Reference

Mucosal mast cells

Mucosal mast cells. III. Effect of quercetin and other flavonoids on antigen-induced histamine secretion from rat intestinal mast cells. Pearce, Frederick L.; Befus, A. Dean; Bienenstock, John (Dep. Chem., Univ. College, London, UK). J. Allergy Clin. Immunol., 73(6), 819-23 (English) 1984. CODEN: JACIBY. ISSN: 0091-6749. DOCUMENT TYPE: Journal CA Section: 1 (Pharmacology) Quercetin [117-39-5], a naturally occurring flavonol structurally related to the antiallergic drug disodium cromoglycate inhibits anaphylactic histamine release from MMC (mucosal mast cells) isolated from the small bowel of rats previously infected with Nippostrongylus brasiliensis. The present effect is immediate and does not decrease on preincubation with the drug. The flavonoids acacetin [480-44-4], apigenin [520-36-5], chrysin [480-40-0] and phloretin [60-82-2] also demonstrate significant activity but are less potent than quercetin. Catechin [154-23-4], flavone [525-82-6], morin [480-16-0], and taxifolin [480-18-2] are inactive. These results resemble those previously reported for the human basophil. In contrast, all compds. with the possible exception of taxifolin demonstrate significant activity against rat PMC (peritoneal mast cells). Acacetin and chrysin are the most effective inhibitors and are more active than quercetin. Rutin [153-18-4] (the glycane of quercetin) and phlorizin [60-81-1] (the glycane of phloretin) are inactive in both systems. These results are discussed in terms of the functional heterogeneity of mast cells from different sources and identify a group of compds. other than doxantrazole (reported previously), which inhibit histamine secretion by MMC.

Modification of platelet function and arachidonic acid metabolism by bioflavonoids

Modification of platelet function and arachidonic acid metabolism by bioflavonoids. Structure-activity relations. Landolfi, Raffaele; Mower, Richard L.; Steiner, Manfred (Mem. Hosp., Brown Univ., Pawtucket, RI 02860, USA). Biochem. Pharmacol., 33(9), 1525-30 (English) 1984. CODEN: BCPCA6. ISSN: 0006-2952. DOCUMENT TYPE: Journal CA Section: 1 (Pharmacology) The mechanism of the antiaggregating activity of flavonoids was studied in vitro. The activity of 15 different compds. was tested on platelet aggregation and arachidonic acid [506-32-1] metab. The effect of flavonoids on platelet adenosine cyclic AMP [60-92-4] levels under basal conditions, as well as after stimulation by prostacyclin (PGI2) [35121-78-9], was also measure. The glycons of flavonoids in general and the flavanone derivs. that were tested did not affect platelet function. On the other hand flavone [525-82-6], chrysin [480-40-0], apigenin [520-36-5] and phloretin [60-82-2] inhibited platelet aggregation by depressing the cyclooxygenase [39391-18-9] pathway. In addn., flavone, chrysin and apigenin reduced the platelet cyclic AMP response to PGI2. This effect was probably mediated by an inhibition of adenylate cyclase [9012-42-4]. Myricetin [529-44-2] and quercetin [117-39-5] however, increased the PGI2-stimulated rise of platelet cyclic AMP. Both of these flavonoids inhibited primarily lipoxygenase [9029-60-1] activity. Modification of platelet cyclic AMP metab. through inhibition of phosphodiesterase [9025-82-5] activity was found to be the probable mechanism of their antiaggregating effect.