Thatiana Lopes Biá Ventura

Antimycobacterial and Anti-Inflammatory Activities of Substituted Chalcones Focusing on an Anti-Tuberculosis Dual Treatment Approach

Tuberculosis (TB) remains a serious public health problem aggravated by the emergence of M. tuberculosis (Mtb) strains resistant to multiple drugs (MDR). Delay in TB treatment, common in the MDR-TB cases, can lead to deleterious life-threatening inflammation in susceptible hyper-reactive individuals, encouraging the discovery of new anti-Mtb drugs and the use of adjunctive therapy based on anti-inflammatory interventions. In this study, a series of forty synthetic chalcones was evaluated in vitro for their anti-inflammatory and antimycobacterial properties and in silico for pharmacokinetic parameters. Seven compounds strongly inhibited NO and PGE2 production by LPS-stimulated macrophages through the specific inhibition of iNOS and COX-2 expression, respectively, with compounds 4 and 5 standing out in this respect. Four of the seven most active compounds were able to inhibit production of TNF-α and IL-1β. Chalcones that were not toxic to cultured macrophages were tested for antimycobacterial activity. Eight compounds were able to inhibit growth of the M. bovis BCG and Mtb H37Rv strains in bacterial cultures and in infected macrophages. Four of them, including compounds 4 and 5, were active against a hypervirulent clinical Mtb isolate as well. In silico analysis of ADMET properties showed that the evaluated chalcones displayed satisfactory pharmacokinetic parameters. In conclusion, the obtained data demonstrate that at least two of the studied chalcones, compounds 4 and 5, are promising antimycobacterial and anti-inflammatory agents, especially focusing on an anti-tuberculosis dual treatment approach.

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.

Hypervirulent Mycobacterium tuberculosis strain triggers necrotic lung pathology associated with enhanced recruitment of neutrophils in resistant C57BL/6 mice

Tuberculosis (TB) is a chronic infectious disease caused by Mycobacterium tuberculosis (Mtb) that in most cases induces irreversible necrosis of lung tissue as a result of excessive inflammatory reactions. The murine model of TB in resistant C57BL/6 mice infected with reference Mtb strains is widely used in TB studies; however, these mice do not show a necrotic pathology, which restricts their use in studies of irreversible tissue damage. Recently, we demonstrated that necrotic lung lesions could be induced in the C57BL/6 mice by highly virulent Mtb strains belonging to the modern Beijing sublineage. However, the pathogenic mechanisms leading to necrosis in this model were not elucidated. In this study, we investigated the dynamics of lung lesions in mice infected with highly virulent Beijing Mtb strain M299, compared with those infected with laboratory Mtb strain H37Rv. The data demonstrate that necrotic lung lesions in mice infected by the strain M299 were associated with enhanced recruitment of myeloid cells, especially neutrophils, and increased levels of proinflammatory cytokines, consistent with exacerbated inflammation. High levels of IFN-γ production contributed to the control of bacterial growth. Further progression to chronic disease was associated with a reduction in the levels of inflammatory mediators in the lungs, the accumulation of foamy macrophages and partial healing of the necrotic tissue by fibrosis. At a late stage of disease, degradation of foamy cells resulted in the liberation of accumulated lipids and persisting bacilli and further activation of inflammation, which promoted lung consolidation. Overall, our studies show that C57BL/6 mice infected with highly virulent Mtb strain may serve as a TB model reproducing an exacerbated inflammatory response in a resistant host to hypervirulent mycobacteria, leading to irreversible necrotic lung lesions.

INIBIÇÃO DA PRODUÇÃO DE ÓXIDO NÍTRICO E EFEITO CITOTÓXICO DE EXTRATO AQUOSO DE ANNONA MURICATA L.

Annona muricata L. e conhecida na medicina popular por sua ampla variedade de efeitos medicinais. A toxicidade de plantas da familia Annonacea e ainda pouco estudada, principalmente em relacao aos componentes de seus frutos. A maioria dos trabalhos cientificos realizados com estas plantas utiliza principalmente as folhas e aborda suas acoes citotoxicas em ensaios biologicos in vitro enfatizando seus efeitos anti-tumorais. Nesse sentido, se observa uma alta prevalencia do uso de Annona muricata L. em oncologia como tratamento coadjuvante, o que ressalta a importância de se conhecer os possiveis efeitos toxicos relacionados ao seu uso. Como as propriedades biologicas de Annona muricata L. nao sao completamente conhecidas, o objetivo deste estudo foi investigar a capacidade inibitoria da producao de oxido nitrico em macrofagos e o potencial citotoxico do extrato aquoso oriundo da polpa dos frutos sobre macrofagos murinos RAW 264.7 e celulas tumorais U937 atraves do teste de liberacao da enzima citoplasmatica lactato desidrogenase e do teste com 3-(4,5 dimetiltiazol-2-il)-2,5-difenil tetrazol. Nossos resultados mostram que a capacidade inibitoria do extrato aquoso (500 mg/mL) na producao de oxido nitrico (NO)em macrofagos RAW 264.7 estimulados por lipolissacarideo (LPS) foi estatisticamente significante (p <0,05) quando comparado aos resultados obtidos em macrofagos controles, embora de forma nao expressiva. O extrato aquoso nao apresentou citotoxicidade para macrofagos RAW 264.7 e celulas leucemicas U937, nao interferindo na viabilidade celular, o que sugere ausencia de morte celular por necrose.