Synthesis and in vitro evaluation of peracetyl and deacetyl glycosides of eugenol, isoeugenol and dihydroeugenol acting against food-contaminating bacteria

Quantitative structure-property relationship modelling for predicting retention indices of essential oils based on an improved horse herd optimization algorithm

The horse herd optimization algorithm (HOA), one of the more contemporary metaheuristic algorithms, has demonstrated superior performance in a number of challenging optimization tasks. In the present work, the descriptor selection issue is resolved by classifying different essential oil retention indices using the binary form, BHOA. Based on internal and external prediction criteria, Z-shape transfer functions (ZTF) were tested to verify their efficiency in improving BHOA performance in QSPR modelling for predicting retention indices of essential oils. The evaluation criteria involved the mean-squared error of the training and testing datasets (MSE), and leave-one-out internal and external validation (Q2). The degree of convergence of the proposed Z-shaped transfer functions was compared. In addition, K-fold cross validation with k = 5 was applied. The results show that ZTF, especially ZTF1, greatly improves the performance of the original BHOA. Comparatively speaking, ZTF, especially ZTF1, exhibits the fastest convergence behaviour of the binary algorithms. It chooses the fewest descriptors and requires the fewest iterations to achieve excellent prediction performance.

Glucosylation of Isoeugenol and Monoterpenes in Corynebacterium glutamicum by YdhE from Bacillus lichenformis

Corynebacterium glutamicum has been regarded as a food-grade microorganism. In recent years, the research to improve the activities of beneficial therapeutics and pharmaceutical substances has resulted in the engineering of the therapeutically favorable cell factory system of C. glutamicum. In this study, we successfully glucosylated isoeugenol and other monoterpene derivatives in C. glutamicum using a promiscuous YdhE, which is a glycosyltransferase from Bacillus lichenformis. For efficient glucosylation, cultivation conditions such as the production time, substrate concentration, carbon source, and culture medium were optimized. Our system successfully converted about 93% of the isoeugenol to glucosylated compounds in the culture. The glucoside compounds were then purified, analyzed, and identified as isoeugenol-1-O-β-d-glucoside and isoeugenol-1-O-β-d-(2″-acetyl)-glucoside.

Synthesis and Structure-Activity Relationship Studies of Novel Aryl Sulfonamides and Their Activity against Human Breast Cancer Cell Lines

A series of structural analogs of aryl sulfonamide hybrid compounds were synthesised and their cytotoxic activity was evaluated against three human breast cancer cell lines (MCF-7, MDA-MB-231 and Hs 578T). The compounds were designed through electronic, hydrophobic and steric modifications using the chemical structure of N-{4-[(2-hydroxy-3-methoxy-5-propylphenyl)sulfamoyl]phenyl}acetamide (referred to as compound 7) as a starting point to then assess a structure-activity relationship (SAR) study. From the data generated, we observed that compounds 9, 10 and 11 (which have modifications in the substituents of the aryl sulfonamide), efficiently reduced the cell viability of MCF-7 and MDA-MB-231 cell cultures. Based on initial data, we selected compounds 10 and 11 for further investigations into their antiproliferative and/or cytotoxic profile against MDA-MB-231 cells, and we noted that compound 10 was the most promising compound in the series. Compound 10 promoted morphological changes and altered the dynamics of cell cycle progression in MDA-MB-231 cells, inducing arrest in G1/S transition. Taken together, these results show that the dihydroeugenol-aryl-sulfonamide hybrid compound 10 (which has an electron withdrawing nitro group) displays promising antiproliferative activity against MDA-MB-231 cell lines.

In vitro antioxidant and antimicrobial activities of clove extract and its effectiveness in bio-composite film on storage stability of goat meat balls

The aim of this study was to find out clove extract's antimicrobial and antioxidant properties, as well as its efficacy as a bioactive ingredient in the development of bio-composite films to increase the storage stability of goat meat balls stored at 4 ± 1°C. The clove extracts (CLEs) were prepared in ethanol, hydroethanol (1:1), and water and evaluated for antioxidant and antimicrobial potential. In vitro assays of CLEs revealed more susceptibility for gram-positive bacteria than gram-negative bacteria. Among the different extracts, the clove ethanol extract (CLEE) had the highest antimicrobial activity against tested microorganisms as well as total phenolics (1.14 mg GAE/g), flavonoids (8.50 µg catechin/g), and DPPH assay (39.59%). Further, the concentration-dependent effect of CLEE (p < 0.05) on thickness and color values and antimicrobial properties of the bio-composite film were observed. The storage qualities of the product T₁ (with film; 450 µl CLEE) such as pH (6.45 ± 0.01), TBARS (0.87 ± 0.06 mg malonaldehyde/kg) value, free fatty acid (0.193 ± 0.001% oleic acid), total mesophilic count (4.98 ± 0.05 log₁₀ CFU/g), and sensory attributes (overall acceptability score: 5.67 on 8-point scale) were better (p < 0.05) than T₀ (without film; control) on day 20 of storage. Thus, the ethanolic clove extract has a superior antioxidant and antimicrobial potential. Its inclusion in the bio-composite film prolonged the storage stability of goat meat balls by controlling lipid oxidation and microbial growth. Practical Application Today's consumers are more attracted towards meat products added with natural ingredients having preservative effects. Clove extract is a classic example of a natural preservative and has excellent antimicrobial and antioxidant potential. The present study revealed that by wrapping the ethanolic clove extract-based bio-composite film on goat meat balls extended the storage stability of the product due to controlled lipid oxidation and microbial growth. Thus, such bio-composite films can be successfully applied on goat meat balls that function as a antimicrobial packaging for providing optimum organoleptic quality and better shelf life.

Tailored Functionalization of Natural Phenols to Improve Biological Activity

Phenols are widespread in nature, being the major components of several plants and essential oils. Natural phenols' anti-microbial, anti-bacterial, anti-oxidant, pharmacological and nutritional properties are, nowadays, well established. Hence, given their peculiar biological role, numerous studies are currently ongoing to overcome their limitations, as well as to enhance their activity. In this review, the functionalization of selected natural phenols is critically examined, mainly highlighting their improved bioactivity after the proper chemical transformations. In particular, functionalization of the most abundant naturally occurring monophenols, diphenols, lipidic phenols, phenolic acids, polyphenols and curcumin derivatives is explored.

In vivo Antibacterial Activity of Star Anise (Illicium verum Hook.) Extract Using Murine MRSA Skin Infection Model in Relation to Its Metabolite Profile

Introduction

Star anise fruits (Illicium verum Hook.) have been used as an important treatment in traditional Chinese medicine. The previous studies reported the activity of the non-polar fractions as potential sources of antibacterial metabolites, and little was done concerning the polar fractions of star anise.

Methods

The antibacterial activity of the star anise aqueous methanolic (50%) extract against multidrug-resistant Acinetobacter baumannii AB5057 and methicillin-resistant Staphylococcus aureus (MRSA USA300) was investigated in vitro (disc diffusion assay, minimum bactericidal concentration determination, anti-biofilm activity and biofilm detachment activity). The antibacterial activity was further tested in vivo using a murine model of MRSA skin infection. Ultra-performance liquid chromatography coupled to high-resolution mass spectrometry (UPLC/HRMS) approach was applied for the identification of the metabolites responsible for the antibacterial activity. The antioxidant potential was evaluated using five in vitro assays: TAC (total antioxidant capacity), DPPH, ABTS, FRAP (ferric reducing antioxidant power) and iron-reducing power.

Results

In vitro, star anise aqueous methanolic extract showed significant inhibition and detachment activity against biofilm formation by the multidrug-resistant and highly virulent Acinetobacter baumannii AB5057 and MRSA USA300. The topical application of the extract in vivo significantly reduced the bacterial load in MRSA-infected skin lesions. The extract showed strong antioxidant activity using five different complementary methods. More than seventy metabolites from different classes were identified: phenolic acids, phenylpropanoids, sesquiterpenes, tannins, lignans and flavonoids.

Conclusion

This study proposes the potential use of star anise polar fraction in anti-virulence strategies against persistent infections and for the treatment of staphylococcal skin infections as a topical antimicrobial agent. To our knowledge, our research is the first to provide the complete polar metabolome list of star anise in an approach to understand the relationship between the chemistry of these metabolites and the proposed antibacterial activity.

Effects of incorporation with clove (Eugenia caryophyllata) essential oil (CEO) on overall performance of chitosan as active coating

This research is focused on improving performance of chitosan based functional material by introducing active additive. A series of assays revealed incorporation with clove essential oil (CEO) significantly improved the physical, chemical and antimicrobial performance of chitosan. In this work, the prepared chitosan-CEO film (CH-CEO) showed varieties in color parameters, mechanical strength and water vapor permeability. Moreover, chitosan was endowed with significant antioxidant and antimicrobial activities, thereby it was used as protective coatings for fresh-cutting apple tubes at ~1 °C. Results demonstrated the treatment slowed down the quality deterioration process of preserved apple samples, especially for firmness and color. As well, CH-CEO coating reduced microbial counts in the preserved apple samples and inhibited the varieties in the chemical properties. The overall observations revealed that CH-CEO film has remarkable potential as an antioxidant and antimicrobial material, especially as an active coating for fresh-cutting foods during storage.

Plant-Climate Interaction Effects: Changes in the Relative Distribution and Concentration of the Volatile Tea Leaf Metabolome in 2014-2016

Climatic conditions affect the chemical composition of edible crops, which can impact flavor, nutrition and overall consumer preferences. To understand these effects, we sampled tea (Camellia sinensis (L.) Kuntze) grown in different environmental conditions. Using a target/nontarget data analysis approach, we detected 564 metabolites from tea grown at two elevations in spring and summer over 3 years in two major tea-producing areas of China. Principal component analysis and partial least squares-discriminant analysis show seasonal, elevational, and yearly differences in tea from Yunnan and Fujian provinces. Independent of location, higher concentrations of compounds with aromas characteristic of farmers' perceptions of high-quality tea were found in spring and high elevation teas. Yunnan teas were distinct from Fujian teas, but the effects of elevation and season were different for the two locations. Elevation was the largest source of metabolite variation in Yunnan yet had no effect in Fujian. In contrast seasonal differences were strong in both locations. Importantly, the year-to-year variation in chemistry at both locations emphasizes the importance of doing multi-year studies, and further highlights the challenge farmers face when trying to produce teas with specific flavor/health (metabolite) profiles.

A sparse QSRR model for predicting retention indices of essential oils based on robust screening approach

A robust screening approach and a sparse quantitative structure-retention relationship (QSRR) model for predicting retention indices (RIs) of 169 constituents of essential oils is proposed. The proposed approach is represented in two steps. First, dimension reduction was performed using the proposed modified robust sure independence screening (MR-SIS) method. Second, prediction of RIs was made using the proposed robust sparse QSRR with smoothly clipped absolute deviation (SCAD) penalty (RSQSRR). The RSQSRR model was internally and externally validated based on [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], Y-randomization test, [Formula: see text], [Formula: see text], and the applicability domain. The validation results indicate that the model is robust and not due to chance correlation. The descriptor selection and prediction performance of the RSQSRR for training dataset outperform the other two used modelling methods. The RSQSRR shows the highest [Formula: see text], [Formula: see text], and [Formula: see text], and the lowest [Formula: see text]. For the test dataset, the RSQSRR shows a high external validation value ([Formula: see text]), and a low value of [Formula: see text] compared with the other methods, indicating its higher predictive ability. In conclusion, the results reveal that the proposed RSQSRR is an efficient approach for modelling high dimensional QSRRs and the method is useful for the estimation of RIs of essential oils that have not been experimentally tested.