Annual Report - IHBT

MEDICINAL AND AROMATIC PLANT CHEMISTRYPICRORHIZA (Picrorhiza kurrooa)P. kurrooa is an important alpine medicinal herb endemic to Himalayas and is used in traditionaland modern medicines for liver disorders. Three molecules, picroside-I, II and cucurbitacin-Cwere isolated and characterized (Fig. 22).picroside i Cucurbitacin-C picroside IIFig. 22 Chemical structures of compounds isolated from P. kurrooaOwing to extensive uprooting of undergroundparts for extraction of picrosides, the plant isnow endangered. However, the work at IHBThas shown the presence of picrosides in leaftissues too (Fig. 23). The plants have higherleaf biomass as compared to underground partsand can serve as a potential source of picrosides.This will prevent the uprooting of undergroundparts thereby allowing plant regeneration insubsequent growing season.Fig. 23 HPLC profile of picroside –I (P-I) and picroside– II (P-II) in leaf tissues of P. kurrooaIn a study to understand the molecular basis of picroside biosynthesis, the promoters of regulatorygenes pkhmgr and pkdxs were analysed. These had TGAC cis-acting elements at multiple locations,the proposed binding sites of WRKY transcription factors. Electrophoretic mobility shift assaysshowed the functionality of TGAC elements. Two WRKY genes were cloned to full-length. Ofthese, the expression of WRKY2 (Fig. 24) showed a positive correlation with picrosides content,suggesting it to be an important regulator of picroside biosynthesis.