Ethnobotanical Leaflets 13: 422-30, 2009.

Antimicrobial Activity of Sphaeranthus indicus L.

V. Duraipandiyan, P. Kannan and S. Ignacimuthu*

Entomology Research Institute, Loyola College, Chennai,

Tamil Nadu,  India 600 034. Email: [email protected]
* Corresponding author

Issued   01 March 2009

Abstract

Aerial parts and flowers of Sphaeranthus indicus were extracted with n-hexane, benzene, chloroform, ethylacetate and acetone. The extracts were screened for their antimicrobial activity using in vitro disc diffusion method at concentrations of 5, 2.5 and 1.25 mg/disc. The Minimum Inhibitory Concentration (MIC) was tested using broth micro dilution method at concentrations ranging from 5 to 0.039 mg/ml. Significant antibacterial and antifungal activity was observed in hexane extract of flower and aerial parts. The flower extract showed MIC as 0.15 mg/ml against Staphylococcus aureus and the highest MIC (5 mg/ml) was noted for S. epidermidis. The n-hexane extracts of flower and aerial parts showed MIC as 0.15 and 1.25 mg/ml respectively against Candida albicans. In conclusion, the S. indicus flower n-hexane extract seems to be a promising antimicrobial agent.

Key words: Antibacterial activity, antifungal activity, minimum inhibitory concentration, Sphaeranthus indicus. 

Introduction

      Different societies across the world have shown great interest in curing illnesses using plants/plant based drugs. Sphaeranthus indicus L. (Asteraceae) a medicinal plant is wide spread in India and Malaysia. S. indicus has long been used in the treatment of skin infection, bronchitis, jaundice and nervous depression (Nadkarni, 1976). The roots and seeds are considered anthelmintic. The herb is also reported to be useful as a tonic to treat indigestion, asthma, leucoderma and dysentery (Chopra et al. 1956). A novel isoflavone glycoside from leaves (Yadava and Kumar, 1999) and a new sesquiterpene glycoside and sphaeranthanolide were isolated from the flowers of S. indicus and it was found to be an immune stimulant (Shekhani et al. 1990). Medicinal information from tribal healers indicated that S. indicus is used to treat skin disease, cough and fever. The bark, ground and mixed with whey, is said to be useful in treating piles. Flowers are credited with alterative, depurative and tonic properties; leaf juice is boiled with milk and sugar-candy and prescribed for cough. An aqueous extract of the whole plant was slightly toxic to American cockroaches (Chopra et al. 1958). The present study was undertaken to assess the antimicrobial property of the solvent extracts of flowers and aerial parts of S. indicus.

Materials and  Methods

Plant material

      S. indicus was collected from paddy fields from Kancheepuram district of Tamil Nadu, India. The plant was identified and confirmed by a taxonomist and the voucher specimen (ERIB-D-73) was deposited in the herbarium at Entomology Research Institute, Loyola College, Chennai, India.

Preparation of plant extracts

      The flowers and the aerial parts were separated, shade dried and coarsely powdered with electric blender. 200 g powder of flowers and aerial parts were soaked separately in 600 ml of n-hexane, in an aspirator bottle for 72 h. The extracts were collected and concentrated at 40ºC under reduced pressure using rotary evaporator. The extract was stored at 4ºC until further use. The remaining plant residue was subsequently extracted with benzene, chloroform and ethylacetate similar manner. 

Test concentrations                                      

     The crude extracts were dissolved in Dimethyl sulphoxide (DMSO) and extracts were loaded on the 6 mm dia. sterile disc (Himedia, Bombay) with the concentrations of 1.25, 2.5, and 5 mg/disc.

Antimicrobial assay

Test cultures

      Bacteria: Bacillus subtilis MTCC 441, Staphylococcus aureus ATCC 25923, Staphylococcus epidermidis MTCC 3615, Enterococcus faecalis ATCC 29212, Escherichia coli ATCC 25922, Pseudomonas aeruginosa 27853 and Klebsiella pneumoniae ATCC 15380 and fungi; Candida albicans MTCC 227, Aspergillus niger MTCC 1344 and Botrytis cinerea.The National Committee for Clinical Laboratory Standards (NCCLS) (1999) recommended antimicrobial susceptibility test strains acquired from Christian Medical College, Vellore were used in this study. The bacterial cultures were maintained in Nutrient Agar (NA) and fungal cultures were maintained in Sabouraud Dextrose Agar (SDA) slants at 4°C.

      The bacterial cultures were inoculated in Mueller Hinton (MH) broth and incubated at 37ºC for 18 h at 150 rpm. The bacterial inoculum was standardized to 0.8 OD at 660 nm and it was used for disc diffusion method. The final inoculum size of 1x10⁵ CFU/ml for bacteria and 1x10⁴ CFU/ml for Candida were used for broth micro dilution technique. Antifungal screening was carried out by broth micro dilution method; the final inoculum size was 1 x 10⁴ spores/ml.

Disc diffusion method

      Preliminary antibacterial screening was carried out using disc diffusion method (Bauer et al. 1966). Discs with different concentrations of plant extracts were placed on the preinoculated Mueller Hinton Agar (MHA)  plates with respective cultures and were incubated at 37^oC for 24 h. Streptomycin (10 µg/disc) and DMSO were used as positive and negative control, respectively. The inhibition zone around the disc (diameter) was measured and recorded.

Minimum Inhibitory Concentrations (MIC)

      Broth micro dilution method (NCCLS 1999) was used to determine the MIC. This was carried out in 96 well microtitre plates containing 200 µl Mueller Hinton Broth with different concentrations of plant extracts. The final concentration of DMSO was maintained at 0.1% in the test broth. Triplicates were maintained along with the negative control. Plates were incubated at 37°C for 12 h for bacteria and at 27°C for fungi.  MIC was determined as the complete inhibition of growth at lowest concentration.

Results

     Flower extracts with hexane gave pale yellow colour and other extracts were pale brown to brown in colour. Extracts from aerial parts were dark green to dark brown in colour. The yield of the flower extract fell in the range of 0.5-1% (w/w) and that of aerial parts were in the range of 1-2% (w/w) of the dried material.

     Hexane extract of S. indicus (flowers and aerial parts) showed antimicrobial activity against most of the bacteria and fungi tested. Flower extract showed higher activity than the aerial parts against Gram positive bacteria such as B.subtilis, S. aureus, S. epidermidis and E. faecalis which were comparable with antibiotic Streptomycin (10 µg/disc) (Table 1). The fungi Aspergillus niger, Botrytis cinerea and C. albicans were inhibited by the extracts of both the flower and aerial parts. Benzene, chloroform, ethyl acetate and acetone extracts of flower and aerial parts showed some activity at higher concentration (5 mg/disc) against gram positive bacteria.

      The hexane extract of flowers showed MIC at 0.31 mg/ml for B. subtilis, 0.15 mg/ml for S. aureus and 5 mg/ml for S. epidermidis. On the other hand, aerial parts showed higher MIC at 2.5 mg/ml for B. subtilis 5mg/ml for Staphylococcus spp. and 5 mg/ml for E. faecalis compared to flower. Most of the gram negative bacteria showed higher MIC (>5 mg/ml) for both the extracts of flower and aerial parts (Table 3).

      The fungus C. albicans showed MIC at 0.15 mg/ml for flower extract and 1.25 mg/ml for hexane extracts of aerial parts. The hexane extract of aerial parts of S. indicus showed promising antifungal activity against B. cinerea. 100% growth inhibition was observed at 0.625 mg/ml concentration and determined as MIC (Table 2).

Table 1 Antimicrobial activity of flower extracts of Sphaeranthus indicus by disc diffusion method

                                   -   no activity

Discussion

      Hexane extracts of flowers and aerial parts of S. indicus exhibited antibacterial and antifungal activity. The essential oil of S. indicus has been reported for its antifungal activity against plant pathogenic fungi (Rao et al., 1971). A sesquiterpene lactone, 7-hydroxyfrullanolide isolated from S. indicus had antimicrobial activity (Atta-ur-Rahman et al., 1989; Perumalsamy et al., 1999). The inhibition zone of antibiotic streptomycin (10 µg/disc) was comparable with both the flower extract (1.25 mg/disc) and aerial parts extract (2.5 mg/disc) against B.subtilis and S. aureus. Similar antibacterial activity was observed in other plants of the same family  (Roose et al., 1998). Higher inhibition zone was observed in B. subtilis at 5 mg/disc for hexane flower extract. The inhibition zone was directly proportional to the concentration used. Hexane flower extract showed MIC at 0.31 mg/ml for Bacillus sp. whereas the aerial part showed higher MIC at 2.5 mg/ml.

Table 2.  Antimicrobial activity of the extracts of aerial parts of Sphaeranthus indicus by disc diffusion method

-  no activity

     The extracts of flower and aerial parts showed inhibition against gram positive organisms but not against gram negative organisms. Similar results were observed in Chrysanthemum coronarium flower extract (Urzua and Mendosa, 2003). Sesquiterpene lactones from Vernonia colorata, possessed high antibacterial activity primarily against Gram positive and low activity against Gram negative species (Rabe et al., 2002) similar to our findings here.

Table 3  Minimum Inhibitory Concentration (MIC) of hexane extracts of Sphaeranthus indicus by broth micro dilution method

      The flower extract showed MIC at 0.15 mg/ml and aerial parts showed MIC at 1.25 mg/ml against C. albicans; this is the first report on anti fungal activity against Candida as per the available literature. The hexane extract of flower showed complete inhibition against A. niger and B. cinerae; the MIC was determined as 1.25 and 0.625 mg/ml respectively. The hexane extract of aerial parts showed MIC as 2.5 and 0.625 mg/ml against A. niger and B. cinerea respectively. The antifungal activity against Trichophyton spp., Epidermophyton floccosum and Microsporum cooki was reported in thiophene compound isolated from Tagetes patula (Asteraceae) (Romagnoli et al., 1998). Antifungal activity was also reported for the ethanol extract of underground parts of Leuzea carthamoides (Asteraceae) against C. albicans, A. fumigatus (Chobot et al., 2003), and Centaurea hermanni (Asteraceae) (Sur-Altiner et al., 1997). which is similar to our results.

Conclusion

      The S. indicus hexane extracts of flower and aerial parts showed good antibacterial activity against gram positive organisms. Flower extracts were more active than the aerial parts. It also possessed strong antifungal activity against Candida and other tested fungi. The findings of the present research may lead to the development of natural antimicrobial agents

References

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Bauer, A.W, Kirby, M.D.K., Sherries, J. C. and  Turck, M. 1966. Antibiotic susceptibility testing by standard single disc diffusion method. Am J. Clin. Pathol. 45:493-6.

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