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.
