Hydroxycitrate as dominating acid in leaves of ambary (Hibiscus cannabinus L.)

Abstract

Hydroxycitric acid (HCA) was first found in plants by Lippmann in 1883. There are possible four stereoisomers of HCA, one of which occurs in Garcinia (-HCA), and another in Hibiscus cannabinus ((+) allo GLA). In animals (–) HCA is a potent inhibitor of ATP-citrate lyase, which catalyzes extramitohondrial cleavage of citrate to oxaloacetate and acetyl-CoA, and can be an effective regulator of fatty acid synthesis, lipid and carbohydrate metabolism. In plants the physiological and biochemical role of HCA has been poorely studied. The aim of this work was to study the composition and content of organic acids in ambary (Hibiscus cannabinus L. ) at different phases of growing season. Organic acid fraction was analyzed by gas chromatography-mass spectrometry instrument with Agilent mass selective detector MSD-5975. In ambary hydroxycitric acid is identified, as well as for the first time malic, fumaric, succinic and oxoglutaric acids were discovered. In etiolated seedlings fumaric acid dominates, hydroxycitric acid is completely absent. With transition of plants to an autotrophic type of food, hydroxycitric acid becomes dominant. In palmately parted leaves during seed formation, sharp decrease of hydroxycitric acid was observed which may be an adaptive response, allowing seeds to accumulate the significant amount of oil. We assume that HCA can be a donor (CO₂), intra cellular source of H₂O and pH regulator in leaves in Hibiscus cannabinus.

Keywords:

ambary, seedlings, leaves, hydroxycitric acid, metabolism