Abstract
Myrtaceae is a plant family widely used in folk medicine and Syzygium and Eugenia are among the most important genera. We investigated the anti-allergic properties of an aqueous leaf extract of Syzygium cumini (L.) Skeels (SC). HPLC analysis revealed that hydrolyzable tannins and flavonoids are the major components of the extract. Oral administration of SC (25-100 mg/kg) in Swiss mice (20-25 g; N = 7/group) inhibited paw edema induced by compound 48/80 (50% inhibition, 100 mg/kg; P <or= 0.05) and, to a lesser extent, the allergic paw edema (23% inhibition, 100 mg/kg; P <or= 0.05). SC treatment also inhibited the edema induced by histamine (58% inhibition; P <or= 0.05) and 5-HT (52% inhibition; P <or= 0.05) but had no effect on platelet-aggregating factor-induced paw edema. SC prevented mast cell degranulation and the consequent histamine release in Wistar rat (180-200 g; N = 7/group) peritoneal mast cells (50% inhibition, 1 microg/mL; P <or= 0.05) induced by compound 48/80. Pre-treatment of BALB/c mice (18-20 g; N = 7/group) with 100 mg/kg of the extract significantly inhibited eosinophil accumulation in allergic pleurisy (from 7.662 +/- 1.524 to 1.89 +/- 0.336 x 10(6)/cavity; P <= 0.001). This effect was related to the inhibition of IL-5 (from 70.9 +/- 25.2 to 12.05 +/- 7.165 pg/mL) and CCL11/eotaxin levels (from 60.4 +/- 8.54 to 32.8 +/- 8.4 ng/mL) in pleural lavage fluid, using ELISA. These findings demonstrate an anti-allergic effect of SC, and indicate that its anti-edematogenic effect is due to the inhibition of mast cell degranulation and of histamine and serotonin effects, whereas the inhibition of eosinophil accumulation in the allergic pleurisy model is probably due to an impairment of CCL11/eotaxin and IL-5 production.
Highlights
Myrtaceae is a plant family widely used in folk medicine in different countries and Eugenia and Syzygium are among its most important genera
We investigated the ability of an aqueous leaf extract of S. cumini extract (SC) to inhibit mouse allergic edema formation and eosinophil accumulation in mouse allergic pleurisy and the mechanisms involved in such phenomena
Effect of Syzygium cumini extract on paw edema triggered by compound 48/80 or ovalbumin
Summary
Myrtaceae is a plant family widely used in folk medicine in different countries and Eugenia and Syzygium are among its most important genera. The allergic process has an important inflammatory component in which mast cell activation and degranulation are the first phenomena observed During this process, mast cells release several inflammatory mediators including histamine, 5-HT, plateletaggregating factor (PAF), leukotrienes, and a variety of cytokines which can elicit many events associated with allergic inflammation, such as edema formation and cellular infiltration [9]. The triggering and regulation of eosinophil accumulation in allergic inflammation depend on the release of cytokines and chemokines such as interleukin-4 (IL-4), IL-5 and CCL11/eotaxin in response to an antigen challenge [10,11] Once they reach the allergic site, eosinophils degranulate and release several mediators, including leukotrienes, major basic protein, PAF, cationic protein, and eosinophil-derived neurotoxin that contribute to extensive tissue damage [12]. We investigated the ability of an aqueous leaf extract of SC to inhibit mouse allergic edema formation and eosinophil accumulation in mouse allergic pleurisy and the mechanisms involved in such phenomena
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