INTRODUCTION:

Staphylococcus aureus is a gram positive, opportunistic pathogen causing mild to life threatening infections. It is one of the most important causes for hospital and community acquired infections and is a common cause of secondary infections in burn patients leading to the mortality ^[1]. Most of the strains of S. aureus made the disease therapy more complicated owing to their ability to develop and transmit resistance against most commonly used antibiotics such as Penicillin, Methicillin, Vancomycin etc ^[2-5]. Hence, there is always a need for search of antimicrobials from natural sources, in particular from plants. Quisqualis indica Linn. (Combretaceae), commonly known as Rangoon Creeper, is an excellent vine for outdoor gardens. It is distributed all over the world especially on China, Philippines, Bangladesh, Myanmar, India and Malaysia ^[6]. Different parts such as flower, stem and leaf of the plant have shown to posses various medicinal and pharmacological properties such as anti-inflammatory ^[7], antioxidant ^[8], antimicrobial ^[6,9], cytotoxic ^[9], insecticidal ^[10], anti-obesity ^[11], anti-diabetic ^[12], immunomodulatory ^[13], hypolipidemic ^[14]. In the present work, the methanol extracts of leaf and flower of Q. indica are screened for their efficacy against the clinical isolates of S. aureus recovered previously from pus samples of burn subjects.

MATERIALS AND METHODS:

Collection and identification of plant materials:

Leaves (L) and flowers (F) of Q. indica were collected at college campus during April 2013 and identified by Mr. Gopal T.D, Assistant Professor, Department of Botany, Sahyadri Science College (Autonomous), Shivamogga.

Extraction of powdered leaf and flower:

The leaves and flowers were shade dried and powdered in a blender. About 25g of powdered materials were extracted in Soxhlet apparatus using methanol (HiMedia, Mumbai). The methanolic extracts (ME) were filtered through Whatman No. 1 filter paper, concentrated in vacuum under reduced pressure and dried in the desiccator ^[15].

Antibacterial activity of leaf and flower extracts:

Agar well diffusion technique was performed to assess inhibitory activity of leaf and flower extracts against six Staphylococcus aureus isolates (previously isolated from pus samples of burn subjects). The isolates of S. aureus were inoculated into sterile Nutrient broth (HiMedia, Mumbai) tubes and incubated overnight at 37^oC. The broth cultures of S. aureus were aseptically swabbed on sterile Nutrient agar (HiMedia, Mumbai) plates using sterile cotton swabs followed by punching wells of 6mm diameter using sterile cork borer. 100µl of leaf and flower extracts (20mg/ml of Dimethyl sulfoxide [DMSO, 25%]), standard antibiotic (Tetracycline, 1mg/ml of sterile distilled water) and DMSO (25%) were added into respectively labeled wells. The plates were incubated at 37^oC for 24 hours and the zone of inhibition was recorded ^[15].

RESULTS AND DISCUSSION:

Table 1: Inhibitory activity of extracts of Q. indica against S. aureus (Sa) isolates

Bacterial Isolates	Zone of inhibition in cm
Bacterial Isolates	LME	FME	Tetracycline
Sa-01	1.0	2.0	3.1
Sa-02	1.3	1.7	2.7
Sa-03	1.2	1.9	2.4
Sa-04	1.3	2.3	3.3
Sa-05	1.3	1.6	3.2
Sa-06	1.2	1.5	2.8

The inhibitory effect of leaf and flower extracts of Q. indica is shown in Table 1. Both the extracts were effective against all isolates of S. aureus. Inhibition caused by flower extract (Zone of inhibition 1.5 to 2.3cm) was higher than that of leaf extract (Zone of inhibition 1.0 to 1.3cm). Inhibition of clinical isolates by reference antibiotic was higher than that of extracts. DMSO did not cause any inhibition of bacteria.

Plants have been considered as an excellent source of medicinal agents for thousands of years. Biologically active compounds present in the medicinal plants have always been of great interest ^[6]. Earlier studies by several researchers have shown the efficacy of plants to inhibit antibiotic resistant S. aureus. Plants such as Garcinia mangostana^[^16], Zanthoxylum clava-herculis^[17], Cinnamomum zeylanicum^[18], Syzygium aromaticum^[18], Cuminum cyminum ^[18]. In an earlier study, Sanguri et al.^[^6] showed antibacterial efficacy of aqueous and methanol extract of leaves of Q. indica. In another study, Jahan et al. ^[9] found inhibitory effect of stem bark extract of Q. indica against a panel of Gram positive and Gram negative bacteria. Kiruthika et al. ^[19] found inhibitory activity of fresh and dry flower extract of Q. indica against methicillin resistant S. aureus.

CONCLUSION:

In the present work, the methanol extract of leaf and flower of Q. indica exhibited antibacterial activity against clinical isolates of S. aureus. Further studies are to be carried out to isolate active principles from the plant materials and to determine their inhibitory activity.

ACKNOWLEDGEMENTS:

Authors thank Dr. N. Mallikarjun, Associate Professor and Chairman and Dr. R. Onkarappa, Associate Professor, Department of Microbiology, Sahyadri Science College (Autonomous) for the support. Authors are thankful to Principal, Sahyadri Science College (Autonomous), Shivamogga for the facilities provided to conduct work and moral support.

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Received on 17.07.2013 Modified on 06.08.2013

Research J. Science and Tech. 6(1): Jan.-Mar. 2014; Page 23-24