The antiallergic properties of two lyophilized extracts obtained from
Capparis spinosaL. flowering buds (capers) by methanol extraction, carried out at room temperature (CAP‐C) or with heating at 60 °C (CAP‐H), were investigated.
The protective effects of CAP‐H and CAP‐C, orally administered (14.28 mg[sol ]kg), were evaluated against
Oleaceaeantigen challenge‐induced and histamine‐induced bronchospasm in anaesthetized guinea‐pigs. Furthermore, the histamine skin prick test was performed on humans, applying a gel formulation containing 2% CAP‐C (the only extract able to protect against histamine‐induced bronchospasm) on the skin for 1 h before histamine application and monitoring the erythema by reflectance spectrophotometry.
The CAP‐H showed a good protective effect against the bronchospasm induced by antigen challenge in sensitized guinea‐pigs; conversely, a significant decrease in the responsiveness to histamine was seen only in CAP‐C pretreated animals. Finally, the CAP‐C gel formulation possessed a marked inhibitory effect (46.07%) against histamine‐induced skin erythema.
These two caper extracts displayed marked antiallergic effectiveness; however, the protective effect of CAP‐H was very likely due to an indirect mechanism (for example, inhibition of mediator release from mast cells or production of arachidonic acid metabolites); conversely, CAP‐C is endowed with direct antihistaminic properties. The different mechanisms of action of CAP‐H and CAP‐C may be related to a difference in the extraction procedure and, thus, in their qualitative[sol ]quantitative chemical profile. Copyright © 2005 John Wiley & Sons, Ltd.