Bangladesh Journal of Pharmacology Volume: 16; Number 3; Year 2021 Cite this article as: Segaran G, Sathiavelu M. Antibacterial activity of Alternanthera versicolor. Bangladesh J Pharmacol. 2021; 16: 114-16. Bangladesh J Pharmacol 2021; 16: 114-116 A Journal of the Bangladesh Pharmacological Society (BDPS) Journal homepage: www.banglajol.info; www.bdpsjournal.org 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, Global Health, 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.v16i3.54940 Letter to the Editor Antibacterial activity of Alternanthera versicolor Sir, Amaranthaceae is a cosmopolitan family with 64 genera and over 800 species. The Chinese crude medicine "Han -lian-cao" is extracted from the whole plant or aerial portion of Alternanthera sessilis and Eclipta prostrate in Taiwan (Hundiwale et al., 2012). A. bettzickiana is a prostrate perennial herb with decorative and food values (Pamila and Karpagam, 2018). The presence of amino acids, alkaloids, carbohydrates, flavonoids, glycosides, saponins, sterols, triterpenoids, tannins, phenolics and protein in A. brasiliana leaves were reported in water and ethanol extracts. Plant alkaloids are the most effective bioactive chemicals. Antioxidant properties are proven to exist in flavonoids and phenols. Antioxidant property and their impact on the defence system against oxidative damage are mainly due to the existence of hydroxyl groups in their structures (Kasthuri et al., 2018). In certain places, A. philoxeroides is useful against bacterial incursions because it contains several bioactive substances such as oleanolic acid, phaeophytin a and phytol. Alternanthin B and N-trans-feruloyl-3, 5-dimethoxytyramine are the antitumor compound from A. philoxeroides (Akbar et al., 2021). Antihistaminic, antihepatotoxic, antiviral (HSV-1 and HIV), antileukemic, anticarcinogenic and diuretic activities are the pharmacological properties reported to be present in A. tenella, A. sessilis, A. philoxeroides, A. brasiliana and A. pungens (Petrus et al., 2014). The study plants were collected from the Vellore Institute of Technology, Vellore District, Tamil Nadu. The fresh and healthy plants were carefully cleaned 3-4 times with running tap water and sterile water. Then the leaves were shade dried for 10 days at room temperature before being powdered with an electric blender. About 10 g of dried leaves powder were soaked in 100 mL of methanol, dichloromethane and ethyl acetate (solvents with different polarity) and kept overnight in a rotating shaker at 120 rpm. Using Whatman filter paper No. 1, the extracts were filtered and the filtrates were kept in an airtight container for further studies. The preliminary phytochemical analysis was done for the different extracts of the study plant using the standard protocol (Sundar et al., 2017). Antibacterial activity of plant crude extracts was performed through the agar well diffusion method (Passari et al., 2015). Bacillus subtilis, Listeria monocytogenes and Staphylococcus aureus (Gram positive) and Escherichia coli and Klebsiella pneumonia (Gram negative) were used as the test pathogen for this study. The agar plates were prepared and seeded with bacterial strains. Using sterile cork borer, wells were made on the agar plate and loaded with 100 µL of plant extracts of different concentrations (25, 50, 100 µg/mL). The plates were incubated overnight at 37°C, and the zone of inhibition was evaluated after the incubation time. Ciprofloxacin is used as positive control (standard). This is the first study to investigate the presence of phytochemicals and antibacterial activity of A. versicolor. The presence of phenol, tannins and saponin in A. versicolor leaf extracts was determined by phytochemical screening. Flavonoids are not present. This research plant possesses bioactive components that are beneficial for its antibacterial property, as per the results of the agar well diffusion experiment (Figure 1). All the screened plant crude extracts have antibacterial potent against L. monocytogenes and S. aureus (Table I). The greatest inhibition zone was recorded with 32 mm inhibition on S. aureus for methanol extract. Ethyl acetate extract exhibits a significant antimicrobial effect towards Gram positive strains B. subtilis, L. monocytogenes, S. aureus. Dichloromethane extract showed lesser antibacterial activity in comparison to other three extracts. The antibacterial activity of A. versicolor has never been reported before. A study recorded an efficient antibacterial activity of A. bettzickiana against different pathogenic microorganisms (Pamila and Karpagam, 2017; Vidhya et al., 2015). B. pumilus, B. subtilis and Salmonella typhi are susceptible to aqueous extracts of A. sessilis and A. philoxeroides. The chloroform : methanolic (1:1) and aqueous extracts of A. philoxeroides were reported to possess antibacterial activity towards Pseudomonas aeruginosa (Akbar et al., 2021). In the liver of ovariectomized mice, A. bettzickiana enhanced superoxide dismutase and catalase activity. The authors thank VIT, Vellore for providing VIT Seed Grant for carrying out this research work. This work is licensed under a Creative Commons Attribution 4.0 International License. You are free to copy, distribute and perform the work. You must attribute the work in the manner specified by the author or licensor Bangladesh J Pharmacol 2021; 16: 114-116 A B 115 C D E Figure 1: Antibacterial activity of ethyl acetate extract of A. versicolor leaves. Bacillus subtilis (A), Listeria monocytogenes (B), Staphylococcus aureus (C), Escherichia coli (D), Klebsiella pneumoniae (E) Table I Antibacterial properties of A. versicolor leaf extracts using agar well diffusion method Extract Methanol Ethyl acetate Dichloromethane Standard (ciprofloxacin in mg) Concentration (µg/mL) Bacillus subtilis Listeria monocytogenes 25 50 100 25 50 100 11 13 17 14 16 17 10 18 21 14 14 16 25 - Zone of inhibition (mm) Staphylococcus aureus Escherichia coli Klebsiella pneumoniae 25 28 32 14 15 18 16 14 16 - 11 12 12 10 - - 50 18 12 11 100 25 15 15 30 40 40 10 36 Gayathri Segaran and Mythili Sathiavelu Department of Biotechnology, School of Biosciences and Technology, Vellore Institute of Technology, Vellore, India. 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