Study of chemical composition and volatile compounds along with in-vitro assay of antioxidant activity of two medicinal rice varieties: Karungkuravai and Mappilai samba.

The objective of this study is to analyze the chemical composition and volatiles present in two medicinal rice varieties of "karungkuravai" and "mappilai samba" and to investigate their total phenolic content and bio activity. Chemical composition of the rice varieties was analyzed using gas chromatography/mass spectroscopy (GC-MS), the volatile compounds are identified using static head space analysis (SHS) followed by GC-MS. Total phenolic content (TPC) is estimated using Folin Ciocalteu colorimetric method, antioxidant assay is done using 1, 1-diphenyl-2-picrylhydrazyl (DPPH) assay and ferric reducing antioxidant power (FRAP) assay. GC-MS and SHS analysis identified pharmaceutically important phytochemicals present in the rice variety. The compounds like "curlone" and "7-chloro-1,3-dihydro-5-phenyl-1-(trimethylsilyl)- 2H-1-4-benzodiazapene-2-one" are identified for the first time in any rice variety. Phenols are found to be present in both rice varieties. Both rice varieties also showed antioxidant activity in both DPPH and FRAP assays and the IC50 values were 91.08 μg/ml and 359.93 μg/ml for "karungkuravai" and "mappilai samba", respectively. . The correlation coefficient and regression analysis of total phenolic content with DPPH assay and FRAP assay show significant positive correlation coefficient values and coefficient of regression values.