Phenolic Content and Scavenging Activity in Moringa oleifera Lam. with Two Types of Leaf Color

Abstract

Background: Moringa plants (Moringa oleifera Lam.) are mostly commercially propagated by seeds, and consequently the seedling populations show a high level of morphological diversity due to segregation. In particular, differences in leaf color can be commonly observed. The main objective of this work was to characterize the leaf color of different moringa plants and successively, relate them to the leaf content of phenols, among which are some flavonoids, and to the scavenging activity on DPPH radicals of leaf extracts. Methods: Red and green leaf petiol plants (three plants each one) were randomly chosen among a plot of 50 potted seed plants of 3-year-old and 2 m high, growing in the city of Morón (Argentina) (34º 64’ 62.61'' SL; 58º 62' 09.69'' WL). Leaves were harvested in April and were taken from the basal, medial, and apical parts of the plant stem (3 leaves per section), and consecutively each leaf was also subdivided into basal, medial and apical sections. Leaf color, total phenol content, individual phenol composition and scavenging activity of DDPH radicals were determined. Results: Petiole and leaflet color were significantly different for a* and b* values, as a consequence, ΔE* was -0.12 and 0.27 between the red leaf plants, but higher (-3.09) between the red and green type leaves. Interestingly, the leaflets of the red leaf type had more green and yellow dyes than those of the green leaf type. Phenol content and the scavenging activity of DPPH radicals were significantly highest in red plant leaves (10.9 mg tannic acid and 45.6 %, respectively) than in green plant leaves (9.1 mg tannic acid and 31.1 %, respectively). Red leaf type had the smallest amounts of rutin and naringenin contents, which were not present in the green leaf type. Nevertheless, the green leaf type showed more catechin hydrate content than the red leaf type. Conclusion: total phenol content and antioxidant activity are modified with sampling and with the leaf color, so these factors must be considered as well as the selection of red leaf plants.