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

Ngaitad S Njinga; Moji T Bakare-Odunola; Sa'ad T Abdullahi; Fehintola F Abdulmajeed; Ronke H Bello; Rihanat A Saadu; Mustapha Aliyu; Godshelp O Egharevba; Bamidele O David; Abiodun O Shittu

Ngaitad S Njinga Department of Pharmaceutical and Medicinal Chemistry, Faculty of Pharmaceutical Sciences, University of Ilorin, P.M.B. 1515, Ilorin, Kwara State, Nigeria.
Moji T Bakare-Odunola Department of Pharmaceutical and Medicinal Chemistry, Faculty of Pharmaceutical Sciences, University of Ilorin, P.M.B. 1515, Ilorin, Kwara State, Nigeria.
Sa'ad T Abdullahi Department of Pharmaceutical and Medicinal Chemistry, Faculty of Pharmaceutical Sciences, University of Ilorin, P.M.B. 1515, Ilorin, Kwara State, Nigeria.
Fehintola F Abdulmajeed 1Department of Pharmaceutical and Medicinal Chemistry, Faculty of Pharmaceutical Sciences, University of Ilorin, P.M.B. 1515, Ilorin, Kwara State, Nigeria.
Ronke H Bello Department of Pharmaceutical Microbiology and Biotechnology, Faculty of Pharmaceutical Sciences, University of Ilorin, P.M.B. 1515, Ilorin, Kwara State, Nigeria.
Rihanat A Saadu Faculty of Pharmaceutical Sciences, University of Ilorin, P.M.B. 1515, Ilorin, Kwara State, Nigeria.
Mustapha Aliyu Faculty of Pharmaceutical Sciences, University of Ilorin, P.M.B. 1515, Ilorin, Kwara State, Nigeria.
Godshelp O Egharevba Industrial Chemistry Programme, Department of Physical Sciences, College of Pure and Applied Sciences, Landmark University, PMB 1001, Omu-Aran, Kwara State, Nige
Bamidele O David Department of Pharmaceutical and Medicinal Chemistry, Faculty of Pharmaceutical Sciences, University of Ilorin, P.M.B. 1515, Ilorin, Kwara State, Nigeria.
Abiodun O Shittu Department of Pharmaceutics and Industrial Pharmacy, Faculty of Pharmaceutical Sciences, University of Ilorin, P.M.B. 1515, Ilorin, Kwara State, Nigeria.

Keywords: Ocimum gratissimum, extract stability, sunlight, ultraviolet light, antimicrobial assay, antiradical activity

Abstract

The content and stability of phenols, flavonoids, saponins and alkaloids in Ocimum
gratissimum upon exposure to sunlight, red and ultra-violet (UV) radiation over a
period of 168 h was investigated as well as the effect of irradiation on its antiradical
and antimicrobial activities. Total phenolic, flavonoids, saponins and alkaloid contents
were determined using standard methods while antiradical and antimicrobial analyses
were determined using 1,1-diphenyl-2-picrylhydrazyl and agar diffusion methods,
respectively. Exposure to sunlight significantly increased (p<0.05) the total phenolic
and alkaloid contents. Ultra-violet and sun light significantly decreased the total
flavonoid and saponin content, while all the three forms of radiation significantly
increased antiradical activity as well as antimicrobial activity against Staphylococcus
aureus. Red and UV light significantly increased the activity against S. aureus while
UV light increased activity against Escherichia coli. These findings suggest
photochemical instability with increased antiradical and antimicrobial activities of the
methanol extracts of O. gratissimum after irradiation.