ABSTRACT:
This study reports the isolation and identification of an antimicrobial alkaloid compound from the soft coral Nepthea sp., providing a significant new contribution to the chemical diversity and biological activities of the Nephtheidae family. The research aimed to isolate secondary metabolites from Nepthea sp. and evaluate their biological activities in vitro and in silico. The in vitro assays included antimicrobial, antioxidant, and toxicity evaluations, while the in silico study explored the potential molecular mechanisms underlying these pharmacological effects. Secondary metabolites were extracted by maceration, followed by separation and purification using Vacuum Liquid Chromatography (VLC) and Radial Chromatography (RC). Structural elucidation through ¹H and ¹³C NMR, DEPT, HMQC, and HMBC spectroscopy identified the isolated compound as (Z)-N-[2'-(4"-hydroxyphenyl)ethyl]-3-methyldodec-2-enamide (C1) with a molecular formula of C21H33NO2, a newly reported alkaloid from the Nepthea genus. The compound exhibited strong antimicrobial activity against S. aureus (2µg/mL), E. coli (1µg/mL), and C. albicans (4µg/mL). Its antioxidant potential was moderate compared with Trolox, showing IC50 values of 42.86µg/mL (DPPH) and 33.74µg/mL (ABTS). The compound displayed lower toxicity than potassium dichromate with an LC50 of 23.54µg/mL. Docking analysis revealed strong binding affinity toward E. coli and xanthine oxidase, supporting its promising pharmacological potential.