Effects of acid hydrolysis on the free radical scavenging capacity and inhibitory activity of the angiotensin converting enzyme of phenolic compounds of two varieties of jamaica (Hibiscus sabdariffa)

Hibiscus sabdariffa (HS) is a specie with interesting biological activity, namely due to the presence of phenolic compounds, both in free form or linked to sugars. An acidic hydrolysis (AH) is important for the biological determination of both glycosides and aglycones. This study investigated the effects of AH, on the free radical scavenging capacity (FRSC) and inhibition of the angiotensin converting enzyme (ACEI) of aqueous extracts (Aq), ethanolic (Et) and acetonic (Ac) of HS calyces of the Criolla (CG) and Alma Blanca (AB) cultivated in Guerrero as well as organic Criolla (COO) and Criolla (CO) varieties cultivated in Oaxaca, Mexico. The Aq of CG had the highest concentrations per 100 g of dry calyces, phenol compounds (1578.21 mg equivalents of gallic acid), anthocyanins (398.27 mg equivalent of cyanidin-3glucoside), flavanols (784.23 mg catechin equivalents) and flavonols (76.35 mg quercetin equivalents) as well as higher values of FRSC and 95% of ACEI attributed to anthocyanins. The acid hydrolysis produces a decrease of the quantified compounds, generating aglycone rich extracts with biological activity, which by increasing the concentration tested, could have higher percentages of ACEI. The extracts, Aq, Et and Ac of AB, CO and COO, were both hydrolyzed or not hydrolyzed and had activity in both determinations that could not be attributed to anthocyanins because they had low or no concentrations.