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The microorganisms that constitute the oral microbiome can cause oral diseases, including dental caries and endodontic infections. The use of natural products could help to overcome bacterial resistance to the antimicrobials that are currently employed in clinical therapy. This study assessed the antimicrobial activity of the Copaifera pubiflora oleoresin and of the compounds isolated from this resin against oral bacteria. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) assays provided values ranging from 6.25 to > 400 μg/mL for the C. pubiflora oleoresin and its isolated compounds. The fractional inhibitory concentration index (FICI) assay showed that the oleoresin and chlorhexidine did not act synergistically. All the tested bacterial strains formed biofilms. MICB 50 determination revealed inhibitory action: values varied from 3.12-25 μg/mL for the oleoresin, and from 0.78 to 25 μg/mL for the ent-hardwickiic acid. Concerning biofilm eradication, the C. pubiflora oleoresin and hardwickiic acid eradicated 99.9 % of some bacterial biofilms. Acid resistance determination showed that S. mutans was resistant to acid in the presence of the oleoresin and ent-hardwickiic acid at pH 4.0, 4.5, and 5.0 at all the tested concentrations. Analysis of DNA/RNA and protein release by the cell membrane demonstrated that the oleoresin and hardwiickic acid damaged the bacterial membrane irreversibly, which affected membrane integrity. Therefore, the C. pubiflora oleoresin and ent-hardwickiic acid have potential antibacterial effect and can be used as new therapeutic alternatives to treat oral diseases such as dental caries and endodontic infections., (Copyright © 2020. Published by Elsevier Masson SAS.)

Continuous hemodialysis system monitoring is necessary to prevent microorganism growth and health problems. This study evaluates single- and dual-species biofilm formation in microtiter plates by using dialysis solutions under aerobiosis or 5% CO 2 atmosphere. Escherichia coli, Pseudomonas aeruginosa, Staphylococcus epidermidis, Candida parapsilosis sensu lato, and Mycobacterium smegmatis produce single-species biofilms in all dialysis solutions in both oxygenation conditions. Dual-species biofilm cultures grown at 5% CO 2 atmosphere and in dialysate containing glucose reveal that M. smegmatis benefits from its association with C. parapsilosis. The dialysate and its constituent solutions support the growth of all the mono-species and the inter-kingdom mycobacterial/yeast biofilms in both aerobiosis and microaerophilic conditions., (Copyright © 2019 Elsevier Inc. All rights reserved.)

The biotransformation of the lignan (-)-cubebin by filamentous fungi Aspergillus terreus and Aspergillus niger is an efficient bioprocess for obtaining (-)-hinokinin and (-)-parabenzlactone. The relevance of getting (-)-hinokinin is due to its promising effect against oral pathogens, especially S. sanguinis (both MIC and MBC 12.5 μg/mL), and other previous reported effects against Chagas disease and as anti-inflammatory. The advantage of using fungal transformation is the use of non-toxic and/or non-pollutant reagents and/or solvents in comparison with semi-synthesis. Microbial transformation of (-)-cubebin is also important to evaluate its human metabolism, since Aspergillus species are capable of mimicking P450 reactions, providing possible products of the metabolism, which is important in the assessment of its efficacy and safety. Furthermore, the present study describes a reliable RP-HPLC method to perform quantification of (-)-hinokinin in fungal extracts. It is simple, fast, selective, linear, precise, accurate and robust according to validation guidelines.

The search for new, effective and safe antimicrobial compounds from plant sources has continued to play an important role in the maintenance of human health since ancient times. Such compounds can be used to help to eradicate microorganisms from the root canal system, preventing/healing periapical diseases. Mikania glomerata (Spreng.), commonly known as "guaco," is a native climbing plant from Brazil that displays a wide range of pharmacological properties. Many of its activities have been attributed to its phytochemical composition, which is mainly composed of diterpenes, such as ent-kaurenoic acid (KA). The present study evaluated the potential activity of an ent-kaurenoic-rich (KA) extract from Mikania glomerata (i.e. Mikania glomerata extract/MGE) and its major compound KA against bacteria that can cause endodontic infections. Time-kill assays were conducted and the minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), anti-biofilm activity, and synergistic antimicrobial activity of MGE and KA were determined. The MGE exhibited MIC and MBC values, which ranged from 6.25 to 100 μg/mL and 12.5 to 200 μg/mL respectively. The MIC and MBC results obtained for the KA, ranged from 3.12 to 100 μg/mL and 3.12 to 200 μg/mL respectively. Time-kill and anti-biofilm activity assays conducted for KA at concentrations between 3.12 and 12.5 μg/mL exhibited bactericidal activity between 6 and 72 h of incubation and 50% inhibition of biofilm formation for Porphyromonas gingivalis (clinical isolate), Propionibacterium acnes (ATCC 6919), Prevotella nigrescens (ATCC 33563), P. melaninogenica (ATCC 25845), Aggregatibacter actinomycetemcomitans (ATCC 43717). For synergistic antimicrobial activity, KA combined with chlorhexidine dichlorohydrate (CHD) had an additive effect with increased efficacy against P. gingivalis (clinical isolate) compared to CHD alone. It was concluded that M. glomerata extract and its major compound ent-kaurenoic acid (KA) showed in vitro antibacterial activity, the latter being a potential biofilm inhibitory agent. They may play important roles in the search for novel sources of agents that can act against bacteria present in endodontic infections., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Antibiotic-resistant bacteria have emerged from the widespread use of antibiotics worldwide and have prompted the search for new sources of antimicrobial substances. Pinus spp. contain several bioactive compounds consisting mainly of terpenes, terpenoids and some other aromatic and aliphatic constituents. These compounds exert important biological effects, and pine oils have found wide application in the industry. In the present study, we have evaluated the potential activity of the resin-oil of Pinus elliottii and its major compound dehydroabietic acid (DA) against multiresistant bacteria by MIC, minimum bactericidal concentration and time-kill assays. The MIC of the resin-oil of P. elliottii varied between 25 and 100 µg ml(-1). As for DA, the MIC and minimum bactericidal concentration varied between 6.25 and 50 and between 6.25 and 100 µg ml(-1), respectively. The time-kill assay conducted with DA at 6.25 µg ml(-1) evidenced bactericidal activity against Staphylococcus epidermidis (American Type Culture Collection 14990) within 24 h. On the basis of these results, the resin-oil of P. elliottii and its major compound DA play an important part in the search for novel sources of agents that can act against multiresistant bacteria., (© 2014 The Authors.)