Ethnobotanical Leaflets 12: 1236-39. 2008.
Preliminary Phytochemical Studies and Antibacterial Activity of Ocimum sanctum L.
Dept. of Plant biology & plant biotechnology,
St. Joseph’s college, Trichirappalli-620 002,
Tamil Nadu, India
Issued 15 December 2008
Ocimum sanctum, commonly known as ‘Sacred basil’ or ‘Holy basil’, is grown as a household plant in India. This preliminary phytochemical study was carried out in acetone, benzene and chloroform extracts and the results showed the presence of numerous phytochemical compounds. The antibacterial activity was analyzed using four different bacterial strains (E.coli, Bacillus subtilis, Staphylococcus aureus and Klebsiella pneumonia) by using agar disc diffusion method. Our bacterial assay revealed that the extracts showed good antibacterial activity, but the acetone extract didn’t show any specific activity. The presence of the phytochemicals signifies the potential of Ocimum sanctum as a source of therapeutic agents and may provide leads in the ongoing search for antimicrobial agent from plants.
Keywords: Holy basil, antibacterial activity, Staphylococcus aureus, agar disc diffusion method.
Medicinal plants have been used for centuries as remedies for human diseases because they contain components of therapeutic value (Nostro et al., 2000). About 80% of the world population relies on the use of traditional medicine which is predominantly based on plant material (WHO, 1993). The scientific studies available on a good number of medicinal plants indicate that promising phytochemicals can be developed for many human health problems (Gupta, 1994; Dahiru et al., 2005), including diabetes, cancer and infectious diseases. The continued investigation into the secondary plant metabolites for anti-infective agents has gained importance, because of the alarming increase in the rate of resistance of pathogenic microorganism to existing antibiotics. Therefore the need to develop efficient, safe and inexpensive drugs from plant sources is of great importance.
In India, herbs have long been used for promotion of health, prevention and treatment of diseases (Evans, 1994). Ocimum sanctum L., commonly known as ‘Tulasi’ in Tamil and holy basil in English, has been claimed to be valuable against a wide variety of diseases. Indian Materia Medica describes the use of the plant in the treatment of a number of ailments like bronchitis, rheumatism and pyrexia (Nadkarni, 1976). Studies on the immunomodulatory effect of O. sanctum have been reported for various animal species (Singh et al., 1996; Singh & Majumdar, 1997; Sadekar et al., 1998).
Methods and Discussion
Preparation of plant extracts
Thirty gm of dried powder of Ocimum sanctum leaves were soaked separately in 100 ml of acetone, benzene and chloroform in a separating funnel for 24 hours with intermittent shaking. The plant extracts were then collected and filtered through Whatmann no.1 filter paper separately. From the filtrates, solvents were dried by heating on water bath. The dried powders of the plant extracts were stored at 400C in air tight bottle.
The preliminary phytochemical study was carried out for phenolic compound (Ferric chloride test), Tannins (Gelatin test), Flavanoids, glycosides (Legals test), Steroides, Carbohydrates (Molisch’s test), Amino acids (Ninhydrin test), Saponin (Foam test), Fixed oils (Spot test), Resin, Thiol and their results were reported in Table 1.
The antibacterial activity was assessed by agar diffusion method (Bauer et al., 1996). For assessing the antibacterial activity of each crude extract (10µL/disc containing 30 µg extract) containing disc, chloramphenicol disc (30 mcg/disc) as positive control were used for assessing antibacterial activity.
Results and Discussion
The preliminary phytochemical studies revealed that the acetone, benzene and chloroform extracts have numerous secondary and primary metabolites (see Table 1). The Acetone, Benzene and chloroform extracts of Ocimum sanctum were studied for their antibacterial activity against four different microorganisms (E.coli, Bacillus subtilis, Staphylococcus aureus and Klebsiella pneumonia) by using Agar disc diffusion method. The results are shown in Table 2.
The results showed that benzene and chloroform extracts of O. sanctum are effective against Staphylococcus aureus, Klebsiella pneumoniae and Bacillus subtilis. There was no activity against E.coli. Acetone extract of O. sanctum shown strong strong activity against klebsiella pneumonia, but less antibacterial activity against Staphylococcus aureus and Bacillus subtilis.
Bauer, A.W., T.M. Sherris and W.H.M. Kirbay, 1996. Antibiotic susceptibility testing by standardizing single disc method. Am.J. Clin. Pathol., 45: 493-496.
Dahiru, D., William, E.T. and Nadroi, M.S. 2005. Protective effects of Ziziphus mauritiana leaf
extract on carbon tetrachloride-induced liver injury. African Journal of Biotechnology, 4(10):1177-1179.
Evans, M., 1994. A Guide to Herbal Remedies. Orient paper back, Delhi: 9–12.
Gupta, S.S. 1994. Prospects and perspectives on natural plant products in medicine. Indian Journal of Pharmacology, 26:1-2.
Nadkarni, K.M., 1976. Nimbah. In Nadkarni (ed.), Indian Materia Medica Vol. I. 3rd edn. Bombay and Popular Prakashan Pvt. Ltd., Bombay, India: 323–325.
Nostro, A., Germanŏ, M.P., D’Angelo, V., Marino, A. and Cannattelli, M.A. 2000. Extraction Methods and Bioautography for Evaluation of Medicinal plants Antimicrobial activity. Letters in Applied Microbiology, 30:379-384.
Sadekar, R.D., A.Y. Kolle, B.S. Barmase and V.F. Desai, 1998. Immunopotentiating effects of Azadirachta indica (Neem) dry leaves powder in broilers, naturally infected with IBD virus. Indian J. Exp. Biol. 36: 1151–1153.
Singh, S. and D.K. Majumdar, 1997. Evaluation of anti-inflammatory activity of fatty acids of O. sanctum fixed oil. Indian J. Exp. Biol. 35: 380–383.
Singh, S., D.K. Majumdar and M.R. Yadav, 1996. Chemical and pharmacological studies on fixed oil of O. sanctum. Indian J. Exp. Biol. 34: 1212–1215.
WHO, (1993) Regional Office for Western Pacific, Research Guidelines for Evaluating the Safety and Efficacy of Herbal Medicines. Manila. p. 2.
Table 1. The preliminary phytochemical constituents of O. sanctum.
(++) ® Dark colour, (+) ® Presence, (-) ® Absence
Table 2. The antimicrobial activity of Ocimum sanctum against bacterial strains.