Phytochemical and Antimicrobial Screening of Indigofera conferta GILLETT (Papilionaceae)

Research Article
Phytochemical and Antimicrobial Screening of Indigofera conferta GILLETT (Papilionaceae)

A.M. Musa, G. Abbas, A.B. Aliyu, M.S. Abdullahi and I.N. Akpulu

Research Journal of Medicinal Plants, 2008, 2(2), 74-78.

Abstract

Antimicrobial activities of the crude methanol extract as well as the n-butanol and residual aqueous fractions from the aerial part of Indigofera conferta used in traditional medicine to treat infected wound were investigated using disc diffusion and broth dilution techniques. The extract and the fractions were tested against Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa, Escherichia coli and Candida albicans using Ampiclox as standard antibiotic. The crude methanol extract and the aqueous fraction exhibited activity against all the organisms tested (zones of inhibition 16-34 and 14-31 mm, respectively). The n-butanol fraction showed activity on Staphylococcus aureus, Bacillus subtilis and Pseudomonas aeruginosa only (zones of inhibition 14-25 mm). Phytochemical screening on crude extract revealed the presence of tannins, flavonoids and steroids. This study showed that the leaves of Indigofera conferta contains active compounds and its antimicrobial activity justifies its use in traditional medicine.

ASCI-ID: 82-42

Table 1). Flavonoids and tannins have been reported to posses antimicrobial activity (Cowan, 1999). The antimicrobial activity of flavonoids is due to their ability to complex with extracellular and soluble protein and to complex with bacterial cell wall while that of tannins may be related to their ability to inactivate microbial adhesions, enzymes and cell envelop proteins (Cowan, 1999). The methanol extract showed zone of inhibition of growth ranging from 16-34 mm against all the test organisms while the residual aqueous fraction produced zone of inhibition ranging from 14-31 mm against the same organisms and for n-butanol fraction, zones of inhibition ranging from 14-25 mm were recorded against Ps. Aeruginosa, Bacillus subtilis and Staphylococcus aureus (Table 2).

The crude methanol extract and residual aqueous fraction were found to have MIC values ranging from 4-6 mg mL^-1 and MBC at 5-7 mg mL^-1 while the n-butanol fraction had MIC values ranging from 5-6 mg mL^-1 and MBC at 6-7 mg mL^-1 (Table 3).

The extract and fractions showed strong activity against S. aureus, this organism is known to play significant role in skin diseases (Srinivasan et al., 2001), this indicate that the plant can be a source of compound that can be effective against skin infections. Pseudomonas aeruginosa and Escherichia coli, two organisms that cause infections that are very difficult to combat due to their multi-drug resistance (Salie et al., 1996; Afolayan and Aliero, 2006) were found to be susceptible to the methanol extract and residual aqueous fraction.

Table 1:	Phytochemical analysis of Indigofera conferta leaves

CME = Crude methanol extract, NBF = n-butanol fraction, AQ = Residual aqueous portion, + = Positive, - = Negative

Table 2:	Results of sensitivity test of methanol extract and fractions against various organisms

Table 3:	MIC and MBC of crude extract and fractions (mg mL^-1)

- = Not determined

This gives an indication that a compound can be obtained from the plant that can be used against infections caused by these organisms. It is important to note that the strong activity of methanol extract and the residual aqueous fraction against Candida albicans indicate that the plant can serve as a source of an antifungal agent and that antifungal compound can be isolated from the residual aqueous fraction.

The antimicrobial activities observed with the methanol extract, n- butanol and residual aqueous fractions suggest the presence of bioactive compound(s) which can serve as antimicrobial agent or lead compound for the synthesis of an effective and less toxic antimicrobial agents.

In conclusion, the study showed that the methanol extract, n-butanol and residual aqueous fractions from the leaves of Indigofera conferta have anti-microbial properties which explain the basis for its use in traditional medicine to treat sore feet.

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