Introduction:The present study deals with the simultaneous HPLC-quantification of phenolic acid(s) in the aerial parts of Diplocyclos palmatus (Cucurbitaceae) and evaluation of their bioactivity potential through in vitro antioxidant assay’s. Method: The HPLC elution was done using C18 column using gradient (binary phases) solvent system at a flow rate of 0.6 ml/min. Total phenolic and, flavonoid contents were determined and the antioxidant potential was estimated by four assay’s viz. DPPH radical scavenging assay, ferric reducing power assay, total antioxidant capacity and 2-deoxy ribose assay. Results: The species is rich in three phenolic acids, among which gallic acid (1708 ug/g) is in maximum concentration followed by caeffic acid (437 ug/g) and protocateuchic acid (337.7 ug/g). Total phenolic content was higher (10.5 mg/g) than flavonoid content (3.78 mg/g) and TAC was found at 0.137 mg/g ASE (ascorbic acid equivalent). IC50 of D. palmatus extract for scavenging of hydroxyl radical by 2-deoxy ribose and DPPH was at concentration of 125.61 ± 0.834 (μg/ml) and 353.71 ± 0.663 (μg/ml) respectively. In vitro antidiabetiv potential, via inhibition of alpha amylase enzyme through starch iodine and 3,5- DNS assay reveals the IC50 of extract at 146.31 ± 0.415 ug/ml and 286.23 ± 0.671 ug/ ml respectively. Conclusion: The species (aerial part) was rich in phenolic acid with potential bioactivity, identified leads will be useful in further chemical characterization and pharmacological validation.