In vitro alexiteric activity of irregular monoterpenes derived from ortho-menthane against Bothrops diporus Cope (Serpentes: Viperidae) venom.

Many plant-derived compounds, mostly of mid-to-high molecular weight, exert alexiteric properties. However, some small phenolic molecules, such as 2-hydroxy-4-methoxybenzoic acid, are also known to be alexiteric by their ability to bind to snake venom proteins. This study presents the in vitro alexiteric activity of 2-isopropenyl-3-methylphenol [carquejiphenol, CARP; a minor compound of Baccharis trimera (Less.) DC. essential oil, BtEO] against Bothrops diporus Cope snake venom through the evaluation of proteolysis inhibition, haemolysis and coagulation and alteration of the venom proteins bands followed by SDS-PAGE. Additional CARP derivatives (ortho-menthane monoterpenes), including carquejol and carquejone, as well as BtEO and non-volatile extracts from B. trimera were included to have a broader picture of the alexiteric bioactivity. Notably, carquejone was the more active among all the tested samples. A basic structure-activity comparison with commercial standards revealed that the α,β-unsaturated carbonyl moiety is essential for the bioactivity.