Antiasthmatic effects of onions. Prevention of platelet-activating factor induced bronchial hyperreactivity to histamine in guinea pigs by diphenylthiosulfinate.

Thiosulfinates are responsible for antiasthmatic and anti-inflammatory properties of onions. We tested the effect of diphenylthiosulfinate on platelet-activating factor (PAF)-induced bronchial hyperreactivity to histamine: According to a randomized crossover protocol, groups of 14 guinea pigs inhaled histamine, were then treated orally with either vehicle or with 10-100 mg/kg diphenylthiosulfinate, inhaled 1 microgram PAF, and thereafter the same histamine dose given prior to PAF. In the control group the histamine response increased threefold; in the treated group the histamine response decreased. The effect of 100 mg diphenylthiosulfinate lasted 12 h. Antihistamine effects were not demonstrable in this test system. We conclude that thiosulfinates inhibit PAF-induced hyperreactivity.