Antimicrobial activity and phenolic composition of varieties of <i>Hibiscus sabdariffa</i> L. with red and white calyces

The antibacterial activities (ABAC) of white calyces varieties (WCV) of <i>Hibiscus sabdariffa</i> L has not been explored in depth. The aims of the study were to determine the ABAC of WCV and the relationship of phenolic composition with ABAC. Four experimental WCV (W1, W2, W3, and W4), and one with red calyces (RCV) were used. The ABAC of ethanol extracts were tested against Gram (+) and Gram (-) bacteria. WCV showed higher ABAC than RCV, and it was associated to flavonoid content which was 60% higher in WCV with respect to RCV. The free phenolic content of W1, W2, and W4 varieties was 50% higher than that observed in RCV and W3 varieties. The standardized abundance of N-feruloyltiramine and quercetin in the extracts of WCV was related with their highest ABAC. WCV are a promising source of phenolic compounds with high ABAC.