Synthetic Cinnamides and Cinnamates: Antimicrobial Activity, Mechanism of Action, and In Silico Study.

The severity of infectious diseases associated with the resistance of microorganisms to drugs highlights the importance of investigating bioactive compounds with antimicrobial potential. Therefore, nineteen synthetic cinnamides and cinnamates having a cinnamoyl nucleus were prepared and submitted for the evaluation of antimicrobial activity against pathogenic fungi and bacteria in this study. To determine the minimum inhibitory concentration (MIC) of the compounds, possible mechanisms of antifungal action, and synergistic effects, microdilution testing in broth was used. The structures of the synthesized products were characterized with FTIR spectroscopy, 1 H-NMR, 13 C-NMR, and HRMS. Derivative 6 presented the best antifungal profile, suggesting that the presence of the butyl substituent potentiates its biological response (MIC = 626.62 µM), followed by compound 4 (672.83 µM) and compound 3 (726.36 µM). All three compounds were fungicidal, with MFC/MIC ≤ 4. For mechanism of action, compounds 4 and 6 directly interacted with the ergosterol present in the fungal plasmatic membrane and with the cell wall. Compound 18 presented the best antibacterial profile (MIC = 458.15 µM), followed by compound 9 (550.96 µM) and compound 6 (626.62 µM), which suggested that the presence of an isopropyl group is important for antibacterial activity. The compounds were bactericidal, with MBC/MIC ≤ 4. Association tests were performed using the Checkerboard method to evaluate potential synergistic effects with nystatin (fungi) and amoxicillin (bacteria). Derivatives 6 and 18 presented additive effects. Molecular docking simulations suggested that the most likely targets of compound 6 in C. albicans were caHOS2 and caRPD3, while the most likely target of compound 18 in S. aureus was saFABH. Our results suggest that these compounds could be used as prototypes to obtain new antimicrobial drugs.

The Use of Essential Oils and Their Isolated Compounds for the Treatment of Oral Candidiasis: A Literature Review.

In this literature review, we present the main scientific findings on the antifungal activity of essential oils (EOs) applicable for a new drug formulation to treat oral candidiasis. Seven literature databases were systematically searched for eligible in vitro and clinical trials. Selected articles were screened for biological activity, botanical species, phytochemical composition, study design, and methodological quality. A total of 26 articles were included in the review, of which 21 were in vitro studies and 5 clinical trials. The most promising EOs were obtained from Allium tubeorosum, Cinnamomum cassia, Cinnamomum zeylanicum, and Coriandrum sativum L. Among the phytochemicals, citral and thymol were the most active. Clinical trials indicated that the EOs from Pelargonium graveolens and Zataria multiflora are potentially effective to treat oral candidiasis. Further nonclinical and clinical studies with these EO are warranted to determine their potential use and safety for the treatment of oral candidiasis.

Investigation of ethnomedicinal use of Commiphora leptophloeos (Mart.) J. B. Gillett (Burseraceae) in treatment of diarrhea.

ETHNOPHARMACOLOGICAL RELEVANCE: Commiphora leptophloeos (Mart.) J.B. Gillett, popularly known as "imburana", "imburana-de-cheiro" or "imburana-de-espinho", has been used in folk medicine for the treatment of gastrointestinal diseases, such as diarrhea. The indian tribes "Kairir-Shokó and shokó use the bark to treat diarrhea. However, there is no scientific evidence to justify the therapeutic use of this species. AIM OF THE STUDY: To investigate the ethnomedicinal use of Commiphora leptophloeos, with respect to the antimicrobial, antisecretory, antimotility and antispasmodic activities of the crude ethanolic extract obtained from its leaves (CL-EtOHL) and the mechanism underlying this action in rodents. MATERIAL AND METHODS: In the evaluation of antibacterial and antifungal activities was determined the minimum inhibitory concentration (MIC) of the extract, against different strains of bacteria and fungi. All experimental protocols were approved by the Animal Ethics Committee of the Federal University of Paraíba (045/2016). In addition, behavioral screening and acute toxicity assessment of CL-EtOHL were performed in female mice (n = 6). In the investigation of antidiarrheal activity (n = 6), frequency of defecation and number of liquid stools, were classified during 4 h, and intestinal fluid and transit were measured. In addition, the antispasmodic effect on rat ileum (n = 5) was also investigated. RESULTS: The ethanolic extract is rich in flavonoids and the main were identified as C-glycosylated flavonoids (isoorientin, orientin, and vitexin). In the evaluation of antimicrobial and antifungal activity, the extract showed moderate efficacy only against the tested strains of Candida krusei ATCC-6258, Candida parapsilosis ATCC-22019 and Candida glabrata ATCC-90030. The extract had no toxic effect until 2000 mg/kg. In castor oil-induced diarrhea, CL-EtOHL inhibited, in a dose-dependent manner, both total defecation frequency (ED50 = 380.4 ± 145.4 mg/kg) and the number of watery stools (ED50 = 151.2 ± 76.3 mg/kg). The extract showed no effect on fluid accumulation or normal intestinal transit. On the other hand, when the animals were pretreated with castor oil, the extract decreased the distance traveled by the activated charcoal (ED50 = 177.0 ± 50.3 mg/kg). In the investigation of antispasmodic effect, CL-EtOHL antagonized the contractions induced by KCl 30 mM (IC50 = 208.2 ± 25.9 µg/mL) and CCh 10-6 M (IC50 = 95. ± 22.0 µg/mL). To verify the participation of muscarinic receptors in this effect, cumulative carbachol curves were performed in the absence and presence of the extract, and a non-competitive pseudo-irreversible antagonism of these receptors was observed. CONCLUSION: The data indicate that ethanol extract obtained from the leaves of Commiphora leptophloeos has an antidiarrheal effect due to inhibition of the intestinal motility and antispasmodic effect, through the antagonism of muscarinic receptors. In addition, we suggest that flavonoids isolated from CL-EtOHL may be responsible for antidiarrheal activity of this extract. This explains its ethnomedicinal use in the treatment of diarrhea.

Antifungal Activity of Essential Oils against Candida albicans Strains Isolated from Users of Dental Prostheses.

OBJECTIVE: The objective of this study was to analyze the antifungal activity of citral, selected by screening natural products, against Candida albicans isolates from subjects who use dental prostheses. METHODOLOGY: Screening of essential oils, including those from Mentha piperita L. (Briq), Origanum vulgare, and Zingiber officinale L., and the phytoconstituents citral and limonene, to select an appropriate natural product. Citral, which mediated the best antifungal response, was selected for biological assays. The minimum inhibitory concentrations (MICs) and minimum fungicidal concentrations (MFCs) for citral and nystatin were determined by the microdilution method. Micromorphological analyses, time-kill curve, and modulation tests were performed. RESULTS: The MIC and MFC of citral were established as 32 µg/mL, consistent with fungicidal activity. The clinical strains were resistant to nystatin. Citral caused micromorphological alteration in the strains. In the time-kill curve, the growth of the clinical strain was reduction in growth equal to 3 log10 colony-forming units per milliliter after exposure to the MIC and MIC × 2 of citral for 2 h. Citral did not modulate the resistance of the studied strains to nystatin. CONCLUSION: This study revealed the potential of citral as a fungicidal agent and highlighted the resistance of clinical strains of C. albicans to nystatin.

Evaluation of Toxicity and Antimicrobial Activity of an Ethanolic Extract from Leaves of Morus alba L. (Moraceae).

This work evaluated an ethanolic extract from Morus alba leaves for toxicity to Artemia salina, oral toxicity to mice, and antimicrobial activity. Phytochemical analysis revealed the presence of coumarins, flavonoids, tannins, and triterpenes in the extract, which did not show toxicity to A. salina nauplii. No mortality and behavioral alterations were detected for mice treated with the extract (300 and 2000 mg/kg b.w.) for 14 days. However, animals that received the highest dose showed reduced MCV and MCHC as well as increased serum alkaline phosphatase activity. In treatments with the extract at both 300 and 2000 mg/kg, there was a reduction in number of leukocytes, with decrease in percentage of lymphocytes and increase in proportion of segmented cells. Histopathological analysis of organs from mice treated with the extract at 2000 mg/kg revealed turgidity of contorted tubules in kidneys, presence of leukocyte infiltration around the liver centrilobular vein, and high dispersion of the spleen white pulp. The extract showed antimicrobial activity against Staphylococcus aureus, Pseudomonas aeruginosa, Candida albicans, Candida krusei, Candida tropicalis, and Aspergillus flavus. In conclusion, the extract contains antimicrobial agents and was not lethal for mice when ingested; however, its use requires caution because it promoted biochemical, hematological, and histopathological alterations.

Evaluation of Antifungal Activity and Mode of Action of New Coumarin Derivative, 7-Hydroxy-6-nitro-2H-1-benzopyran-2-one, against Aspergillus spp.

Aspergillus spp. produce a wide variety of diseases. For the treatment of such infections, the azoles and Amphotericin B are used in various formulations. The treatment of fungal diseases is often ineffective, because of increases in azole resistance and their several associated adverse effects. To overcome these problems, natural products and their derivatives are interesting alternatives. The aim of this study was to examine the effects of coumarin derivative, 7-hydroxy-6-nitro-2H-1-benzopyran-2-one (Cou-NO2), both alone and with antifungal drugs. Its mode of action against Aspergillus spp. Cou-NO2 was tested to evaluate its effects on mycelia growth and germination of fungal conidia of Aspergillus spp. We also investigated possible Cou-NO2 action on cell walls (0.8 M sorbitol) and on Cou-NO2 to ergosterol binding in the cell membrane. The study shows that Cou-NO2 is capable of inhibiting both the mycelia growth and germination of conidia for the species tested, and that its action affects the structure of the fungal cell wall. At subinhibitory concentration, Cou-NO2 enhanced the in vitro effects of azoles. Moreover, in combination with azoles (voriconazole and itraconazole) Cou-NO2 displays an additive effect. Thus, our study supports the use of coumarin derivative 7-hydroxy-6-nitro-2H-1-benzopyran-2-one as an antifungal agent against Aspergillus species.

First chemical constituents from Cordia exaltata Lam and antimicrobial activity of two neolignans.

The phytochemical study of Cordia exaltata Lam. (Boraginaceae) led to the isolation, through chromatographic techniques, of nineteen secondary metabolites: 8,8'dimethyl-3,4,3',4'-dimethylenedioxy-7-oxo-2,7'cyclolignan (1), 8,8'-dimethyl-4,5-dimethoxy-3',4'-methylenodioxy-7-oxo-2,7'cyclolignan (2), sitosterol (3a), stigmasterol (3b), sitosterol-3-O-ß-D-glucopyranoside (4a), stigmasterol-3-O-ß-D-glucopyranoside (4b), phaeophytin A (5), 13²-hydroxyphaeophytin A (6), 17³-ethoxypheophorbide A (7), 13²-hydroxy-17³-ethoxypheophorbide A (8), m-methoxy-p-hydroxybenzaldehyde (9), (E)-7-(3,4-dihydroxyphenyl)-7-propenoic acid (10), 1-benzopyran-2-one (11), 7-hydroxy-1-benzopyran-2-one (12), 2,5-bis-(3',4'-methylenedioxiphenyl)-3,4-dimethyltetrahydrofuran (13), 3,4,5,3',5'-pentamethoxy-1'-allyl-8.O.4'-neolignan (14), 3,5,7,3',4'-pentahydroxyflavonol (15), 5,7-dihydroxy-4'-methoxyflavone (16), 5,8-dihydroxy-7,4'-dimethoxyflavone (17), kaempherol 3-O-ß-D-glucosyl-6''-α-L-ramnopyranoside (18) and kaempherol 3,7-di-O-α-L-ramnopyranoside (19). Their structures were identified by ¹H and ¹³C-NMR using one and two-dimensional techniques. In addition, the antimicrobial activity of compounds 1, 2, 13 and 14 against bacteria and fungi are reported here for the first time.

Efecto combinado del aceite esencial de Cinnamomum zeylanicum blume y nistatina sobre cepas de Candida no-albicans / Combined effect of Cinnamomum zeylanicum blume essential oil and nystatin on strains of non-albicans Candida

Introduction: considering the emergence of resistant species of albicans and non-albicans Candida to agents therapeutically available as a result of the increased number of immunocompromised population and of the increasingly frequent use of prophylaxis and empirical treatment with antifungals, it's verified that there is a clear and emerging need to introduce new antimicrobials agents in the therapeutic arsenal. The purpose of this study was to evaluate the antifungal activity of essential oil of Cinnamomum zeylanicum Blume alone and combined with Nystatin on strains of C. tropicalis and C. krusei. Methods: this was an experimental research in laboratory. It was determined the Minimum Inhibitory Concentration, using the microdilution method, as well as the Fractional Inhibitory Concentration to determine the possible synergistic effects of the association. Strains of C. tropicalis ATCC 40147 and C. krusei ATCC 40042 were used in the tests. When assessed separately, C. zeylanicum essential oil and Nystatin presented Minimum Inhibitory Concentration of 312,5 µg/mL and 64 µg/mL, respectively, on both tested strains. Results: When combined, were found Minimum Inhibitory Concentration of 39 µg/mL and 32 µg/mL for the essential oil and for Nystatin, respectively. The Fractional Inhibitory Concentration value was 0,6024 for both tested strains, indicating additivity of the inhibitory effect on fungal growth. Conclusions: the results indicate that C. zeylanicum essential oil has antifungal activity against the strains of non-albicans Candida evaluated and that its association with Nystatin potentiates this effect(AU)

Introducción: es necesaria la introducción de nuevos agentes antimicrobianos por el surgimiento de especies de Candida albicans y no albicans resistentes a los agentes terapéuticos disponibles .El objetivo del estudio fue evaluar la actividad antifúngica del aceite esencial de Cinnamomum zeylanicum Blume aislado y asociado con nistatina sobre cepas Candida tropicalis y Candida krusei. Métodos: se realizó una investigación experimental de laboratorio. La concentración mínima inhibitoria fue determinada utilizando el método de microdilución, y la concentración inhibitoria fraccionada se usó para determinar los posibles efectos sinérgicos de la asociación. Para las pruebas fueron utilizadas las cepas de C. tropicalis ATCC 40147 y C. krusei ATCC 40042. Se usaron el aceite esencial de C. zeylanicum y nistatina. Cuando fueron evaluados por separado presentaron la concentración mínima inhibitoria de 312,5 µg/mL y de 64 µg/mL, respectivamente, sobre ambas cepas ensayadas. Resultados: una vez asociados, la concentración mínima inhibitoria fue de 39 µg/mL para el aceite esencial y de 32 µg/mL para la nistatina. El valor de la concentración inhibitoria fraccionada para ambas cepas probadas fue de 0,6024, lo que indica adicción del efecto inhibidor sobre el crecimiento de hongos. Conclusiones: los resultados indican que el aceite esencial de C. zeylanicum tiene actividad antifúngica frente a las cepas de Candida no albicans y que la asociación del mismo con la nistatina promueve la potenciación de este efecto(AU)

Antifungal activity of Thymus vulgaris L. essential oil and its constituent phytochemicals against Rhizopus oryzae: interaction with ergosterol.

Mucormycoses are emerging infections that have high rates of morbidity and mortality. They show high resistance to antifungal agents, and there is a limited therapeutic arsenal currently available, therefore, there is a great need to give priority to testing therapeutic agents for the treatment of mucormycosis. Along this line, the use of essential oils and phytoconstituents has been emphasized as a new therapeutic approach. The objective of this work was to investigate the antifungal activity of the essential oil (EO) of Thymus vulgaris, and its constituents thymol and p-cymene against Rhizopus oryzae, through microbiological screening, determination of minimal inhibitory concentration (MICs) and minimal fungicidal concentration (MFCs), effects on mycelial growth and germination of sporangiospores and interaction with ergosterol. The MIC of EO and thymol varied 128-512 µg/mL, but the MFC of EO and thymol varied 512-1024 µg/mL and 128-1024 µg/mL, respectively. The results also showed that EO and thymol significantly inhibited mycelial development and germination of sporangiospores. Investigation of the mechanism of antifungal action showed that EO and thymol interact with ergosterol. These data indicate that EO of T. vulgaris and thymol possess strong antifungal activity, which can be related to their interaction with ergosterol, supporting the possible use of these products in the treatment of mucormycosis.

Antimicrobial Activity of Indigofera suffruticosa.

Various organic and aqueous extracts of leaves of Indigofera suffruticosa Mill (Fabaceae) obtained by infusion and maceration were screened for their antibacterial and antifungal activities. The extracts were tested against 5 different species of human pathogenic bacteria and 17 fungal strains by the agar-solid diffusion method. Most of the extracts were devoid of antifungal and antibacterial activities, except the aqueous extract of leaves of I. suffruticosa obtained by infusion, which showed strong inhibitory activity against the Gram-positive bacteria Staphylococcus aureus with a minimal inhibitory concentration (MIC) of 5000 microg ml(-1). The MIC values to dermatophyte strains were 2500 microg ml(-1) against Trichophyton rubrum (LM-09, LM-13) and Microsporum canis. This study suggests that aqueous extracts of leaves of I. suffruticosa obtained by infusion can be used in the treatment of skin diseases caused by dermatophytes.