Introduction: Gynura procumbens (Lour.) Merr. (Family: Asteraceae) is mainly popular in South-East Asian countries for its traditional medicinal properties. It is usually used as a traditional medicine for the treatment of eruptive fevers, rash, kidney disease, migraines, constipation, hypertension, diabetes mellitus, and cancer. It is commonly used as a traditional medicine in Vietnam for the treatment of many diseases. Methods: The leaves and trunks of G. procumbens were collected, macerated with methanol. The extracts from MeOH-soluble extract were processed by the column chromatographic technique to give pure compounds and the nuclear magnetic resonance methods were applied to determine their chemical structures. The inhibitory activities of these extracts against α-glucosidase were conducted and compared with acarbose. Results: Seven organic compounds were isolated and determined the structures, including syringic acid (1), quercetin (2), N,N-dimethylanthranilic acid (3), dehydrovomifoliol (4), β-sitosterol 3-O-β-D-glucopyranoside (5), schottenol (6), montanic acid (7). The inhibition of α-glucosidase test results the IC50 values of the four extracts which were lower than those of acarbose. Conclusion: Seven pure compounds were identified from the leaves and trunks of G. procumbens, including two compounds being isolated from G. procumbens for the first time. The test results showed that the the parts of G. procumbens were active as α-glucosidase inhibitor, which would be useful to support the treatment for diabetes.

Euphorbia hirta Linn. (co sua la lon in Vietnamese) belongs to Euphorbiaceae family, is a group of small prostrate herbaceous annual weed in Vietnam. It is abundant in waste places and open grasslands and distributes in most Asian countries. E. hirta is traditionally used in the treatment of gastrointestinal disorders, bronchial and respiratory. The aqueous extract exhibits anxiolytic, analgesic, antipyretic, and anti-inflammatory activities. Strong anti-diabetic activity of Euphorbiaceae family in general and E. hirta in particular was reported in the past investigations. E. hirta has been studied by various investigations and several active constituents have been isolated and identified successfully. Most of those compounds have strong biological activities. At the first step in the processing of the isolation of bioactive compounds from the ethyl acetate extract, we isolated four purified compounds, including methyl gallate (1), quercetin (2), myrecitin (3), and quercitrin (4). The chemical structures of those compounds were elucidated by spectroscopic methods and compared with published data in the literature.

Two new limonoids, named nimbandiol A (1) and azadirachtolid E (2) were isolated from the leaves of Azadirachta indica, along with deoxyazadirachtolid (3), a known compound. Their structures were determined by spectroscopic methods and compared with literatures. Three compounds (1-3) showed moderate a-glucosidase inhibitory activities against Saccharomyces cerevisiae a-glucosidase with IC50 values of 38.7 mM, 85.76 mM and 48.24 mM, respectively.