Location and tissue effects on phytochemical composition and in vitro antioxidant activity of Moringa oleifera

Abstract

Moringa oleifera is a rich source of polyphenols, but its content and profile may vary according to environmental conditions, harvest season, and plant tissue. This study was carried out in order to determine the phenolic compounds by HPLC/MS, as well as, the in vitro antioxidant activity of extracts from leaflets and petioles of Moringa oleifera planted in three locations. The content of total polyphenolic compounds was estimated. In addition, hydrolyzable polyphenols were determined using the Folin-Ciocalteu technique, while, condensed polyphenols were estimated employing the butanol-HCl method. These chemical compounds were identified by high-performance liquid chromatography coupled to masses spectrometry (HPLC/MS). In vitro antioxidant activity of the extracts was evaluated using the 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2-azino-bis-3-ethylenebenzothiozoline-6-sulfonic acid (ABTS) and the ferric reducing antioxidant power (FRAP) methods. The polyphenolic compounds were found mainly in the leaflets. The HPLC/MS allowed the identification of 15 compounds of the hydroxycinnamic acid, anthocyanin, flavonols, methoxyflavone, tyrosol, dihydrochalcones, flavones, and methoxyflavone families. The ethanolic extracts showed high antioxidant activity for DPPH, ABTS, and FRAP, especially, those obtained from the leaflets produced at Ramos Arizpe, Coahuila. The amounts of condensed were higher than those of hydrolyzable polyphenols in the moringa grew at three environments. While the highest amount of condensed polyphenols was observed in moringa grew at Ramos Arizpe. Thus, the presence of these polyphenol compounds may explain the great antioxidant activity (98.45% inhibition) showed with the ABTS radical, in the moringa ethanolic extracts from Ramos Arizpe. These results indicate that moringa may have great potential as a natural antioxidant agent.