Variation of Total Curcuminoids Content, Antioxidant Activity and Genetic Diversity in Turmeric (Curcuma longa L.) Collections

Abstract

Turmeric has recently been developed as an antiulcer drug and as a mosquito repellant on a commercial scale. However, the material supplied to the factory has not been uniform and has contained lower amounts of active compound than specified in the Thai Herbal Pharmacopoeia. The objective of this study was to reveal the genetic diversity and variation in active compounds and the bioactivity of turmeric collected from different parts of Thailand. The total curcuminoids content and antioxidant activity of 67 samples of Curcuma longa L. and one sample of C. mangga rhizome from various locations were analyzed before and after planting. The highest total curcuminoids content was found in the samples from the central region while the lowest content was found in the samples from the Lao PDR The antioxidant activities of extracts were assayed with DPPH and compared with ascorbic acid. The highest antioxidant activity (EC₅₀ 8.04±3.77 mg/ml) was found in the samples from the central region, which
was highly correlated with the curcuminoids content. The antioxidant activity of turmeric from all regions decreased after planting for six months. The RAPD technique was performed to detect genetic diversity in the turmeric samples. Nineteen RAPD primers yielded 184 bands of which 166 were polymorphic. At 68.4% genetic similarity, the samples were separated into four groups. The results indicated the possibility of selecting high quality clones for large-scale production.