In our preliminary study, B.orellana exhibited the ability to suppress the inflammatory activities of a number
of mediators, with AEBO having inhibited up to 99% of paw edema induced by carrageenan (data not published).
Indeed, when bradykinin was later used to induce acute inflammation in the same rat models, it was confirmed
that up to 82% of the increased vascular permeability was successfully alleviated upon administration of AEBO
[6]. Histamine is one of the inflammogens that contributes to acute inflammation and increase of vascular permeability [15]. The present study documents for the first time the ability of AEBO to suppress the histamine-induced inflammation in rats. Paw edema assay is a useful tool for investigating agents with potential anti-inflammatory capabilities. The present study showed that exposure of rat’s paw to histamine triggered an elevation in fluid extravasations from microvessels inthe vicinity, an event that led to tissue swelling. The results showed that AEBO was able to significantly suppress histamine-induced paw edema in rats, and this may probably be due to the inhibition of the H1 receptor or other signaling molecules down its pathway. Histamine H1 receptor expressed in endothelial cells of blood vessels is important for regulating vascular permeability [10], and increased permeability occurs once it is activated