Rhodomyrtus tomentosa (Myrtaceae) has been employed in traditional Thai medicine to treat colic diarrhoea, dysentery, abscesses, haemorrhage, and gynaecopathy. In addition, it has been used to formulate skin-whitening, anti-aging and skin beautifying agents. Ethnomedical activities of this plant may be due its antioxidant property. Hence, the aim of this study was to evaluate both in vitro and in vivo antioxidant activities of R. tomentosa leaf extract. In vitro antioxidant activity of the extract was assessed by lipid peroxidation inhibition capacity, ferric reducing antioxidant power, and metal chelating activity. R. tomentosa extract demonstrated its free radical scavenging effects in concentration dependent manner. In vivo antioxidant activity of the extract was conducted in Swiss Albino mice. Levels of thio-barbituric acid reactive substances (TBARS), glutathione (GSH), and the activities of antioxidant enzymes including superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) in blood, liver, and kidney were analyzed using microtitre plate photometer. Administration of CCl4 caused significant increase in TBARS and decrease in GSH, SOD, CAT and GPx levels. In contrast, R. tomentosa extract (0.8 g/kg) effectively prevented these alterations and maintained the antioxidant status. The results suggest that R. tomentosa extract can serve as a potent antioxidant.

No abstract

One new cyclohexenone derivative (1) was isolated from Diaporthaceous fungus PSU-H2 together with six known compounds, dothiorelone A (2), dothiorelone C (3), 2,3-dihydromycoepoxydiene (4), (+)-mycoepoxydiene (5), deacetylmycoepoxydiene (6) and tyrosol (7). The structures were elucidated by spectroscopic methods. Their cytotoxic activity against human breast cancer cell line, MCF-7, was evaluated.

Background: Potent calcium uptake is essential for calcium balance and normal health. Prolonged low intake of calcium is associated with osteoporosis, dental changes, cataracts, and alterations in the brain. However, calcium is difficult to be directly absorbed from the food due to the insoluble calcium salt precipitation that occurs in the intestinal environment. Methods: Tilapia protein hydrolysate (TPH) was prepared by alcalase digestion. The Calcium-binding activity was measured using calcium colorimetric assay, the absorption at 612 nm. The interaction between TPH and calcium was examined by spectroscopic analysis, ultraviolet absorption and fluorescence measurement. TPH-calcium-binding stability in the human digestion system was evaluated by in vitro pepsin-pancreatin hydrolysis simulating human gastric and intestinal digestion. The effects of food components on TPH-calcium-binding activity was also analyzed. The enhancement of transepithelial calcium transport by TPH was determined by in vitro Caco2 epithelial cell-like monolayer. Results: TPH produced from Nile tilapia (Oreochromis niloticus) exhibited calcium-binding activity. It was the peptides in the hydrolysate that contributed to calcium-binding since the spectroscopic changes induced by calcium were characteristic of peptide bonds and tryptophan residues. The calcium binding of TPH was compatible with food matrices. Most food components including saccharides, amino acids and vitamins showed positive or no effects on calcium-binding. The calcium-binding of TPH was also stable in the simulated gastrointestinal digestion system. Pepsin and pancreatin did not considerably change the calcium-binding activity of TPH. Of note, TPH reduced precipitation of calcium by oxalate and phytate, the two most anti-nutritional factors present in green leafy vegetables. Finally, we showed that TPH significantly promoted transepithelial calcium transport in the Caco-2 cell permeability model. Conclusions: Tilapia protein hydrolysate produced by alcalase digestion possessed calcium-binding activity and prevent precipitation of calcium by a mineral chelating agent as well as enhanced transepithelial calcium transport in Caco2 cell. The result implicated the potential of TPH as a functional food ingredient for promoting calcium absorption. Keywords: Tilapia protein hydrolysate; Calcium binding peptides; Calcium absorption

No abstract