Plant Protection (Scientific Journal of Agriculture)

Plant Protection (Scientific Journal of Agriculture)

Comparative antimicrobial efficacies and phytochemical profiling of three plant extracts against Pseudomonas syringae: a Preliminary study

Document Type : Short communication-ٍEnglish

Authors
Department of Life Sciences, Christ University, Bengaluru – 560029, Karnataka, India
Abstract
This study evaluated the phytochemical profile and antimicrobial effects of extracts from Colocasia esculenta, Ocimum tenuiflorum, and Murraya koenigii. Well diffusion tests and minimum inhibitory concentration (MIC) testing revealed that the extracts of Murraya koenigii and Ocimum tenuiflorum exhibited comparable antibacterial activity against Pseudomonas syringae. Although this difference was not statistically significant, Murraya showed a numerically larger mean zone of inhibition (21.0±4.6 mm at 100 mg/mL) than Ocimum (13.3±1.2 mm). The least active was Colocasia esculenta with a zone of inhibition of 12.3±0.6 mm. Phytochemical screening revealed that all extracts included alkaloids, phenolics, flavonoids, and terpenoids. Although the experiment was qualitative, the GC-MS data clearly showed the main factors impacting antibacterial activity. While Ocimum tenuiflorum included significant phenolic and terpenoid compounds, including eugenol, caryophyllene, and linalool, Murraya koenigii contained carbazole alkaloids, such as mahanimbine and koenimbine. In contrast, Colocasia esculenta primarily include sterols and fatty acids, which are consistent with its lower inhibition zones and generally have less antibacterial qualities. A limitation of this study is that the active constituents were not isolated or quantitatively evaluated. These compounds from plants have potential as long term substitutes for synthetic antimicrobials, complementing sustainable agricultural methods. Further research is required to identify and characterise the active components for usage in agriculture and medicine. Thus, this study highlights the use of traditional medicinal plants to address the issues of existing antibiotic resistance and provide sustainable solutions.
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