Isolation, chemical derivatizations and biological activities of sesquiterpenolides from chicory and costus roots
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Date
2018
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Punjab Agricultural University, Ludhiana
Abstract
The dissertation incorporates the Isolation, chemical derivatizations and biological activities of sesquiterpenolides from chicory and costus roots. The roots of chicory/costus were room dried and extracted by Soxhlet extractor using sequential extraction method with hexane, dichloromethane and methanol as the solvents. GC-MS analysis showed the presence of 22 and 35 compounds in chicory and costus hexane extracts. Isoalantolactone, dehydrocostus lactone and alantolactone were isolated as pure compounds from root extracts via extensive column chromatography over silica gel. Reduction of these isolated compounds was carried out using sodium borohydride. Allylic oxidation of isoalantolactone and dehydrocostus lactone was carried out selenium dioxide-TBHP and selenium dioxide impregnated silica gel-TBHP. Decomposition of pyrazoline derivatives of sesquiterpene lactones under heat, microwave and thermo-sonication were carried out. Chicory/costus root extracts, isolated and derivatized compounds were tested for in vitro antioxidant and antifungal activities against three rice pathogens at different concentrations. The antioxidant potential was evaluated using five different methods viz. DPPH, Hydroxyl, Nitric oxide, superoxide radical scavenging and FRAP assay methods. All the extracts showed promising antioxidant and antifungal activity. Methanol extract of chicory was most active amongst all tested extracts whereas dihydroxy dehydrocostus lactone was the most active sesquiterpenolide amongst tested compounds. Antifungal activity of hexane extract was better than all tested extracts. Isoalantolacone was most effective sesquiterpenoid out of all isolated and derivatized compounds. Field evaluation of bioactive extract revealed that chicory and costus roots hexane extracts were highly effective in controlling disease under field conditions.
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