In vitro schistosomicidal effects of aqueous and dichloromethane fractions from leaves and stems of Piper species and the isolation of an active amide from P. amalago L. (Piperaceae).

Dichloromethane and aqueous fractions from leaves and stems of Piper arboreum Aubl., P. aduncum L., P. amalago L., P. crassinervium H.B. & K., P. diospyrifolium Kunth, P. hispidum Sw. and P. xylosteoides (Kunth) Steud. were tested against adult worms of Schistosoma mansoni. The in vitro activity was evaluated in terms of mortality, number of separated worms and number of worms with reduced motor activity. Most dichloromethane fractions from all Piper species showed moderate schistosomicidal activity, but aqueous fractions were not active. The dichloromethane fraction of P. amalago leaves (at 100 µg/ml) showed the highest activity, resulting in worm mortality, the separation of worm pairs and reduced motor activity. Chromatographic fractionation of the dichloromethane fraction of P. amalago leaves led to the isolation of its major compound, which was also tested against adults of S. mansoni. The isolated piperamide N-[7-(3',4'-methylenedioxyphenyl)-2(Z),4(Z)-heptadienoyl] pyrrolidine, at 100 µ m, resulted in the mortality of all adult worms after 24 h of incubation. The findings suggest that species of Piper are potential sources of schistosomicidal compounds.

Schistosomicidal and trypanocidal structure-activity relationships for (±)-licarin A and its (-)- and (+)-enantiomers.

(±)-Licarin A (1) was obtained by oxidative coupling, and its enantiomers, (-)-licarin A (2) and (+)-licarin A (3), were resolved by chiral HPLC. Schistosomicidal and trypanocidal activities of these compounds were evaluated in vitro against Schistosoma mansoni adult worms and trypomastigote forms of Trypanosoma cruzi. The racemic mixture (1) displayed significant schistosomicidal activity with an LC50 value of 53.57 µM and moderate trypanocidal activity with an IC50 value of 127.17 µM. On the other hand, the (-)-enantiomer (2), displaying a LC50 value of 91.71 µM, was more active against S. mansoni than the (+)-enantiomer (3), which did not show activity. For the trypanocidal assay, enantiomer 2 showed more significant activity (IC50 of 23.46 µM) than enantiomer 3, which showed an IC50 value of 87.73 µM. Therefore, these results suggest that (±)-licarin A (1) and (-)-licarin A (2) are promising compounds that could be used for the development of schistosomicidal and trypanocidal agents.

In vitro antileishmanial, antiplasmodial and cytotoxic activities of phenolics and triterpenoids from Baccharis dracunculifolia D. C. (Asteraceae).

Baccharis dracunculifolia (Asteraceae), the most important plant source of the Brazilian green propolis (GPE), displayed in vitro activity against Leishmania donovani, with an IC(50) value of 45 microg/mL, while GPE presented an IC(50) value of 49 microg/mL. Among the isolated compounds of B. dracunculifolia, ursolic acid, and hautriwaic acid lactone showed IC(50) values of 3.7 microg/mL and 7.0 microg/mL, respectively. Uvaol, acacetin, and ermanin displayed moderate antileishmanial activity. Regarding the antiplasmodial assay against Plasmodium falciparum, BdE and GPE gave similar IC(50) values (about 20 microg/mL), while Hautriwaic acid lactone led to an IC(50) value of 0.8 microg/mL (D6 clone).

Hypoglicemic effect of Leandra lacunosa in normal and alloxan-induced diabetic rats.

Leandra lacunosa, popularly known as "erva-do-jabuti", is used in Brazilian folkloric medicine for the treatment of diabetes mellitus. Based on this traditional indication, the aim of this work was to evaluate the hypoglycemic activity of the hydroalcoholic extract of L. lacunosa aerial parts (LLH) in normal and alloxan-induced diabetic rats. Chromatographic fractionation of LLH was also carried out by several techniques, affording isolation of the following major compounds: ursolic acid (1), kaempferol (2), luteolin (3), and quercetin (4). The oral administration of LLH (500 mg/kg) in normal rats caused a significant reduction of 24.7% (P<0.05) in the blood glucose levels after 2 h of treatment, while the administration of chlorpropamide (20 mg/kg, p.o.) led to a reduction of 40.2% (P<0.01). After oral administration of glucose (10 g/kg, p.o.), LLH (500 mg/kg, p.o.) significantly inhibited the increase in blood glucose levels compared with the negative control group. The oral treatment with LLH (500 mg/kg) in alloxan-induced diabetic rats significantly reduced the blood glucose levels in 47.8% after 4 h of treatment, while chlorpropamide resulted in a significant reduction of 71.7% in the 4th hour. Our results showed that LLH, displays hypoglycemic activity, which may be related to the effect of the major compounds identified in the crude extract. This study seems to provide biological evidence for the folkloric use of L. lacunosa in the treatment of diabetes mellitus.

Analgesic and anti-inflammatory activity of a crude root extract of Pfaffia glomerata (Spreng) Pedersen.

The anti-inflammatory and antinociceptive effects of the crude hydroalcoholic extract (PE) of Pfaffia glomerata roots was assessed in the carrageenan-induced rat paw edema at the doses of 100, 200 and 300 mg/kg, using different animal models. An anti-inflammatory dose effect response correlation of r=0.997 and Y=11.67x+0.02 was found. At the same doses, the extract-inhibited acetic acid-induced writhing in mice, but no dose response correlation was found. Oral administration of 100 mg/kg of PE and 0.5 mg/kg of dexamethazone inhibited by 29 and 61%, the granulomatous tissue formation (p>0.05), respectively. These results indicate the potential of this plant extract to treat chronic inflammation. At the assayed doses no significant activity was found in the hot plate test, as well as in the cell migration-induced by carrageenan.

Effect of Brazilian green propolis on the production of reactive oxygen species by stimulated neutrophils.

The activity of a crude ethanol extract of green propolis and its fractions obtained by partition with hexane, chloroform and n-butanol was assessed on luminol- and lucigenin- enhanced chemiluminescence (CL) produced by rabbit neutrophils (PMNs) stimulated with particles of serum-opsonized zymosan (OZ). The total production of reactive oxygen species (ROS) by PMNs was measured by the luminol-enhanced CL (LumCL) assay and the production of the superoxide anion (O2*-) by the lucigenin-enhanced CL (LucCL) assay. All evaluated propolis samples had inhibitory effect on the LumCL and LucCL, which was concentration dependent. The n-butanol and chloroform fractions displayed the highest inhibitory effect on the LumCL produced by PMNs stimulated with OZ, in comparison with both the ethanol extract and the hexane fraction. Besides, the hexane fraction was the one which presented the highest effect for the LucCL assay. Some isolated compounds from both n-butanol and chloroform fractions were also assessed, including kaempferide, isosakuranetin, aromadendrine-4'-methyl-ether and 3-prenyl-p-coumaric acid. Kaempferide presented the highest inhibitory effect on the LumCL in comparison with the other compounds. Moreover, under the conditions assessed, the studied green propolis samples and isolated compounds were not toxic to the rabbit PMNs.

Analgesic and anti-inflammatory activities evaluation of (-)-O-acetyl, (-)-O-methyl, (-)-O-dimethylethylamine cubebin and their preparation from (-)-cubebin.

The anti-inflammatory and antinociceptive effects of the acetylated (2), methylated (3) and aminated (4) derivatives of cubebin (1), obtained by its reaction with acetic anhydride, methyl iodide and dimethylethylamine chloride, respectively, were investigated, using different animal models. The compound (2) was the most effective anti-inflammatory one in the carrageenin-induced paw edema in rats and was the only one which showed dose-response correlation for this assay with r = 0.993 and Y = 64.58x + 0.22. Besides, compounds (2) and (4) were more effective than cubebin in inhibiting acetic acid-induced writhing in mice, producing dose-response correlation with doses of 10, 20 and 30 mg/kg, respectively. Regarding the hot plate and the cell migration tests in rats, none of the four tested compounds showed activity. Overall, the results showed that the acetylation and amination of cubebin were efficient in enhancing its analgesic activity, as well as its anti-inflammatory activity.

Evaluation of the trypanocidal and leishmanicidal in vitro activity of the crude hydroalcoholic extract of Pfaffia glomerata (Amarathanceae) roots.

Three different concentrations (1, 10 and 50 microg/ml) of lyophilized hydroalcoholic crude extract of Pfaffia glomerata roots were assayed in vitro against strains of Trypanosoma cruzi (Y) and Leishmania braziliensis. It was observed that P. glomerata hydroalcoholic extract was relatively active within the tested concentrations for L. (V) braziliensis, but inactive against T. cruzi. Despite the fact that both protozoans belong to the Trypanosomatidae family, we suggest that the difference observed for activity should be related to the biological differences between the two parasite species.