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Tetrastigma angustifolia (Roxb.) Deb is an evergreen shrub belonging to the family Vitaceae. This plant species has been used for thousand years in Ayurvedic medicine. Ethnomedicinal study also documents the use of T. angustifolia leaves in the management of diabetes. On the other hand, Oxalis debilis Kunth. is a tristylous plant commonly known as pink woodsorrel belong to the family Oxalidaceae. This plant has been used traditionally for the treatment of dysentery and diarrhea. Ethnobotanical study also reports the use of leaf decoction of O. debilis in the treatment of diabetes. In our earlier work, the antidiabetic activity of hydro-alcoholic leaf extracts of T angustifolia and O. debilis have been reported. In spite of ethnomedicinal implications and several scientific studies in the recent past, phytochemical investigations in support of the antidiabetic potential of these plant species are yet to be explored. Therefore, the present study was aimed at the isolation of bioactive phytoconstituents as antidiabetic principle( s) from T angustifolia and O. debilis leaves. In this paper, two bioactive compounds, namely apigenin derivative (AGD) and stigmasterol (STM) were isolated from the methanolic leaf extracts of T. angustifolia and O. debilis, respectively by column chromatographic technique. The structures of the isolated compounds were established by spectroscopic/ spectrometric techniques including FT-IR, H-1 NMR and C-13 NMR and Mass. The isolated flavonoids were identified as 8-hydroxyapigenin 7-O-beta-D glucopyranoside, a derivative of apigenin (AGD) and stigmasta-5,22-dien-3,beta-ol i.e., stigmasterol (STM). The antidiabetic potential of AGD and STM was evaluated by in vitro alpha-glucosidase and alpha-amylase inhibitory assays. To validate the antidiabetic efficacy, molecular docking and dynamics studies were performed using AutoDock Vina and GROMACS software. In vitro assays revealed the antidiabetic potential of AGD and STM with alpha-glucosidase and alpha-amylase inhibitory activities. From docking and MD simulation studies, promising binding affinity of AGD and STM for human lysosomal alpha-glucosidase (5NN8) and human pancreatic alpha-amylase enzymes (1B2Y) with favorable binding modes, stable protein-ligand complexes and well defined protein-ligand interactions were observed. Based on in vitro and in silico studies, our study reports the antidiabetic potential of the isolated apigenin derivative, AGD (a new flavonoid molecule) and stigmasterol, STM (an existing plant sterol) with alpha-glucosidase and alpha-amylase inhibitory activities. However, the flavonoid molecule, AGD possesses better antidiabetic profile than the steroid molecule, STM particularly against human alpha-amylase enzyme. Our present investigation successfully validates the traditional as well as ethnomedicinal claims of T. angustifolia and O. debilis as antidiabetic medicines. (C) 2021 SAAB. Published by Elsevier B.V. All rights reserved.

Ethnomedicinal survey documents the traditional practices of Tetrastigma angustifolia leaves in the management of diabetes in the North-eastern region of India. The present study was aimed at isolation of possible antidiabetic principle(s) from T. angustifolia leaves and evaluation of antidiabetic efficacy of isolated compound(s) in experimental animal model. The methanolic extract of T. angustifolia leaves was obtained by Soxhlet extraction method and subjected to silica gel column chromatography (100-200 mesh). Fraction 18-176 chloroform:methanol (70:30) yielded a pale yellow colored compound. The structure of pure compound was elucidated with the help of UV, IR, NMR and Mass spectrometric/techniques. The antioxidant activity of the isolated compound was evaluated in vitro by various radical scavenfing assay methods.. Oral acute toxicity study was carried out according to OECD guideline 423 in Wistar rats. The antidiabetic efficacy of the isolated compound was evaluated in STZ-induced diabetic rats at the dose of 5 mg/kg b.w. for duration of 21 days. The present study reports a new flavocnoid compound isolated from the methanolic extract of T. angustifolia leaves and identified as 8-hydroxyapigenin 7-O-D-glucopyranoside. The flavonoid compound exhibited potent antidiabetic (hypoglicemic) activity in STZ-induced diabetic rats with promising antioxidant (radical scavenging activity) potential in vitro.

Despite the availability of synthetic antidiabetic drugs, diabetes mellitus is still affecting millions of people with increasing rate of disease incidence and mortality throughout the world. Ethnomedicinal survey documents the traditional usefulness of Callicarpa arborea Roxb. stem bark in the management of diabetes mellitus.In our study, hydro-alcoholic extract (HAE) of Callicarpa arborea stem bark was prepared according to WHO guidelines for herbal drugs, and screened for antidiabetic activity in streptozotocin (STZ)-induced diabetic rats. Acute oral toxicity and in vitro antioxidant activity studies along with phytochemical analyses of HAE were also carried out.Acute oral toxicity study indicated that HAE was safe up to a dose of 2000mg/kg body weight of rats. Results of antidiabetic activity study revealed that HAE of C. arborea stem bark possesses significant (p0.05) hypoglycemic activity compared to normal control group in experimental rats. Histological observations of treated pancreas and liver tissues confirmed the antidiabetic efficacy of HAE. In antioxidant activity, HAE exhibited significant radical scavenging activity.From results, it can be concluded that HAE of C. arborea stem bark may have possible role as herbal antioxidants in the prevention and/or treatment of oxidative stress-induced diabetes mellitus. The antioxidant property of plant phenolic and flavonoid contents present in HAE might be responsible for the antidiabetic efficacy of C. arborea stem bark.