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The antinociceptive effects of morusin (1), the main prenylflavonoid present in the Morus nigra root barks have been investigated in classical models of pain in mice. The results showed that 1 exhibits a promising antinociceptive or analgesic profile by the intraperitoneal route, being more potent than some standard drugs used as reference. The mechanism by which the morusin exerts antinociceptive activity still remains undetermined, but our results strongly suggest that it involves the participation of the opioid system.

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We describe here the antinociceptive action of the crude extract (CE), the chemical isolation and characterisation and preliminary pharmacological analysis of 24-hydroxytormentic acid, isolated from the stem bark of Ocotea suaveolens (Lauraceae). The CE given by i.p. or p.o. routes, 30 min and 1 h prior, produced significant inhibition of abdominal constrictions caused by acetic acid and also inhibited both phases of formalin-induced licking in mice. The antinociception caused by the CE, given by i.p. and p.o. routes, lasted up to 4 and 2h, respectively. When assessed in the hot-plate test, the CE was inactive. Its antinociceptive action was not associated with non-specific effects such as muscle relaxation or sedation. The antinociception of CE was not influenced by naloxone, L-arginine or DL-p-chlorophenylalanine methyl ester, when assessed against the formalin assay. The triterpene 24-hydroxytormentic acid, given i.p. 30 min before testing, produced significant, dose-related and equipotent antinociceptive action against both phases of formalin-induced licking in mice. These results demonstrate, for the first time, the occurrence of the triterpene 24-hydroxytormentic acid in the stem bark of Ocotea suaveolens, and show that the CE and 24-hydroxytormentic acid exhibit marked antinociception against the neurogenic and the inflamamtory algesic responses induced by formalin in mice. The mechanism by which this compound and CE produces antinociception still remains unclear, but is unlikely to involve the activation of opioid, nitric oxide or serotonin systems or non-specific peripheral or central depressant actions.

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The aim of this study was to isolate and characterize the constituents of the hydroalcoholic extract (HE) of the leaves, stems and roots from P. caroliniensis, and also to evaluate the preliminary antinociceptive action of the HE and purified compounds in mice. Phytosterols, quercetin, gallic acid ethyl ester and geraniin were identified in P. caroliniensis on the basis of 1H and 13C NMR spectral data and by mixed co-TLC and co-HPLC injection with authentic samples. The HE of P. caroliniensis (10-100 mg kg-1, i.p.) inhibited, in a dose-related manner, acetic acid-induced abdominal constrictions in mice, with a mean ID50 value of 23.7 mg kg-1. In the formalin test, the HE given intraperitoneally (1-30 mg kg-1) or orally (25-600 mg kg-1) caused graded inhibitions of both the neurogenic (first phase) and the inflammatory response (late phase) of formalin-induced licking. The HE was 54-fold more effective in inhibiting the late phase than it was in inhibiting the first phase of the formalin test, with mean ID50 values of 3.6 and 196.4 mg kg-1, respectively. The HE failed, however, to affect the oedematogenic response associated with the late phase of formalin-induced pain. In addition, the reference drug, aspirin, given intraperitoneally (1-100 mg kg-1) or orally (100-600 mg kg-1), caused significant inhibition of the late but not the first phase of the formalin test. Pharmacological analysis also revealed that quercetin, gallic acid ethyl ester and a semi-purified fraction of flavonoids (1-100 mg kg-1, i.p.) exhibited graded and significant antinociception against acetic acid-induced abdominal constriction. The mean ID50 values (mg kg-1) for these effects were: 18.8, 34.7 and 5.3, respectively. It is concluded that quercetin, gallic acid ethyl ester and some as yet unidentified flavonoids might account for the antinociceptive action reported for the HE of P. caroliniensis.

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The present study describes the occurrence of two ellagitannins in the ethanolic extract of the leaves and stems of Phyllanthus sellowianus (Euphorbiaceae). Their preliminary antinociceptive properties were also evaluated. The two ellagitannins were identified on the basis of 1H- and 13C-NMR spectra data and by mixed co-TLC and co-HPLC injection with an authentic sample of furosin and geraniin. Preliminary pharmacological analysis revealed that both furosin and geraniin (3 to 30 mg/kg, i.p.), given 30 min before testing, exhibited significant and dose-related antinociceptive properties against acetic acid-induced abdominal constrictions in mice. Geraniin and furosin were about six- to seven-fold more potent at the ID50 level (micromol/kg) as analgesics than aspirin and acetaminophen, respectively, although they were less efficacious when compared with the standard drugs. These data extend our previous studies and indicate that the two ellagitannins isolated from P.sellowianus, identified as furosin and geraniin are, at least in part, responsible for the antinociceptive actions reported previously for the hydroalcoholic extract of P.sellowianus and other plants belonging to the genus Phyllanthus.

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Vochysia divergens Pohl (Vochysiaceae) is a tree commonly found in wet soils of 'Pantanal' of Mato Grosso, Brazil, and used in folk medicine against infections and asthma. We have studied different extracts and some isolated compounds from this plant for antibacterial activity. From the extracts of the stem bark beta-sitosterol, betulinic acid and sericic acid were isolated. The minimal inhibitory concentration (MIC) for Staphylococcus aureus were: ethanolic extract (MIC = 1.5 mg/ml); ethyl acetate extract (MIC = 2.0 mg/ml); and sericic acid (MIC = 1.0 mg/ml). Escherichia coli was resistant until 5 mg/ml.

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1. This study examines the effects of methanolic extract (ME) and its main constituent, sorocein A, isolated from the roots of Sorocea bonplandii on agonist-induced contractions in the rat uterus (RU) and in the guinea pig ileum (GPI) in vitro. 2. ME (25-100 micrograms/ml), added to RU for 20 min, caused a graded and parallel shift to the right of bradykinin (BK)-mediated contractions with an apparent pA2 value (-log g/ml) of 5.0 ME caused a rightward shift of the acetylcholine (ACh) and oxytocin-induced contractions associated with a marked depression of their maximal responses. 3. In GPI, ME produced a non-competitive antagonism against BK-induced contraction, while responses to ACh and histamine were shifted to the right in a graded fashion, yielding pA2 values (g/ml) of 5 in both cases. 4. The purified compound sorocein A (15-60 microM) caused a parallel and graded rightward displacement of BK and ACh concentration-response curves in RU with pA2 values (molar basis) of 4.9 and 5.2. 5. Sorocein A also dose-dependently shifted to the right ACh and histamine-mediated contractions in GPI, yielding pA2 values of 5.1 and 4.8, respectively. 6. However, sorocein A antagonized in a non-competitive manner BK-induced contraction in GPI, characterized by a graded displacement to the right of the dose-response curve, and progressive depression of the maximal contraction.

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Akagerine (3) was isolated from three different species of South American Strychnos: from S. gardneri A. D.C. (Rio de Janeiro, Brazil), together with 11-methoxydiaboline (2); from S. jobertiana Baillon (Brazil), together with diaboline (1): and from S. parvifolia D.C. (Bahia, Brazil).

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