Antimicrobial and Cytotoxic Activities of Turbinaria conoides (J.Agardh) Kuetz

Brown alga, Turbinaria conoides was successively extracted with n-hexane, cyclohexane, methanol and ethanol:water (1:1). The extracts were evaluated for antibacterial and antifungal activities by disc diffusion method. Minimal inhibitory concentration was determined for active extracts by broth dilution method. The antiviral activity and cytotoxicity of the extracts were tested in human embryonic lung (HEL) cells (herpes simplex virus-1, herpes simplex virus-2, vaccinia virus, vesicular stomatitis virus and herpes simplex virus-1 TK- KOS ACVr), human epithelial (HeLa) cells (vesicular stomatitis virus and coxsackie virus B4) and Vero cells (parainfluenza-3 virus, reovirus-1, sindbis virus coxsackie virus B4 and punta toro virus). The results revealed that extracts exhibited cytotoxicity ranged from 20 to >100 µg/mL. Moderate activity was demonstrated by n-hexane and cyclohexane extracts against viruses, whereas methanol and ethanol:water (1:1) extracts were not active. Ethanol:water (1:1) presented neither antibacterial nor antifungal activity against tested organisms. Cyclohexane extract possessed a broad array of antibacterial activity and exhibited remarkable antifungal property. It is noteworthy that minimal inhibitory concentration of cyclohexane extract against Aspergillus niger is comparable with that of clotrimazole. This potentiality demonstrates that it could be used to treat bacterial and fungal infections.