Mosquito larvicidal and bactericidal action of crude extract of marine brown alga Turbinaria conoides

Abstract

Mosquito related problems and bacterial resistance against synthetic chemicals have become acute in recent years, therefore to solve this, the search for biochemicals is on. Marine brown algae have been traditionally used as nutraceuticals and it contains a rich source of bioactive compounds, hitherto many novel bioactive compounds are yet to be explored. For this research, a marine brown alga of Turbinaria conoides was collected from Mandapam, Tamil Nadu and compounds were extracted using various solvents such as polar (ethanol, acetone) and nonpolar (benzene and diethyl ether). The crude extracts were checked for mosquito larvicidal (Culex quinquifasciatus), bactericidal (Staphylococcus aureus) and antifungal (Aspergillus niger) activity. The crude extract of diethyl ether showed potential larvicidal activity as 50% lethal concentration (LC₅₀) was noted at 104 mg/L followed by acetone (469 mg/L), benzene (781 mg/L) and ethanol (1917 mg/L), respectively. Also, an active antibacterial effect in diethyl ether extract was superior as a 4 mm zone of inhibition (ZoI) was found with 0.1 mg extract followed by acetone (4 mm ZoI at 1.2 mg extract). Intriguingly, no fungicidal was observed in any extract which rather supported the fungal growth. Based on this result, the acetone and diethyl ether extract showed worthy duel activity compounds and analyzed for GC-MS and observed three novel compounds in the acetone extract. These compounds might be involved in the antilarval and antibacterial action and will be analyzed in the future. The results of this study are very useful for our human society because of the potential for a better life through the treatment of diseases.