Synthesis and biological investigation of 3,3,6,6-tetramethyl-9-styryl-1,8-dioxooctahydroxanthene promoted by Fe₃O₄-supported citric acid as a magnetically recoverable catalyst

A green and attractive protocol was developed to produce 3,3,6,6-tetramethyl-9-styryl-1,8-dioxooctahydroxanthene using magnetically separable Fe₃O₄ modified by citric acid (Fe₃O₄-CA) as catalyst. After catalyst characterization using XRD, Particle Sizer, SEM and EDAX, the Fe₃O₄-CA was then applied in dioxooctahydroxanthene synthesis with several optimizations, such as % wt. of catalyst, reaction time, temperature and solvent. The best protocol was found when the reaction is conducted using 5% wt. of catalyst at 50°C for 6 h reaction time in methanol, with the highest yield of 80%. The product obtained was confirmed by FTIR, UV-Vis, LC-MS,¹H- and¹³C-NMR analysis. In biological investigation, dioxooctahydroxanthene showed higher radical scavenging activity with IC₅₀ of 24.17 ppm, whereas it has comparable antibacterial activity than cinnamaldehyde as its precursor.