Exploring the therapeutic dimensions of Morinda citrifolia: Antibacterial efficacy, phytochemical profiling, and the prospect of a health-promoting beverage

Abstract

Morinda citrifolia, commonly known as noni, has attracted attention for its potential medicinal properties, especially in traditional Polynesian and Sri Lankan folk medicine. Considering the global need for novel antibiotics due to the emergence of antibiotic-resistant bacterial strains, this study investigates the antibacterial activity of Morinda citrifolia cultivated in Sri Lanka. The objective is to explore antibacterial efficacy, and identify active compounds within the plant, emphasizing its suitability for pharmaceutical applications. Focused on the unique environmental conditions of Sri Lanka, the research addresses a critical gap in the existing literature, where comprehensive studies on the antibacterial properties of Morinda citrifolia cultivated in this region are scarce. The investigation systematically evaluates variations in antibacterial activity by examining distinct plant components (roots, leaves, bark, and fruit) and utilizing diverse solvent extraction methods. Samples are meticulously collected from three major districts in Sri Lanka— Colombo, Gampaha, and Kalutara. Solvent extraction methodologies include methanol, petroleum ether, and acetone. Antibacterial efficacy is assessed against five microorganisms (Escherichia coli, Staphylococcus aureus, Bacillus cereus, Pseudomonas aeruginosa, and Klebsiella pneumoniae) through a disc diffusion assay. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) are determined to ascertain the concentration inhibiting bacterial growth and ensuring eradication, while phytochemical screening elucidates active compounds within Morinda citrifolia extracts. Results of this study reveal solvent-specific variations in antibacterial efficacy, with methanol and acetone extracts demonstrating heightened effectiveness. Combined extracts exhibit augmented antibacterial activity, suggesting potential synergistic effects. MIC and MBC assessments confirm the bactericidal efficacy of Morinda citrifolia extracts, with methanol and acetone extracts consistently displaying the lowest values, both exhibiting MIC and MBC results of 100 mg/ml. Phytochemical screening reveals a diverse spectrum of active compounds within the plant, including terpenoids, steroids, saponins, phenols/tannins, carbohydrates, and flavonoids. This research, serving as the inaugural step in the development of a therapeutic beverage utilizing Morinda citrifolia, underscores the plant's potential application in novel antimicrobial therapies against resistant strains. The findings corroborate that Morinda citrifolia exhibits notable antibacterial resistance against pathogenic bacteria, albeit with efficacy levels lower than those of gentamicin. This underscores the therapeutic potential of Morinda citrifolia in terms of antibacterial efficacy and phytochemical constituents. The results strongly suggest the viability of developing a health-promoting beverage derived from Morinda citrifolia, though further research is warranted. Nonetheless, the study substantiates both the plant's antibacterial efficacy and the identification of key active compounds, accentuating its potential in pharmaceutical applications.