Comparative phytochemistry, antioxidant, antidiabetic, and anti-inflammatory activities of traditionally used Ocimum basilicum L. Ocimum gratissimum L., and Ocimum tenuiflorum L.

Ocimum spp. are the widely studied herbal plants because of their diverse biological activities. The present study aimed at comparative extraction of secondary metabolites and evaluation of their biological activities in different solvents such as acetone, ethanol, methanol, and water. Three Ocimum species, namely Ocimum basilicum L. (Green tulsi), Ocimum gratissimum L. (Jungli tulsi), and Ocimum tenuiflorum (Black tulsi), were selected for this study. Leaf extracts from dried powder of these species were prepared in different solvents. The contents of total phenolics, flavonoids, and total condensed tannins were estimated using standard assays. Fingerprint analysis using UV, Fourier transform infrared (FT-IR), and fluorescent spectroscopy was also conducted. Total antioxidant, antidiabetic, and anti-inflammatory activities of the extracts were evaluated. Fingerprint analysis indicated the presence of a sufficient level of polyphenolics in all the solvent extracts. Among all the solvents, acetone provided a higher yield of phenolics, flavonoids, and tannins in all Ocimum species. Black Ocimum showed the maximum level of antioxidants. All Ocimum extracts exhibited a sufficient level of antidiabetic and anti-inflammatory activities. The results indicated that by using appropriate solvents, bioactive compounds from Ocimum species can be extracted and used as therapeutic agents with potential biological activities.