanka for centuries. The present study was carried out to investigate whether PFP in the form of pinattu could reduce serum glucose levels of mild diabetic (Type-II) patients who were not on a drug regimen with a view to developing pinattu as an anti-diabetic food component. Patients (newly diagnosed, Type-11, mild diabetic patients) attending the diabetic clinic at the Family Practice Centre, University of Sri Jayewardenepura, Sri Lanka, were subjected to a glucose challenge (75 g/50 kg BW) after a 10 hour overnight fast and the blood glucose levels determined. On subsequent visits of each patient (3 days after the first visit) blood glucose was determined after administration of PFP in the form of pinattu (6 g/50 kg BW) or fibre (4 g/50 kg BW) extracted from PFP prior to the glucose challenge. The methodology employed was the cross over method where each patient was its own control. In all mild diabetic patients treated with pinattu, there was a significant reduction (p< 0.01, by 15-48%) in blood glucose concentration after a glucose challenge. Therefore the results of the present study suggest that pinattu (dried PFP) could be used as an anti-hyperglycemic agent.Item Possible interaction of herbal tea and carbamazepine(De Gruyter, 2003) Thabrew, M.I.; Munasinghe, T.M.J.; Chackrewarthy, S.; Senarath, S.A study was conducted using Wistar rats to determine the effect of concurrent administration of a herbal tea prepared from dried flowers of Cassia auriculata and carbamazepine on (a) blood levels of the prescription drug and (b) changes in toxicity (as assessed by changes in hematological parameters, liver and kidney function, and histology of major body organs) that may occur due to drug interaction. Results demonstrate that in rats receiving the herbal tea and carbamazepine, the blood levels of the prescription drug were significantly enhanced by 47.1% (p <0.04) when compared with the levels in animals receiving only carbamazepine, with no apparent changes in toxicity. Concurrent ingestion of the herbal tea prepared from Cassia auriculata flowers with carbamazepine may therefore influence the bioavailability of the prescribed drug and hence its therapeutic potential.Item Oral hypoglygaemic activity of Ipomea aquatica in streptozotocin induced diabetic wistar rats and type II diabetics(Wiley, 2003) Malalavidhane, T.S.; Wickremasinghe, S.M.D.N.; Perera, M.S.A.; Jansz, E.R.Ipomoea aquatica Forsk is a common green leafy vegetable consumed in many parts of the world. The present study was designed to investigate theoral hypoglycaemic activity of Ipomea aquatica in streptozotocin induced diabetic Wistar rats, and Type II diabetic patients. Experimental diabetes was induced with streptozotocin in Wistar rats. The rats were then divided into test and control groups. In addition to the standard feed given to both groups the test was fed with the shredded leaves of Ipomoea aquatica (3.4 g/kg) for one week. Type II diabetic patients were subjected to a glucose challenge before and after a single dose of blended I. aquatica. Patients acted as their own controls. The results revealed that consumption of the shredded, fresh, edible portion of I. aquatica for one week, effectively reduced the fasting blood sugar level of streptozotocin-induced diabetic rats (p = 0.01). When subjected to a glucose challenge, the Type II diabetic subjects showed a significant reduction (p = 0.001) in the serum glucose concentration 2 h after the glucose load. However, it was not significantly reduced at 1 h (p < 0.09) post glucose load. There was a 29.4% decrease in the serum glucose concentration of the diabetic patients when treated with the plant extract.Item Protection against diethylnitrosamine induced hepatocarcinogenecity by an indigenous herbal remedy comprised of Nigella sativa, Hemidesmus indicus and Simlax glabra: a preliminary study(Medknow Publications, 2003) Iddamaldeniya, S.S.; Wickremasinghe, S.M.D.N.; Thabrew, M.I.; Ranatunge, N.; Tammitiyagodage, M.G.BBACKGROUND: A decoction comprised of Nigella sativa seeds, Hemidesmus indicus root and Smilax glabra rhizome is used to treat cancer patients in Sri Lanka. However, the anti-carcinogenic properties of this decoction have not been experimentally confirmed. The purpose of this study was to determine whether the above decoction could protect against chemically induce hepatocarcinogenesis. METHODS: The effects of this decoction on diethylnitrosamine (DEN) induced hepatocarcinogenesis were examined in male Wistar rats using the medium term bioassay system of Ito, based on a 2-step model of hepatocarcinogenesis. Rats were randomly divided into 6 groups of 10 each. Groups 1 to 4 were injected with DEN (200 mg/kg) to initiate carcinogenesis. Twenty-four hours later groups 1 and 2 were administered the decoction at 4 g/kg body weight/day (dose 1) and 6 g/kg body weight/day (dose 2), respectively. Group 3 and group 4 were given distilled water instead of the decoction and a suspension of garlic powder (20 g/kg body weight/day) in distilled water (positive control), respectively. Group 5 and 6 were injected with normal saline and twenty-four hours later group 5 was given distilled water (normal control) while group 6 was given decoction dose 2 (decoction control). Oral feeding continued for two weeks after which all rats were subjected to 2/3 partial hepatectomy to promote carcinogenesis. Oral feeding continued for eight more weeks. At the end of the 10th week, rats were sacrificed and samples of livers taken for immunohistochemical studies. Carcinogenic potential was scored by comparing the number, area and staining intensity of glutathione S-transferase placental form (GST-P) positive foci and the number of cells/cm2 of the positive foci in the livers of the six groups of rats. RESULTS: The number and area of DEN-mediated GST-P positive foci, number of cells/cm2 of foci and staining intensity of the foci were significantly (P > 0.001) reduced by the decoction and garlic in the order dose 2 = garlic >dose 1. CONCLUSION: Overall results indicate that the decoction comprised of N. sativa, S. glabra and H. indicus has the potential to protect rat liver against DEN induced hepatocarcinogenesissItem Diuretic activity of leaf and stem decoctions of Anisomeles indica(2003) Dharmasiri, M.G.; Ratnasooriya, W.D.; Thabrew, M.I.Anisomeles indica (Lamiaceae) is a wild perennial herb growing in South and South East Asia. A decoction of leaves and stems of this plant is said to be diuretic but this point has not been verified in a controlled scientific investigation. The aim of the study was to scientifically investigate the diuretic activity of the decoctions of leaves and stems of both preflowering (E1) and flowering (E2) plants. Rats were used for experiments. The results showed that A. indica has powerful diurecti action and justify the use of the plant in traditional medicine in Sri Lanka. It is concluded that only the preflowering plants possessed marked diuretic activity. The selection of proper stage of the plant is vital for the induction of diuresis.Item Water extracts of leaves and stems of pre-flowering but not flowering plants possess analgesic and antihyperalgesic activities in rat(Informa Healthcare, 2003) Dharmasiri, M.G.; Ratnasooriya, W.D.; Thabrew, M.I.According to Sri Lankan traditional medicine, a decoction made from stems and leaves of Anisomeles indica Kuntze (Lamiaceae) possesses analgesic activity. However, the validity of this claim has not been scientifically tested. The aim of this study was to investigate analgesic and antihyperalgesic activities of this plant using a water extract made from the leaves and stems. The water extracts were made from leaves and stems of both preflowering (E1) and flowering plants (E2). E1 showed a dose-dependent analgesic effect up to 6 h of treatment when tested in rats using the hot plate and the tail flick techniques. Further, the analgesic effect of E1 was not accompanied by toxic effects. This effect was neither gender dependent nor dependent on the stage of the estrous cycle. E1 also showed a dose-dependent antihyperalgesic activity in the hot plate test. In contrast, E2 did not show any analgesic effect (500 mg/kg). The analgesic effect produced by E1 was not abolished by naloxone. E1 dose-dependently retarded the amplitude of the spontaneous contractions of isolated dioestrous rat uterus. Further, E1 induced a dosedependent plasma membrane stabilisation effect on rat erythrocytes. Collectively, these observations suggest that the analgesic and antihyperalgesic effects of E1 are mediated from inhibition of COX-1, thus impairing the synthesis of prostaglandins. A change in chemical contents that accompanies flowering could be one possible reason for the inability of E2 to demonstrate analgesic effect.Item In-vitro studies on the immunomodulatory effects of extracts of Osbeckia aspera(Elsevier, 2001) Nicholl, D.S.; Daniels, H.M.; Thabrew, M.I.; Grayer, R.J.; Simmonds, M.S.J.; Hughes, R.S.Ayruvedic medical practitioners in Sri Lanka use aqueous extracts of the mature leaves of Osbeckia aspera to treat liver disease. The extract has been shown to have hepatoprotective effects in vitro and in vivo, and to have inhibitory effects on the complement system and on in vitro phagocytosis by polymorphonuclear cells. The aim of this study was to investigate the effect of an aqueous extract of Osbeckia on lymphocyte proliferation stimulated by mitogens and antigen. In control peripheral blood mononuclear cells (PBMC), high concentrations of the Osbeckia extract were inhibitory to proliferation stimulated by phytohaemagglutinin (PHA) and tuberculin purified protein derivative (PPD). On stimulation by phorbol myristate acetate and ionomycin (PMA+I) the extract showed stimulation of proliferation at low concentrations (<10 microg/ml) with inhibition at higher concentrations. A similar inhibitory pattern on mitogen/antigen stimulation was seen with PBMC from patients with chronic hepatitis C virus (HCV) infection. These results suggest that the inhibitory agent(s) in the aqueous extract of Osbeckia may have an effect on antigen-presenting cell function. The combined hepatoprotective and immunosuppressive effects of the extract are more likely to be beneficial in acute hepatitis rather than chronic hepatitis viral infection.Item A Comparative study of the beneficial effects of Osbeckia octandra and Osbeckia aspera in liver dysfunction in rats(University of Colombo, 1999) Thabrew, M.I.; Jayathilake, K.A.P.W.A study was conducted to compare the protective effects of aqueous extracts of Osbeckia octandra and Osbeckia aspera against carbon tetrachloride (CCl4)-mediated liver damage in Sprague Dawley rats by assessing their ability to protect livers against the toxin-mediated alterations in the liver histopathology and the serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and alkaline phosphatase. Within 24 h of administering a sub-lethal dose (0.2 ml/l00 g, i.p.) of CCI4 to rats, the ALT, AST and alkaline phosphatase activities were found to be 380.8 percent, 101.4 percent and 222.2 percent higher respectively, than the corresponding base values in control animals untreated with the toxin. By pre-treatment of rats for 7 days with an aqueous extract of either the O.octandra or O.aspera, the CCI4-mediated changes in the serum enzyme activities could be considerably reduced. Thus, in rats pre-treated with an extract of O.octandra or O.aspera, the CCI4 was able to cause only a 33.7 percent or 27.6 percent increase in ALT activity, a 9.2 percent or 4.2 percent increase in AST activity and a 16.6 percent or 17.6 percent increase in alkaline phosphatase activity respectively, above the corresponding values in control animals. In post-treatment experiments also when serum enzyme levels in rats treated only with CCI4 and left to recover for 4 days were compared with those in rats treated orally for 3 days with either plant extract starting 24 h after the toxin administration, it was found that both plant extracts were able to protect the livers against the toxin mediated changes, to a similar extent. Thus, on the 4th day after CCI4 treatment, the serum ALT, AST and alkaline phosphatase activities were still 162 percent,76.5 percent and 90.1 percent respectively, higher than the corresponding values in control animals. In the O.octandra and O.aspera post-treated groups, the corresponding increases in the activities of ALT, AST and alkaline phosphatase respectively, were only 53.8 percent and 35.5 percent for ALT, 39.2 percent and 41.6 percent for AST and 29 percent and 18.6 percent for alkaline phosphatase. In both the pre-treatment and the post-treatment experiments it was also observed that, the CCl4 -mediated alterations in liver histopathology could be prevented to a similar extent by both plant extracts. The overall results indicate that aqueous extracts of the leaves of both O.octandra and O.aspera possess very similar hepatoprotective abilities, thus rationalizing the use of both these plants in traditional medicine for the treatment of liver disease.Item Cytoprotective effect of Osbeckia aspera against oxidative damage to HepG2 cells(Lippincott Williams and Wilkins, 1998) Thabrew, M.I.Aqueous extracts of the leaves of plants of the Osbeckia family are used in Sri Lanka for treatment of liver disease. The extract contains antioxidant compounds and in vitro experiments were performed to determine the antioxidant effects of an extract of Osbeckia aspera. The plant extract significantly protected HepG2 cells against the peroxidating effects of cumene hydroperoxide and tert-butyl hydroperoxide. The protection against cell damage from both hepatotoxic compounds was similar to that of silymarin, but not asgreat as that shown by (+)-catechin. Antioxidant compounds in Osbeckia aspera may be an important mechanism responsible for the in vivo hepatoprotective activity of this plant.Item Screening of hepatoprotective plant components using a HepG2 cell cytotoxicity assay(Wiley, 1997) Thabrew, M.I.; Hughes, R.D.; Mcfarlane, I.G.Identification of the active components of plants with hepatoprotective properties requires screening of large numbers of samples during fractionation and purification. A screening assay has been developed based on protection of human liver-derived HepG2 cells against toxic damage. Various hepatotoxins were incubated with HepG2 cells in 96-well microtitre plates (30,000 cells well-1) for 1 h and viability was determined by metabolism of the tetrazolium dye 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxy phenyl)-2-(4-sulphophenyl)-2H-tetrazolium (MTS). Bromobenzene (10 mM) and 2,6-dimethyl-N-acetyl-p-quinoneimine (2,6-diMeNAPQI, 200 mM) had greater toxic effects than tert-butyl hydroperoxide (1.8 mM) or galactosamine (10 mM), reducing mean viability to 44.6 +/- 1.2% (s.e.m.) and 56.1 +/- 2.1% of control, respectively. Protection against toxic damage by these agents was tested using a crude extract of a known hepatoprotective Sri Lankan plant, Osbeckia aspera, and two pure established hepatoprotective plant compounds, (+)-catechin and silymarin (1 mg mL-1). Viability was significantly improved by Osbeckia (by 37.7 +/- 2.4%, P < 0.05, and 36.5 +/- 2.1%, P < 0.05, for bromobenzene and 2,6-diMeNAPQI toxicity, respectively). Comparable values for (+)-catechin were 68.6 +/- 2.9% and 63.5 +/- 1.1%, and for silymarin 24.9 +/- 1.4% and 25.0 +/- 1.6%. This rapid and reproducible assay should prove useful for the isolation and identification of active hepatoprotective compounds in crude plant extracts.
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