in silico Study Reveals Potential Docking Sites of δ 2-isoxazolines derivates for Inhibiting Russell’s Viper PLA2 Toxin

Snake venom phospholipase A2s (svPLA2s) has been known as the most abundant component and predominant cause of Russell’s viper envenomation. Limitation to serum therapy and considerable pharmacological interest led the researcher to synthesized multi-toxic PLA2 inhibitors, δ2-isoxazolines derivate. Although δ2- isoxazolines derivate already proved inhibitor activity in Group II svPLA2 with known IC50, their mechanism of action remains unveiled. Our recent study investigated their inhibitory activity via molecular docking. The virtual screening revealed that the ligand with diverse structures tied to the relatively same active site region. The result sheds light on the significance of His48 and Asp49 as part of the pro-inflammatory eliciting region. ADME analysis was also performed to filter and identify the best potential inhibitor acceptable for human use. This moiety leads to finding a better therapeutic strategy of svPLA2 inhibitors both as an alternative to serum anti-venom treatment.

A New Group II Phospholipase A2 from Walterinnesia aegyptia Venom with Antimicrobial, Antifungal, and Cytotoxic Potential

Many venomous species, especially snakes, contain a variety of secreted phospholipases A2 that contribute to venom toxicity and prey digestion. We characterized a novel highly toxic phospholipase A2 of group II, WaPLA2-II, from the snake venom of Saudi Walterinnesia aegyptia (W. aegyptia). The enzyme was purified using a reverse phase C18 column. It is a monomeric protein with a molecular weight of approximately 14 kDa and an NH2-terminal amino acid sequence exhibiting similarity to the PLA2 group II enzymes. WaPLA2-II, which contains 2.5% (w/w) glycosylation, reached a maximal specific activity of 1250 U/mg at pH 9.5 and 55 °C in the presence of Ca2+ and bile salts. WaPLA2-II was also highly stable over a large pH and temperature range. A strong correlation between antimicrobial and indirect hemolytic activities of WaPLA2 was observed. Additionally, WaPLA2-II was found to be significantly cytotoxic only on cancerous cells. However, chemical modification with para-Bromophenacyl bromide (p-BPB) inhibited WaPLA2-II enzymatic activity without affecting its antitumor effect, suggesting the presence of a separate ‘pharmacological site’ in snake venom phospholipase A2 via its receptor binding affinity. This enzyme is a candidate for applications including the treatment of phospholipid-rich industrial effluents and for the food production industry. Furthermore, it may represent a new therapeutic lead molecule for treating cancer and microbial infections.

Enzymatic Activity and Brine Shrimp Lethality of Venom From the Large Brown Spitting Cobra (Naja Ashei) and Its Neutralization by Antivenom

Objective: Naja ashei is a snake of medical importance in Kenya, Ethiopia, Somalia, Uganda, and Tanzania. However, little is known about the enzymatic and toxic activities of Naja ashei venom and crucially, the capacity of commercially available antivenom to neutralize these effects. This study aimed to fill this gap by evaluating the enzymatic and toxic activities of N. ashei venom as well as the capacity of commercially available antivenoms to neutralize these effects. Results: The enzymatic/snake venom phospholipase A2/svPLA2 activity of Naja ashei venom is dose-dependent while the toxic effects of the venom in the brine shrimp animal model are dose and time-dependent. Commercially available antivenoms have poor neutralization capacity against the svPLA2 activity of Naja ashei venom. One ml of commercial antivenom manufactured in Mexico neutralized 0.21 mg of Naja ashei venom. However, the antivenom manufactured in India was ineffective against Naja ashei venom-induced brine shrimp lethality.