Screening of Biological Activity of Selected Medicinal Orchids of Western Ghats, Karnataka, India

The present work was carried out to investigate the presence of bioactive compounds in selected medicinal orchids such as Dendrobium jerdonianum, Dendrobium barbatulum, Eria mysorensis, Bulbophyllum neilgherrense, and Pholidota pallida. The phytochemical, antibacterial, and antioxidant properties of the plants were evaluated using extracts obtained through chloroform, methanol, and aqueous extraction methods, respectively. The results of the phytochemical test showed the presence of diverse classes of secondary metabolites such as alkaloids, steroids, triterpenes, saponins, tannins, flavonoids, carbohydrates, resins, proteins, glycosides, and phenolics. The presence of these phytochemicals varied among different solvent extracts among the selected plants. Among the plant extracts tested, D. Jerdonianum and P. pallida offered significant p ≥ 0.05 antibacterial properties against Escherichia coli, Salmonella typhi, Bacillus subtilis, Shigella flexneri, and Pseudomonas aeruginosa with a minimum inhibitory concentration (MIC) ranging from 0.312 to 2.5 mg/mL. Among the plant extracts tested, methanol extract of Erythrina mysorensis (29.38%), B. neilgherrense (15.92%), P. pallida (13.84%), and D. barbatulum (13.10%) showed highest phenolic contents, followed by chloroform and aqueous extracts in all the plants. E. mysoriensis and D. jerdonianum exhibited highest antioxidant properties at 85.41% and 81.28% (with IC50 values of 36.49 and 43.72 μg/mL), respectively, while the positive control, gallic acid, displayed antioxidant properties of 94.61% (with an IC50 values of 30.49 μg/mL). These results warrant further studies on using these selected orchids for therapeutic and pharmaceutical applications.