Inhibitory Potential of Cocoa Leaves Polyphenolics-Rich Extract on Xanthine Oxidase and Angiotensin 1-Converting Enzyme

Abstract

The over-activities of xanthine oxidase (XO) and angiotensin 1-converting enzyme (ACE) contribute to the pathogenesis of gout and hypertension, respectively. Polyphenolics and other natural inhibitors of XO and ACE have been shown to be useful for managing these two diseases. Therefore, this study evaluated the inhibitory potential of cocoa leaves polyphenolics-rich extract on XO and ACE, and its free radicals (2,2- diphenylpicrylhydrazyl [DPPH*] and 2,2´-azino-bis-3-ethylbenzthiazoline-6-sulphonic [ABTS*+]) scavenging ability, in vitro. The XO and ACE inhibition; and DPPH* and ABTS*+ scavenging assays were carried out using Spectrophotometric methods. Flavonoids and phenolic acids content of the extract was quantified using high performance liquid chromatrography coupled with diode array detection (HPLC-DAD). The extract strongly inhibited XO and ACE in a dose dependent pattern, with half-maximal inhibitory concentration (IC50) of 33.15 ± 1.84 μg/mL and 18.72 ± 1.05 μg/mL, respectively. The extract also scavenged DPPH* and ABTS*+. The HPLC-DAD analysis of the extract revealed the presence of flavonoids including catechin, rutin, quercetin and apigenin; and phenolic acids including gallic, caffeic and p-coumaric acids; with quercetin and caffeic acid as the most abundant flavonoid and phenolic acid , respectively. Cocoa leaves may be useful for preventing and managing gout and hypertension, through XO and ACE inhibition.