BIOACTIVITY-GUIDED ISOLATION OF PREVIOUSLY UNDESCRIBED MACROCYCLIC PYRONE DERIVATIVES FROM ECHINOIDEA SEA URCHIN Stomopneustes variolaris
In the present study two macrocyclic pyrone derivatives such as (6E,10E)-methyl 10-butyl-4a-methyl-2-oxo-3,4,4a,5,8,9,12,12a-octahydro-2H-cyclodeca[b]pyran-8-carboxylate (1) and methyl 82-((6E,10E)-4a-methyl-10-(102-methylbutyl)-2-oxo-3,4,4a,5,8,9,12,12a-octahydro-2H-cyclodeca[b]pyran-8-yl)acetate (2) were isolated from the gonadal extract of echinoidea sea urchin, Stomopneustes variolaris using various chromatographic techniques. Their structures were identified using extensive spectroscopic experiments. The macrocyclic pyrone derivatives, bearing 2-methylbutyl side chain (1) exhibited significantly greater antioxidant properties as determined by 2,2-diphenyl-1-picrylhydrazyl (DPPH) (IC50 0.65 mg mL-1) and ABTS+ {2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid)} (IC50 0.73 mg mL-1) than other studied compound with butyl side chain (2) (IC50 > 0.75 mg mL-1). The macrocyclic pyrone derivative (1) exhibit greater anti-inflammatory potentials as identified by the lower IC50 values for 5-lipoxygenase inhibitory assay (IC50 0.93 mg mL-1) than the other compound (2) (IC50 0.93 mg mL-1) in the studied series. The greater electronic parameters of compound 1, obtained from structure activity analyses, along with lower binding energies (-9.72 and -9.89 kcal mol-1) and docking score (-10.08 and -10.41 kcal mol-1) from molecular docking studies manifested towards its greater bioactive potentials than other studied macrocyclic pyrone derivative, 2. These bioactive potentials of the title compound leads to its utility as a potential functional food component and lead molecule in the preparation of pharmacophores.
