HPLC-UV Standard Phenolic Constituents of African Bush Mango (Irvingia gabonensis) and Molecular Docking on Polyphenol Oxidases

Abstract

Introduction: Irvingia gabonensis belongs to the Irvingiaceae plant family and commonly known as the African bush mango, wild mango, Dika nut and Manguier sauvage. The fruits of I. gabonensis are edible and their use in traditional medicine has been reported for the treatment of diabetes, diarrhea, wound ulcer, hepatic disorder, microbial infections, and inflammatory pains.  Aim: This study aimed to identify the standard phenolic contents of I. gabonensis fruit pulp and peel extracts and investigate the bind energy on polyphenol oxidase in order to know why browning of I. gabonensis fruit is often rapidly occur and how to prevent it with suitable inhibitor in an industrial processing. Results: The phenolics that were identified include ellagic acid, cinnamic acid, gallic acid, 3-friedelanone, lupeol, kaempferol, quercetin, alpha-curcumene and zingiberene. The two PPO from Solanum lycopersicum (PDB ID: 6HQI) and Mangifera indica (PDB: D2XZ13_model) have different binding energies across the ligands with highest score by 3-friedelanone (-14.3 and -16.1 kcal/mol respectively), followed by lupeol (-13.9 and -14.6 kcal/mol respectively). The differences in the binding energies across the plant PPOs could be due to variation in the amino acid composition and more importantly the amino acid residues that participate in the catalytic and allosteric activities Conclusion: This study has shown the reason behind rapid browning that usually occur in I. gabonensis and more importantly, the need for effective edible inhibitors of PPO.