No abstract

Pretreatment of rats with hesperidin (50 and 100 mg kg-1, s.c.) reduced the paw oedema induced by carrageenan by 47 and 63%, respectively, within 5 h. The effect was equivalent to that produced by indomethacin (10 mg kg-1, p.o.), although unrelated to the administered dose, particularly at high doses. At 100 mg kg-1 hesperidin decreased the rat paw oedema induced by dextran by 33%, without influencing the histamine-induced paw oedema. Hesperidin also inhibited pleurisy induced by carrageenan, reducing the volume of exudate and the number of migrating leucocytes by 48 and 34%, respectively, of control values. Equal doses of duartin and claussequinone were ineffective in all the above tests. Pretreatment of mice with hesperidin (100 mg kg-1, s.c.) reduced acetic acid-induced abdominal constriction by 50%, but did not affect the tail flick response. Hyperthermia induced by yeast in rats was slightly reduced by hesperidin. No lesions of the gastric mucosae were detected in rats pretreated with hesperidin. The results indicate that hesperidin obtained from citrus cultures may present a potential therapeutical use as a mild anti-inflammatory agent, being also useful as a precursor of new flavonoids endowed with such activity.

The perhydro, derivative of histrionicotoxin rev ersibly blocks thle excitatory ionic traisduction system in the synaptic anld sarcolemmal membranes of mainnalian. slkeletal mtiscle cells. The efficacy of perliydrohistrionicotoxin as an1 antagonist at the post-synaptic remlbraine is increased by the transienit prese'ice of acetylcholine in the entdplate of ininervated muscles and at extrajunctional rece)Lors in denervated imutiscles. 'The excitatory action of acetylcholine at posts-ynaptic inembranes clearly involves at least two stages: first, the combination of the tramismitter with a receptor site, and second, the induced inreeaze in Na+ and K+ conductances that cause the transient depolarization of the membrane. Little is knownl about thel molecular basis for the coul)ling between these two steps. Hypotheses (1---6) include (a) topographically-separate AICh receptors and ion conductance modulators § (1CM); (b) a cooperative complex consisting of receptor and ICAM subunits; and (c) one macromolecule, serving as both receptor and ICM. a-Bungarotoxin (BuTX) has been proposed as a specific reagent for the acetylcholine receptor site in vertebrate skeletal muscle synapse (7-10). No such specific probe for the postsynaptic ICM has been described. The results reported herein suggest that the perhydroderivative (H12-

Baccharis triptera Mart, is a widespread Compositae used in Brazilian folk medicine to treat gastrointestinal disturbances, rheumatic disease, mild fever, diabetes and as an anti-helminthic. Water extract of small branches of the plant (WE) administered to mice and rats (0.1 to 2 g/kg, p.o.) did not alter spontaneous motor activity, sleeping time induced by barbiturates or the tail-flick response in mice. The extract decreased by 40% the number of writhings induced by 0.8% acetic acid, i.p., but did not influence paw edema induced by carrageenan or dextran in rats. WE (2 g/kg, p.o.) decreased the intestinal transit of charcoal in mice by 20%. Gastric secretion in pylorus ligated rats was reduced after treatment with WE (1 and 2 g/kg, i.p. or intraduodenal) and the gastric pH was raised. The extract (1 g/kg, p.o.) prevented gastric ulcers induced in rats by immobilization at 4 degrees C, but not those induced by indomethacin (10 mg/kg, s.c.). The results indicate that WE may relieve gastrointestinal disorders by reducing acid secretion and gastrointestinal hiperactivity. Neither analgesic nor anti-inflammatory activities were detectable.