Ethnobotanical Leaflets 12: 1236-39. 2008.
Preliminary Phytochemical Studies and Antibacterial Activity of Ocimum sanctum L.
Dept. of Plant biology & plant biotechnology,
Issued 15 December 2008
commonly known as ‘Sacred basil’ or ‘Holy basil’, is grown as a household
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.
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.
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Table 1. The preliminary phytochemical constituents of O. sanctum.
(++) ® Dark colour, (+) ® Presence, (-) ® Absence
Table 2. The antimicrobial activity of Ocimum sanctum against bacterial strains.