African Journal of Biomedical Research, Vol. 9, Vol. 1, 2006, pp. 67-68

Short Communication

Antifungal potential of flower head extract of Spilanthes acmella Linn. 

Sabitha A. Rani and Suryanarayana U. Murty*

Bioinformatics Group (Biology Division), Indian Institute of Chemical Technology, Hyderabad 500 007, India.
*Author to whom the correspondence should addressed: Tel. 00-91-40-27193134; Fax: 00-91-40-27160757

Code Number: md06011

Keywords: Antifungal/ evaluation/ flower head extract/ S.acmella/ inhibition zone)

INTRODUCTION 

The indiscriminate use of chemical pesticides has given rise to serious environmental pollution, genetic resistance of pests, toxic residues in stored products and hazards from handling etc. Therefore, there is a need to develop botanical pesticides which are effective, biodegradable, broad-spectrum of activity and do not leave any harmful effect on environment.  During last few decades, many plant species have been screened and plant-based products from a variety of sources have been identified and developed in this regard. The Asteraceae constitutes one of the largest vascular plant family, with 30,000 species and over 1100 genera. Most of these plants exhibit antimicrobial activity due to the production of sesquiterpene as principal secondary metabolites.

The present study was aimed to evaluate the Spilanthes acmella Linn. (Asteraceae) against the potential human pathogens Asperigillus flavus,  A. paraciticus and agricultural pathogens  Fusarium oxysporium and F.  moniliformis.The genus Spilanthes contains 35 tropical species, of which three of them are reported from India.  Spilanthes acmella Linn. (Family-Asteraceae) is an important medicinal plant commonly known as Akarkara or toothache plant with rich source of therapeutic constituents.    It is an annual, spreading plant with bi-coloured, red/gold flower buds.  The roots, flower heads and whole aerial part yield a compound known as spilanthol, which is a powerful stimulant, sialogogue and local anesthetic. In Ayurvedic system of medicine, flower heads and roots are used in treatment of scabies, psoriasis, scurvy, toothache, infections of gums and throat, paralysis of tongue and remedy for stammering in children (Anonymus, 1976).  Because of its high medicinal value, there is a much demand of this plant in the market.

Plant Material and Chemical Extraction:

The dried flower heads of Spilanthes acmella were procured from the garden, IICT, Hyderabad.  Flower heads were air dried and extracted with petroleum ether (40-60°C) using a Soxhlet apparatus. The extracts were filtered and concentrated in vacuum rotavapour. Different concentrations of plant extract (0.1, 0.4. 1.0.1.6, and 2.0 mg.) were made by dissolving in DMSO (Dimethyle Sulphoxide). 

Test organisms: Four test organisms, Aspergillus niger, Aspergillus paraciticus, Fusarium oxysporium, Fusarium monilifarmis, were obtained from Institute of Microbial Technology, Chandigarh and maintained on Potato Dextrose Agar (PDA).  

Bioassay: Agar cup bioassay was employed for testing antifungal activity of plant extract (Linday, 1962).  The ready-made PDA medium (Hi-media, 39g) was suspended in distilled water and autoclaved at pressure of 15 lb/inc² for 20 min. Seven days old   cultures of   test organisms (0.5 ml) were seeded onto plate and uniformly spread with   spreader.  Six to eight wells (8mm) were made on PDA plate with sterile cork borer. To each well, different concentrations of test solutions (0.1mg to2.0 mg) were added. Controls were maintained with DMSO only. The treated and the controls were kept in an incubator at 37°C for 24h to 78h and inhibition zones were measured.  Three to four replicates were maintained for each treatment. 

RESULTS AND DISCUSSION  

Effect of different concentrations (0.1 to 2.0 mg) of S.acmella flower head extract was tested against four different fungi (Table 1).  All the concentrations of the test solution inhibited the fungal species with varying degree of sensitivity.   The anti-fungal activity was very less at 0. 1mg concentration. The low activity of extract at lower concentrations may be due to the crude nature of the test solution.  The diameter of inhibition zones ranged from 0.1 to 2.3 cm    among different fungal species and increased with the increase in concentration of test solution. The maximum zone of inhibition was found at 2000μg concentration. Among the test organisms, high inhibition zones were observed in F.  oxysporium (2.3 cm) and F.moniliformis. (2.1 cm) followed by A. niger (2.0) and A. paraciticus (1.8 cm).  

Table 1: Antifungal activity of Spilanthes acmella (flower head) extract on different fungi.

A similar study of screening the natural plant extracts against different fungal and bacterial pathogens was well recorded in literature (Ahmad et al 2000; Fabry et al 1998). Since plants have co-evolved with pathogens, it is reasonable to expect a variety of such compounds with specific as well as general antifungal activity (Darokar   et al 1998). The activity of different concentration of S..acmella extractmay bedue to the presence of pungent amide spilanthol and alkamides (Nakatani, 1992). Besides this, non-volatile sesquiterpenoids and saponins are also reported. (Krishnaswami et al 1975; Mukharya  et al 1986).. Though some earlier reports of antimicrobial activity of some Asteraceae members (Rai et al 1999) and S calva   (Rai et al 2004) were available, the present study of antifungal activity of S. acmella is a significant contribution. The present study   has shown that the flower head extract of S.acmella   possesses remarkable fungi toxic activity against many human and agricultural pathogens. Thus, there is a possibility of developing this plantas a source of antifungal agent and further investigations are necessary to identify the bioactive principles. 

Acknowledgements:

The authors are grateful to DST, New Delhi for financial assistance  and the  Director, IICT, Hyderabad for his encouragement and support. 

REFERENCES