Free radicals scavenging activity of Mongolian endemic and Vietnamese medicinal plants

Abstract

In a purpose to study Vietnamese medicinal and Mongolian endemic plants exhibiting antioxidant activity against oxidative stress, we have prepared 50% ethanol extracts from air-dried 25 Mongolian plants and, water and dichloromethane fractions from 50% ethanol extracts of air-dried 14 Vietnamese plants. The samples have been screened for free radical scavenging activity in vitro assay systems: DPPH radical and NO radical scavenging assays. Interestingly, 50% ethanol extract of Garcinia oblongifolia (IC50=6µg/ml) and its dichloromethane fraction (IC50=6.9µg/ml), 50% ethanol extract of Ficus racemosa (IC50=6.9µg/ml) among Vietnamese plants showed significant radical scavenging activities with the IC50 value lower than that of α-tocopherol (IC50=8.4 µg/ml) using as positive control. And, 50% ethanol extracts of Limonium aureum (IC50=39.6µg/ml), Thymus gobicus Tscern (IC50=43.5µg/ml), and Rheum uninerve Maxim (IC50=43.7µg/ml) showed good radical scavenging activities. The result of NO scavenging activity showed that all 18 plants showed strong free radical scavenging activity in NO scavenging assay. The most significant activities were the ethanol extracts of Asparagus gobicus Ivanova ex Grubov (IC50=2.68mg/ml), Rheum uninerve Maxim. (IC50=2.75mg/ml), Salsola collina Pall. (IC50=31.3mg/ml) in Mongolian samples and Hiptage benghelensis (L.) (IC50=1.67mg/ml), Gouania leptostachya DC. (IC50=2.34mg/ml), and Asarum petelotii O.C.Schmidt (IC50=2.63mg/ml) in Vietnamese samples. Several Vietnamese plants already in therapeutic use might exert some of their effects as natural antioxidants. The majority of the tested Mongolian endemic and sub-endemic plants were never studied for bioactivity before.