Effect of pineapple, orange and watermelon juices on phosphodiesterase, monoamine oxidase and angiotensin-I converting enzyme activities in rat heart and brain homogenates

Abstract

Fruit juices are commonly consumed in many parts of the world for their nutritional and medicinal benefits. More specifically, Pineapple (Ananas comosus), orange (Citrus sinensis) and watermelon (Citrullus lanatus var. lanatus) juices are used in folklore for the prevention and management of cardiovascular and neurodegenerative diseases, though there is dearth of information on the mechanism for such medicinal benefits. Thetrefore, this study sought to characterize the effect of these commonly consumed fruit juices on phosphodiesterase (PDE), monoamine oxidase (MAO) and angiotensin-I converting enzyme (ACE) activities in rat heart and brain homogenates. The fruits were sourced for and the juices extracted, freeze dried and then reconstituted for the analysis. The abilities of these juices to protect the heart and brain against Fe2+ induced oxidative damage were also investigated in vitro. The results revealed that the juices inhibited PDE, MAO and ACE activities in a concentration-dependent manner in rat heart and brain homogenates with orange having the highest inhibitory ability. The juices also inhibited Fe2+ induced malondialdehyde production in rat heart and brain in a concentration-dependent manner. This study revealed that the inhibition of these enzymes and prevention of oxidative damage could be part of the mechanisms by which these fruits could serve as dietary intervention for the prevention and management of cardiovascular and neurodegenerative diseases.