Rose myrtle (Rhodomyrtus tomentosa) extract and its component, piceatannol, enhance the activity of DNA polymerase and suppress the inflammatory response elicited by UVB­induced DNA damage in skin cells.

A number of naturally occurring agents are hypothesized to protect against ultraviolet (UV)­induced skin damage. The present study screened >50 plant extracts for inhibitors of UVB­induced cytotoxicity, using cultured normal human epidermal keratinocytes (NHEK), and identified that the fruit of rose myrtle (Rhodomyrtus tomentosa) was the most marked inhibitor of cell death. The protective effect of rose myrtle extract and the two key components, piceatannol and piceatannol­4'­O­ß­D­glucopyranoside, on UVB­induced damage and inflammation in cultured NHEK was investigated. The 80% ethanol extract from rose myrtle fruit with piceatannol exhibited protection of UVB­induced cytotoxicity in NHEK; however, piceatannol­4'­O­ß­D­glucopyranoside exhibited no protection, as determined by a 3­(4,5­dimethylthiazol­2­yl)­2,5­diphenyltetrazolium bromide assay. This extract and piceatannol reduced the production of UVB­induced cyclobutane pyrimidine dimers and enhanced the cellular enzyme activity of the DNA polymerases in UVB­irradiated NHEK, suggesting that UVB­stimulated DNA damage was repaired by the polymerases. In addition, the secretion of prostaglandin E2, which is an inflammatory mediator, was decreased. These results indicated that rose myrtle fruit extract and its key constituent, piceatannol, are potential photoprotective candidates for UV­induced skin damage.

Dietary kakrol (Momordica dioica Roxb.) flesh inhibits triacylglycerol absorption and lowers the risk for development of fatty liver in rats.

Kakrol (Momordica dioica Roxb.) is a cucurbitaceous vegetable native to India and Bangladesh. Bitter gourd (Momordica charantia Linn.), a species related to kakrol, has been shown to have pharmacological properties including antidiabetic and antisteatotic effects. In this study, we investigated the effect of dietary kakrol on lipid metabolism in rats. Sprague-Dawley rats were fed AIN-76 formula diets containing 3% freeze-dried powders of whole kakrol or bitter gourd for two weeks. Results showed significantly lowered liver cholesterol and triacylglycerol levels in rats fed on both diets. Fecal lipid excretion increased in rats fed the kakrol diet, and lymphatic transport of triacylglycerol and phospholipids decreased in rats fed the kakrol diet after permanent lymph cannulation. Furthermore, n-butanol extract from kakrol caused a significant concentration-dependent decrease in the pancreatic lipase activity in vitro. These results indicate that the mechanisms of action on lipid metabolism in kakrol and bitter gourd are different and that dietary kakrol reduces liver lipids by inhibiting lipid absorption.