Antibacterial activity of a new monocarbonyl analog of curcumin MAC 4 is associated with divisome disruption.

Curcumin (CUR) is a symmetrical dicarbonyl compound with antibacterial activity. On the other hand, pharmacokinetic and chemical stability limitations hinder its therapeutic application. Monocarbonyl analogs of curcumin (MACs) have been shown to overcome these barriers. We synthesized and investigated the antibacterial activity of a series of unsymmetrical MACs derived from acetone against Mycobacterium tuberculosis and Gram-negative and Gram-positive species. Phenolic MACs 4, 6 and 8 showed a broad spectrum and potent activity, mainly against M. tuberculosis, Acinetobacter baumannii and methicillin-resistant Staphylococcus aureus (MRSA), with MIC (minimum inhibitory concentration) values ranging from 0.9 to 15.6 µg/mL. The investigation regarding toxicity on human lung cells (MRC-5 and A549 lines) revealed MAC 4 was more selective than MACs 6 and 8, with SI (selectivity index) values ranging from 5.4 to 15.6. In addition, MAC 4 did not demonstrate genotoxic effects on A549 cells and it was more stable than CUR in phosphate buffer (pH 7.4) for 24 h at 37 °C. Fluorescence and phase contrast microscopies indicated that MAC 4 has the ability to disrupt the divisome of Bacillus subtilis without damaging its cytoplasmic membrane. However, biochemical investigations demonstrated that MAC 4 did not affect the GTPase activity of B. subtilis FtsZ, which is the main constituent of the bacterial divisome. These results corroborated that MAC 4 is a promising antitubercular and antibacterial agent.

Investigating the Modes of Action of the Antimicrobial Chalcones BC1 and T9A.

Xanthomonas citri subsp. citri (X. citri) is an important phytopathogen and causes Asiatic Citrus Canker (ACC). To control ACC, copper sprays are commonly used. As copper is an environmentally damaging heavy metal, new antimicrobials are needed to combat citrus canker. Here, we explored the antimicrobial activity of chalcones, specifically the methoxychalcone BC1 and the hydroxychalcone T9A, against X. citri and the model organism Bacillus subtilis. BC1 and T9A prevented growth of X. citri and B. subtilis in concentrations varying from 20 µg/mL to 40 µg/mL. BC1 and T9A decreased incorporation of radiolabeled precursors of DNA, RNA, protein, and peptidoglycan in X. citri and B. subtilis. Both compounds mildly affected respiratory activity in X. citri, but T9A strongly decreased respiratory activity in B. subtilis. In line with that finding, intracellular ATP decreased strongly in B. subtilis upon T9A treatment, whereas BC1 increased intracellular ATP. In X. citri, both compounds resulted in a decrease in intracellular ATP. Cell division seems not to be affected in X. citri, and, although in B. subtilis the formation of FtsZ-rings is affected, a FtsZ GTPase activity assay suggests that this is an indirect effect. The chalcones studied here represent a sustainable alternative to copper for the control of ACC, and further studies are ongoing to elucidate their precise modes of action.

Methoxychalcones: Effect of Methoxyl Group on the Antifungal, Antibacterial and Antiproliferative Activities.

BACKGROUND: Chalcones substituted by methoxyl groups have presented a broad spectrum of bioactivities, including antifungal, antibacterial and antiproliferative effects. However, a clear and unambiguous investigation about the relevance of this substituent on the chalcone framework has not been described. OBJECTIVE: The purpose of this work is to assess the antibacterial, antifungal and antiproliferative activities of the two series of seventeen synthesized regioisomeric methoxychalcones. Series I and II were constituted by chalcones substituted by methoxyl groups on rings A (5-12) and B (13-21), respectively. In addition, the library of methoxychalcones was submitted to in silico drug-likeness and pharmacokinetics properties predictions. METHODS: Methoxychalcones were synthesized and their structures were confirmed by NMR spectral data analyses. Evaluations of antimicrobial activity were performed against five species of Candida, two Gram-negative and five Gram-positive species. For antiproliferative activity, methoxychalcones were evaluated against four human tumorigenic cell lines, as well as human non-tumorigenic keratinocytes. Drug-likeness and pharmacokinetics properties were predicted using Molinspiration and PreADMET toolkits. RESULTS: In general, chalcones of series I are the most potent antifungal, antibacterial and antiproliferative agents. 3', 4', 5'-Trimethoxychalcone (12) demonstrated potent antifungal activity against Candida krusei (MIC = 3.9 µg/mL), eight times more potent than fluconazole (reference antifungal drug). 3'-Methoxychalcone (6) displayed anti-Pseudomonas activity (MIC = 7.8 µg/mL). 2',5'-Dimethoxychalcone (9) displayed potent antiproliferative effect against C-33A (cervix), A-431 (skin) and MCF-7 (breast), with IC50 values ranging from 7.7 to 9.2 µM. Its potency was superior to curcumin (reference antiproliferative compound), which exhibited IC50 values ranging from 10.4 to 19.0 µM. CONCLUSION: Our studies corroborated the relevance of methoxychalcones as antifungal, antibacterial and antiproliferative agents. In addition, we elucidated influence of the position and number of methoxyl groups toward bioactivity. In silico predictions indicated good drug-likeness and pharmacokinetics properties to the library of methoxychalcones.

Potentiation of epidural lidocaine by co-administering tramadol by either intramuscular or epidural route in cats.

This study investigated the analgesic and systemic effects of intramuscular (IM) versus epidural (EP) administration of tramadol as an adjunct to EP injection of lidocaine in cats. Six healthy, domestic, shorthair female cats underwent general anesthesia. A prospective, randomized, crossover trial was then conducted with each cat receiving the following 3 treatments: EP injection of 2% lidocaine [LEP; 3.0 mg/kg body weight (BW)]; EP injection of a combination of lidocaine and 5% tramadol (LTEP; 3.0 and 2.0 mg/kg BW, respectively); or EP injection of lidocaine and IM injection of tramadol (LEPTIM; 3.0 and 2.0 mg/kg BW, respectively). Systemic effects, spread and duration of analgesia, behavior, and motor blockade were determined before treatment and at predetermined intervals afterwards. The duration of analgesia was 120 ± 31 min for LTEP, 71 ± 17 min for LEPTIM, and 53 ± 6 min for LEP (P < 0.05; mean ± SD). The cranial spread of analgesia obtained with LTEP was similar to that with LEP or LEPTIM, extending to dermatomic region T13-L1. Complete motor blockade was similar for the 3 treatments. It was concluded that tramadol produces similar side effects in cats after either EP or IM administration. Our findings indicate that EP and IM tramadol (2 mg/kg BW) with EP lidocaine produce satisfactory analgesia in cats. As an adjunct to lidocaine, EP tramadol provides a longer duration of analgesia than IM administration. The adverse effects produced by EP and IM administration of tramadol were not different. Further studies are needed to determine whether EP administration of tramadol could play a role in managing postoperative pain in cats when co-administered with lidocaine after painful surgical procedures.

La présente étude visait à déterminer les effets analgésiques et systémiques de l'administration intramusculaire (IM) ou épidurale (EP) de tramadol comme un ajout à l'injection EP de lidocaïne chez des chats. Six chattes domestiques à poils courts ont été soumises à une anesthésie générale. Une étude prospective croisée aléatoire a été menée, chaque chat recevant les trois traitements suivants : injection EP de lidocaïne 2 % [LEP; 3,0 mg/kg poids corporels (PC)]; injection EP d'une combinaison de lidocaïne et de tramadol 5 % (LTEP; 3,0 et 2,0 mg/kg PC, respectivement); ou injection EP de lidocaïne et injection IM de tramadol (LEPTIM; 3,0 et 2,0 mg/kg PC, respectivement). Les effets systémiques, l'étendue et la durée de l'analgésie, le comportement, et le blocage moteur furent déterminés avant le traitement et à des intervalles prédéterminés par la suite. La durée de l'analgésie était de 120 ± 31 min pour LTEP, 71 ± 17 min pour LEPTIM, et 53 ± 6 min pour LEP (P < 0,05; moyenne ± écart-type). L'étendue crâniale de l'analgésie obtenue avec LTEP était similaire à celle avec LEP ou LEPTIM, s'étendant jusqu'au dermatome T13-L1. Le blocage moteur complet était similaire pour les trois traitements. Il a été conclu que chez le chat le tramadol produit des effets secondaires similaires qu'il soit administré par voie EP ou IM. Nos résultats indiquent que du tramadol (2 mg/kg PC) donné EP et IM avec de la lidocaïne EP induit une analgésie satisfaisante chez les chats. Comme supplément à la lidocaïne, le tramadol administré EP fourni une durée prolongée de l'analgésie que lorsqu'administré IM. Les effets indésirables produits par l'administration EP et IM de tramadol n'étaient pas différents. Des études supplémentaires sont nécessaires afin de déterminer si l'administration EP de tramadol pourrait jouer un rôle dans la gestion de la douleur post-opératoire chez les chats lorsqu'administré conjointement avec de la lidocaïne suite à une procédure chirurgicale douloureuse.(Traduit par Docteur Serge Messier).