Exploiting exopolysaccharides from microalgae to block the toxic in vitro effects of Bothrops sp. venom

Abstract

Snakebite envenomation causes various toxic effects in humans, including death. Antivenoms are effectively prevent death but cannot completely block local muscle tissue damage, resulting in amputation and disability; thus, complementary therapies are needed. In this study, the ability of exopolysaccharides extracted from the microalgae Chlorella sorokiniana, Scenedesmus obliquus, Nannochloris sp. Naumann, and Scenedesmus acuminatus to inhibit the proteolytic, plasma coagulant, and phospholipase A₂ (PLA₂) activities of Bothrops jararaca, B. jararacussu, and B. neuwiedi venoms was assessed. Exopolysaccharides from C. sorokiniana, S. obliquus, Nannochloris sp. Naumann, and S. acuminatus inhibited the proteolytic activity of B. jararaca venom by 25%, 99%, 97%, and 13%, respectively; B. jararacussu venom by 14%, 50%, 46%, and 12%, respectively; and B. neuwiedi venom by 1%, 78%, 62%, and 1%, respectively. Exopolysaccharides from S. obliquus and Nannochloris sp. Naumann prevented the coagulation induced by snake venom and decreased the PLA₂ activity by 15% and 30%, respectively. None of the four exopolysaccharides lysed red blood cells and, thus, can be considered as nonhemotoxic compounds. Therefore, microalgae exopolysaccharides may be a candidate as complementary therapies for envenomation by snakes in regions where such incidents are common.

Keywords: Antidote; Exopolysaccharides; Microalgae; Neutralization; Snake venoms; Toxic activities.

Fig. 1

Chromatograms of exopolysaccharides C1 from C. sorokiniana (A), 1509 from Nannochloris sp. Naumann (B), S302 from S. obliquus (C), and S329 from S. acuminatus (D).

Fig. 2

Effect of exopolysaccharides on the proteolytic activity of B. jararaca, B. jararacussu, and B. neuwiedi venom. B. jararaca (A), B. jararacussu (B), and B. neuwiedi (C) venoms were incubated with saline solution or C1, S302, 1509, or S329 for 5 min at 37 °C. Venom plus saline yielded 100% of proteolytic activity. The results are expressed as the means ± SD (n = 6). * p < 0.05 compared with venom plus saline.

Fig. 3

Effect of exopolysaccharides on plasma coagulation caused by B. jararaca, B. jararacussu, and B. neuwiedi venom. 20 µg/mL B. jararaca (A), 30 µg/mL B. jararacussu (B), and 15 µg/mL B. neuwiedi (C) venom samples were incubated with saline (S) or C1, S302, 1509, or S329 at a 1:10 ratio for 5 min at 37 °C, and then added to the medium. The coagulation of the plasma was then monitored. The results are expressed as the means ± SD (n = 6). * p < 0.05 compared with venom plus saline.

Fig. 4

Effect of exopolysaccharides on the PLA₂ activity of B. jararaca, B. jararacussu, and B. neuwiedi venom. B. jararaca (A), B. jararacussu (B), and B. neuwiedi (C) venom (50 µg/mL) was incubated with saline or with 500 µg/mL C1, S302, 1509, or S329 for 5 min at 37 °C. PLA₂ activity was measured as described. The results are expressed as the means ± SD (n = 6). * p < 0.05 compared with venom plus saline.