Insights of Terminalia citrina (Gaertn.) Roxb. Ex Fleming inhibiting multidrug resistant Acinetobacter baumannii

• T. citrina inhibited bacterial growth against the sepsis causing MDR A. baumannii clinical isolates AB0014, AB0015, and AB0018. • Bioactivity guided fractionation led to the identification of five phytocompounds. • The active fraction of T. citrina is attributed to inducing alterations in the cellular morphology of A. baumannii . • In-vitro and in-vivo toxicity assessment of T. citrina demonstrated no signs of toxicity or behavioural changes. The Northeast region of India is renowned for its rich biodiversity and unique flora, including many plants with unstudied medicinal properties . Terminalia citrina is a medicinal plant traditionally used to treat chronic fever, loss of appetite, diarrhoea, asthma, boils, dizziness, haemorrhoids, anaemia, eye diseases, and infections. This study highlights potential bioactive compounds of T. citrina with antimicrobial activity against sepsis-causing pathogens, specifically Acinetobacter baumannii isolates, and presents the toxicity studies conducted on an animal model. The study focused on validating the traditional use of medicinal plants for treating microbial infections and assessing their toxicity in an animal model. T. citrina plant species were collected and evaluated for antimicrobial activity against sepsis causing MDR pathogens Acinetobacter baumannii, Klebsiella pneumoniae , and Escherichia coli . The bioactive metabolites were identified using liquid chromatography–mass spectrometry (LC-MS). The in-vitro cytotoxicity of the active fraction was assessed using the MTT assay on the Caco-2 cell line followed by in-vivo toxicity study in BALB/c mice. The crude extract of T. citrina , obtained using a hydroalcoholic solvent, inhibited the growth of A. baumannii isolates AB0014, AB0015, and AB0018. LC-MS analysis identified five metabolites in the EM2 subfraction of T. citrina . The MTT assay demonstrated no cytotoxic effects on the Caco-2 cell line. Treatment of A. baumannii isolate AB0014 with the EM2 subfraction of T. citrina at 2.82 mg/mL altered cellular morphology, causing cell shrinkage and growth inhibition. Acute and subacute oral toxicity studies of T. citrina (EM2) showed no signs of toxicity or behavioural changes. T. citrina found in Manipur, India, exhibited antimicrobial activity on MDR A. baumannii clinical isolates. The presence of phenolic compounds -in T. citrina (EM2) may be attributed to the antimicrobial activity. The T. citrina active fraction (EM2) may be an alternative candidate for developing a new drug for managing sepsis. • T. citrina inhibits the growth of sepsis causing MDR pathogen A. baumannii isolates (AB0014, AB0015 & AB0018). • 5 major bioactive compounds present in the sub fractions of T. citrina . • Alterations in cellular morphology, cell shrinkage and inhibition of growth, were observed in the treated cells.