Antimycobacterial and anti-inflammatory activities of thiourea derivatives focusing on treatment approaches for severe pulmonary tuberculosis.

Tuberculosis (TB) remains a serious public health problem and one of the main concern is the emergence of multidrug-resistant and extensively resistant TB. Hyper-reactive patients develop inflammatory necrotic lung lesions that aggravate the pathology and facilitate transmission of mycobacteria. Treatment of severe TB is a major clinical challenge that has few effective solutions and patients face a poor prognosis, years of treatment and different adverse drug reactions. In this work, fifteen novel and thirty-one unusual thiourea derivatives were synthesized and evaluated in vitro for their antimycobacterial and anti-inflammatory potential and, in silico for ADMET parameters and for structure-activity relationship (SAR). Thioureas derivatives 10, 15, 16, 28 and 29 that had shown low cytotoxicity and high activities were selected for further investigation, after SAR study. These five thioureas derivatives inhibited Mtb H37Rv growth in bacterial culture and in infected macrophages, highlighting thiourea derivative 28 (MIC50 2.0 ± 1.1 and 2.3 ± 1.1 µM, respectively). Moreover, these compounds were active against the hypervirulent clinical Mtb strain M299, in bacterial culture, especially 16, 28 and 29, and in extracellular clumps, highlighting 29, with MIC50 5.6 ± 1.2 µM. Regarding inflammation, they inhibited NO through the suppression of iNOS expression, and also inhibited the production of TNF-α and IL-1ß. In silico studies were carried out suggesting that these five compounds could be administered by oral route and have low toxicological effects when compared to rifampicin. In conclusion, our data show that, at least, thiourea derivatives 16, 28 and 29 are promising antimycobacterial and anti-inflammatory agents, and candidates for further prospective studies aiming new anti-TB drugs, that can be used on a dual approach for the treatment of severe TB cases associated with exacerbated inflammation.

Biological activities and phytochemical profile of Passiflora mucronata from the Brazilian restinga

ABSTRACT In general, Passiflora species have been reported for their folk medicinal use as sedative and anti-inflammatory. However, P. caerulea has already been reported to treat pulmonary diseases. Severe pulmonary tuberculosis, generally caused by Mycobacterium tuberculosis strains resistant to multiple drugs, can lead to deleterious inflammation and high mortality, encouraging new approaches in drug discovery. Thus, the aim of this work was to evaluate the Passiflora mucronata Lam., Passifloraceae, potential for tuberculosis treatment. Specifically, related to antimycobacterial activity and anti-inflammatory related effects (based on inhibition of nitric oxide, tumor necrosis factor-alpha production and antioxidant potential), as well as the chemical profile of P. mucronata. High performance liquid chromatography coupled with diode-array ultraviolet and mass spectrometer analyses of crude hydroalcoholic extract and ethyl acetate fraction showed the presence of flavonoids. Ethyl acetate fraction showed to be as antioxidant as Ginkgo biloba standard extract with EC50 of 14.61 ± 1.25 µg/ml. One major flavonoid isolated from ethyl acetate fraction was characterized as isoorientin. The hexane fraction and its main isolated compound, the triterpene β-amyrin, exhibited significant growth inhibitory activity against Mycobacterium bovis BCG (MIC50 1.61 ± 1.43 and 3.93 ± 1.05 µg/ml, respectively). In addition, Passiflora mucronata samples, specially hexane and dichloromethane fractions, as well as pure β-amyrin, showed a dose-related inhibition of lipopolysaccharide (LPS)-induced nitric oxide production. In conclusion, Passiflora mucronata presented relevant biological potential and should be considered for further studies using in vivo pulmonary tuberculosis model.

Nitric oxide production, inhibitory, antioxidant and antimycobacterial activities of the fruits extract and flavonoid content of Schinus terebinthifolius

The extract of the fruits from Schinus terebinthifolius Raddi, Anacardiaceae, was obtained by exhaustive extraction with methanol. Its fractions and isolated compounds were collected by fractionation with RP-2 column chromatography. The crude extract, the flavonoid fraction and the isolated compound identified as apigenin (1), were investigated regarding its inhibitory action of nitric oxide production by LPS-stimulated macrophages, antioxidant activity by DPPH and the antimycobacterial activity against Mycobacterium bovis BCG. The samples exhibited a significant inhibitory effect on the nitric oxide production (e.g., 1, IC50 19.23 ± 1.64 µg/ml) and also showed antioxidant activity. In addition, S. terebinthifolius samples inhibited the mycobacterial growth ( e.g., 1, IC50 14.53 ± 1.25 µg/ml). The necessary concentration to produce 50% of the maximum response (IC50) of these activities did not elicit a significant cytotoxic effect when compared with the positive control (100% of lysis). The antioxidant and nitric oxide inhibition activity displayed by S. terebinthifolius corroborates its ethnopharmacological use of this specie as an anti-inflammatory. In addition, our results suggest that the flavonoids of S. terebinthifolius are responsible for the activities found. We, describe for the first time the activity against Mycobacterium bovis BCG and the inhibition of nitric oxide production for S. terebinthifolius.

Sesquiterpenes from the Brazilian red alga Laurencia dendroidea J. Agardh.

Two new chamigrane sesquiterpenes 1-2 and three known compounds 3-5 were isolated from a lipophilic extract of the red alga Laurencia dendroidea collected from the Southeastern Brazilian coast. Dendroidone (1) and dendroidiol (2) were isolated from samples collected at Biscaia Inlet, Angra dos Reis, Rio de Janeiro and at Manguinhos Beach, Serra, Espírito Santo, respectively. Debromoelatol (3), obtusane (4) and (1S*,2S*,3S*,5S*,8S*,9S*)-2,3,5,9-tetramethyltricyclo[6.3.0.0¹·5]undecan-2-ol (5) were obtained from specimens collected at Vermelha Beach, Parati, Rio de Janeiro. The structures of new compounds were elucidated by extensive NMR (¹H-, ¹³C-, COSY, HSQC, HMBC and NOESY) and high resolution mass spectrometry analysis. Additionally, the absolute configuration of compound 2 was assigned by X-ray analysis. Full spectroscopic data is described for the first time for compound 3. Anti-inflammatory and antimycobacterial activities of compounds 2-5 were evaluated. Compounds 3-5 inhibited the release of inflammatory mediator NO while TNF-α levels were only affected by 3. All compounds tested displayed moderate antimycobacterial action.

Antimycobacterial activity and alkaloid prospection of Psychotria species (Rubiaceae) from the Brazilian Atlantic Rainforest.

Ten Psychotria species were collected in two fragments of Atlantic Forest in Rio de Janeiro: Psychotria pubigera (P1A and B), P. ruelliifolia (P2), P. suterela (P3), P. stachyoides (P4), P. capitata (P5), P. glaziovii (P6), P. leiocarpa (P7), P. nuda (P8), P. racemosa (P9) and P. vellosiana (P10). Ethanol extracts of these species were evaluated for their antimycobacterial activity, in an attempt to find new antituberculosis agents. Psychotria pubigera (P1A), P. ruelliifolia (P2) and P. stachyoides (P4) were the most active against Mycobacterium. The anti-inflammatory potential of these extracts was also evaluated in vitro to learn if they inhibit nitric oxide (NO) production in macrophages and if they have free-radical scavenging properties, because inflammation is a severe problem caused by tuberculosis, especially when the infection is from M. bovis or M. tuberculosis. Psychotria suterela (P3), P. stachyoides (P4) and P. capitata (P5) were the most active in inhibiting macrophage NO production but they were not the most antioxidant species. This suggests that NO inhibitory activity is not due to the scavenging of NO generated but due to a specific inhibition of iNOS activity or expression. In addition, cytotoxicity was tested in the macrophages (the host cells of the Mycobacterium) and it was verified that the extracts selectively killed the bacteria and not the host cells. When analyzing antimycobacterial, cytotoxicity and NO inhibitory activities in combination, P. stachyoides (P4) was the most promising anti-TB extract tested. Further, indol alkaloids were detected in P. suterela and P. nuda, and 5,6-dihydro-ß-carboline alkaloids in all of the species studied, with the highest amounts found in P. capitata and P. racemosa.