Characterization of bioactive compounds from raw and ripe Mangifera indica L. peel extracts

Abstract

Mango is one of the important tropical fruits in the world. As it is a seasonal fruit, it is processed for various products. During its processing, peel is one of the major byproducts, which is being wasted. Bioactive conserves were extracted using 80% acetone from peels of raw and ripe mango fruits and subjected to acid hydrolysis. The prominent phenolic compounds identified by HPLC were protocatechuic acid, gentisic acid and gallic acid. The phenolic acid derivatives present in acetone extracts of raw and ripe peels were tentatively identified by LC–MS. Gallic acid, syringic acid, mangiferin, ellagic acid, gentisyl-protocatechuic acid, quercetin were the phenolic compounds identified in both raw and ripe peels, while raw peel showed the presence of glycosylated iriflophenone and maclurin derivatives also. β-Carotene was the major carotenoid followed by violaxanthin and lutein. Thus, both raw and ripe mango peel extracts have different phenolic compounds and carotenoids, which will have various pharmaceutical applications.

Introduction

Epidemiological evidences suggest that diet rich in fruits and vegetables provide health benefits such as prevention of cardiovascular diseases and certain types of cancer (Arouma, 2003, Miller et al., 2000). These health beneficial effects are due to the presence of various bioactive compounds that are present in fruits and vegetables (Ajila et al., 2007a, Hertog et al., 1993, Heim et al., 2002, Parr and Bolwell, 2000). Phenolic compounds and carotenoids are the major bioactive compounds found in fruits and vegetables and these compounds are shown to exhibit antioxidant, antiallergenic, antiarthrogenic, antiinflamatory, antimicrobial and antithrombotic effects (Ajila et al., 2007b, Bravo, 1998, Middleton et al., 2000, Puupponen-Pimia et al., 2001). Phenolic acids like gallic acid and quercitin are claimed to have activity against allergy, hypertension, arthritis and cancer (Borbalan et al., 2003, Fernandez–Pachon et al., 2004). Mangiferin, which is shown to be the predominant constituent of mango stem bark extract is reported to display a variety of pharmacological effects (Guha et al., 1996, Sanchez et al., 2000).

Byproducts from different fruit processing industries, which were traditionally treated as environmental pollutants, are being recognized as source for obtaining valuable components. Mango is one of the important tropical fruits in the world and India contributes major part of the world production. India produced 13.5 MMT of mango fruits, while the world production was 33.45 MMT (FAO, 2007). Mango fruits are processed for various products as it is a seasonal fruit. Peel is one of the major byproducts during mango processing. It constitutes about 15–20% of the fruit weight. At present peel is discarded as waste and becoming a source of pollution. Recently, Ajila et al. (2007a) reported that mango peel extracts from two different mango varieties at different stages of fruit maturity showed good amount of polyphenols and carotenoids. It was also reported that peel extracts exhibited potential antioxidant activities (Ajila et al., 2007b) and protected against H₂O₂ induced oxidative damage in rat erythrocytes (Ajila and Prasada Rao, 2008). The present study will focus on the identification of bioactive compounds such as phenolic acids and their derivatives, and carotenoids present in peels of ripe and raw fruits of an Indian mango variety.