RESUMO
Heracleum vicinum Boiss., a perennial plant of Angelica in Umbelliferae, is mainly distributed in Sichuan and Hunan of China. Trichophyton rubrum is a common skin fungus causing dermatophyte. The previous experimental study found that the ethanol extract from Heracleum vicinum Boiss. had excellent anti-Trichophyton rubrum activity, especially the ethanol extract further extracted with petroleum ether and dichloromethane has the best antibacterial effect and has good potential for treating dermatophytes. In this study, Heracleum vicinum Boiss. was extracted with ethanol by microwave-assisted ultrasonic extraction method and isolated with silica gel column to obtain a coumarin compound M1-1 by the guidance of anti-Trichophyton rubrum activity, which was characterized by nuclear magnetic resonance spectroscopy(13C-NMR), hydrogen nuclear magnetic resonance (1H-NMR), Fourier transform infrared spectroscopy (FTIR), high-resolution mass spectrometry (HR-ESI-MS), and ultraviolet (UV) and identified as imperatorin and belonged to coumarins, with the minimum inhibitory concentration (MIC) against Trichophyton rubrum of 12.5 µg/mL. According to the discussion on the inhibitory mechanism of the compound, we found that the compound may exert its inhibitory effect by destroying the mycelial membrane and inhibiting the mycelial growth of Trichophyton rubrum. In a word, imperatorin isolated from Heracleum vicinum Boiss. is expected to be used as an antibacterial agent to treat dermatophytes a potential natural compound against Trichophyton rubrum, and a template for drug development of dermatophytes the future.
Assuntos
Arthrodermataceae , Heracleum , Cumarínicos/farmacologia , Extratos Vegetais/farmacologia , Extratos Vegetais/química , Etanol/farmacologia , Antifúngicos/farmacologia , Testes de Sensibilidade MicrobianaRESUMO
This study aims to explore the antimicrobial activity of rifampicin (RIF) and ascorbic acid (ASC) co-loaded into alginate (ALG)/chitosan (CS) nanoparticles (RIF/ASC NPs) and tested for their antibacterial activity against several strains of methicillin-sensitive Staphylococcus aureus (MSSA) and methicillin-resistant Staphylococcus aureus (MRSA). Also, the present research focused on exploring the possible antibacterial mechanism of action of these RIF/ASC NPs, which demonstrated a significant biocide activity against the S. aureus strains with minimum inhibitory concentrations (MIC) between 2- and 8-fold lower than those one exhibited with the free antibiotic RIF. The proposed antimicrobial mechanism of action of the RIF/ASC NPs seems to be the result of collaborative effects between NPs and the RIF/ASC antibiotic combination. Moreover, results indicated that the functionalized RIF/ASC NP surface played a crucial role on the processes of NP adhesion into the bacterial surface, the alterations on the cell membrane integrity, and the cell uptake of the RIF/ASC antibiotic into bacteria. Further, the in vivo lung deposition pattern of empty NPs labeled (NPs-FITC) with isothiocyanate fluorescein in rats was investigated post intratracheal instillation of NPs. In summary, findings from this work show that our novel designed engineered RIF/ASC co-loaded NPs could be a suitable system for antibiotic lung administration with promising perspectives for effective treatments of pulmonary intracellular infections for those known antibiotics that are losing effectiveness due to antimicrobial resistance problems. Graphical Abstract.
Assuntos
Antibacterianos/administração & dosagem , Quitosana , Staphylococcus aureus Resistente à Meticilina , Nanopartículas , Rifampina/administração & dosagem , Alginatos , Animais , Antibacterianos/farmacologia , Pulmão , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Ratos , Rifampina/farmacologia , Staphylococcus aureus/efeitos dos fármacosRESUMO
This is a report on the synergistic interactions (SIs) between melampolide-type sesquiterpene lactones 1-8 from Acanthospermum hispidum DC., and oxacillin or gentamicin, against four pathogenic strains of Staphylococcus aureus and Enterococcus faecalis; two of them were multi-resistant strains obtained from chronic infectious processes. Our results showed that all associations of 1-8 with antibiotics (ATBs) are more effective than pure ATBs to control pathogenic strains of S. aureus and E. faecalis. The most relevant SIs were observed when the major lactone of A. hispidum, acanthospermal B [5], was combined with gentamicin (protein synthesis inhibitor) against an ex vivo culture of methicillin-resistant S. aureus SAR 1, displaying a significant MIC reduction in 5 (312.5 to 78.1 µg/mL), and gentamicin (120 µg/mL to 3 µg/mL). Compound 4 improved the antibiotic potency of oxacillin (cell wall synthesis inhibitor) against ampicillin-resistant E. faecalis (60 µg/mL to 1.5 µg/mL). It is important to remark that three beneficial lactobacilli were resistant to 1-8 and their mixtures with gentamicin or oxacillin in effective concentrations against pathogenic bacteria. Synergism between ATBs and phytochemicals is a therapeutically helpful concept to improve ATB efficacy and prevent resistance. The present results show that selective SIs occur between melampolides and gentamicin or oxacillin, and open a new field of research.