RESUMO
OBJECTIVE: Bay leaf, one of the plants in Indonesia that has been shown to have activities to reduce cholesterol in the blood. HMG-CoA Reductase inhibition is one of many mechanisms in lowering the level of cholesterol in the blood. Here, we reported the inhibitory activity of HMG-CoA Reductase of bay leaves ethanol extracts that we suspected to be the mechanism of action of bay leaves in reducing cholesterol in the blood. In this research we also investigated the correlation between the inhibitory activities, the total phenol content and antioxidant activities of bay leaves (Syzygium polianthum) ethanol extracts. METHODS: The inhibitory activity of HMG-CoA Reductase was determined kinetically at 340 nm using simvastatin as positive control. In vitro scavenging assays of 2,2-diphenyl-1-picrylhydrazyl (DPPH), ferric ion reducing antioxidant power (FRAP), and beta-carotene method were used to determine the antioxidant activities. The total phenolic content was determined by Folin-Ciocalteu's method. RESULTS: The IC50 of bay leaves ethanolic extract obtained by percolation and soxhlet extraction method towards HMG-CoA Reductase enzyme activity were 49.50 ± 0.700 µg/mL and 15.50 ± 0.707 µg/mL, respectively, while the IC50 of simvastatin was 0.00238 ± 0.00004 µg/mL. The antioxidant activity and total phenolic content of bay leaves ethanolic extract obtained by Soxhlet extraction method was higher compared to the percolation method (DPPH and beta-carotene assay results). The 3D linear analysis showed that there was a high correlation between the inhibition activities of HMG-CoA Reductase pattern of both extract types and the total phenol pattern and also the antioxidant pattern of these extracts. CONCLUSION: The result showed that the bay leaves ethanolic extract have a potent activity to reduce the cholesterol serum level by inhibition of HMG-CoA Reductase activity. The activity was due to the phenolic compounds in the extracts as well as the antioxidant activity of the extracts.
RESUMO
BACKGROUND: Our previous preclinical study showed that the extract mixture (EM) of Andrographis paniculata (Burm. f.) Wall. ex Nees (AP) and Syzygium polyanthum (Wight.) Walp (SP) leaves had antidiabetic effects and were beneficial on alloxan-induced diabetic rats. PURPOSE: The objectives of this study were to: 1) identify the phytochemical compounds present in aqueous extract of AP and SP and 2) examine the benefits of the EM of AP and SP leaves in lowering blood glucose in the presence of standard antidiabetic treatment using metformin in type 2 diabetic patients in Indonesian Traditional Medicine Polyclinic of Dr. Soetomo General Hospital in Surabaya. METHODS: Phytochemical analysis of aqueous leaf extract of AP and SP was performed using standard chemical tests, TLC, and GC-MS. Furthermore, a total of 54 subjects with T2DM participated in this study and were randomly assigned to either the intervention group supplemented with the extract mixture of AP and SP at a dose 900⯠mg/day for 8 weeks, or the control group which received placebo tablets in a randomized placebo-controlled double-blinded parallel clinical trial. Both groups received metformin at dose 1000⯠mg/day. Body weight, blood pressure, fasting blood glucose, postprandial glucose, haemoglobin A1c, triglycerides, total cholesterol, low density lipoprotein, high density lipoprotein, and markers of liver and kidney damage were measured. RESULTS: The results of phytochemical analysis showed that the glycosides, terpenoids, alkaloids, flavonoids, saponins, and tannins were found to be present in the extract mixture. GC-MS analyses of AP and SP showed the presence of 19 and 12 peaks, respectively. Methyl ester of 9-octadecenoic and eicosanoic acid were determined as the main constituents of both species. Moreover, the results of clinical study suggested that the extract mixture improved the decrease of fasting blood glucose and postprandial glucose, significantly lowered body mass index compared with the control group. The EM appeared beneficial for SGPT values and uric acid levels. CONCLUSION: Overall, the results of this study suggested the potential beneficial effects of the extract mixture for use as complementary medicine alongside conventional treatment of metformin. The extract mixture contained many highly potent compounds for treating T2DM and preventing short- and long-term risk complications of diabetes.
