Elevation-Driven Variation in Chemical Composition and Biological Activities of Rhododendron anthopogon Essential Oil: A Case Study From the Himalaya.

This study investigated the chemical composition and biological properties of essential oil extracted from Rhododendron anthopogon D.Don collected from three different sites along an elevation gradient (3200 to 3900 m) in the Kashmir Himalaya. Gas chromatography-mass spectrometry (GC-MS) analysis revealed significant qualitative and quantitative variations in essential oil composition, with yields ranging from 0.31% to 0.43% (w/v). A total of 59 compounds were identified, including 31 unique compounds at the highest elevation, Site-3 (3900 m). Antioxidant activity, assessed by DPPH, ABTS, and FRAP assays, increased significantly (p < 0.05) with elevation. The essential oil from Site-3 exhibited the strongest antibacterial and antifungal activities, with minimum inhibitory concentrations (MICs) of 6.25 µg/mL against Micrococcus luteus and 24.33 µg/mL against Candida glabrata. It also demonstrated superior in vitro antiproliferative effects against six human cancer cell lines via MTT assay. Therefore, the findings of the present study demonstrate elevation-driven shifts in R. anthopogon essential oil yield, composition, and bioactivities in the Kashmir Himalaya, highlighting adaptive responses to altitudinal stress and the potential for targeted high-elevation harvesting in phytotherapy. These findings enhance our understanding of the interplay between environmental factors and the therapeutic potential of R. anthopogon essential oil at varying elevations.