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Tannins represent a heterogeneous group of high-molecular-weight polyphenols that are ubiquitous among plant families, especially in cereals, as well as in many fruits and vegetables. Hydrolysable and condensed tannins, in addition to phlorotannins from marine algae, are the main classes of these bioactive compounds. Despite their low bioavailability, tannins have many beneficial pharmacological effects, such as anti-inflammatory, antioxidant, antidiabetic, anticancer, and cardioprotective effects. Microbiota-mediated hydrolysis of tannins produces highly bioaccessible metabolites, which have been extensively studied and account for most of the health effects attributed to tannins. This review article summarises the effect of the human microbiota on the metabolism of different tannin groups and the expected health benefits that may be induced by such mutual interactions. Microbial metabolism of tannins yields highly bioaccessible microbial metabolites that account for most of the systemic effects of tannins. This article also uses explainable artificial intelligence to define the molecular signatures of gut-biotransformed tannin metabolites that are correlated with chemical and biological activity. An understanding of microbiota–tannin interactions, tannin metabolism-related phenotypes (metabotypes) and chemical tannin-metabolites motifs is of great importance for harnessing the biological effects of tannins for drug discovery and other health benefits.

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Coffee is a worldwide beverage of increasing consumption, owing to its unique flavor and several health benefits. Metabolites of coffee are numerous and could be classified on various bases, of which some are endogenous to coffee seeds, i.e., alkaloids, diterpenes, sugars, and amino acids, while others are generated during coffee processing, for example during roasting and brewing, such as furans, pyrazines, and melanoidins. As a beverage, it provides various distinct flavors, i.e., sourness, bitterness, and an astringent taste attributed to the presence of carboxylic acids, alkaloids, and chlorogenic acids. To resolve such a complex chemical makeup and to relate chemical composition to coffee effects, large-scale metabolomics technologies are being increasingly reported in the literature for proof of coffee quality and efficacy. This review summarizes the applications of various mass spectrometry (MS)- and nuclear magnetic resonance (NMR)-based metabolomics technologies in determining the impact of coffee breeding, origin, roasting, and brewing on coffee chemical composition, and considers this in relation to quality control (QC) determination, for example, by classifying defected and non-defected seeds or detecting the adulteration of raw materials. Resolving the coffee metabolome can aid future attempts to yield coffee seeds of desirable traits and best flavor types.

Anti-biofilm represents an urge to face drug resistance. Nymphaea alba L. flowers and rhizomes have been traditionally used in Ayurvedic medicine for dyspepsia, enteritis, diarrhea and as an antiseptic. This study was designed to identify the main constituents of Nymphaea alba L. rhizomes and their antibiofilm activity. 70% aqueous ethanolic extract (AEE) of N. alba rhizomes was analyzed by liquid chromatography, high resolution, mass spectrometry (LC-HRMS) for its phytoconstituents in the positive and negative modes in addition to column chromatographic separation. Sixty-four phenolic compounds were identified for the first time in N. alba rhizomes. Hydrolysable tannins represent the majority with identification of galloyl hexoside derivative, hexahydroxydiphenic (HHDP) derivatives, glycosylated phenolic acids and glycosylated flavonoids. Five phenolics have been isolated and identified as gallic acid and its methyl and ethyl ester in addition to ellagic acid and pentagalloyl glucose. Minimum inhibitory concentrations (MIC) and anti-biofilm activity for the extract and the major isolated compounds were determined. Radical scavenging activity using 2.2Di (4-tert-octylphenyl)-1-picryl-hydrazyl (DPPH) assay as well as cytotoxic activity using 3-(4, 5-dimethyl thiazol-2-yl)-2, 5-diphenyl tetrazolium bromide (MTT) assay have also been evaluated. MIC of N. alba rhizomes against Staphylococcus aureus was 0.25 mg/mL compared with 0.1 mg/mL for methyl gallate. The best reduction in biofilm formation (84.9%) as well as the best radical scavenging (IC 50 3 µg/mL) and cytotoxic (IC 50 9.61 ± 0.3 µg/mL) activities were observed with methyl gallate. This is the first study for in-depth characterization of phenolic compounds in N. alba rhizomes revealing it as a valuable source of phenolic compounds and promising anti-biofilm forming agent of natural origin.