Asmawati, Abd Rahim (2012) Antidiabetic activity of leptospermum flavescens in alloxan - induced diabetic rats / Asmawati Abd Rahim. Masters thesis, University of Malaya.
Abstract
The phytochemical analysis was carried out using hexane, chloroform and water extraction of the leaves and stems of L. flavescens. The detection methods used were thin layer chromatography (TLC), high performance liquid chromatography (HPLC) and liquid chromatography mass spectrometry combined with mass spectrometry (LCMS/MS). The TLC of all extracts using three solvents screened for flavonoids, alkaloids, saponins, terpenoids and essential oils. The HPLC have been identified quercetin, gallic acid and tannic acid using authentic standards. The HPLC chromatograms were poorly separated and not very convincing to confirm the three compounds. However the liquid chromatography mass spectrometry combined with mass spectrometry (LCMS/MS) has successfully identified 13 metabolites. The leaves of water crude extracts showed the highest total phenols have 163.61 GAE mg/g dry mass. While the leaves of hexane crude extracts showed the highest total flavonoids have 145.55 QE mg/g dry mass. The enzymatic bioassay system results showed the highest inhibition of GP is leaves of water extracted 86.56 %, hexane extract of leaves gives 83.58 % GP inhibition, chloroform of leaves extract gives 81.59 % GP inhibition. While the stems of hexane crude extract gives 64.67 % GP inhibition, stems of chloroform extract gives 56.71% and stems of water extract gives 44.77 %. These indicated that the GP inhibitions are due to the presence of phenols and flavonoids. Determination of LC50 value of the crude extract from brine shrimp lethality assay (BSLA) showed the highest LC50 value was chloroform extraction of stems 609.14 μg/ml, while the lowest LC50 value was chloroform extract from leaves 21.54 μg/ml. The effect of L. flavescens in alloxan induced diabetic rats such determination the oral glucose tolerance test (OGTT) in normal rats showed the leaves and stems water extract at doses of 0.2 g/kg and 0.5 g/kg produced a maximum fall at 60 minutes after glucose administration, the determination acute toxicity of L. flavescens in normal rats showed the water extract of L. flavescens did not show any mortality and none of the treated rats showed any visible symptoms of toxicity up to a doses of 0.5 g/kg. The effects of administration of L. flavescens extracts in diabetic rats by measuring fasting blood glucose level (FBGL) of leaves and stems of water extract at 0.2 g/kg and 0.5 g/kg significantly decreased the FBGL of the diabetic rats from an initial level and became to normal by 20th day, the effect on serum lipid profile and liver function study showed the administration of the leaves and stems (0.2 g/kg and 0.5 g/kg) of L. flavescens water extract and Glipizide (5 mg/kg) tended to bring significantly toward normal values. The changes in body weight (BW) were no significant difference between the L. flavescens water extract and Glipizide in diabetic rats treated. These showed that the L. flavescens water extract can control in the loss of body weight as compared to the diabetic control group that loss of body weight.
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