In the present work, dried aerial parts of Baccharis ligustrina (Asteraceae) were subjected to microwave assisted extraction (MAE) using aqueous solution of 1-butyl-3-methylimidazolium bromide (BMImBr) and the obtained extract was successively partitioned using hexane and EtOAc. Using reduced amounts of extracts and efficient chromatographic steps, four acyl C6C3 derivatives (n-hexacosyl ferulate, n-hexacosyl, n-octacosyl, and n-triacontyl p-coumarates) were obtained from hexane phase whereas two C6C3 acids (ferulic and p-coumaric) were obtained from EtOAc phase. Isolated phenylpropanoids were evaluated against amastigote forms of parasite Trypanosoma cruzi. As result, it was observed that p-coumaric and ferulic acids were inactives whereas alkyl derivatives displayed EC50 values of 6.5 µmol L-1 (n-octacosyl p-coumarate), 9.3 µmol L-1 (n-triacontyl p-coumarate), 15.7 µmol L-1 (n-hexacosyl p-coumarate), and 32.2 µmol L-1 (n-hexacosyl ferulate). All tested compounds displayed reduced toxicity against NCTC cells (CC50 > 200 mmol L-1).

Electrochemical procedures have emerged as a powerful tool for the synthesis of complex organic molecules including transformation of natural products. In this study, the electrosynthesis of biseugenol in MeOH afforded one new oxidized derivative, which was characterized as methoxyl-oxo-biseugenol (MOB) by nuclear magnetic resonance (NMR) and electrospray ionization-high resolution mass spectrometry (ESI-HRMS) analysis. Since biseugenol was previously described as a cytotoxic natural product, MOB was also tested against tumoral cells B16F10-Nex2 (murine metastatic melanoma) and SKMEL-25 (human metastatic melanoma) as well as against non-tumoral cells MØ Raw 264.7 (murine macrophage immortalized) and HUVEC (human umbilical endothelium). As results, MOB showed inhibitory concentration that affects 50% of cells (IC50) values of 9.5 ± 1.6 mg mL-1(B16F10Nex2), 13.2 ± 2.5 mg mL-1 (SKMEL-25), 19.9 ± 3.5 mg mL-1 (MØ Raw 264.7) and 36.3 ± 7.4 mg mL-1 (HUVEC). Therefore, selectivity index (SI) values of MOB to tumoral cells B16F10Nex2 and SKMEL-25 were calculated as 2.1 and 2.8, respectively, higher than biseugenol (1.4 and 1.7, respectively). Based on these results, the superior cytotoxic activity of MOB in comparison to biseugenol could be associated, at least in part, to the presence of a non-aromatic ring and a conjugated carbonyl system instead of a phenol moiety.

The nitrofurazone (NF) electrochemical reduction has been studied by cyclic voltammetry (CV) and square wave voltammetry (SWV) in non-aqueous medium using three different ionic liquids (IL): BMImTf2N, BMImBF4 and BMMImTf2N, having a carbon fiber microelectrode as working electrode. In all of them, two reversible cathodic peaks were recorded for NF. Under higher frequency values, only one reversible cathodic peak was registered. The systems reversibility could also be observed by CV, since a reversible redox couple was registered for this reduction. The systems reversibility with product and reagent adsorptions on the electrode surface was confirmed and the electrons number involved in this reduction indicated the nitro-anion radical formation followed by its respective dianion. For the first reduction, the EC mechanism (an electrochemical step followed by a chemical one) was considered for the systems in aprotic medium, in which there was a probable second-order chemical reaction after the charge transfer process, being the kinetic constants calculated following the Olmstead and Nicholson model.

In the present work, leaves of Pentacalia desiderabilis (Asteraceae) were subjected to extraction using aqueous 1-butyl-3-methylimidazolium bromide (BMImBr) in the microwave assisted extraction (MAE). The obtained extract was partitioned using CH2Cl2 and antifungal activity against Cladosporium cladosporioides and C. sphaerospermum of the organic phase was evaluated. Sequentially, this material was subjected to several chromatographic procedures to afford four quinoid derivatives identified as jacaranone (1), methyl-jacaranone (2), quinolacetic acid (3), and methyl 1-hydroxy-4-oxo-cyclohexaneacetate (4), being the first occurrence of compounds 2 - 4 in P. desiderabilis. Isolated quinoid derivatives were submitted to bioautography assay and the obtained results indicated that compounds 1 - 3 are active against Cladosporium cladosporioides (0.78, 12.5 and 12.5 µg, respectively) and C. sphaerospermum (3.13, 12.5 and 12.5 µg, respectively).

In the present work, dried leaves of Saururus cernuus (Saururaceae) were subjected to extraction using an ionic liquid (1-butyl-3-methylimidazolium bromide - BMImBr) in the microwave assisted extraction (MAE). The obtained extract was partitioned using n-hexane and cytotoxicity activity of this organic phase against murine melanoma cell line (B16F10-Nex2) was evaluated in vitro. Since this extract displayed activity (100% of cell death at 200 µg mL-1) it was subjected to a bioactivity-guided fractionation to afford four related neolignans: threo-austrobailignan-5 (1), threo-austrobailignan-6 (2), threo-dihydroguaiaretic acid (3) and saucernetin (4). Their chemical structures were established based on NMR and MS spectral analysis. Among the isolated neolignans, compound 2 exhibited the highest cytotoxic activity against HeLa (human cervical melanoma) cells with IC50 of 28.3 ± 3.9 µg mL-1 (86 ± 12 µmol L-1). Furthermore, compounds 2 and 3 exhibited the highest cytotoxic activity against A2058 (human melanoma) cells with IC50 of 44.3 ± 4.2 µg mL-1 (135 ± 13 µmol L-1) and 41.5 ± 7.5 µg mL-1 (126 ± 23 µmol L-1), respectively, similar to positive control cisplatin (IC50 = 43.2 ± 3.2 µg mL-1 or 144 ± 11 µmol L-1). Otherwise, compound 4 was inactive (IC50 > 100 µg mL-1 or > 300 µmol L-1). The obtained results provide important data for the selection of bioactive neolignans with promising cytotoxic potential using a simple and fast method employing a green solvent as 1-butyl-3-methylimidazolium bromide (BMImBr).

This work reports the application of an ionic liquid (1-butyl-3-methylimidazolium bromide, BMImBr) in the microwave assisted extraction (MAE) of metabolites from fruits of Schinus terebinthifolius. Dried fruits were individually extracted using BMImBr:H2O 1:1, v/v (experiment 1) and pure H2O (experiment 2) by MAE (10 min at 60 ºC). After partition using EtOAc, the yield to experiment 1 was about 23% while to experiment 2 was 0.1%. The EtOAc fraction obtained from experiment 1 was purified by chromatographic methods to afford 3-oxotirucalla-7,24Z-dien-27-oic acid, 3a-hydroxytirucalla-7,24Z-dien-27-oic acid, 3a-acetoxytirucalla-7,24Z-dien-27-oic acid, gallic acid, and ethyl gallate, being the first occurrence of the third compound as natural product. Cytotoxic activity was evaluated in vitro against cancer cell lines (A2058, HeLa, SiHa, HCT, SKBR-3, U87, and B16F2Nex2), being 3a-acetoxytirucalla-7,24Z-dien-27-oic acid the more active metabolite with IC50 ranging from 10.9 ± 1.3 to 17.3 ± 1.4 µg mL-1, lower than that determined to positive control cisplatin.