Using bioisosterism as a medicinal chemistry tool, 16 3,5-diaryl-isoxazole analogues of the tetrahydrofuran neolignans veraguensin, grandisin and machilin G were synthesized via 1,3-dipolar cycloaddition reactions, with yields from 43% to 90%. Antitrypanosomatid activities were evaluated against Trypanosoma cruzi, Leishmania (L.) amazonensis and Leishmania (V.) braziliensis. All compounds were selective for the Leishmania genus and inactive against T. cruzi. Isoxazole analogues showed a standard activity on both promastigotes of L. amazonensis and L. braziliensis. The most active compounds were 15, 16 and 19 with IC 50 values of 2.0, 3.3 and 9.5 μM against L. amazonensis and IC 50 values of 1.2, 2.1 and 6.4 μM on L. braziliensis, respectively. All compounds were noncytotoxic, showing lower cytotoxicity (>250 μM) than pentamidine (78.9 μM). Regarding the structure-activity relationship (SAR), the methylenedioxy group was essential to antileishmanial activity against promastigotes. Replacement of the tetrahydrofuran nucleus by an isoxazole core improved the antileishmanial activity. K E Y W O R D S bioisosterism, cycloaddition [3+2], isoxazole, neolignans 314 | TREFZGER ET al.

Background Thrombocytopenia (TP) is the major event associated with linezolid (LZD) therapy. We investigated the incidence and risk factors for thrombocytopenia in hospitalized adults who received LZD (1200 mg/day) between 2015 and 2017. HIV-positive, death during follow-up and those with a baseline platelet count ≤100 × 10 3 /mm 3 were excluded. Method TP was defined as a decrease in platelet count of ≥20% from the baseline level at the initiation of linezolid therapy and a final count of <100 × 10 3 /mm 3 . The odds ratios (OR) for thrombocytopenia were obtained using multivariate stepwise logistic regression analysis. Main results A total of 66 patients were included (mean age [SD] 62 [18], male gender [%], 37 [56]). LZD-associated TP was identified in 12 patients (18.2%). For TP, the adjusted OR [95% CI] of the platelet count ≤200 × 10 3 /mm 3 , serum creatinine and renal impairment at baseline were 5.66 [1.15–27.9], 4.57 [1.26–16.5] and 9.41 [1.09–80.54], respectively. Male gender and dosage per weight per day (DPWD) >20 mg/kg/day were not risk factors. Conclusion The results showed that the incidence of linezolid-induced thrombocytopenia was lower in patients with normal renal function and higher in those with platelet counts ≤200 × 10 3 /mm 3 or serum creatinine >1.5 mg/dL at the start of the treatment.

We have devised a procedure for the synthesis of analogs of combretastatin A-4 (CA-4) containing sulfur and selenium atoms as spacer groups between the aromatic rings. CA-4 is well known for its potent activity as an inhibitor of tubulin polymerization, and its prodrugs combretastatin A-4 phosphate (CA-4P) and combretastatin A-1 phosphate (CA-1P) are being investigated as antitumor agents that cause tumor vascular collapse in addition to their activity as cytotoxic compounds. Here we report the preparation of two sulfur analogs and one selenium analog of CA-4. All synthesized compounds, as well as several synthetic intermediates, were evaluated for inhibition of tubulin polymerization and for cytotoxic activity in human cancer cells. Compounds 3 and 4 were active at nM concentration against MCF-7 breast cancer cells. As inhibitors of tubulin polymerization, both 3 and 4 were more active than CA-4 itself. In addition, 4 was the most active of these agents against 786, HT-29 and PC-3 cancer cells. Molecular modeling binding studies are also reported for compounds 1, 3, 4 and CA-4 to tubulin within the colchicine site.

A cytotoxicity-guided fractionation of the roots of Galianthe thalictroides afforded a new β-carboline alkaloid, 1-(hydroxymethyl)-3-(2-hydroxypropan-2-yl)-2-(5-methoxy-9H- β-carbolin-1-yl)cyclopentanol, which exhibited strong cytotoxic activity against three human cancer cell lines (MCF-7, 786-0, and UACC62). Its structure was established on the basis of 1D- and 2D-NMR spectroscopic techniques supported by HRMS data.

Leishmaniasis is a neglected tropical disease, affecting more than 350 million people globally. However, there is currently no vaccine available against human leishmaniasis, and current treatment is hampered by high cost, side-effects, and painful administration routes. It has become a United Nations goal to end leishmaniasis epidemics by 2030, and multitarget drug strategy emerges as a promising alternative. Among the multitarget compounds, flavonoids are a renowned class of natural products, and a structurally diverse library can be prepared through organic synthesis, which can be tested for biological effectiveness. In this study, we synthesised 17 flavonoid analogues using a scalable, easy-to-reproduce, and inexpensive method. All synthesised compounds presented an impressive inhibition capacity against rCPB2.8, rCPB3, and rH84Y enzymes, which are highly expressed in the amastigote stage, the target form of the parasite. Compounds 3c, f12a, and f12b were found to be effective against all isoforms. Furthermore, their intermolecular interactions were also investigated through a molecular modelling study. These compounds were highly potent against the parasite and demonstrated low cytotoxic action against mammalian cells. These results are pioneering, representing an advance in the investigation of the mechanisms behind the antileishmanial action of flavonoid derivatives. Moreover, compounds have been shown to be promising leads for the design of other cysteine protease inhibitors for the treatment of leishmaniasis diseases.

Context: New antileishmanias are needed because of toxicity, high cost and resistance problems associated with available drugs. Nectandra (Lauraceae) produces several classes of compounds but its essential oil has not previously been reported to have antileishmania activity.Objective: We evaluated the cytotoxicity and antileishmania activity of essential oils from Nectandra amazonum Nees, N. gardneri Meisn., N. hihua (Ruiz & Pav.) Rohwer and N. megapotamica (Spreng.) Mez.Materials and methods:Nectandra oils were extracted from stem bark/leaves by hydrodistillation and compounds were identified by GC-MS. Oils were tested against Leishmania infantum and L. amazonensis intracellular amastigotes and nitric oxide production was evaluated. Cytotoxicity was achieved on NIH/3T3 and J774.A1 cells for the selectivity index (SI).Results and discussion:Nectandra gardneri was active against L. infantum and L. amazonensis (IC50 =  2.7 ± 1.3/2.1 ± 1.06 μg/mL) and contained 85.4% sesquiterpenes, of which 58.2% was intermediol. Besides low cytotoxicity (SI >11.3), N. gardneri induced a significant increase in NO production by L. infantum-infected macrophages. Nectandra hihua had the best activity on L. infantum amastigotes (IC50 =  0.2 ± 1.1 μg/mL). This oil was 89.0% sesquiterpenes, with 28.1% bicyclogermacrene. The two specimens of N. megapotamica had different activities on amastigotes. The one richer in sesquiterpenes (49.9%) was active against both species (IC50 =  12.5 ± 1.4/21.3 ± 1.2) and had phenylpropanoid E-asarone as the main compound (42.4%). Nectandra amazonum showed moderate activity on both the species (IC50 =  31.9 ± 2.0/22.1 ± 1.3 μg/mL) and low selectivity (0.9 < SI >2.6), probably due to the major presence of β-caryophyllene (28.5%).Conclusions: Our data identify compounds that can now be isolated and used for the development of new antileishmanias.

Propolis samples collected from five areas in Mato Grosso do Sul state, Midwest Brazil, comprising portions of the Cerrado, Pantanal, and Atlantic Forest ecosystems, were investigated for metabolomic profiles and evaluated for antioxidant and antitumor potential. Chemical profiles were determined by HPLC-DAD-MS/MS data and evaluated using principal component analysis and hierarchical clustering analysis to discern chemical composition patterns. Based on phytogeographical origin and chemical composition, 20 potential markers were identified and five groups were distinguished: (I) Cerrado/Central, (II) Atlantic Forest/South, (III) Cerrado−Pantanal transition area/ Northwest, (IV) Cerrado/North, and (V) Pantanal/West. Drawing on HPLC-DAD-MS/MS and NMR data, 47 compounds were successfully or tentatively identified, including prenylated phenylpropanoids, flavonoids, isoflavonoids, and di-and triterpenoids, among other constituents. Isoflavonoids, typically found in red propolis from Northeast Brazil, are being reported for the first time in a propolis sample from the Midwest. A new prenylated aromatic compound, (E)-3-[4-hydroxy-3-(2-hydroxy-3methylbut-3-en-1-yl)-5-(3-methylbut-2-en-1-yl)phenyl]propenoic acid, was obtained. Samples in group II exhibited promising antitumor potential against prostate and breast carcinoma cells, as did samples in groups III and IV against the latter cell line. The sample in group I, despite containing the highest amount of total phenolic compounds and being the only sample to exhibit scavenging activity against DPPH, was not the most cytotoxic against the cell lines tested.

Background Cultural traditions attribute to pineal gland an important role for spiritual experiences. Mediumship and spirit possession are cultural phenomena found worldwide which have been described as having dissociative and psychotic‐like characteristics, but with nonpathological aspects. A sympathetic activation pattern in response to spirit possession has been reported in some studies, but empirical data on pineal gland is scarce in this context. Methods We aimed to investigate pineal gland and pituitary volumes, as well as urinary 6‐sulfatoxymelatonin levels in 16 alleged mediums (Medium Group‐MG) compared with 16 healthy nonmedium controls (Control Group) (Experiment 1). Furthermore, we aimed to evaluate urinary 6‐sulfatoxymelatonin and stress reactivity in GM ( n = 10) under different physiological conditions (Experiment 2). Results In Experiment 1, MG presented higher scores of anomalous experiences, but there were no between‐group differences regarding mental health or subjective sleep quality. Similar pineal gland and pituitary volumes were observed between groups. There were no between‐group differences in urinary 6‐sulfatoxymelatonin collected under equivalent baseline conditions. In Experiment 2, the rise of anxiety and heart rate in response to mediumistic experience was intermediate between a nonstressful control task (reading) and a stressful control task (Trier Social Stress Test—TSST). No significant differences were observed in 6‐sulfatoxymelatonin urinary levels between the three conditions. The pattern of stress reactivity during the TSST was normal, but with an attenuated salivary cortisol response. Conclusion The normal neuroimaging and stress reactivity findings in MG contrast with the abnormal results usually observed in subjects with psychotic and dissociative disorders.