In Vitro Inhibitory Effects of Coconut Husk Extract on Some Enzymes Relevant to the Pathogenesis of Obesity, Gout and Hypertension

Abstract

Coconut husk is a potential natural source of some important bioactive compounds with several health benefits. In this study, the inhibitory effects of polyphenolics-rich extract of coconut husk on pancreatic lipase (PL), xanthine oxidase (XO) and angiotensin 1-converting enzyme (ACE), being enzymes whose over-activities contribute to the pathogenesis of obesity, gout and hypertension, respectively, were investigated. Free radicals (DPPH* and ABTS*⁺) scavenging ability, and HPLC-DAD profile of the flavonoids and phenolic acids constituents of the extract were also evaluated. The extract strongly inhibited PL, XO and ACE in a dose-dependent pattern, with IC₅₀ values of 12.34 ± 1.25 μg/mL, 26.20 ± 2.46 μg/mL and 17.64 ± 1.89 μg/mL, respectively. The extract effectively scavenged DPPH* and ABTS*⁺. The flavonoids in the extract were in the order of quercetin > apigenin > kaempferol > rutin; while the phenolic acids were in the order of p-coumaric acid > chlorogenic acid > gallic acid > caffeic acid. Hence, coconut husk may be a low-cost natural product for managing obesity, gout and hypertension, and alleviating oxidative stress; through inhibition of PL, XO and ACE, and scavenging of free radicals. The combined effects of the flavonoids and phenolic acids constituents of the husk may be responsible for these bioactivities.

Key words:

• Coconut husk
• phenolic compounds
• pancreatic lipase
• xanthine oxidase
• angiotensin I-converting enzyme