Fine resolution analysis of bacterial communities associated with Neochloris oleoabundans culture and insights into terpenes as contamination control agents.

Biological contamination is one of the main bottlenecks in microalgae production, reducing quality and productivity and sometimes leading to the complete loss of the cultures. Selecting terpenes can be a pathway toward eco-friendly contamination control in microalgae cultures. This work evaluated the presence of bacterial contaminants in N. oleoabundans cultures through HTS and 16 S analysis and their susceptibility to six natural terpenes (α-pinene, ß-pinene, limonene, trans-cinnamaldehyde, linalool, and eugenol). The principal phyla identified were Proteobacteria, Bacteroidetes, and Actinobacteria, and based on these data, 89 bacterial isolates of seven genera were obtained (36 Aureimonas sp., 27 Microbacterium sp., 5 Pseudomonas sp., 9 Bacillus sp., 14 Shinella sp., 1 Brevundimonas sp., and 1 Exiguobacterium sp.) at 25ºC in the presence of light. It was possible to observe that Beta-pinene 50 mg L- 1 only inhibited Bacillus sp. In contrast, Alpha-pinene, Linalool, and Trans-cinnamaldehyde, at a concentration of 6.25 mg L- 1 efficiently inhibited most isolates. The inhibition percentages found were 79-99%.

Antifungal activity and aroma persistence of free and encapsulated Cinnamomum cassia essential oil in maize.

The objective of this study was to evaluate the chemical composition and antifungal activity of free and encapsulated Cinnamomum cassia essential oil (EO) against Penicillium crustosum, Alternaria alternata, and Aspergillus flavus, and the aroma persistence in maize flour. Trans-cinnamaldehyde (TC) was identified as the major compound (86 %) in the C. cassia EO. The EO was encapsulated by spray-dryer with 45.26 % efficiency using gum arabic (GA) and maltodextrin (MD) in a ratio of 1:1 (m/m). C. cassia EO showed antifungal activity against A. alternata, A. flavus, and P. crustosum, with a minimum inhibitory concentration (MIC) of 0.5 % for both free and standard TC, and 5 % for the encapsulated EO. Fungal growth inhibition was evaluated under exposition to vapors at different concentrations of C. cassia EO and TC standard, with MIC of 6 % and 8 % against P. crustosum, 4 % and 1 % A. alternata, and 4 % A. flavus, respectively. The sensory analysis results of the free and encapsulated C. cassia EO in maize flour showed a significant difference between the treated samples in relation to the standard sample (p < 0.05). The sample with free EO has high aroma intensity persistence, while the samples treated with encapsulated EO were evaluated as being closer to the standard sample. The results suggest that the encapsulated C. cassia EOs can be used as natural alternatives to control fungi in maize flour.

Chitosan microparticles as entrapment system for trans- cinnamaldehyde: Synthesis, drug loading, and in vitro cytotoxicity evaluation.

The ionic gelation method was used to study the effect of the crosslinking agent, sodium tripolyphosphate on average particle size (Dp) and zeta potential (ζp) of chitosan microparticles (CSMP) unloaded and loaded with trans-cinnamaldehyde (TCIN). The obtained values of Dp and ζp trend as 117.6 ±â€¯0.4 ≤ Dp ≤ 478.5 ±â€¯3.5 nm and +27.8 ±â€¯1.3 ≤ ζp ≤ +103.5 ±â€¯4.2 mV, respectively. The entrapment efficiency of TCIN in CSMP was 9.1 ±â€¯2.0% and 71.5 ±â€¯2.9% was released after 360 min (pH = 6.5) which reveals a potential anti-cancer activity in acidic environment. Cytotoxicity of TCIN in DMSO (0-50 µM) was evaluated on MDCK and HeLa cell lines and exhibited low effect at either 24 or 48 h of exposure; whereas TCIN-loaded CSMP (0-50 µM) showed, after 24 h of exposure, 67.6 ±â€¯7.0 and 64.5 ±â€¯3.9% cytotoxicity for MDCK and HeLa cell lines, respectively. At 48 h of exposure, TCIN-loaded CSMP achieved 81.1 ±â€¯0.26 and 77.9 ±â€¯4.2% cytotoxicity for MDCK and HeLa cell lines, respectively.

Evaluation of the antimicrobial activity of Cinnamomum zeylanicum essential oil and trans-Cinnamaldehyde against resistant Mycobacterium tuberculosis / Avaliação da atividade antimicrobiana do óleo essencial do cinnamomum zeylanicum essential oil e do trans-cinamaldeído contra mycobacterium tuberculosis resistente

The essential oil (EO) extracted from the bark of Cinnamomum zeylanicum (Czey; also known as cinnamon), mostly derives its properties from its major compound trans-cinnamaldehyde (TCin). The present study evaluated the antimycobacterial activity of the essential oil from Czey (CzeyEO) and TCin against sensitive and resistant clinical isolates of Mycobacterium tuberculosis, as well as the combinatorial effects of CzeyEO and TCin with the anti-tuberculosis (TB) drugs rifampicin (RIF) and isoniazid (INH). The resazurin microtiter assay method was used to determine the minimum inhibitory concentration (MIC) of the components tested on the clinical isolates of M. tuberculosis. The effects of the CzeyEO/RIF, CzeyEO/INH, TCin/RIF, and TCin/INH combinations on the M. tuberculosis H37Rv reference strain were evaluated using the checkerboard method to determine the fractional inhibitory concentration index (FICI). CzeyEO and TCin inhibited all bacterial clinical isolates. In the interactive experiment, CzeyEO and TCin were found to be highly effective in reducing the resistance of resistant M. tuberculosis to RIF and INH. All four tested combinations demonstrated synergistic and additive effects, with no antagonistic effects. The synergistic combinations of CzeyEO/RIF and CzeyEO/INH exhibited FICI values of 0.375 and 0.5, respectively, while the TCin/RIF and TCin/INH combinations exhibited FICI values of 0.31 and 0.5, respectively. These results indicate that CzeyEO and TCin are potential candidates for the treatment of drug-resistant tuberculosis in combination therapy with INH and RIF.

O óleo essencial (EO) extraído da casca do Cinnamomum zeylanicum (CzeyEO), conhecido como canela, tem como seu principal composto o trans-cinamaldeído (TCin). O presente estudo avaliou a atividade antimicobacteriana de CzeyEO e do TCin contra isolados clínicos sensíveis e resistentes de Mycobacterium tuberculosis, bem como os efeitos das associações de CzeyEO e do TCin com os fármacos anti-TB, rifampicina (RIF) e isoniazida (INH). A técnica de ensaio de microtitulação da resazurina foi utilizada para determinar a concentração inibitória mínima (CIM) dos componentes testados nos isolados clínicos de M. tuberculosis. Os efeitos das associações CzeyEO/RIF, CzeyEO/INH, TCin/RIF e TCin/INH contra a cepa de referência H37Rv de M. tuberculosis foram avaliados pelo método Checkerboard, determinando o índice de concentração inibitória fracionária (ICIF). Todos os isolados clínicos bacterianos foram inibidos por CzeyEO e TCin. As interações de CzeyEO e TCin foram altamente eficazes na redução da resistência do M. tuberculosisresistente a RIF e INH. Todas as quatro combinações testadas resultaram em efeitos sinérgicos e aditivos, sem efeito antagônico. Ambas as associações de sinergismo de CzeyEO/RIF e CzeyEO/INH mostraram valores de ICIF de 0,375 e 0,5, enquanto as associações de TCin/RIF e TCin/INH apresentaram valores de ICIF de 0,31 e 0,5. CzeyEO e TCin são potenciais candidatos em terapia combinada com INH e RIF para o tratamento da tuberculose resistente.

Use of microbial models to evaluate the effect of UV-C light and trans-cinnamaldehyde on the native microbial load of grapefruit (Citrus × paradisi) juice.

The aim of this research was to evaluate the storage stability (5 °C), and microbial modeling, of Rubi red grapefruit (Citrus × paradisi) juice treated with ultraviolet-C (UV-C) light (0, 10 and 20 min), alone or in combination with trans-cinnamaldehyde (trans-CAH) (0, 25 and 50 µg/mL). A 32 factorial design was used and data modeled with the Weibull, Modified Gompertz and Logistic models. A response surface model was used to evaluate the effect of modeling parameters for suggesting the optimum treatment conditions. Treated and some untreated juice lasted up to 9 days without physicochemical and microbial changes. At the higher combination of UV-C light and trans-CAH, the microbial load of grapefruit juice was maintained below 100 CFU/mL up to 15 days. For mesophiles, the three predictive models indicated that the parameters n and Nmax decreased and the parameters λ and tc increased as the combination of UV-C light and trans-CAH increased. The response surface modeling of the parameters obtained by the predictive models showed acceptable correlation for mesophiles (R2 = 0.815-0.977) but not for yeasts (R2 = 0.618-0.815). The three predictive models showed that, the concentration of trans-CAH had more effect on stopping the microbial growth than the UV-C light treatment.

Antibacterial mechanisms of cinnamon and its constituents: A review.

BACKGROUND: In the current healthcare environment, an alarming rise in multi-drug resistant bacterial infections has led to a global health threat. The lack of new antibiotics has created a need for developing alternative strategies. OBJECTIVE: Understanding the antibacterial mechanisms of cinnamon and its constituents is crucial to enhance it as a potential new source of antibiotic. The objective of this review is to provide a compilation of all described mechanisms of antibacterial action of cinnamon and its constituents and synergism with commercial antibiotics in order to better understand how cinnamon and its constituents can collaborate as alternative treatment to multi-drug resistant bacterial infections. METHODS: The relevant references on antibacterial activities of cinnamon and its constituents were searched. Meanwhile, the references were classified according to the type of mechanism of action against bacteria. Relationships of cinnamon or its constituents and antibiotics were also analyzed and summarized. RESULTS: Cinnamon extracts, essential oils, and their compounds have been reported to inhibit bacteria by damaging cell membrane; altering the lipid profile; inhibiting ATPases, cell division, membrane porins, motility, and biofilm formation; and via anti-quorum sensing effects. CONCLUSION: This review describes the antibacterial effects of cinnamon and its constituents, such as cinnamaldehyde and cinnamic acid, against pathogenic Gram-positive and Gram-negative bacteria. The review also provides an overview of the current knowledge of the primary modes of action of these compounds as well as the synergistic interactions between cinnamon or its constituents with known antibacterial agents. This information will be useful in improving the effectiveness of therapeutics based on these compounds.