Antibacterial activity of various extracts of Abutilon pannosum (Forst.f.) Schlecht. leaves

In our present study, we carried out the antibacterial activity of the plant Abutilon pannosum (Forst.f.) Schlecht., which is a cosmopolitan genus belonging to the family of Malvaceae. Different parts of this plant are in use to treat various ailments in ethnomedicine especially its leaves have been used for treating infections. We studied the anti bacterial activity of the extracts prepared from the dried leaves of A. pannosum (Forst.f.) Schlecht., using agar-well diffusion method against both Gram positive and negative microorganisms. Among all the extracts the ethanolic extract of the leaves showed significant (P<0.001) antibacterial activity comparable to the standard penicillin potassium and streptomycin sulphate against selected gram positive and gram negative bacteria.


INTRODUCTION
Malvaceae is a cosmopolitan family with 88 genera and more than 2300 species distributed in tropical, subtropical and temperate regions. Abutilon is one of the important genus of this family (Nasir and Ali, 1979). Various species of the genus Abutilon is used in indigenous medicines for the treatment of various ailments (Bagi et al., 1985;Rahuman et al., 2008, Land andNorton, 1973). Among this, Abutilon pannosum, is an under shrub and is distributed in India, Pakistan, Tropical Africa, China and Arabia. The only reference available in the literature on this species describes the presence of quercetine kaemferol and flavonoids derivative (Sharma and Ahmad, 1989;Abedin, 1980;Akiyama et al., 2001;Sammia, 2008;Gaind and Chopra, 1976). A. pannosum roots are medicinally used in jaundice (Hatil, 2009;Badami et al., 1976). No information in the literature was found concerning its possible antibacterial activity. However, some experiments have shown antibacterial activity on some other species of genus Abutilon (Robert, 1986;Muhammad et al., 2009;Arulsamy et al., 2009;Survase et al., 2012).
The present study was carried out to determine the antibacterial activity of different extracts of the leaves on Gram positive and negative micro-organisms against penicillin potassium (20 units/ml) and streptomycin sulphate (25 μg/ ml).

Collection of plant materials
The leaves of A. pannosum used in this study were collected from Beed Parli Road, Beed District (M.S.) India, Accession no. 7781, voucher specimen deposited in the Department of Botany of Dr. Babasaheb Ambedkar Marathwada University, Aurangabad. The leaves were shade dried and powdered. Two hundred grams of the powder were successively extracted with different solvents and *Corresponding author. E-mail: sasurvase@gmail.com. the extractive values were calculated.

Reagents and chemicals
Standard drugs Penicillin potassium and streptomycin sulphate were collected from Government of Science Institute and Y. B. Chavan Pharmacy College, Aurangabad. Peptone, beef extract and all other chemical grade were obtained in the Department of Botany, Dr. Babasaheb Ambedkar Marathwada University, Research Laboratories, Aurangabad.

Preparation of the extracts
Different extracts of the dry powdered leaves were prepared by successive continuous hot percolation using Soxhlet extractor with different solvents like petroleum ether, acetone, Hexene, methanol and water. All the extracts were filtered and evaporated to dryness under reduced pressure and stored in the refrigerator for future use.

Evaluation of antibacterial activity
The antibacterial activity was carried out by the agar well diffusion method using Muller Hinton agar plates (Nair andChanda, 2004, Singh et al. 1988). Petroleum ether, acetone, hexane, methanol extract and water extract were dissolved in dimethyl sulphoxide (250 mg/10 ml). Streptomycin sulphate (25 μg/ml) and penicillin potassium (20 units/ml) were used as standards for Gram positive bacteria and Gram negative bacteria, respectively. 0.1 ml of the samples was added to each cup. The zones of inhibition produced by the extracts were compared with the standards.

Statistical analysis
The results obtained were analyzed statistically using student test and any p < 0.001 considered significant (Mungikar, 2003).

RESULTS
The extractive values of different solvents were tabulated in Table 1. The methanolic extract of A. pannosum was found to produce significant (P<0.001) anti bacterial activity, than the other extracts, against the Gram positive organisms like Bacillus subtilis, Staphylo-coccus aureus, Sarcina leuka, Bacillus megaterium and Gram negative organisms like Escherichia coli, Pseudomonas aeruginosa, Proteus vulgaris, Shigella sonnie, when compared with the standard antibiotics, Penicillin potassium and Streptomycin sulphate are tabulated in Tables 2 and 3. The petroleum ether extract did not produce any significant antibacterial activity (P>0.05) when compared with standards.

DISCUSSION
The results of the agar-well diffusion method showed that the crude methanolic extracts of A. pannosum exhibits antimicrobial activity against the Gram positive organisms such as B. subtilis, S. aureus, S. leuka, B. megaterium and gram negative organisms E. coli, P. aerugenosa, P. vulgaris, S. sonnie with a maximum diameter of zone of inhibition ranging from 23.3 mm accompanied by ≥19.4 and 17.1, 20.5, 21.4, 20.0, 23.5 and 21.1 mm, respectively. It produced a comparable activity similar to the standard antibiotics taken for the study.
active principle responsible for the activity will reveal one or more novel antibacterial agents.