CHARACTERIZATION OF THE MOST PROMISING FRACTION OF Swietenia macrophylla ACTIVE AGAINST MYOTOXIC PHOSPHOLIPASES A2 : IDENTIFICATION OF CATECHIN AS ONE OF THE ACTIVE COMPOUNDS

Abstract

Background: The pharmacological effects produced by snakebite accidents involve the actions of several enzymes, of which those of the phospholipases A 2 (PLA 2 ) exhibit a wide variety of effects such as edema and myotoxicity. Some plant extracts have been antagonists of crude snake venoms and toxins. Based on promising bioactivity, Swietenia macrophylla King was selected for further studies. Objective: The purpose of this study was to identify the PLA 2 inhibitors present in the crude extract of S. macrophylla that could be promising leads in neutralizing the local effects of ophidian accidents. Methods: Bioassay-guided fractionation of the ethanolic extract of the leaves of S. macrophylla lead to the detection of (+)-catechin, characterized through gas chromatography coupled with mass spectrometry (GC-MS), and confirmed by HPLC. The PLA 2 inhibitory activity was measured with the Dole method and a spectrophotometric assay with 4-Nitro-3-octanoyloxy-benzoic acid (4N3OBA). Cytotoxicity was done on C2C12 murine myoblast. Results: Fraction F5 and (+)-Catechin inhibited the PLA 2 activity of B. asper venom, in a dosedependent way. In addition, (+)-Catechin showed an inhibition level of 83.1 ± 3.1 % of the enzymatic activity of one PLA 2 purified from the venom of Crotalus durissus cumanensis using 4N3OBA as substrate. Also the ethanolic extract and fraction F5 showed inhibition of the cytotoxicity induced by the Bothrops atrox venom and their Lys 49 PLA 2 (80 and 100% respectively). Molecular docking results suggested that OH from 4´ and 5' carbons of (+)-catechin could form hydrogen bonds with carboxylate moiety of residue Asp49, while OH from 5 could form a hydrogen bond with Asn 6. Additional Van der Waals interactions were also proposed. Conclusion: Swietenia macrophylla exhibited strong inhibitory activity against PLA 2 s enzymes. Catechin, one of the components in the active fraction F5, is proposed as being partially responsible for the bioactivity.

Quantitative Characterization of the Hemorrhagic, Necrotic, Coagulation-Altering Properties and Edema-Forming Effects of Zebra Snake (Naja nigricincta nigricincta) Venom

“…These authors also suggested the involvement of other toxins which acted directly on the endothelial cells of capillaries and venules thus increasing their permeability. Histamine release from mast cells as a result of phospholipases and cytotoxins was also a possible mechanism [ 47 ]. Another suggested mechanism was the release of prostaglandins resulting from phospholipase A 2 -induced liberation of arachidonic acid from plasma membranes [ 44 ].…”

Effects of Two Fractions of Swietenia macrophylla and Catechin on Muscle Damage Induced by Bothrops Venom and PLA2

“…These results obtained in vivo were in accordance with studies of enzymatic inhibition in vitro. Specifically, Preciado et al [41] reported that F4 and F6 inhibited the activity of B. asper PLA 2 by 71 ± 8% and 63 ± 4%, respectively, at a PLA 2 :F4 or F6 ratio of 1:10.These authors also used molecular docking to show that (+)-catechin blocked the entrance of the hydrophobic channel of PLA 2 from South American rattlesnake ( Crotalus durissus terrificus ) venom. In F4, in addition to catechin, palmitic and oleic acids were identified, whereas in F6, palmitic, stearic, and protocatechuic acids were identified [41].…”

“…Docking experiments revealed the existence of hydrogen-bonded polar and hydrophobic interactions, which suggested that other flavonoids with similar structures may also bind to PLA 2 . This mechanism was proposed for catechin, which is a major component in the fractions of S. macrophylla identified by gas chromatography coupled to mass spectrometry [41].…”

“…Almost all plant parts are used in traditional medicine for the treatment of various human illnesses [40]. Recent work in vitro has shown that an extract of S. macrophylla leaves inhibits the PLA 2 activity and cytotoxicity of Colombian Bothrops asper venom and a PLA 2 -rich fraction of this venom [24,41].…”

“…Studies in vitro have shown that an extract of S. macrohpylla King inhibits the PLA 2 activity of B. asper venom and a PLA 2 isolated from this venom [41,42]. In this work, we examined the ability of two fractions of an S. macrophylla leaf extract and of catechin (an abundant component in these fractions) to attenuate the myonecrosis caused by a PLA 2 from Colombian B. asper venom in mouse gastrocnemius muscle and to prevent the neuromuscular action of Brazilian B. marmoratus venom in mouse isolated phrenic nerve-diaphragm preparations.…”