Antiproliferative activity on Trypanosoma cruzi (Y strain) of the triterpene 3ß,6ß,16ß-trihidroxilup-20 (29)-ene isolated from Combretum leprosum.

Chagas disease infects approximately seven million people worldwide. Benznidazole is effective only in the acute phase of the disease, with an average cure rate of 80% between acute and recent cases. Therefore, there is an urgent need to find new bioactive substances that can be effective against parasites without causing so many complications to the host. In this study, the triterpene 3ß-6ß-16ß-trihydroxilup-20 (29)-ene (CLF-1) was isolated from Combretum leprosum, and its molecular structure was determined by NMR and infrared spectroscopy. The CLF-1 was also evaluated in vitro and in silico as potential trypanocidal agent against epimastigote and trypomastigote forms of Trypanosoma cruzi (Y strain). The CLF-1 demonstrated good results highlighted by lower IC50 (76.0 ± 8.72 µM, 75.1 ± 11.0 µM, and 70.3 ± 45.4 µM) for epimastigotes at 24, 48 and 72 h, and LC50 (71.6 ± 11.6 µM) for trypomastigotes forms. The molecular docking study shows that the CLF-1 was able to interact with important TcGAPDH residues, suggesting that this natural compound may preferentially exert its effect by compromising the glycolytic pathway in T. cruzi. The ADMET study together with the MTT results indicated that the CLF-1 is well-absorbed in the intestine and has low toxicity. Thus, this work adds new evidence that CLF-1 can potentially be used as a candidate for the development of new options for the treatment of Chagas disease.Communicated by Ramaswamy H. Sarma.

Gas chromatography coupled to mass spectrometry (GC-MS) characterization and evaluation of antibacterial bioactivities of the essential oils from Piper arboreum Aubl., Piper aduncum L. e Piper gaudichaudianum Kunth.

The objective of this study was to determine the chemical profile and to evaluate the antibacterial activity of the essential oils of Piper species and modulation of the antibiotic activity, using the microdilution method to determine the minimum inhibitory concentration. The chemical components were characterized by gas chromatography coupled to mass spectrometry, which revealed ß-copaen-4-α-ol (31.38%), spathulenol (25.92%), and germacrene B (21.53%) as major constituents of the essential oils of Piper arboreum, Piper aduncum, and Piper gaudichaudianum, respectively. The essential oils analyzed in this study did not present a clinically relevant activity against standard and multiresistant Escherichia coli. However, in the case of multiresistant Staphylococcus aureus, there was a significant activity, corroborating with reports in the literature, where Gram-positive bacteria are more susceptible to antimicrobial activity. The essential oils modulated the effect of the antibiotics norfloxacin and gentamicin, having on the latter greater modulating effect; however, for erythromycin, no statistically significant effect was observed. In conclusion, the results obtained in this study demonstrated that the essential oils of the analyzed Piper species present an inhibitory effect against S. aureus and modulate antibiotic activity, most of which presents synergistic activity.

Chemical Composition and Antioxidant Activity of Essential Oils from Populations of Baccharis dracunculifolia DC. in Southern Brazil

HIGHLIGHTS Essential oils from populations of B. dracunculifolia were investigated. β-pinene and (E)-nerolidol were the main compounds in B. dracunculifolia populations. The difference in the chemical profile of the essential oils is quantitative only. There is a negative correlation between the antioxidant activity and spathulenol.

Abstract Baccharis dracunculifolia DC. is a Brazilian native plant, presenting wide chemical diversity and numerous pharmaceutical and industrial applications. This research assessed the yield, antioxidant activity and the chemical similarity of essential oils from 10 populations of B. dracunculifolia in the state of Paraná, southern Brazil. The extraction of the volatile compounds was carried out by hydrodistillation, the chemical composition was determined by GC/FID and GC/MS and the antioxidant activity by the DPPH method. The essential oil yield of wild B. dracunculifolia populations ranged from 0.14 to 0.87%. The oils were predominantly composed of oxygenated sesquiterpenes (34.16 - 51.01%), monoterpene hydrocarbons (18.02 - 46.17%) and sesquiterpenes hydrocarbons (9.60 - 17.70%). The major compounds found in all populations were β-pinene (7.65 - 29.8%) and (E)-nerolidol (9.11 - 21.68%). Essential oil solutions (20%) from different populations presented antioxidant capacity ranging from 27.78 to 91.67%. A negative correlation was found between the antioxidant activity and spathulenol (r = -0.696). Multivariate analyses separated the populations into three groups: (1) low concentrations of α-pinene (2.02 - 2.06%), (2) high concentrations of α-pinene (4.17 - 4.61%) and β-pinene (22.54 - 29.80%), and (3) intermediate concentrations of α-pinene (2.38 - 3.31%), β-pinene (12.77 - 19.03%) and spathulenol (6.02 - 9.06%).

GC-MS-FID characterization and antibacterial activity of the Mikania cordifolia essential oil and limonene against MDR strains.

The present study evaluated the effect of the essential oil of Mikania cordifolia (EOMc) and its major constituent limonene alone or associated with antibacterial drugs against Multidrug Resistant Bacteria (MDR). To evaluate the antibacterial activity, the minimum inhibitory concentrations (MIC) of the oil and limonene against Pseudomonas aeruginosa, Escherichia coli and Staphylococcus aureus were determined. The antibiotic-modulating activity was assessed using subinhibitory concentrations (MIC/8) of these substances in combination with conventional antibacterial drugs. Although no relevant antibacterial activity of the natural products was detected, both substances modulated the action of antibiotics against resistant bacteria. The EOMc demonstrated the best modulating effect against P. aeruginosa, presenting synergistic effects when associated with gentamicin and norfloxacin. In addition, the oil reduced the MIC of norfloxacin against E. coli as well as reduced the MIC of gentamicin against S. aureus. On the other hand, the best effect of limonene was obtained against S. aureus. Thus, it is concluded that the essential oil Mikania cordifolia and the isolated compound limonene do not have clinically significant antibacterial effect, but modulate the action of antibiotics against MDR bacteria.