Abstract
The purpose of this study was to investigate the essential oil composition, phytochemicals, and antioxidant activity from the leaves of Piper crassipes. Essential oil was obtained from the leaves by hydrodistillation, and its chemical compositions was determined using gas chromatography (GC) and gas chromatography mass spectrometry (GC-MS). Soxhlet extraction was performed for the leaves part, followed by isolation of phytochemicals using silica gel column chromatography. The chemical structures of isolated compounds were determined using spectral analysis (Infrared Spectroscopy, Nuclear Magnetic Resonance Spectroscopy, and Mass Spectrometry) and comparison with literature data. Antioxidant activity was evaluated using the 2,2- diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assay and total phenolic content. Twenty-two compounds (97.8%) were identified in the leaf oil with chavibetol (59.8%), chavibetol acetate (10.4%), _-muurolene (5.4%), and germacrene D (4.6%) as major compounds. Ten compounds were isolated from the leaf extracts, including asaricin, chavibetol, dillapiole, _-sitosterol, 5,7-dimethoxyflavone, 4',5,7- trimethoxyflavone, N-(3-phenylpropanoyl)pyrole, chavicol, N-isobuty1-(2E,4E,14Z)- eicosatrienamide, and 4-allyl resorcinol. Both methanol extract and chavicol exhibited significant antioxidant activity in the DPPH assay with IC50 values of 44.0 and 25.5 _g/mL, respectively. In conclusion, the essential oil of P. crassipes contains phenylpropanoids as major compounds. Ten compounds were isolated from P. crassipes leaf extract and are reported for the first time in this species. These findings highlight the antioxidant activity of Piper extracts for potential medicinal applications.