Metal-Flavonoid Interactions-From Simple Complexes to Advanced Systems.

For many years, metal-flavonoid complexes have been widely studied as a part of drug discovery programs, but in the last decade their importance in materials science has increased significantly. A deeper understanding of the role of metal ions and flavonoids in constructing simple complexes and more advanced hybrid networks will facilitate the assembly of materials with tailored architecture and functionality. In this Review, we highlight the most essential data on metal-flavonoid systems, presenting a promising alternative in the design of hybrid inorganic-organic materials. We focus mainly on systems containing CuII/I and FeIII/II ions, which are necessary in natural and industrial catalysis. We discuss two kinds of interactions that typically ensure the formation of metal-flavonoid systems, namely coordination and redox reactions. Our intention is to cover the fundamentals of metal-flavonoid systems to show how this knowledge has been already transferred from small molecules to complex materials.

Sustainable extraction of bioactive compound from apple pomace through lactic acid bacteria (LAB) fermentation.

Apple pomace (AP), a by-product of the juice industry, is a rich and inexpensive source of natural bioactive substances, including phenolic compounds, that exhibit health-promoting effects. The recovery of these compounds from plant material using only classical extraction techniques and environmentally friendly solvents is often ineffective due to the entrapment of some compounds in the complex structures of plant cell walls. Lactic Acid Bacteria (LAB) fermentation can be a simple technology to increase the content of phenolic compounds, as well as the antioxidant activity of plant material. In this study, pomace from conventionally grown apples (Malus Domestica) of the Ligol cultivar were fermented with selected LAB strains (Lpb. plantarum KKP 3182, Lpb. plantarum KKP 1527, Lpb. plantarum ZFB 200), commercial starter cultures of Lpb. plantarum, and spontaneously. The fermented material was then subjected to ultrasound-assisted extraction, and the resulting extracts were analysed for their composition (phenolic compounds, triterpenoids, simple organic acids), and antioxidant activity. We found that: (1) the total phenolic content of AP extracts fermented with Lpb. plantarum KKP 1527 was about 30% higher than that of non-fermented AP extracts, (2) extracts of AP fermented with Lpb. plantarum KKP 1527 characterized a higher value of the antioxidant activity, (3) an increase in gallic acid procyanidin A2, protocatechuic acid, and procyanidin B2, while a decrease in rutin and quercetin was observed. The results indicated that AP fermented with Lpb. plantarum KKP 1527 may be a powerful and low-cost source of natural antioxidants which have applications in many industries.

Starter culture-related changes in free amino acids, biogenic amines profile, and antioxidant properties of fermented red beetroot grown in Poland.

Fermentation of two red beet cultivars (Wodan and Alto) with single-strain starter cultures consisting of selected strains of lactic acid bacteria (LAB) of plant origin (Weissella cibaria KKP2058, Levilactobacillus brevis ZF165) and a multi-strain culture (containing W. cibaria KKP2058, L. brevis ZF165, Lactiplantibacillus plantarum KKP1822, Limosilactobacillus fermentum KKP1820, and Leuconostoc mesenteroides JEIIF) was performed to evaluate their impact on betalains, free amino acids, formation of biogenic amines, and antioxidative properties of the juice formed. Next-generation sequencing data analysis used to identify the microbial community revealed that the starter cultures promoted the dominance of the genus Lactobacillus, and decreased the proportion of spoilage bacteria compared to spontaneously fermented juices. Generally, the fermentation process significantly influenced the amount of the analyzed compounds, leading in most cases to their reduction. The observed changes in the studied parameters depended on the starter culture used, indicating different metabolic activities of the LAB strains towards bioactive compounds. The use of multi-strain starter cultures allowed to largely prevent the reduction of betacyanins and histamine formation.

Natural Cinnamic Acid Derivatives: A Comprehensive Study on Structural, Anti/Pro-Oxidant, and Environmental Impacts.

Cinnamic acid (CA), p-coumaric acid (4-hydroxycinnamic acid, 4-HCA), caffeic acid (3,4-vdihydroxycinnamic acid, 3,4-dHCA), and 3,4,5-trihydroxycinnamic acid (3,4,5-tHCA) were studied for their structural, anti-/pro-oxidant properties and biodegradability. The FT-IR, FT-Raman, UV/Vis, 1H and 13C NMR, and quantum chemical calculations in B3LYP/6-311++G** were performed to study the effect on number and position of hydroxyl group in the ring on the molecular structure of molecules. The antioxidant properties of the derivatives were examined using DPPH● and HO● radicals scavenging assays, ferric ion reducing antioxidant power (FRAP), cupric reducing antioxidant capacity (CUPRAC), inhibition of linoleic acid oxidation, as well as the biological antioxidant assay with Saccharomyces cerevisiae. Moreover, the pro-oxidant activity of compounds in Trolox oxidation assay was estimated. The effect of the derivatives on environment on the basis of increasing the carbon and nitrogen compounds transformation processes occurring in biological wastewater treatment was studied.

Silage quality and biogas production from Spartina pectinata L. fermented with a novel xylan-degrading strain of Lactobacillus buchneri M B/00077.

The aim of the current study was to determine the ability of the Lactobacillus buchneri M B/00077 strain to degrade xylan, its impact on the quality of silage made from the lignocellulosic biomass of Spartina pectinata L., as well as the efficiency of biogas production. In the model in vitro conditions the L. buchneri M B/00077 strain was able to grow in a medium using xylan as the sole source of carbon, and xylanolytic activity was detected in the post-culture medium. In the L. buchneri M B/00077 genome, genes encoding endo-1,4-xylanase and ß-xylosidase were identified. The silages prepared using L. buchneri M B/00077 were characterized by a higher concentration of acetic and propionic acids compared to the controls or the silages prepared with the addition of commercial xylanase. The addition of bacteria increased the efficiency of biogas production. From the silages treated with L. buchneri M B/00077, 10% and 20% more biogas was obtained than from the controls and the silages treated with commercial xylanase, respectively. The results of the current study indicated the strain L. buchneri M B/00077 as being a promising candidate for further application in the field of pretreatment of lignocellulosic biomass.

Recent Developments in Effective Antioxidants: The Structure and Antioxidant Properties.

Since the last few years, the growing interest in the use of natural and synthetic antioxidants as functional food ingredients and dietary supplements, is observed. The imbalance between the number of antioxidants and free radicals is the cause of oxidative damages of proteins, lipids, and DNA. The aim of the study was the review of recent developments in antioxidants. One of the crucial issues in food technology, medicine, and biotechnology is the excess free radicals reduction to obtain healthy food. The major problem is receiving more effective antioxidants. The study aimed to analyze the properties of efficient antioxidants and a better understanding of the molecular mechanism of antioxidant processes. Our researches and sparing literature data prove that the ligand antioxidant properties complexed by selected metals may significantly affect the free radical neutralization. According to our preliminary observation, this efficiency is improved mainly by the metals of high ion potential, e.g., Fe(III), Cr(III), Ln(III), Y(III). The complexes of delocalized electronic charge are better antioxidants. Experimental literature results of antioxidant assays, such as diphenylpicrylhydrazyl (DPPH) and ferric reducing activity power assay (FRAP), were compared to thermodynamic parameters obtained with computational methods. The mechanisms of free radicals creation were described based on the experimental literature data. Changes in HOMO energy distribution in phenolic acids with an increasing number of hydroxyl groups were observed. The antioxidant properties of flavonoids are strongly dependent on the hydroxyl group position and the catechol moiety. The number of methoxy groups in the phenolic acid molecules influences antioxidant activity. The use of synchrotron techniques in the antioxidants electronic structure analysis was proposed.

Antimicrobial Properties of Mandelic Acid, Gallic Acid and their Derivatives.

PURPOSE: Alpha-hydroxy acids (AHAs) are one of the classes of hydroxy acids being beneficial for human health. The manuscript summarizes the biological properties of two popular members of AHAs, i.e., Mandelic Acid (MA) and Gallic Acid (GA), with particular emphasis on antimicrobial properties. Moreover, attempts to design new derivatives improving the natural properties of AHAs by using the chemical and physical approach are discussed. METHODS: Antimicrobial properties of MA, an arylalkyl AHA containing phenyl group attached to α- carbon, and GA, an aromatic trihydroxybenzoic acid containing the phenolic ring and carboxylic acid functional group, and their derivatives against common human and plant pathogenic fungi have been reviewed. RESULTS: The antimicrobial activity of MA and GA is a complex phenomenon strictly correlated with other properties exhibited by these acids, e.g., pro-oxidative activity and hydrophobicity. In most cases, the acids derivatives exhibited higher antimicrobial activity than the acids themselves. This is probably because of the higher lipophilicity of moiety that allows better penetration through the cell membrane. CONCLUSION: MA and GA present an excellent health-promoting tool and are valuable starting materials for the design of new compounds such as metal complexes with alkali, or alkali earth metals. The lipophilic, antimicrobial, and pro-oxidative properties act synergistically, supporting the pharmacological and therapeutic effect of acids and their derivatives.

Biocontrol ability and volatile organic compounds production as a putative mode of action of yeast strains isolated from organic grapes and rye grains.

The inhibiting activity of three yeast strains belonging to Pichia kudriavzevii, Pichia occidentalis, and Meyerozyma quilliermondii/Meyerozyma caribbica genera against common plant pathogens representing Mucor spp., Penicillium chrysogenum, Penicillium expansum, Aspergillus flavus, Fusarium cereals, Fusarium poae, as well as Botrytis cinerea genera was investigated. The yeast strains tested had a positive impact on growth inhibition of all target plant pathogens. The degree of inhibition was more than 50% and varied depending on both the yeast antagonist and the mold. Ethyl esters of medium-chain fatty acids, phenylethyl alcohol, and its acetate ester prevailed among the analyzed volatile organic compounds (VOCs) emitted by yeasts in the presence of the target plant pathogens. Due to the method used, assuming no contact between the antagonist and the pathogen, the antagonistic activity of the yeast strains studied resulted mainly from the production of biologically active VOCs. Moreover, the antagonistic activity was not only restricted to a single plant pathogen but effective towards molds of different genera, making the yeast strains studied very useful for potential application in biological control.