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Mitragyna speciosa Korth (kratom) is a tropical indigenous tree of Southeast Asia. It is commonly consumed by the people due to its various pharmacological properties. The leaves of this plant are traditionally used for the treatment of several diseases including pain, fever, cough, anxiety, depression, obesity, diarrhoea, wound healing, diabetes, hypertension as well as for the prevention of cancer and improvement of sexual performance. Phytochemical investigations have confirmed the presence of more than forty alkaloids along with the presence of other bioactive secondary metabolites. Among the alkaloids isolated, mitragynine and 7-hydroxymitragynine along with their derivatives have been widely evaluated and reported to possess various pharmacological effects. Hence, the aim of this review is to shed light on the traditional uses of kratom and the scientific studies to justify the folkloric claims and active principles responsible for the various medicinal effects associated with the leaves of this plant. This review highlights the potential benefits and toxicities associated with M. speciosa leaves along with the phytochemistry. Moreover, the existing gaps in the field of M. speciosa study have been identified along with the future directions to further avail the benefits of this plant species.

Fruit of salak (Salacca zalacca) is traditionally used and commercialized as an antidiabetic agent. However, the scientific evidence to prove this traditional use is lacking. This research was aimed to evaluate the metabolic changes of obese-diabetic (OBDC) rats treated with S. zalacca fruit extract using proton-nuclear magnetic resonance ( 1 H NMR)-based metabolomics approach. This research presents the first report on the in vitro antidiabetic effect of S. zalacca fruits extract using this approach. The obtained results indicated that the administration of 400 mg/kg bw of 60% ethanolic S. zalacca extract for 6 weeks significantly decreased the blood glucose level and normalized the blood lipid profile of the OBDC rats. The potential biomarkers in urine were 2-oxoglutarate, alanine, leucine, succinate 3-hydroxybutyrate, taurine, betaine, allantoin, acetate, dimethylamine, creatine, creatinine, glucose, phenyl-acetylglycine, and hippurate. Based on the data obtained, the 60% ethanolic extract could not fully improved the metabolic complications of diabetic rats. The extract of S. zalacca fruit was able to decrease the ketones bodies as 3-hydroxybutyrate and acetoacetate. It also improved energy metabolism, involving glucose, acetate, lactate, 2-hydroxybutyrate, 2-oxoglutarate, citrate, and succinate. Moreover, it decreased metabolites from gut microflora, including choline. This extract had significant effect on amino acid metabolism, metabolites from gut microflora, bile acid metabolism and creatine. The result can further support the traditional claims of S. zalacca fruits in management of diabetes. This finding might be valuable in understanding the molecular mechanism and pharmacological properties of this medicinal plant for managing diabetes mellitus., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Flavonoids have been reported to exert antihyperglycemic effects and have potential to enhance the current therapy options against type 2 diabetes mellitus. However, the structure activity relationships (SAR) studies of flavonoids against this disease have not been thoroughly comprehended. Hence, in the present study, 14 structurally related flavonoids viz. wogonin, techtochrysin, norwogonin, isoscutellarein, hypolaetin, kaempferol, quercetin, methyl ether of wogonin, acetate of wogonin, acetate of norwogonin, 8-hydroxy-7-methoxyflavone, chrysin, (+)-catechin and (-)-epicatechin were taken into account for in vitro antidiabetic evaluation. Cell viability of RIN-5F pancreatic cells and 3T3-L1 pre-adipocyte cells was initially tested, then an insulin secretion assay of RIN-5F as well as adipogenesis and glucose uptake measurements of adipocyte were investigated. Subsequently, protein expressions study through adipokines measurement (leptin, adiponectin, TNF-α, RBP-4) via enzyme-linked immunosorbent assay (ELISA) kit, Western blotting analysis against GLUT4 and C/EBP-α as well as molecular docking against GLUT1 were analyzed. The results from cell culture antidiabetic assays (insulin secretion, adipogenesis, and glucose uptake), protein expressions and molecular docking pointed that the methoxy group at position C-8 is responsible for antidiabetic property of selected flavonoids via glucose uptake mechanism indicated by up regulation of GLUT4 and C/EBP-α expressions. The mechanism could be enhanced by the addition of an acetate group at C-5 and C-7 of the flavone skeleton.

Salak fruit ( Salacca zalacca ), commonly known as snake fruit, is used indigenously as food and for medicinal applications in Southeast Asia. This study was conducted to evaluate the α-glucosidase inhibitory activity of salak fruit extracts in correlation to its Fourier transform infrared spectroscopy (FT-IR) fingerprint, utilizing orthogonal partial least square. This calibration model was applied to develop a rapid analytical method tool for quality control of this fruit. A total of 36 extracts prepared with different solvent ratios of ethanol⁻water (100, 80, 60, 40.20, 0% v / v ) and their α-glucosidase inhibitory activities determined. The FT-IR spectra of ethanol⁻water extracts measured in the region of 400 and 4000 cm −1 at a resolution of 4 cm −1 . Multivariate analysis with a combination of orthogonal partial least-squares (OPLS) algorithm was used to correlate the bioactivity of the samples with the FT-IR spectral data. The OPLS biplot model identified several functional groups (C⁻H, C=O, C⁻N, N⁻H, C⁻O, and C=C) which actively induced α-glucosidase inhibitory activity.

Hypertension is a pathological condition in which the blood pressure is higher than under normal physiological conditions, i.e., 140/90 mmHg or higher. Blood pressure is measured as the force exerted by the blood pumped by the heart against the walls of arteries (aorta) and distributed throughout the body. Use of complementary and alternative medicine as a cure for hypertension is a common phenomenon because of the high risk of cardiovascular complications and kidney diseases caused by conventional Western medicine. It is reported that high blood pressure causes ~49% of myocardial infarction and 62% of strokes. Effective treatment of hypertension is restricted by adverse effects and cost of the medication. Moxibustion is the application of heat by burning a small bundle of tightly bound moxa, to targeted acupoint, and sometimes it is used along with acupuncture. Encouraging results have been reported on randomized trials indicating the efficacy of moxibustion. But more controlled clinical trials are required to further establish the potential efficacy of moxibustion approach in hypertension., Competing Interests: There are no conflicts of interest.

The best described pharmacological property of flavonoids is their capacity to act as potent antioxidant that has been reported to play an important role in the alleviation of diabetes mellitus. Flavonoids biochemical properties are structure dependent; however, they are yet to be thoroughly understood. Hence, the main aim of this work was to investigate the antioxidant and antidiabetic properties of some structurally related flavonoids to identify key positions responsible, their correlation, and the effect of methylation and acetylation on the same properties. Antioxidant potential was evaluated through dot blot, 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging, ABTS + radical scavenging, ferric reducing antioxidant power (FRAP), and xanthine oxidase inhibitory (XOI) assays. Antidiabetic effect was investigated through α -glucosidase and dipeptidyl peptidase-4 (DPP-4) assays. Results showed that the total number and the configuration of hydroxyl groups played an important role in regulating antioxidant and antidiabetic properties in scavenging DPPH radical, ABTS + radical, and FRAP assays and improved both α -glucosidase and DPP-4 activities. Presence of C-2-C-3 double bond and C-4 ketonic group are two essential structural features in the bioactivity of flavonoids especially for antidiabetic property. Methylation and acetylation of hydroxyl groups were found to diminish the in vitro antioxidant and antidiabetic properties of the flavonoids.