Raquel Oliveira dos Santos Fontenelle

Antifungal activity of essential oils of Croton species from the Brazilian Caatinga biome

Aims:  To find new antifungal agents among essential oils from Brazilian Croton species.

The anatomical distribution and antimicrobial susceptibility of yeast species isolated from healthy dogs.

The aim of this work was to identify the predominant yeast species present at different anatomical sites in healthy dogs and to determine their in vitro antimicrobial susceptibility using a broth microdilution assay. Samples were collected from the preputial, vaginal, oral and perianal mucosae and the isolates cultured were identified according to their morphological characteristics and biochemical profile. Malassezia pachydermatis was the most commonly isolated yeast, followed by Candida parapsilosis, Candida tropicalis, Candida albicans, Saccharomyces cerevisiae and Rhodotorula spp. Minimum inhibitory concentrations of the azole derivatives ketoconazole, itraconazole and fluconazole against Candida spp. were 0.03-16 microg/mL, 0.06 to >16 microg/mL and 0.5-64 microg/mL, respectively and Candida isolates were sensitive to caspofungin and amphotericin B. Although all isolates of M. pachydermatis were sensitive to itraconazole, fluconazole, ketoconazole and amphotericin B, they were found to be resistant to caspofungin. The study has highlighted that Candida spp., M. pachydermatis, S. cerevisiae and Rhodotorula spp. are part of the normal canine surface microbiota and some of these organisms exhibit in vitro resistance to commonly used antimicrobials.

Antifungal Activity, Toxicity and Chemical Composition of the Essential Oil of Coriandrum sativum L. Fruits

The aims of this study were to test the antifungal activity, toxicity and chemical composition of essential oil from C. sativum L. fruits. The essential oil, obtained by hydro-distillation, was analyzed by gas chromatography/mass spectroscopy. Linalool was the main constituent (58.22%). The oil was considered bioactive, showing an LC50 value of 23 µg/mL in the Artemia salina lethality test. The antifungal activity was evaluated against Microsporum canis and Candida spp. by the agar-well diffusion method and the minimum inhibitory concentration (MIC) and the minimum fungicidal concentration (MFC) were established by the broth microdilution method. The essential oil induced growth inhibition zones of 28 ± 5.42 and 9.25 ± 0.5 for M. canis and Candida spp. respectively. The MICs and MFCs for M. canis strains ranged from 78 to 620 and 150 to 1,250 µg/mL, and the MICs and MFCs for Candida spp strains ranged from 310 to 620 and 620 to 1,250 µg/mL, respectively. C. sativum essential oil is active in vitro against M. canis and Candida spp. demonstrating good antifungal activity.

Alkylphenol Activity against Candida spp. and Microsporum canis: A Focus on the Antifungal Activity of Thymol, Eugenol and O-Methyl Derivatives.

In recent years there has been an increasing search for new antifungal compounds due to the side effects of conventional antifungal drugs and fungal resistance. The aims of this study were to test in vitro the activity of thymol, eugenol, estragole and anethole and some O-methyl-derivatives (methylthymol and methyleugenol) against Candida spp. and Microsporum canis. The broth microdilution method was used to determine the minimum inhibitory concentration (MIC). The minimum fungicidal concentrations (MFC) for both Candida spp. and M. canis were found by subculturing each fungal suspension on potato dextrose agar. Thymol, methylthymol, eugenol, methyl-eugenol, anethole, estragole and griseofulvin respectively, presented the following MIC values against M. canis: 4.8–9.7; 78–150; 39; 78–150; 78–150; 19–39 µg/mL and 0.006–2.5 μg/mL. The MFC values for all compounds ranged from 9.7 to 31 µg/mL. Concerning Candida spp, thymol, methylthymol, eugenol, methyleugenol, anethole, estragole and amphotericin, respectively, showed the following MIC values: 39; 620–1250; 150–620; 310–620; 620; 620–1250 and 0.25–2.0 μg/mL. The MFC values varied from 78 to 2500 µg/mL. All tested compounds thus showed in vitro antifungal activity against Candida spp. and M. canis. Therefore, further studies should be carried out to confirm the usefulness of these alkylphenols in vivo.

The genus Eupatorium L. (Asteraceae): A review of their antimicrobial activity

In recent years, the number of infectious diseases linked to the occurrence of bacterial and fungal resistance has increased, leading to extensive search for new drugs to treat these infections. Species of the Asteraceae family and the genus Eupatorium, have high biological potential and are used in folk medicine to treat various diseases. This review article presents the main phytochemical and biological characteristics of the Asteraceae family and the genus Eupatorium s.l., whose antimicrobial activity is promising, especially antibacterial and antifungal activity. The current review was achieved using an organized search of the scientific data published on antimicrobial activity and phytochemical of the species of the genus Eupatorium using various databases, including PubMed, ScienceDirect, Scopus, Scielo, SciFinder and Google Scholar. The species of Eupatorium are rich in terpenes, phytosterols and sesquiterpene lactones, the latter being chemotaxonomic markers of the group, with broad anticancer, antiplasmodial and antimicrobial activity, making them promising for the development of new drugs. Various species of Eupatorium seems to hold great potential for in-depth investigation for antimicrobial activities. Many species have broad folk use, with scientific confirmation of its antimicrobial properties making these plants potential sources of safer and more effective treatments. Key words: Compositae, Eupatorium s.l., antimicrobial potential, ethnopharmacology, ethnobotany.

Insights into the candidacidal mechanism of Ctn[15–34] – a carboxyl-terminal, crotalicidin-derived peptide related to cathelicidins

Purpose. Ctn[15‐34], a carboxyl‐terminal fragment of crotalicidin (a cathelicidin from the venom gland of a South American rattlesnake), has shown antifungal activity against clinical and standard strains of Candida species. The aim of the present work was to investigate the underlying mechanisms of the candidicidal activity of Ctn[15‐34]. Methodology. The time‐kill profile and drug synergism were evaluated by means of a microdilution assay and multi‐parametric flow cytometry. The presumptive interaction of Ctn[15‐34] with lipid membranes was estimated in vitro with a lipid‐mimic compound, the chromogenic substance 4‐nitro‐3‐(octanoyloxy)benzoic acid (4N3OBA). Results/Key findings. The absorbance increment (at 425 nm) indicated a concentration‐ and time‐dependent in‐solution association between Ctn[15‐34] and 4N3OBA. The interaction of Ctn[15‐34] with Candida cells was confirmed by flow cytometric measurements with the 5(6)‐carboxyfluorescein‐labelled peptide (CF‐Ctn[15‐34]). Analysis of the killing time of Candida exposed to Ctn[15‐34] and amphotericin B (AMB) showed that both the peptide and polyene drug reduce the number of c.f.u. but in mechanistically different ways. The Ctn[15‐34] peptide alone caused yeast cell membrane disruption, which was confirmed by lactate dehydrogenase leakage and biomarkers of cell death mediated by necrosis. Conclusion. Overall, Ctn[15‐34] displays a synergistic antifungal activity with AMB, an effect that can be further developed into a multi‐target therapeutic option with other antimycotics currently in use.

Atividade antimicrobiana e potencial terapêutico do gênero Lippia sensu lato (Verbenaceae)

(Antimicrobial activity and therapeutic potential of the genus Lippia sensu lato (Verbenaceae)). The growing number of infectious diseases combined with the continuous increase of antimicrobial resistance of certain microorganisms justify the constant search for new drugs. Given this situation, plants are a rich source of bioactive resources of pharmacological interest. The Verbenaceae family, especially the genus Lippia L., has representatives with potential already confirmed against various pathogens; the species of Lippia are widely used in folk medicine for their anti-inflammatory, antifungal, antiseptic, anti-hypertensive, anxiolytic, anti-leishmania, antiviral, and digestive properties, among other applications. This review gathers information about the antimicrobial potential of the main species of the genus Lippia, relating to the type of extract, its constituents, and the importance of this genus in the investigation of natural products and their phytochemical and biological characteristics.

Partial purification of trypsin/papain inhibitors from Hymenaea courbaril L. seeds and antibacterial effect of protein fractions

The crude extract and protein fractions of Hymenaea courbaril L. seeds were investigated for the presence of trypsin and papain inhibitors and antimicrobial activity against Vibrio parahaemolyticus, Staphylococcus aureus, and Escherichia coli. Protein fractions were obtained from the crude extract after precipitation with ammonium sulfate into three saturation ranges (0-30%, 30-60%, and 60-90%), called Hc030, Hc3060, and Hc6090, respectively. The crude extract and protein fractions inhibited trypsin and papain activity, but to different degrees. Antimicrobial activity was observed in Hc030 and Hc3060 fractions, but only against V. parahaemolyticus.The inhibitor isolated from the Hc3060 fraction was more effective in inhibiting trypsin (100% inhibition) than papain (54% inhibition), and showed an apparent molecular mass of 20 kDa. This study shows that H. courbaril seeds contain proteins with protease-inhibiting and antibacterial activity, indicating that this species is a source of bioactive compounds.

Chemical Characterization and the Antimicrobial Potential of Species of the Genus Senna Mill. (Fabaceae)

This review article aims to present the main characteristics about the antibacterial, antifungal and chemical composition of 18 species of Senna Mill. found in various parts of the world using dissertations and articles, all available in CAPES Newspapers (http://www.periodicos.capes.gov), Scielo (http://www.scielo.org), Science Direct (http:// www.sciencedirect.com) and Google Scholar (http://www.scholar.google.com) (1997 to 2016). All the species studied presented antibacterial and antifungal activity. It was also verified that the investigated species presented structurally diverse chemical composition. Compounds of several classes were identified as anthraquinones, flavonoids, saponins, tannins, among others.