South African Journal of Botany - 2015

Crocus sativus L. belongs to family Iridaceae and its stigma part which forms commercial saffron has been used as a spice and medicine ever since the Greek-Minoan civilization. Saffron is considered the most expensive spice in the world and the site for the biosynthesis of peculiar metabolites (apocarotenoids), responsible for its characteristic color, flavor, and aroma. There is enough literature citing the antioxidant properties of saffron metabolites, but most of the knowledge accumulated so far comes from stigma part only, while other plant parts particularly the vegetative tissues have not been worked out. The present study was conducted to evaluate and compare the chemical composition and antioxidant activity of three different tissue types of Crocus viz: stigma, corm, and leaf. The phytochemical analysis carried out using LC-MS showed that the major constituents identified were flavonoids like kaempferol, taxifolin, naringenin, etc. and apocarotenoids including crocin, crocetin, and their derivatives. Also the total phenolic, flavonoid, and carotenoid contents were determined. The antioxidant property of these tissue types was also investigated and compared by biochemical assays like, DPPH, NBT, and FRAP. The ethanolic fraction of stigma demonstrated the strongest antioxidant activity which could be attributed to its highest content of phenolics and flavonoids. Stigma extract was further evaluated for its role in alleviating oxidative stress in plants, yeast, and bacteria. The results showed that stigma extract reduced methylviologen induced chlorophyll damage, lipid peroxidation, and protein oxidation in plants thereby rendering them more tolerant to stress. It was also shown to alleviate H2O2 mediated oxidative stress tolerance in bacteria and yeast.