Effects of Ultra-Violet, Red and Sun Light on the Stability of Phytochemicals, Antiradical and Antimicrobial Activity of Ocimum gratissimum Linn. (Lamiaceae)

The content and stability of phenols, flavonoids, saponins and alkaloids in Ocimumgratissimum upon exposure to sunlight, red and ultra-violet (UV) radiation over aperiod of 168 h was investigated as well as the effect of irradiation on its antiradicaland antimicrobial activities. Total phenolic, flavonoids, saponins and alkaloid contentswere determined using standard methods while antiradical and antimicrobial analyseswere determined using 1,1-diphenyl-2-picrylhydrazyl and agar diffusion methods,respectively. Exposure to sunlight significantly increased (p\u003c0.05) the total phenolicand alkaloid contents. Ultra-violet and sun light significantly decreased the totalflavonoid and saponin content, while all the three forms of radiation significantlyincreased antiradical activity as well as antimicrobial activity against Staphylococcusaureus. Red and UV light significantly increased the activity against S. aureus whileUV light increased activity against Escherichia coli. These findings suggestphotochemical instability with increased antiradical and antimicrobial activities of themethanol extracts of O. gratissimum after irradiation.