LC-MS-assisted metabolomic profiling of the Red Sea-derived brown algae Sargassum cinereum “Sargassaceae” dereplicated eleven compounds 1–11. Further phytochemical investigation afforded two new aryl cresol 12–13, along with eight known compounds 14–21. Both new metabolites, along with 19, showed moderate in vitro antiproliferative activity against HepG2, MCF-7, and Caco-2. Pharmacophore-based virtual screening suggested both 5-LOX and 15-LOX as the most probable target linked to their observed antiproliferative activity. The in vitro enzyme assays revealed 12 and 13 were able to inhibit 5-LOX more preferentially than 15-LOX, while 19 showed a convergent inhibitory activity toward both enzymes. Further in-depth in silico investigation revealed the molecular interactions inside both enzymes’ active sites and explained the varying inhibitory activity for 12 and 13 toward 5-LOX and 15-LOX.

Heat shock protein 90 (Hsp90) is a validated molecular chaperone considered as the new key recipient for cancer intervention. The current study illustrates the synthesis of novel spirooxindole-dihydropyrimidinones (4a-j) by Fe 3 O 4 nanoparticles intervened synthesis and their Hsp90 ATPase inhibitory activity was investigated by the malachite green assay. All the compounds in the study demonstrated a moderate to potent ATPase inhibitory profile, with IC 50 values ranging from 0.18 to 6.80 μM. Compounds 4j, 4h, 4f, and 4i exhibited maximum inhibitory potential with IC 50 values of 0.18, 0.20, 0.35, and 0.55 μM, respectively. They were found to be better than the standard drug, geldanamycin (Hsp9 ATPase inhibition IC 50 = 0.90 μM). Compounds 4h and 4j with IC 50 values of 22.82 ± 0.532, 20.78 ± 0.234 and 21.32 ± 0.765, 28.43 ± 0.653 µM showed significantly greater potencies against the MCF-7 and HepG2 cell lines, respectively. Compound 4j showed good antioxidant activities in the DPPH test and H 2 O 2 assay (IC 50 = 20.13.23 ± 0.32 and 23.27 ± 0.32 μg/mL) when compared with the standard ascorbic acid (IC 50 = 19.16 ± 0.20 and 20.66 ± 1.09 μg/mL). A molecular docking study was performed to observe the binding efficiency and steric interactions of the lead moiety.

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