Evaluation of pharmacological properties and phenolic profile of Hypericum japonicum Thunb. from Western Ghats of India

Abstract

Background

Phenolic content of the plants and their associated bioactivities depend upon the geographical regions where they grow. Therefore antimicrobial, antioxidant activities and phenolic profile of Hypericum japonicum collected from Western Ghats of Karnataka, India had been evaluated in this study.

Methods

Total phenolic and flavonol contents of H. japonicum methanolic extract was estimated spectrometrically. The extract was qualitatively screened for bioactive phytochemicals. Antimicrobial activity was assessed by disk diffusion and broth microdilution methods. The extract was tested for DPPH scavenging, molybdenum reduction, lipid peroxidation inhibition, DNA damage protection and β-carotene bleaching inhibition. Phenolic profiling of the extract was done by high performance liquid chromatography.

Results

The extract inhibited all tested bacteria except Pseudomonas aeruginosa. Total antioxidant activity of the extract was 37.28 ± 0.54 μg/mg. IC₅₀ value for DPPH radical quenching was 77.7 ± 5.6 μg (P < 0.05). β-carotene bleaching and lipid peroxidation were inhibited by 83.18% and 95.38% respectively. The extract also protected the DNA from hydroxyl radical mediated damage. Chlorogenic acid, ferulic acid, vanillic acid, quercetin, epicatechin and phloroglucinol were profiled in the extract.

Conclusion

This is the first report on bioactivity and phenolic profile of H. japonicum growing in Western Ghats, Karnataka, India. The study evidently showed the potency of H. japonicum from Western Ghats to be used in the food and pharmaceutical industries as a dietary supplement of antioxidants and rich source of vital phenolic acids and flavonoids.