Relationship between pharmacological actions and enzymatic activities of the venom of Trimeresurus gramineus.

Abstract

The venom of Trimeresurus gramineus was separated into five fractions, namely α, β, γ, δ and ϵ, by means of starch zone electrophoresis. The most toxic, γ-fraction, which possesses the highest caseinolytic activity, exerts the highest hemorrhagic as well as anticoagulant activities. β-fraction also has a high hemorrhagic activity, but is almost devoid of caseinolytic and anticoagulant activities. EDTA greatly decreases lethality as well as hemorrhagic and caseinolytic activities, thus hemorrhage combined with anticoagulant activity seems to play a leading role in lethality of the venom. Both hemorrhagic and caseinolytic activities are also inhibited by either cysteine or heat treatment. β-, γ- and δ-fractions possess high phospholipase A activity and strongly release histamine from the rat diaphragm preparation. Since the capillary permeability increasing activity (CPIA) of these fractions is inhibited markedly by diphenhydramine and less markedly by methysergide, it appears that phospholipase A plays an important role in CPIA by releasing histamine. However, since DFP also partially inhibits CPIA and the combined use of diphenhydramine, methysergide and DFP completely inhibits CPIA of the venom, the bradykinin-releasing activity of the venom may be also involved. The least toxic, α-fraction, which possesses the highest thrombin-like as well as arginine ester hydrolytic activities, is much weaker in the above-mentioned activities. ϵ-fraction exerts strong local irritation on the rabbit eye, but is almost devoid of other activities.