Bangladesh Journal of Pharmacology Volume: 11; Number 2; Year 2016 Cite this article as: Chander MP, Vijayachari P. In vitro antimicrobial and anti-oxidant potentials of selected me- dicinal plants used by the indigenous tribes of Andaman and Nicobar Islands, India. Bangladesh J Pharmacol. 2016; 11: 330-32. In vitro antimicrobial and anti-oxidant potentials of selected medicinal plants used by the indigenous tribes of Andaman and Nicobar Islands, India Sir, Systematic screening of plants used in traditional medi- cines could pave the way for the discovery of novel and effective compounds (Diallo et al., 1999). In the contem- porary, emergence of multidrug resistant strains of bacteria is being frequently noticed, and quite recently, this phenomenon has been critically analyzed and documented (Chethana et al., 2013). It indicated the necessity to continue the search for newer compounds to combat new infections. In the present study, the traditional knowledge of treatment among the Nicobarese tribe was generated (Chander et al., 2014), and 18 plant species which are regularly used in traditional medicines were selected, to determine their antibacterial and anti-oxidant activities as well as preliminary photochemical analysis. Hundred grams of coarsely powdered dry leaves were extracted by cold percolation method, by using 95% methanol as a solvent and keeping it for 72 hours at room temperature (Chattopadhyay et al., 2001). The whole plant extract was collected in a conical flask, filtered, and the solvent was evaporated to dryness under reduced pressure in an evaporator (Eppendroff 5304) at 45°C. Resulted residues were stored at 4°C for the purpose of further in vitro studies. The plant extracts were screened for the presence of different classes of secondary metabolites including alkaloids, flavonoids, triterpenes, sterols, tannins and saponins using previously described methods (Harborne, 1998; Kokate et al., 2004). The plant extracts were screened for antibacterial activity using the agar well diffusion method (Rojas et al., 2006). DPPH assays of sample were performed according to the procedure as reported by Singh et al. (2015). The phytochemical studies reveals that the extracts of medicinal plants have variety of phytochemical consti- tuents, namely alkaloids, triterpenes, flavonoids, tannins, steroids and saponins, whereas some of the phytochemical are restricted to certain medicinal plant species except the alkaloids which was reported in all the studied plant species (Table I). However, saponins were absent in seven extracts while in six extracts tannins were not found. A Journal of the Bangladesh Pharmacological Society (BDPS) Bangladesh J Pharmacol 2016; 11: 330-332 Journal homepage: www.banglajol.info Abstracted/indexed in Academic Search Complete, Agroforestry Abstracts, Asia Journals Online, Bangladesh Journals Online, Biological Abstracts, BIOSIS Previews, CAB Abstracts, Current Abstracts, Directory of Open Access Journals, EMBASE/Excerpta Medica, Google Scholar, HINARI (WHO), International Pharmaceutical Abstracts, Open J-gate, Science Citation Index Expanded, SCOPUS and Social Sciences Citation Index ISSN: 1991-0088; DOI: 10.3329/bjp.v11i2.26771 Letter to the Editor Table I Phytochemical analysis of the methanol extracts of selected ethnomedicinal plants Scientific name Alkaloids Flavonoids Triterpenoids Sterols Tannins Saponins Abutilon indicum (L.) Sweet Present Present Present Present Present Present Ageratum conyzoides L. Present Present Present Present Absent Absent Annona squamosa L. Present Present Present Present Present Absent Boesenbergia rotunda (L.) Mansf. Present Present Present Present Present Present Cleome viscosa L. Present Present Absent Absent Present Present Ganophyllum falcatum Blume. Present Present Present Present Present Present Glyptopetalum calocarpum (Kurz.) Prain Present Present Present Present Present Present Ipomoea obscura (L.) Ker.- Gawl. Present Absent Absent Present Present Absent Leea aequata L. Present Absent Present Present Absent Absent Leea indica (Burm.f.) Merr. Present Present Present Present Absent Absent Macaranga peltata (Roxb.) Muell. Present Absent Present Present Absent Absent Morinda citrifolia L. Present Present Present Present Present Present Moringa oleifera Lam Present Present Present Present Absent Present Premna corymbosa (Burm.f.) Rottl. et Willd. Present Present Present Absent Present Absent Senna alata (L.) Roxb. Present Present Absent Absent Absent Present Tabernaemontana crispa Roxb. Present Absent Absent Absent Present Present Urena lobata L. Present Present Present Present Present Present Wedelia biflora (L.) DC. Present Present Present Present Present Present The antimicrobial activities of the investigated extracts against human pathogens used by agar well diffusion method were shown in Table II. Extracts was compared with gentamicin and nystatin as standards. Results obtained in the current study relieved that selected plant extracts were found to possess potential anti- microbial activity against tested organisms. The M. citrifolia extract showed activity against all the pathogens tested followed by B. rotunda and G. calocarpum while the highest activity (21.7 ± 0.6) was shown by M. citrifolia against K. pneumonia. The effect of anti-oxidant on DPPH radical scavenging was thought to be due to their hydrogen donating ability or radical scavenging activity. The free radical scavenging activity depends upon the chemical composition of extracts (Nilgun et al., 2007). The DPPH radical scavenging results showed that M. citrifolia extract exhibited highest activity having IC50 value 26.4 ± 0.9 µg/mL followed by L. indica and M. oleifera (Table II). Thus, this study indicates that scientific studies carried out on medicinal plants having traditional claims of effectiveness might warrant fruitful results. The authors acknowledge to the Indian Council of Medical Research (ICMR), New Delhi, India for providing financial grant for the study (Project No. Tribal/43/2008-ECD-II). Authors are also thankful to Botanical Survey of India, Port Blair for their help in identification of plant specimens. M. Punnam Chander and P. Vijayachari Department of Medical Microbiology and Molecular Biology, Regional Medical Research Centre (Indian Council of Medical Research), Port Blair 744 101, Andaman and Nicobar Islands, India. Corresponding author: email: pblicmr@sancharnet.in Bangladesh J Pharmacol 2016; 11: 330-332 331 Table II Antimicrobial and anti-oxidant activities of the selected ethnomedicinal plants Botanical Name Sa Se Bc Ec Pa Kp Ca DPPH activity IC50 (µg/mL) A. indicum – – – 11.0 ± 0.0 – 9.7 ± 0.6 – 80.7 ± 0.5 A. conyzoides – – – – – – – 96.1 ± 1.7 A. squamosa – – – – – – – 49.3 ± 0.7 B. rotunda 14.3 ± 0.6 17.7 ± 0.6 17.0 ± 0.0 14.7 ± 1.5 9.7 ± 0.6 12.3 ± 0.6 – 51.4 ± 2.7 C. viscosa – – – – – – – 136.1 ± 2.3 G. falcatum – – – 14.7 ± 0.6 – – – 149.5 ± 3.3 G. calocarpum 18.3 ± 1.5 15.7 ± 1.5 19.7 ± 0.6 – 11.3 ± 0.6 – – 63.2 ± 0.1 I. obscura – – – – – – – 557.6 ± 32.6 L. aequata 12.3 ± 0.6 – – 12.0 ± 0.0 – – – 67.5 ± 0.6 L. indica – – – – – – – 44.2 ± 0.2 M. peltata – – – – – – – 46.7 ± 0.8 M. citrifolia 21.3 ± 0.6 17.0 ± 1.0 14.0 ± 1.0 15.7 ± 1.5 13.3 ± 1.2 21.7 ± 0.6 13.3 ± 0.6 26.4 ± 0.9 M. oleifera – – 10.7 ± 0.6 – – 9.7 ± 0.6 – 44.9 ± 0.2 P. corymbosa 11.3 ± 2.1 – 12.7 ± 0.6 – – – 74.3 ± 0.6 S. alata – – – – – – 12.0 ± 1.0 124.2 ± 1.3 T. crispa – – – – – – – 64.3 ± 2.9 U. lobata – 11.3 ± 0.6 14.0 ± 0.0 10.0 ± 0.0 – – – 47.5 ± 3.1 W. biflora 13.3 ± 0.6 – – – – – – 263.9 ± 12.3 Ascorbic acid ND ND ND ND ND ND ND 13.9 ± 0.1 Gentamicin 17.7 ± 0.6 21.7 ± 0.6 22.7 ± 1.2 18.3 ± 0.6 12.7 ± 0.6 14.0 ± 0.0 – ND Nystatin – – – – – – 17.7 ± 0.6 ND Sa- S. aureus; Se- S. epidermidis; Bc- B. cereus; Ec- E. coli; Pa- P. aeruginosa; Kp- K. pneumonia; Ca- C. albicans; ‘–‘ indicates No activity; ‘ND’ Not done References Chander MP, Kartick C, Gangadhar J, Vijayachari P. 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