Antioxidative and melanin production inhibitory effects of Syzygium cumini extracts

Syzygium cumini (L.) Skeels is a famous herbal tree in Myrtaceae family. Antioxidative activity of its ethanolic extract was determined using DPPH assay and the result showed that S. cumini leaf extract (SLE) exhibited stronger antioxidative properties than its branch extract (SBE) with IC50 values at 4.58±0.07 and 5.80±0.03 µg/mL, respectively. Moreover, both SLE and SBE revealed high total phenolic contents which were related to their antioxidative activities. In addition, inhibition of melanin production was assessed in B16-F10 murine melanoma cells. After 48 hr of incubation at concentrations between 0.06- 1.00 mg/mL, cells exhibited no toxicity and inhibited melanin production. RT-PCR analysis indicated the extracts inhibited the expression of tyrosinase, tyrosinase-related protein (TRP)-1 and TRP-2 genes in a dose-dependent manner. The findings reveal the antioxidative and melanin production inhibitory properties of the S. cumini extracts. In particular, SLE should be further developed for skin whitening products

Gastroprotective effect of hydroalcoholic extract of Ocimum africanum leaves

Ocimum africanum Lour. (hairy basil, hoary basil or lemon basil) is an aromatic herb in Asian and Thai cuisine that has been used as a carminative, a digestion enhancement and remedy for gastrointestinal disturbance in Thai traditional medicine. This study was performed to evaluate the gastroprotective effect of O.africanum leaf extract in acid/alcohol-induced gastric lesion in rats. Pretreatment of the plant extract can prevent the gastric damage in a dose-dependent manner. At 125 mg/kg of body weight, the plant extract attenuated the inflammation with % ulcer index of 5.08±1.41, whereas at doses of 250 and 500 mg/kg of body weight, the gastric lesion was completely prevented in the manner similar to what was observed in omeprazole pretreated animals (% ulcer index of 1.0±61.94, 0.1±10.45 and 0.00±0.00, respectively). The protective effect of the plant extract against acid/alcohol-induced gastric damage relates to its high antioxidative property and the ability to enhance the activities of three antioxidative enzymes, i.e. superoxide dismutase, catalase and glutathione peroxidase. Preliminary phytochemical investigation demonstrated that certain phenolic compounds such as rosmarinic acid, caffeic acid and vanillic acid might take part in the protective effects