Bangladesh Journal of Pharmacology Volume: 18; Number 2; Year 2023 Cite this article as: Shankar S, Ravi ND, Sathiavelu M. Antibacterial activity of Calathea insignis. Bangladesh J Pharmacol. 2023; 18: 75-76. Antibacterial activity of Calathea insignis Sir, Calathea insignis (also known as C. lancifolia, Goeppertia insignis, and G. lancifolia, and Maranta insignis) is a flowering plant native to South America. Its leaves are narrow, erect, lance-shaped yellowish green colour with dark alternating patches and are dark reddish- purple on the lower side. It is used as an ornamental plant because of the colour, shape, and pattern of the leaves (Nguyen et al., 2018). Methanolic extract of the plant C. zebrine has shown good antibacterial activity against bacterial pathogens like Staphylococcus aureus (9 mm), Escherichia coli (17 mm), Streptococci sp (17 mm), and Proteus vulgaris (17 mm) where erythromycin is used as a control. It has a reducing power activity of about 83 mg/mL (Sethi et al., 2015). This study is aimed at evaluating the phytochemical and antibacterial activity of the leaf extracts of the C. insignis plant against bacterial pathogens by using the agar well diffusion method. This is the first study using the extracts of the C. insignis plant. The fresh and healthy leaves of the plant were collected from Thotta kalai nursery garden, ECR, Chennai, Tamilnadu, India. The leaves of the plant were washed well with tap water to remove dust particles and dried without sunlight for 2 weeks. After drying, the leaves were powdered using an electric blender. Solvents like methanol and ethyl acetate which have different polari- ties were used for the extract preparation. About 1 g of the leaf powder was soaked in 100 mL of each solvent in a conical flask and sealed well using parafilm. It is kept in a shaker of 120 rpm for 48 hours. After 48 hours the extracts were filtered using Whatman filter paper No. 1 and evaporated for one week to obtain the crude extracts. Phytochemical screening of the leaf extracts were done according to the protocol (Shankar et al., 2018). The antibacterial activity of the leaf extracts was investiga- ted against Klebsiella pneumoniae, E. coli, Streptococ- cus pneumoniae, and S. aureus by using the agar well diffusion method. The pathogens were stock cultured in nutrient broth. The bacterial culture to be tested was spread on freshly prepared Muller Hinton agar plates with a sterile cotton swab moistened with bacterial culture. By using a sterile cork borer, wells were made in the agar plates and loaded with 100 µL of leaf extract at different concentrations (100, 50, 25 µg/mL), and streptomycin antibiotic disc was used as a positive control. The plates were incubated at 37⁰C for 24 hours and after the incubation period, the zone of inhibition was measured (Sundar et al., 2019). Phytochemical analysis of the leaf extracts indicated the presence of phenol, saponins, and tannins and the absence of flavonoids and terpenoids (Table I). The plant C. zebrine showed the highest percentage of tannins (23 mg/mL) and phenolic content (24.3 mg/ mL) (Sethi et al., 2015). The ethanolic extract of Anthu- rium andraeanum stem showed the presence of phyto- chemicals like tannin and alkaloid along with signi- ficant antibacterial activity against Bacillus cereus (10 mm), K. pneumonia (12 mm) and E. coli (13 mm). (Shazh- ni et al., 2016). Qualitative screening of phytochemical components of Plumbago zeylanica leaves revealed the presence of phenolics, alkaloids, flavonoids, and tan- nins, etc., and also the alcoholic leaf extract of the plant P. zeylanica showed good inhibitory activity against Pseudomonas aeruginosa (17 mm), E. coli (16 mm), B. subtilis (11 mm) and S. aureus (10 mm) at 100 mg/mL (Dhale and Markandeya, 2011). The aqueous extract of blue flowering Silybum marianum plant exhibits signifi- cant phenolic (0.413%) and tannin (0.693%) contents as well as the plant possess potential antibacterial activity against B. subtilis (17 mm), P. vulgaris (15 mm) and S. aureus (21 mm) (Shah et al., 2011). Antibacterial activity was performed for methanol and ethyl acetate leaf extract of the plant C. insignis. The results of the agar well diffusion assay showed signifi- cant activity in both the leaf extracts against S. aureus (Table II). The zone of inhibition was highest A Journal of the Bangladesh Pharmacological Society (BDPS) Bangladesh J Pharmacol 2023; 18: 75-76 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.v18i2.64676 Letter to the Editor 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 Table I Phytochemical screening of Calathea insignis leaf extracts Phytochemicals Methanol Ethyl acetate Flavonoids - - Phenol +++ + Saponins ++ + Terpenoids - - Tannins + +++ +++ indicates highly positive; ++ indicates moderately positive; + indicates low positive; - indicates negative in S. aureus with 28 mm at 100 µg/mL which is follow- ed by 25 mm at 50 µg/mL in the ethyl acetate extract. Whereas, methanolic extract possesses good antibac- terial activity against S. aureus (23 mm) and E. coli (25 mm) at 100 µg/mL. S. pneumoniae and K. pneumo- niae did not show any activity in the extracts. The methanolic extract of Diffenbachia sp showed a signifi- cant antibacterial effect against Cornybacterium diphthe- riae with 12 mm of the zone of inhibition (Chunduri et al., 2015). The methanolic extract of D. penninervi- um showed a 27 mm inhibition zone against E. coli (Kebede et al., 2021). This is the first report on phytochemical screening and in vitro antibacterial screening of C. insignis leaf extracts. Financial support: Vellore Institute of Technology (SG ID: SG20220100) Conflict of Interest: The authors declare that they have no conflict of interest. Acknowledgment: The authors thank VIT, Vellore for providing a VIT seed grant for carrying out this research. Saranya Shankar, Narmadha Devi Ravi and Mythili Sathiavelu Department of Biotechnology, School of Bio Sciences and Technology, Vellore Institute of Technology, Vellore, India. Corresponding author: email: smythili@vit.ac.in References Chunduri JR, Jagtap P, Panchal S, Sagar S. Indoor ornamental plants and their antimicrobial properties. Int J Institutional Pharm Life Sci. 2015; 5: 246-49. Dhale DA, Markandeya SK. Antimicrobial and phytochemical screening of Plumbago zeylanica Linn. (Plumbaginaceae) leaf. J Exp Sci. 2011; 2: 4-6. Kebede T, Gadisa E, Tufa A. 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Phytochemical consti- tuents of Dracaena Mahatma leaves and their antibacterial, antioxidant, and anti-inflammatory significance. Biotechnol Res Innov. 2018; 2: 1-8. Shazhni AJR, Renu M, Murugan M. Phytochemical screening and in vitro antimicrobial activities of an ornamental plant Anthurium andraeanum. J Pharm Sci Res. 2016; 8: 668-70. Sundar RDV, Srikanth L, Manognya PS, Yuvaraja S, Aruna- chalam S. In vitro antibacterial activity of Dracaena victoria leaf extract. Bangladesh J Pharmacol. 2019; 14: 202- 03. 76 Bangladesh J Pharmacol 2023; 18: 75-76 Table II Antibacterial activity of Calathea insignis leaf extracts using agar well diffusion method Extract Concentration (µg/mL) Organisms Zone of inhibition (mm) Staphylococcus aureus Klebsiella pneumonia Escherichia coli Streptococcus pneumonia Methanol 25 15 - - - 50 19 - 20 - 100 23 - 25 - Ethyl acetate 25 - - 10 - 50 25 - - - 100 28 - - - Standard (Streptomycin) 10 (mg) 18 28 20 25 mailto:mohanrajupu62@gmail.com