Currently, there is a growing interest in screening and quantifying antioxidants from biological samples in the quest for natural and effective antioxidants to combat free radical-related pathological complications. Antioxidant assays play a crucial role in high-throughput and cost-effective assessment of antioxidant capacities of natural products such as medicinal plants and food samples. However, several investigators have expressed concerns about the reliability of existing in vitro assays. Such concerns arise mainly from the poor correlation between in vitro and in vivo results. In addition, in vitro assays have the problem of reproducibility. To date, antioxidant capacities are measured using a panel of assays whereby each assay has its own advantages and limitations. This unparalleled review hotly disputes on in vitro antioxidant assays and elaborates on the chemistry behind each assay with the aim to point out respective principles/concepts. The following critical questions are also addressed: (1) What make antioxidant assays coloured? (2) What is the reason for working at a particular wavelength? (3) What are the advantages and limitations of each assay? and (4) Why is a particular colour observed in antioxidant–oxidant chemical reactions? Furthermore, this review details the chemical mechanism of reactions that occur in each assay together with a colour ribbon to illustrate changes in colour. The review ends with a critical conclusion on existing assays and suggests constructive improvements on how to develop an adequate and universal antioxidant assay.

https://www.mdpi.com/2076-3921/9/8/709/pdf

The Versatility of Antioxidant Assays in Food Science and Safety-Chemistry, Applications, Strengths, and Limitations.

Jujube fruit: A potential nutritious fruit for the development of functional food products

Researchers are nowadays focused on the importance of bioactive compounds (BACs) of natural origin, which are secondary metabolites derived from seeds, food and fermentation-based metabolic products. Several factors such as food matrix, molecule's size, environmental factors and association with gastrointestinal (GI) material, can impede the bioavailability and absorption of these BACs in host cell systems and target sites. Natural BACs like flavonoids, carotenoids, phenolic acids, etc. are particularly important for the production of functional foods and medicinal products, which may have industrial relevance also. Thus the isolation of such natural BACs can be promising multifunctional extracts that can be used in food applications to aid health-promoting effects in host cell systems. Sufficient evidences are however required to make a health claim and to promote functional foods in international markets. This review focuses primarily on recent developments and modulatory roles of potential health-promoting food BACs. Analyses on the techno-chemical and physiological features of functional food components are addressed besides discussing their analytical methods, bioavailability and bioaccessibility. The current study also considers the health potential of BACs and their rising demand in form of functional foods in the world.

Functional importance of bioactive compounds of foods with Potential Health Benefits: A review on recent trends

Antimicrobial activity of essential plant oils and their major components

Zizyphus spina-christi L. has antimicrobial properties because of the presence of biologically active compounds. Alternaria is an opportunistic pathogen that causes leaf spots, rots, and blights on a variety of plant parts. This study aimed to reduce the usage of synthetically derived fungicides. Identification of the bioactive components present in leaves and fruits methanolic extracts of Z. spina-christi was performed using high-performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS). The efficacy of the two methanol extracts was tested against (a) in vitro fungal growth and (b) pathogenicity control on non-wounded and wounded tomato fruits. The results revealed that gallic acid and ellagic acid were the major components in leaves extract while quercetin was the major component in fruits extract. In addition, Phenol, 2,5-bis(1,1-dimethylethyl) (40.24%) and Decane, 2-methyl-(18.53%) were the most abundant components in the leaf extract, and the presence of D-mannonic acid, 2,3,5,6-tetrakis-o-(trimethylsilyl), and γ-lactone (22.72%) were major components in fruits extract. The methanolic extracts of Z. spina-christi leaves and fruits demonstrated significant antifungal activity against the growth of Alternaria alternata, A. citri, and A. radicina with variable inhibition percentages at different concentrations. Pathogenicity was increased when the skin was injured, as expected. Both extracts reduced the percentage of infected fruits.

/pdf/bioactive-compounds-and-antifungal-activity-of-leaves-and-1ytuhunq.pdf

Bioactive Compounds and Antifungal Activity of Leaves and Fruits Methanolic Extracts of Ziziphus spina-christi L.

Ziziphus lotus L. (Lam.) and Z. mauritiana Lam., as a widespread species in Tunisia, are well known for their medicinal and food uses. The aim of the present study was to screen the content of total polyphenols, flavonoids, and condensed tannins together with the radical scavenging capacity and the antimicrobial activity of leaves, fruits and seeds extracts of Z. lotus and Z. mauritiana from different localities. Results showed that leaves extracts presented the highest phenolic compounds content for both species. Furthermore, LC-ESI-MS analysis allowed the identification of 28 bioactive compounds regardless of species and organs, with the predominance of quinic acid and rutin. Leaves extract of Z. mauritiana possessed the highest total antioxidant capacity. The antimicrobial tests showed that leaves extracts of Z. mauritiana and Z. lotus from Oued Esseder exhibited the highest activity against four bacterial strains (Staphylococcus aureus, Listeria monocytogenes, Salmonella typhimurium and Escherichia coli). The main results showed that the studied species of Ziziphus genus are an excellent source of natural bioactive molecules that could be an interesting material for industrial and food purposes.

/pdf/bioactive-compounds-antioxidant-and-antimicrobial-activities-3ctcr9v1mb.pdf

Mohamed Bagues

Papers

Bioactive compounds, antioxidant and antimicrobial activities of extracts from different plant parts of two Ziziphus Mill. species.