Evaluation of in vitro anti-Leishmanial activity of some brown, green and red algae from the Persian Gulf.

Background and Objectives: Leishmaniasis is a protozoan parasitic disease which is transmitted by the female Phlebotomus sand fly and is prevalent in four continents. The first-choice treatment for the leishmaniasis is pentavalent antimonials, which are potentially toxic and often ineffective and use of them exhibit therapeutic failure. These pharmaceutical problems point towards the need to develop novel chemotherapeutic agents. Seaweeds are considered as source of bioactive metabolites characterized by a broad spectrum of biological activities. Materials and Methods: In this experimental study, cold and hot water crude extracts of four species of green, brown and red marine algae "Caulerpa sertularioides, Gracilaria corticata, Gracillaria salicornia and Sargassum oligocystum" collected along the Bushehr coast of the Persian Gulf (southwest of Iran), prepared and their in vitro activities against Leishmania major promastigote were evaluated by using the MTT assay test. Results: The cold and hot water crude extracts of four algae species exhibited different anti-Leishmanial activities. The minimum inhibitory concentration of hot water extracts calculated as IC₅₀ was as follows: Caulerpa sertularioides (IC₅₀ ≤ 85 µg/ml), Gracilaria corticata (IC₅₀ ≤ 38 µg/ml), Gracillaria salicornia (IC₅₀ ≤ 46 µg/ml) and Sargassum oligocystum (IC₅₀9 ≤ 78 µg/ml, while these values for cold water extracts were (IC₅₀ >125 µg/ml) for Caulerpa Sertularioides (IC₅₀ >65 µg/ml) for Gracilaria corticata (IC₅₀ >74 µg/ml) for Gracilaria salicornia and (IC₅₀ >105 µg/ml) for Sargassum oligocystum, IC₅₀ values for reference drug (Amphotericin B) was (0.16-0.2 µg/ml). Discussion: According to the results, inhibitory effects of the crude extracts from these four species algae specially hot water crude extracts from "Gracilaria corticata, Gracillaria salicornia and Sargassum oligocystum" are significant and in accordance with other studies that has been done on different algae species. So these results are sufficiently promising to be followed with further studies on isolation and characterization of pure compounds from these algae species as well as in vivo experiments, a work that is already under way in our laboratory. [ABSTRACT FROM AUTHOR]