Effects of different drugs on passive cutaneous anaphylaxis elicited in the mouse ear at 1.5 hours

Structures of novel norstilbene dimer, longusone A, and three new stilbene dimers, longusols A, B, and C, with antiallergic and radical scavenging activities from Egyptian natural medicine Cyperus longus

The methanolic extract of the whole plant of Cyperus longus originating in Egypt was found to show antiallergic effect on ear passive cutaneous anaphylaxis reactions in mice. By bioassay-guided separation, 11 stilbenes and stilbene dimers including a novel norstilbene dimer, longusone A, and three new stilbene dimers, longusols A, B, and C, were isolated. Their structures were elucidated on the basis of chemical and physicochemical evidence. Among the isolates, longusol B (IC(50)=96 µM), luteolin (3.0 µM), resveratrol (17 µM), piceatannol (24 µM), and cassigarols E (84 µM) and G (84 µM) were found to inhibit the release of β-hexosaminidase, as a marker of antigen-induced degranulations, in rat basophilic leukemia (RBL-2H3) cells. In addition, the methanolic extract and the constituents showed 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity (SC(50)=22 µg/ml and 2.8-29 µM, respectively).

Bioactive Saponins and Glycosides. XXVII. Structures of New Cucurbitane-Type Triterpene Glycosides and Antiallergic Constituents from Citrullus colocynthis

The methanolic extract from the fruit of Citrullus colocynthis showed an inhibitory effect on ear passive cutaneous anaphylaxis reactions as a type I allergic model in mice. From the methanolic extract, two new cucurbitane-type triterpene glycosides, colocynthosides A and B, were isolated together with 17 known constituents. The structures of colocynthosides A and B were elucidated on the basis of chemical and physicochemical evidence. In addition, the principal cucurbitane-type triterpene glycoside, cucurbitacin E 2-O-beta-D-glucopyranoside, and its aglycon, cucurbitacin E, exhibited the antiallergic activity at a dose of 100 and 1.25 mg/kg, p.o., respectively.

Antiallergic principles from Alpinia galanga: structural requirements of phenylpropanoids for inhibition of degranulation and release of TNF-alpha and IL-4 in RBL-2H3 cells

The 80% aqueous acetone extract of the rhizomes of Alpinia galanga was found to inhibit release of beta-hexosaminidase, as a marker of antigen-IgE-mediated degranulation in RBL-2H3 cells. Nine known phenylpropanoids and p-hydroxybenzaldehyde were isolated from the extract. Among them, 1'S-1'-acetoxychavicol acetate and 1'S-1'-acetoxyeugenol acetate exhibited potent inhibitory activity with IC(50) values of 15 and 19 microM. From the effects of various related compounds, both the 1'- and 4-acetoxyl groups of 1'S-1'-acetoxychavicol acetate and 1'S-1'-acetoxyeugenol acetate were essential for their strong activity, and the 2'-3' double bond enhanced the activity. In addition, 1'S-1'-acetoxychavicol acetate and 1'S-1'-acetoxyeugenol acetate inhibited ear passive cutaneous anaphylaxis reactions in mice and the antigen-IgE-mediated TNF-alpha and IL-4 production, both of which participate in the late phase of type I allergic reactions, in RBL-2H3 cells.

Involvement of leukotrienes in allergic inflammation in mice

The involvement of leukotrienes in the anaphylactic paw edema was investigated in sensitized boosted or unboosted mice. No difference was noted in the intensity of the antigen-induced paw edema between boosted and unboosted animals. Since the non-steroidal anti-inflammatory agents, indomethacin and aspirin, were inactive, cyclooxygenase products are not involved in the anaphylactic reaction in boosted or unboosted mice. In contrast, the mixed lipoxygenase/cyclooxygenase inhibitor, BW 755C (3-amino-1-m-(trifluoroethyl)phenyl-2-pyrazoline), and the LTD4 (leukotriene D4) receptor antagonist, LY 171883 (1-(2-hydroxy-3-propyl-4-(4-(1H-tetrazol-5-yl)butoxy)phenyl)eth anone, reduced the edema in boosted but not unboosted mice, suggesting the involvement of lipoxygenase metabolites in the allergic edema in boosted mice. Dexamethasone was only effective in inhibiting allergic edema in boosted mice when administered 12 h before provocation, but failed to reduce the edema in unboosted mice. Our results suggest that the booster injection during immunization shifts the anaphylactic mouse paw edema from a leukotriene-independent to a leukotriene-dependent reaction.

Active cutaneous anaphylaxis (ACA) in the mouse ear

Active cutaneous anaphylaxis (ACA) was studied in the ear of female BALB/c mice. Mice were immunized with ovalbumin in the presence of aluminium hydroxide gel or complete Freund's adjuvant (CFA). Two weeks after the immunization, ACA was elicited in the mouse ear by injecting 10 microliters of antigen solution intradermally into the ear lobe. ACA was assessed by the amount of extravasated dye, which was given intravenously just after the antigen injection. Antiallergic drugs (tranilast, ketotifen and azelastine), antihistamines (chlorpheniramine, diphenhydramine and mequitazine), beta-stimulants (isoproterenol and salbutamol), theophylline and glucocorticoids (hydrocortisone, prednisolone and dexamethasone) inhibited the reaction significantly. These drugs inhibited both ACA in mice immunized with alum-precipitated antigen and ACA in mice injected with CFA-emulsified antigen similarly. ACA in the mouse ear might be a useful tool for studying drugs for allergy.

Interference of antihistamines and anti-allergic drugs with antigen-induced paw edema in boosted and unboosted mice

The protective effects of two antihistamines and two anti-allergic drugs against anaphylactic paw edema were studied in immunized animals that had or had not received a booster injection of antigen. The injection of 1 or 10 micrograms/paw ovalbumin induced acute paw edema of similar intensity in both groups. The antihistamine meclizine and the mixed anti histamine/anti-5-HT antagonist cyproheptadine reduced the anaphylactic reaction by 55 and 84% respectively, in non-boosted animals and were less effective against edema induced by 1 microgram antigen in boosted animals. The effectiveness of these drugs was also reduced when boosted mice were challenged with 10 micrograms antigen, where meclizine and cyproheptadine inhibited edema by 31 and 59%, respectively. The anti-allergic compounds ketotifen and azelastine, although effective against allergic inflammation in non-boosted mice, had a reduced or no effect in boosted mice. Our results suggest that allergic edema is less sensitive to antihistamine and anti-allergic drugs in boosted mice, which may be accounted for by an increased role of other mediators.