Judul: Study on antihyperglycemic mechanism of extract mixture of piper crocatum leaves and cinnamomum burmannii bark as potential functional drink
Abstrak: Piper crocatum, one of Indonesia’s medicinal plants, has antihyperglycemic activity despite its bitter taste. Considering that Indonesia was the 4th largest country whose population suffered from diabetes mellitus with a prevalence of 8.6% of the total population in 2005, the necessity to increase the potency of red piper betel is of great importance. This can be done by producing it as functional drink. For this reason, this research aimed to determine : (1) the formulation of a mixture of water extract of P. crocatum leaves and C. burmannii bark which have antioxidative activities by measuring their superoxide dismutase and catalase enzyme, and anti-hyperglycemic activity in vitro by measuring their a-glucosidase activity; (2) the evaluation of sub acute toxicity study on the selected formula using male and female Sprague dawley rats; (3) the functional effect of the chosen formula, especially its anti-hyperglycemic activity in streptozotocin-induced diabetics rats. P. crocatum leaves and C. burmannii bark powder were boiled in water separately for 15 minutes, and filtered. The filtrate was used in the formulation of mixing water extract of P.crocatum leaves and C. burmannii bark in a ratio of (5:0); (5:1); (5:3); (5:5); and (0:5). Each of this formula was then added with stevia (sweeteners) of 0.67% (v/v). In the evaluation of the sub acute toxicity, the chosen formula was administered orally into 4 groups of Sprague dawley rats with different doses (0, 630, 1260, 1890 mg/kg bw) for 28 days. In anti-hyperglycemic activity study, streptozotocin induced diabetics rats (50 mg/kg bw) were administered orally by a dosage of (0; 630; 1260 and 1890 mg/kg bw) for 14 days. During the treatment period, blood glucose level was recorded at 5 day-intervals, and at the end of treatment the rats were killed by chemical anesthesia. The blood was taken for further analysis, such as blood serum glucose, blood serum lipid, insulin, and red blood cell SOD; and catalase activities were also studied. The results showed that the formula with the ratio (5:3) was the chosen formula with the following characteristic parameters: activity of SOD at 3.32 ± 0.08 U/ml, catalase activity 0.18 ± 0.02 U/ml, and a- glucosidase inhibitor activity 61.00 ± 2.55%, and total phenolic compounds 1067.65 ± 0.90 ppm. In the sub acute toxicity, there were no significant differences in the body weight, food intake, hematological analysis, blood chemistry analysis (glucose, cholesterol, triglycerides, creatinine, SGPT, and SGOT), organ weights, and histopathological analysis among the control groups and treated animals. In vivo anti-hyperglycemic activity showed that 14 days of daily treatment of 1260 mg/kg bw dose of functional drink significantly (p<0.05) reduced blood glucose level (51%), and increased the amount of ß cell, Langerhans island of pancreas organ, and red blood cell SOD activity. There was no significant (p<0.05) increase in blood serum insulin level and catalase activity. In addition, extract mixtures of the chosen formula could prevent blood serum lipid level of diabetic rats from increasing.
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Judul: Metabolomic Application in Identification α-Glucosidase Inhibitor from Vegetables and Spices
Abstrak: Diabetes mellitus is a degenerative disease with a high prevalence worldwide. Plant-based foods such as vegetables and spices were often reported to be able to reduce the risk of and even cure diabetes mellitus, especially type 2 (T2DM). Indonesia has many natural resources such as vegetables and spices that can be sources of antidiabetic foods. However, the antidiabetic activity of many vegetables and spices have not been evaluated. Besides, studies to observe the bioactive compounds responsible for the antidiabetic activity of vegetables and spices are still limited. One of the antidiabetic activities commonly studied from plant species is the α-glucosidase inhibition. Therefore, the objective of this study was to evaluate the potency of α-glucosidase inhibition of 11 vegetables and 4 spices commonly consumed in Indonesia and to identify their bioactive compound using a metabolomic approach. This study consisted of 3 stages: 1) Screening α-glucosidase inhibition activity of Indonesian vegetables and spices, (2) characterization of antioxidant compound from selected plant (obtained from the first stage) using UHPLC-HRMS and identification of its α-glucosidase inhibitor using NMR- and HPLC combined with UHPLC-HRMS metabolomics, and (3) verification of α-glucosidase inhibition activity of putative compounds (obtained from the second stage) through in silico analysis. The results of the first study showed that the highest antioxidant and α-glucosidase inhibition activity was found in leaves extract of Syzygium polyanthum followed by Pluchea indica with the values of the IC50 antioxidant activity being 2.46 and 4.34 μg/ml, respectively. The values of their IC50 of α-glucosidase inhibition were 11.76 and 12.17 μg/ml, respectively. Interestingly, the total phenolic content of these two samples was also higher than others with 25.37 and 37.99 μg GAE/mg extract, respectively. The 1H-NMR fingerprinting analysis showed that each sample had different spectral profile, especially at the aromatic region (chemical shift (δ) > 5.7). Further metabolite profiling on the 1H-NMR of S. polyanthum revealed the presence of gallic acid, syringic acid, and myricetin, whereas 5-O-caffeoylquinic acid, 4,5-di-O-caffeoylquinic acid methyl ester, and esculetin were found in the 1H-NMR of P. indica. Previous studies reported that all identified compounds had antidiabetic activity especially through α-glucosidase inhibition. Thus, those compounds might be associated with the α-glucosidase inhibition activity of S. polyanthum and P. Indica, which was investigated further in the next step. Based on the results of the first study, S. polyanthum leaves were chosen for the second stage. Dried leaves of S. polyanthum were fractionated using solvents with different polarity sequentially i.e. hexane, combination of hexane-acetone, acetone, combination of acetone-water and water to obtain 14 fractions. Analysis of antioxidant activity through the ability to reduce radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) indicated that at a tested concentration of 500 μg/ml, Fraction 9/F9 (obtained from acetone:water = 4:1) gave the highest antioxidant activity followed by Fraction 1/F1 (obtained from hexane 100%), Fraction 10/F10 (obtained from acetone:water = 3:2) and Fraction 3 (obtained from hexane:acetone = 4:1) with the values of 95.21, 94.82, 93.37 and 93.19%, respectively. The characterization of the UHPLC-HRMS chromatogram of F9 identified the presence of gallic acid, trans-aconitic acid, and myricetin, while only gallic acid and trans-aconitic acid were identified in
Keyword: α-glucosidase, antioxidant, docking, HPLC-UHPLC-HRMS, metabolomics, NMR, Syzygium polyanthum

Judul: Metrik Einstein (Anti-) Self-Dual Berdimensi Empat dengan Metode Cartan
Abstrak: Gravitational field equation can be formulated in differential forms (differential geometry), which describes gravity as a manifestation of the curvature of space-time. Curvature of space-time is characterized by a metric that satisfies the gravitational field equation. With differential forms it can be formulated the (anti-) self-dual Einstein equation, which is a modification of the Cartan structure in (anti-) self-dual basis. Calculation of (anti-) self-dual metric with (anti-) self-dual Einstein equation is simpler than the calculation using Christoffel symbols.
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