Allergy-preventive effects of flowers of Campsis grandiflora

Abstract

We used an in vivo assay system, which we had previously developed to search for allergy-preventive substances from natural sources. [1] This method monitors the decrease in blood flow (BF) in the tail vein of mice subjected to hen egg-white lysozyme (HEL) sensitization. The BF decrease is very complicated, involving various factors such as NO from iNOS, TXA2, PGI2, ET-1, granulocytic elastase, COX-1, 2 and cNOS. [2] Using this assay system, we found that the MeOH extract (CG) of flowers of Campsis grandiflora Thumb. (Bignoniaceae) significantly reduced the decrease of BF. Flowers of C. grandiflora have been used in traditional Chinese medicine to treat bruises, pruritus, diuresis and thrombosis. In this study, we report on the allergy-preventive effects of CG and its active compounds. The BF of HEL-sensitized mice (control group) gradually and significantly decreased, falling to about 70% of the BF of normal mice at day 9. CG could significantly the decrease of BF. Active-guided fractionation of CG led to isolation of apigenin (1), acteoside (2) from the most active AcOEt fraction and rengyoside (3), rengyol (4) and isorengyol (5) from a few active n-BuOH extracts. Among these compounds, 1 and 2 significantly reduced the decrease of BF. 1 has been reported to inhibit platelet aggregation and inhibit the expression of iNOS or COX-2, while 2 have been reported to have anti-inflammatory and antioxidant effects. Our findings show that CG could be useful for preventing allergy. Details of the mode of action are under investigation.