Biochemical and pharmacological characterization of toxins obtained from the fire coral Millepora complanata

• Published in: Comparative biochemistry and physiology. Toxicology & pharmacology Vol. 146; no. 4; pp. 511 - 518
• Main Authors: Ibarra-Alvarado, César, Alejandro García, J., Aguilar, Manuel B., Rojas, Alejandra, Falcón, Andrés, Heimer de la Cotera, Edgar P.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.11.2007
• Subjects: Animals; Aorta, Thoracic - drug effects; Calcium - pharmacology; Chromatography, High Pressure Liquid; Cnidarian Venoms - chemistry; Cnidarian Venoms - enzymology; Cnidarian Venoms - pharmacology; Dose-Response Relationship, Drug; Drug Interactions; Electrophoresis, Polyacrylamide Gel; Erythrocytes - drug effects; Hemolysis; Hemolysis - drug effects; Hydrozoa - metabolism; Male; Millepora complanata; Muscle Contraction - drug effects; Muscle, Smooth, Vascular - drug effects; Muscle, Smooth, Vascular - physiology; Phospholipase A 2; Phospholipases A2 - analysis; Phospholipases A2 - pharmacology; Rats; Rats, Wistar; Toxin; Vasoconstriction; Vasoconstriction - drug effects; Vasoconstrictor Agents - analysis; Vasoconstrictor Agents - pharmacology; ASW, Caribbean Sea; Hemolysis; Toxin; Phospholipase A 2; Millepora complanata; Vasoconstriction
• ISSN: 1532-0456; 1878-1659
• DOI: 10.1016/j.cbpc.2007.06.002

Millepora complanata is a normal resident of coral reefs in the Mexican Caribbean. In this study, we describe for the first time the vasoconstrictor, phospholipase A 2 (PLA 2), and hemolytic activities elicited by a crude extract obtained from M. complanata. This extract caused a concentration-dependent contraction of isolated rat aortic rings (EC 50 = 22.4 ± 1.1 μg protein/mL). This effect was endothelium independent and significantly reduced in the absence of extracellular Ca 2+ and when the intracellular Ca 2+ stores were depleted. In addition, the crude extract obtained from M. complanata showed PLA 2 activity (7.231 ± 0.092 mmol min − 1 mg − 1 ) and hemolysis of rat erythrocytes (HU 50 = 1.64 ± 1.04 μg protein/mL). The hemolysis increased in the presence of Ca 2+ and decreased in the presence of cholesterol. Furthermore, this hemolysis was significantly reduced after incubation with an inhibitor of PLA 2 enzymes. The hemolytic and vasoconstrictor effects were abolished after incubating the extract under denaturing conditions. Reverse phase chromatography of the M. complanata extract afforded 19 fractions (F1 to F19). F4 induced hemolysis and contained mainly a protein of 30 kDa, probably a PLA 2 enzyme, while F8 and F11, containing mainly proteins of 15 and 20 kDa respectively, produced vasoconstrictor effects mediated by different mechanisms of action.