Elevated level of polysaccharides in a high level UV-B tolerant cell line of Bupleurum scorzonerifolium Willd

Abstract

A cell line of Bupleurum scorzonerifolium Willd with high level tolerance to UV-B radiation was obtained through exposure of the protoplasts to high doses of UV-B radiation at the intensity of 380 μW/cm² for 240 s. The cell line was named anti-UV-B cell line and proved to be a mutant from the original protoplast by RAPD tests and kept the genetic stability among different generations. Chemical analyses showed that, the anti-UV-B cell line contained excessively higher content of polysaccharides and relatively higher content of triterpenes than those from the wild-type plants and cell lines from unscreened protoplasts. To understand the possible contribution of polysaccharides to its high tolerance to UV-B radiation, the antioxidant activity of the polysaccharides in this cell line was evaluated by free radical 2, 2-diphenyl-1-picrylhydrazyl (DPPH) method. The results showed a significant antioxidant effect of the polysaccharides from this cell line in a concentration-dependent manner. This indicated that, the high content of polysaccharides might account for the high tolerance to UV-B radiation of this anti-UV-B B. scorzonerifolium cell line. Furthermore, this cell line displayed vigorous growth ability with high content of polysaccharides and triterpenes under artificial conditions, especially in the bioreactor, indicating it could have promising application potential for industrial production of antioxidant in medical and cosmetic areas.

Key words: Bupleurum scorzonerifolium Willd, polysaccharides, in vitro culture, UV-B tolerance, antioxidant.