The present work deals with the isolation of essential oil from the leaves of Casearia tomentosa as well as its chemical characterization by GC-MS and evaluation of in vitro pharmacological activities. The crude essential oil was obtained using Clevenger apparatus. Thirteen compounds were identified representing 77.62% of the total oil composition. The oil was mainly composed of 9,12-Octadecadienoic acid, ethyl ester (31.45%) followed of the 9,12,15-Octadecatrienoic acid, ethyl ester (20.11%), Phytol (10.70%), Di-epi-alpha-cedrene (3.74%), β-bisabolene (1.87%), β-Caryophyllene (0.83%) and some other trace components. Antidiabetic activity estimated by α- amylase and α- glucosidase inhibitory assay and antioxidant activity by 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay and ferric reducing antioxidant potential (FRAP) method while antibacterial activity was performed by disk diffusion method. The results demonstrated prominent α- amylase (IC50 = 184.47 ± 1.06 μg/mL), α- glucosidase (IC50 = 91.10 ± 0.80 μg/mL) inhibition, DPPH radical scavenging (IC50=75.50 ± 0.60μg/mL) and FRAP activity (37.55 ± 0.66 μM/mL, FRAP value 1.636). Antimicrobial activity performed towards the selected five human pathogenic bacterial cultures like Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumonia and Salmonella typhi. Highest inhibitory activity was seen against Staphylococcus aureus (zone of inhibition 12.2 mm) while the weakest activity was demonstrated against Pseudomonas aeruginosa (zone of inhibition 8.9 mm). Overall results revealed that C. tomentosa leaves (CTL) essential oil exhibits potent antidiabetic, antioxidant and antibacterial activities. This is the first study regarding the isolation of essential oil from the leaves of Casearia tomentosa and its pharmacological activities

Objective: In present study different extracts of the leaves of plant Casearia tomentosa was investigated for the phytochemical screening, total phenolic content and various pharmacological activities like antioxidant, antidiabetic, antibacterial.Methods: Leaves of C. tomentosa were successively extracted by soxhlet extraction method using petroleum ether, chloroform, ethyl acetate and ethanol. The preliminary phytochemical investigation of different extracts was carried out according to standard methods. Antioxidant activity evaluated by 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay and ferric reducing antioxidant potential (FRAP) method. Total phenolic content was evaluated by Folin-ciocalteau method. Antidiabetic activity estimated by α-amylase and α-glucosidase inhibitory assay while antibacterial activity was performed by disk diffusion method. Conclusion:The present study suggests that Casearia tomentosa leaves can be used as a potential source of natural antioxidant and natural antidiabetic, antibacterial agents.