Phytochemistry, antibacterial and toxicity properties of Phyllanthus emblica linn fruit extracts against gastrointestinal pathogens and their interactions with antibiotics

Phyllanthus emblica L. (syn. Emblica officinalis Gaertn.), widely known as amla or Indian gooseberry, holds a significant place in Ayurvedic medicine due to its reputed benefits in promoting longevity, enhancing digestion, and strengthening immunity. Traditionally, its fruits have been used to treat respiratory infections, skin ailments, and gastrointestinal disorders. This research examined the antibacterial activity of P. emblica fruit extracts against the major gastrointestinal bacterial pathogens Bacillus cereus , Shigella flexneri , Shigella sonnei , and Salmonella typhimurium , utilising agar diffusion and broth microdilution assays. Zones of inhibition (10–13 mm) were observed for S. sonnei , S. flexneri , and B. cereus on agar, while the minimum inhibitory concentration (MIC) values varied between 185 and 2531 µg/mL. However, the aqueous and methanolic extracts demonstrated weak activity against S. typhimurium , with MIC values ranging from 2956 to 5063 µg/mL and no detectable inhibition on agar plates. The impact of combining the extracts with selected conventional antibiotics was further assessed through the calculation of the sum of fractional inhibition concentration (∑FIC) where 15 additive (∑FIC = 0.5 – 1.0) and 9 antagonistic interactions (∑FIC > 4.0) were observed between extract and antibiotics against the gastrointestinal pathogens. Phytochemical analysis using liquid chromatography–mass spectrometry (LC-MS) identified noteworthy flavonoids, terpenoids, phenolic acids, and tannins. Toxicity evaluation using Artemia nauplii bioassays indicated that all extracts were nontoxic. These findings highlight the antibacterial potential and safety of P. emblica extracts, making them promising candidates for antibiotic development. Their mechanisms of action and detailed phytochemical properties require further study. • The antibacterial activity of P. emblica fruit extracts were examined against a panel of bacterial gastrointestinal bacterial pathogens. • Noteworthy antibacterial activity is reported for P. emblica fruit extracts for the first time against for S. sonnei , S. flexneri , and B. cereus. • The effects of combining the extracts with a panel of conventional antibiotics was also examined by ƩFIC and isobologram analysis. • LC-MS metabolomic analysis was used to putatively identify noteworthy phytochemicals and their antibacterial effects are discussed. • Toxicity of the extracts was also evaluated using Artemia nauplii bioassays as a measure of t6he extracts’ safety.