Antioxidant activities in stem bark, leaves, and fruits of Olea ferruginea Royle grow in Himachal Pradesh, in relation to altitudinal changes

Abstract

Background: Olea ferruginea Royle is one of the important plant which is commonly used by local people for their health benefits as folk medicine. The secondary metabolites of plants vary due to different abiotic and biotic stresses. In the present study, variation in phenolics and flavonoids content and antioxidant activity due to altitude, variation has been studied. Aim: The aim of the study was to investigate the phytochemical content and antioxidant activity of the stem bark, leaf, and fruits of O. ferruginea collected from five populations (Thalaut, Sapangi, Suind, Kolibeher, and Kais) of North-west Indian Himalayan. Materials and Methods: Stem bark, leaf, and fruit extracts were prepared by the maceration process using 80% (v/v) methanol and phytochemicals (phenolics and flavonoids) contents as well as their antioxidant activities were analyzed using in vitro assays, namely DPPH (2, 2-Diphenyl-1-picrylhydrazyl) ABTS (2, 2'-Azino-bis 3-ethylbenzothiazoline- 6-sulfonic acid), and ferric-reducing antioxidant power (FRAP). Results: The results revealed that phenolics (mg GAE/g fw) and flavonoids (mg QE/g fw) varied between 5.2–9, 5.1–9.4 and 4.6–8, and 0.8–1.8, 8.8–22.8 and 0.8–1.1, respectively, in stem bark, leaf, and fruits. Average DPPH, ABTS, and FRAP activities were found highest in the methanol extracts of stem bark, leaf, and fruits, respectively, of O. ferruginea plants. The biochemical attributes of the test plant's parts showed positive and significant correlations with altitudes (R2 = 0.86–0.99; P Conclusion: The present study reveals that stem bark, leaf, and fruits of the O. ferruginea are a rich source of natural antioxidants and may be exploited for commercial and health benefits.