Bioactive Phenolic Compounds from the Egyptian Red Sea Seagrass Thalassodendron ciliatum

Five flavonoids (rutin, asebotin, 3-hydroxyasebotin, quercetin-3-O-beta-D-xylopyranoside, and a racemic mixture of catechin) and caffeic acid were isolated and identified for the first time from seagrass, Thalassodendron ciliatum, collected from the Hurghada region in Egypt. The crude extract and the isolated pure compounds were evaluated for their cytotoxic activities against HCT-116, HEPG, MCF-7, and HeLa human cancer cell lines, for their antiviral activity against Herpes Simplex and hepatitis A viruses, and for their antioxidant activity.