Bioactive potential of Rhododendron lowndesii: Extraction, antioxidant analysis, antimicrobial assay, and Liquid...

Rhododendron lowndesii Davidian is an endemic medicinal plant of Nepal found in an altitude range of 3000-4100 m. This study investigates the phytochemical composition and bioactivities of its methanolic extract. The aerial part of the plant was extracted through methanol maceration to achieve 31.50% ± 0.92% yield. Qualitative and quantitative phytochemical analysis of the extract revealed the presence of alkaloids, flavonoids, phenols, steroids, terpenoids, coumarins, and carbohydrates, with a total phenolic content of 175.63 ± 1.37 mg GAE/g and total flavonoid content (TFC) of 1090.36 ± 2.29 mgQE/g. Antioxidant activity assay of the extract suggested its strong radical scavenging activity through DPPH (IC₅₀:19.46 ± 1.85 µg/mL) and ABST is 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) assays (IC_50: 13.4 ± 0.20 µg/mL). Antibacterial activity as determined by the disc diffusion method, showed significant effect against Bacillus subtilis, Enterococcus faecalis, and Staphylococcus aureus (minimum inhibitory concentration: 312.5-1250 µg/mL) but limited efficacy against Salmonella enterica. High-resolution liquid chromatography-mass spectrometry identified pharmacologically significant compounds, including zapotin and cepharanthine. These findings suggest that R. lowndesii has rich phytochemical profile and bioactivity; this supports its potential as a medicinal plant and need of its pharmacological research.