Browsing by Author "McFarlane, I.G."

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    Antioxidant activity of Obseckia aspera
    (1998) Thabrew, M.I.; Hughes, R.D.; McFarlane, I.G.
    Plants of the Osbeckia family have been shown to possess hepatoprotective properties, which could be due to the presence of antioxidant compounds. The plant extract was shown to inhibit significantly in a dose-dependent manner, the activities of the DPPH(1,1-diphenyl-2-picrylhydrazyl) free radical (EC50 of 27.5 g/mL), xanthine oxidase (EC50 of 1.16 mg/mL) and demonstrate a scavenging effect on hydroxyl radical mediated damage to deoxyribose (EC50 of 140 g/mL). The plant extract possessed some prooxidant activity from the effect on bleomycin-induced DNA damage, but this was less than that shown by comparable concentrations of (+)-catechin or silymarin
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    Protection against galactosamine and test-butyl hydroperoxide induced hepatocyte damage by Melothria maderaspatana extract
    (Wiley, 1995) Thabrew, M.I.; Gove, C.D.; Hughes, R.D.; McFarlane, I.G.; Williams, R.
    The aqueous extract of Melothria maderaspatana is used by traditional medical practitioners to treat jaundice in man. The effect of Melothria maderaspatana extract on damage induced in freshly isolated rat hepatocytes by D-galactosamine and tert-butyl hydroperoxide (TBH) has been investigated. On incubation of hepatocytes with galactosamine or TBH in the presence of the plant extract, a significant dose-dependent protection against hepatocyte damage was observed, with maximum protection at a concentration of 500 g/mL. At this concentration the galactosamine-induced release of lactate dehydrogenase (LDH) and aspartate amino-transferase (AST) were reduced by 40.7 percent + or - 4.2 percent and 37.7 percent + or - 6.1 percent respectively, compared with control incubations. The TBH-induced lipid peroxidation (estimated from malondialdehyde production) was decreased by 26.0 + or - 3.7 percent together with a 38.4 percent + or - 4.4 percent and 40.8 + or - 7.6 percent reduction in the release of cellular LDH and AST respectively into the incubation medium. On post-treatment with the plant extract the protective activity was found to decrease with increase in time of exposure of the cells to either of the toxins. The direct protective effects of Melothria extract on hepatocytes support the use of this plant as a herbal remedy.
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    Protective effects of Osbeckia octandra against galactosamine and tert-butyl hydroperoxide induced hepatocyte damage
    (Elsevier, 1995) Thabrew, M.I.; Gove, C.D.; Hughes, R.D.; McFarlane, I.G.; Williams, R.
    Ayurvedic and other 'traditional' medical practitioners in Sri Lanka use the mature leaves of the plant Osbeckia octandra for its hepatoprotective properties. In this study the effects of an aqueous extract of Osbeckia octandra against injury induced by D-galactosamine and tert-butyl hydroperoxide (TBH) were investigated in freshly isolated rat hepatocytes. The plant extract (500 micrograms/ml) significantly reduced the inhibition of protein synthesis (as assessed by the incorporation of 14C-leucine into protein) in hepatocytes incubated for 1 h with 10 mM galactosamine by a mean of 25.6 +/- 3.6% and decreased the release of cellular lactate dehydrogenase (LDH) and aspartate aminotransferase (AST) enzyme activities into the medium by 55.3% and 32.8%, respectively. With TBH, the plant extract decreased lipid peroxidation (estimated from malondialdehyde formation) by a mean of 29.9 +/- 1.1% together with a 46.8% and 54.7% decrease in the release of LDH and AST, respectively into the incubation medium. Significant protection was also obtained when the Osbeckia extract was added to the incubation medium up to 30 min after pre-exposure of the hepatocytes to either galactosamine or, to a lesser extent, TBH. The results support the use of Osbeckia as a hepatoprotective agent.
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    Protective effects of Osbeckia octandra against paracetamol-induced liver injury
    (Informa Healthcare, 1995) Thabrew, M.I.; Hughes, R.D.; Gove, C.D.; Portmann, B.; Williams, R.; McFarlane, I.G.
    Osbeckia octandra is a plant used in traditional medicine to treat jaundice and other liver disorders. In this study, the effects of Osbeckia leaf extract on paracetamol-induced liver injury were investigated both in vivo in mice and in rat hepatocytes in vitro. 2. Oral administration of Osbeckiaextract (330 mg/kg) at the same time as paracetamol (450 mg/kg) to mice, resulted in a significant protection (p < 0.05) against liver damage, as assessed by improvements in the blood Normotest (39.1 +/- 1.9 versus 46.3 +/- 2.0 s), total liver glutathione (730 +/- 39 versus 574 +/- 27 micrograms/250 mg liver), plasma aspartate aminotransferase level (916 +/- 225 versus 1965 +/- 291 iu/l), and liver histopathology at 24 h after paracetamol administration. 3. In experiments to assess the direct effects of Osbeckia extract, significant protection was also found in freshly isolated rat hepatocytes against damage induced by 185 microM 2,6-dimethyl N-acetyl p-quinoneimine (2,6-diMeNAPQI, an analogue of NAPQI, the toxic metabolite of paracetamol) in vitro. When Osbeckia extract (500 micrograms/ml) was added to the incubation medium at the same time as 2,6-diMeNAPQI significant changes in cell viability (78.4 +/- 3.3 versus 47.2 +/- 5.8% of control, p < 0.001), cell reduced glutathione (GSH) level (35.0 +/- 3.1 versus 23.8 +/- 1.5%, p = 0.009), and reduced release of lactate dehydrogenase (129.9 +/- 6.6 versus 224.6 +/- 12.1%, p < 0.001) were demonstrated after 1 h incubation as compared with 2,6-diMeNAPQI alone. 4. Significant protection was still obtained against 2,6-diMeNAPQI in vitro when addition of Osbeckia extract was delayed by 20 min. These results indicate that Osbeckia extract can protect against paracetamol-induced liver injury