Distinguishing Activities in the Photodynamic Arsenals of the Pigmented Ciliates Blepharisma sinuosum Sawaya, 1940 and Blepharisma japonicum Suzuki, 1954 (Ciliophora: Heterotrichea).

Abstract

Blepharismins are photodynamic hypericin-like dianthrones produced as a variable pigment blend in Blepharisma ciliates and mostly studied in the Afro-Asiatic Blepharisma japonicum. The present work describes the bioactivity of pigments from the Brazilian Blepharisma sinuosum. Comparative analyses showed that the pigments from both species can trigger photo-induced modifications in phospholipids, but different redox properties and biological activities were assigned for each pigment blend. Stronger activities were detected for B.sinuosum pigments, with the lethal concentration LC50 10×lower than B.japonicum pigments in light-irradiated tests against Bacillus cereus and less than half for treatments on the human HeLa tumor cells. HPLC showed B.sinuosum producing a simpler pigment blend, mostly with the blepharismin-C (~70%) and blepharismin-E (~30%) types. Each blepharismin engaged a specific dose-response profile on sensitive cells. The blepharismin-B and blepharismin-C were the most toxic pigments, showing LC50 ~2.5-3.0µm and~100µm on B.cereus and HeLa cells, respectively, after illumination. Similarity clustering analysis compiling the bioactivity data revealed two groups of blepharismins: the most active, B and C, and the less active, A, D and E. The B.sinuosum pigment blend includes one representative of each clade. Functional and medical implications are discussed.