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Setting: Department of Clinical Analysis and Biomedicine, State University of Maringa, Maringa, Parana, Brazil., Objective: To evaluate the in vitro interaction between eupomatenoid-5 (EUP-5), extracted from Piper solmsianum C. DC. var. solmsianum, and first-line anti-tuberculosis drugs against Mycobacterium tuberculosis H₃₇Rv and 20 clinical isolates., Design: Resazurin drugs combination microtiter assay (REDCA) was performed to determine the interaction between EUP-5 and isoniazid, rifampicin (RMP) and ethambutol (EMB)., Results: Synergism was observed in M. tuberculosis H₃₇Rv and eight clinical isolates with EUP-5+RMP, and in M. tuberculosis H₃₇Rv and 17 clinical isolates with EUP-5+EMB combinations., Conclusion: EUP-5 is a promising compound for further studies on the development of anti-tuberculosis drugs.

The antinociceptive properties of some fractions and two pure compounds, conocarpan and orientin, obtained from P. solmsianum leaves were investigated in several models of pain in mice. The results indicated that this plant exhibits a promising antinociceptive profile, as it produces active principles which are several times more active than some reference drugs used for comparison. The main compound tested, orientin, caused potent and dose-dependent effects against acetic acid-induced writhing and capsaicin- and glutamate-induced nociception, being more effective against the first one, with an ID(50) value of 6.5 mg/kg (14.5 micromol/kg). Orientin was about 20-fold more potent than acetylsalicylic acid and 3.5-fold more active than indomethacin. The antinociceptive effects of this plant may be attributed, at least partially, to the presence of conocarpan and, in particular, to the flavonoid orientin.

We have studied the crude methanolic extract (CME), some fractions (hexane, dichloromethane and ethyl acetate) and four pure compounds: eupomatenoid-3 (1), eupomatenoid-5 (2), conocarpan (3) and orientin (4), from Piper solmsianum, for possible antifungal activity against 12 pathogenic fungi. The minimal inhibitory concentration (MIC) was determined and the experiments showed that the CME exhibited antifungal action against all the dermatophytes tested, with MIC values of between 20 microg/ml to 60 microg/ml. Similar activity also was verified for the hexane, dichloromethane and ethyl acetate fractions. However, the starting material (CME), and all the fractions, did not exert inhibitory effect against hyaline hyphomycetes and were only discretely active against the zigomycetes and yeasts. Compounds 2, 3 and 4 also exhibited pronounced activity against all the dermatophytes tested (MIC< or =1 to 9 microg/ml) with potency as high as the standard antifungal drug (ketoconazole). Compound 3 also exhibited activity against all the yeasts tested. In conclusion, the antifungal activity of P. solmsianum seems to be related mainly to the presence of compounds 2, 3 (neolignans) and 4 (flavonoid), however it was verified that another active compound, as yet unidentified, exists in the plant.