Deciphering the phytoconstituents of marine Amphiroa fragilissima: A comprehensive GC-MS, structural, spectroscopic, topological, and biological insights

In this study, Amphiroa fragilissima, a red macroalga from marine sources, was subjected to GC-MS analysis to detail the existence of bioactive phytoconstituents. The peak compound cholesteryl propionate was investigated using combined theoretical (DFT) and experimental spectroscopic approaches to emphasize the vibrational, biological, structural, solvent effect in electronic, MEP (molecular electrostatic potential), FMO (frontier molecular orbitals) properties, and topological insights. The structural framework of cholesteryl propionate comprises 172 and 85 bond angles and distances, respectively. The vibrational wavenumbers revealed characteristic peaks of CH 3 , CH 2 , CH, and CO functional groups. The electronic spectra were recorded in gas and solvent environments, showing significant π→π* transitions. The HOMO-LUMO energy gaps were calculated at 6.1426 eV (gas), 6.2104 eV (ethanol), and 6.2398 eV (chloroform), reflecting solvent-induced electronic stabilization. In Mulliken electron distribution, the carbonyl carbon (C28) exhibited a high positive charge (0.6157e) due to electron withdrawal by the electronegative oxygen atom. The color maps of ELF and LOL demonstrate localized covalent interactions and electron delocalization around the steroidal framework. Cholesteryl propionate complies with Lipinski’s rule supporting its drug-likeness properties. Furthermore, the molecular docking analysis demonstrates inhibitory activity against antiapoptotic proteins, confirming its potential in-silico anti-proliferative characteristics. • Fractions from hexane extract of Amphiroa fragilissima revealed the presence of phytocompounds. • The TD-DFT calculation highlights the solvent impact on electronic and FMO properties. • The electron-rich and poor regions within the molecular structure were investigated. • The localized and delocalized regions were calculated using topological analysis. • Molecular docking revealed the binding affinity of cholesteryl propionate with antiapoptotic proteins.