Effect of yeast extract and chitosan on shoot proliferation, morphology and antioxidant activity of <i>Curcuma mangga in vitro</i> plantlets

Abstract

This paper reported the effect of yeast extract and chitosan with combination of yeast extract on the growth and morphological changes and production of phenolics in the in vitro plantlets of Curcuma mangga. Yeast extract did not show any effect on the biomass and shoot proliferation of in vitro plantlets. However, the plantlets showed morphological abnormality when exposed to higher concentration of yeast extract (3.5 mgL^-1 and above) supplemented into the culture medium. Plantlets cultured in media supplemented with 3.5 and 5.0 mgL^-1 of yeast extract showed higher radical scavenging activity (RSA) which also indicated that stress induced by yeast extract might elicit the production of secondary metabolites which acted as free radical scavenger in 1,1-diphenyl-2- picrylhydrazyl (DPPH) assay. The plantlets treated with different concentration of chitosan combined with 3.5 mgL^-1 of yeast extract affected the biomass of C. mangga. The plantlets that were cultured in media supplemented with 150 mgL^-1 of chitosan combined and 3.5 mgL^-1 of yeast extract showed higher RSA towards DPPH as compared to the other treatments. Kinetic of DPPH free RSA from C. mangga extract was considered slow as compared to quercetin and the correlation between total phenolic content and RSA was poor (R² = 0.2293) for yeast extract and (R² = 0.0373) for chitosan combination with yeast extract. This indicated that the presence of phenolic compounds in the extracts were not the major factor contributing to the anti-oxidative activity of C. mangga.

Key words: Curcuma mangga, in-vitro, elicitor, phenolics, anti-oxidative activities.