Abstract

SUXO, Yaquelin et al. Sapogenins from the husk of chenopodium quinoa, the obtaining of their derivatives, and the evaluation of their cytotoxic activity. Rev. Bol. Quim [online]. 2018, vol.35, n.3, pp.98-107. ISSN 0250-5460.

Abstract In this paper, we present the evaluation of two types of methods for obtaining sapogenins by acid hydrolysis of a hydroalcoholic extract rich in saponins from quinoa husks. In the first method, called microwave method, the acid solution of saponins was pre-stirred for one minute in a microwave and then was heated and stirred at 100 °C for 15 min. In the second one, called conventional method, the same acid solution was heated and stirred at 80 °C for 4 h. The results show that the conventional method is better to obtain more quantity of sapogenins. Then four sapogenins were isolated: oleanolic acid (1), methyl oleanate (2), hederagenin (3), and phytolaccagenic acid (4). The cytotoxicity of the compounds was evaluated in human JIMT-1 breast cáncer cells and human MCF-10A normal-like breast epithelial cells. The most active compound is hederagenin, which is more toxic in JIMT-1 cells (IC₅₀ 27.3 µM) than in MCF-10A cells (IC₅₀ 39.6 µM). Methyl oleanate is somewhat less toxic than hederagenin while oleanolic acid and phytolaccagenic acid needed treatment concentrations up to 100 uM to become cytotoxic. Finally, we obtained four new derivatives of oleanolic acid, the major sapogenin isolated, by oxidation of the OH group in C-3 to carbonyl (5) and subsequent reaction of aldol condensation, adding to carbon C-2 the follow aldehydes: benzaldehyde 6a, p- methylbenzaldehyde 6b, m-methylbenzaldehyde 6c, and o-methylbenzaldehyde 6d, these synthesis were carried out in order to incorporate a Michael-acceptor into a molecular structure to enhance the biological activity, we obtained yields of around 50% for 6a and 6b, and of around 10% for 6c and 6d.

Keywords : Quinoa; Sapogenms; Acid hydrolysis; Oleanolic acid derivatives; Cytotoxic evaluation; JIMT-1; MCF-10A cells.

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