Large Inter- and Intraspecies Variability of Polyphenols and Proanthocyanidins in Eight Temperate Forage Species Indicates Potential for Their Exploitation as Nutraceuticals

Investigating the efficacy of purified tannin extracts from underutilized temperate forages in reducing enteric methane emissions in vitro

The study investigated how the concentration and composition of purified tannin extracts, at various inclusion rates, affect the ruminal in vitro fermentation parameters. Tannin extracts were isolated from four different forage species: birdsfoot trefoil (Lotus corniculatus), sulla (Hedysarum coronarium), big trefoil (Lotus pedunculatus), and salad burnet (Sanguisorba minor). Plants extracts were purified by Sephadex LH-20 gel chromatography and analyzed by UPLC-ESI-MS/MS. The results showed a large variation among the extracts from different species in terms of tannin composition and structural features. The extracts from salad burnet were dominated by hydrolysable tannins, comprising mainly ellagitannins. The extracts derived from sulla and big trefoil contained predominantly proanthocyanidins (PA), primarily composed of prodelphinidins with high mean degree of polymerisation (mDP). Birdsfoot trefoil extracts comprised procyanidin-rich PAs with low mDP. To determine whether the combined presence of tannins and flavonoid together lead to synergistic or antagonistic effects, the tannin extracts were incubated both with or without rutin at concentrations of 10, 20, and 30 g/kg DM, using a base substrate of perennial ryegrass (Lolium perenne, control). In general, all the tannin extracts decreased methane (CH4) production compared to the control, while no significant effect of rutin was observed on both gas (GP) and CH4 production, neither pure, nor in the simultaneous presence of tannins. The highest CH4 reduction (15%, at 30 g/kg DM) was observed from sulla and big trefoil extracts compared to control, but this was also supplemented with a concomitant reduction in GP (11%) indicating a reduction in feed digestibility. The extracts from birdsfoot trefoil and salad burnet reduced CH4 by up to 12% without significantly reducing GP, indicating the importance of tannin composition on ruminal fermentation.

A chromosome-level genome assembly for Onobrychis viciifolia reveals gene copy number gain underlying enhanced proanthocyanidin biosynthesis

Sainfoin (Onobrychis viciifolia), which belongs to subfamily Papilionoideae of Leguminosae, is a vital perennial forage known as "holy hay" due to its high contents of crude proteins and proanthocyanidins (PAs, also called condensed tannins) that have various pharmacological properties in animal feed, such as alleviating rumen tympanic disease in ruminants. In this study, we select an autotetraploid common sainfoin (2n = 4x = 28) and report its high-quality chromosome-level genome assembly with 28 pseudochromosomes and four haplotypes (~1950.14 Mb, contig N50 = 10.91 Mb). The copy numbers of genes involved in PA biosynthesis in sainfoin are significantly greater than those in four selected Fabales species, namely, autotetraploid Medicago sativa and three other diploid species, Lotus japonicus, Medicago truncatula, and Glycine max. Furthermore, gene expansion is confirmed to be the key contributor to the increased expression of these genes and subsequent PA enhancement in sainfoin. Transcriptomic analyses reveal that the expression of genes involved in the PA biosynthesis pathway is significantly increased in the lines with high PA content compared to the lines with medium and low PA content. The sainfoin genome assembly will improve our understanding of leguminous genome evolution and biosynthesis of secondary metabolites in sainfoin.

Uncovering nutritional metabolites and candidate genes involved in flavonoid metabolism in Houttuynia cordata through combined metabolomic and transcriptomic analyses

The perennial herb Houttuynia cordata has long been cultivated and used as medicinal and edible plant in Asia. Nowadays, increasing attention is attracted due to its numerous health benefits. Flavonoids are the main chemical constituents exerting pharmacological activities. In the present study, we investigated both metabolome and transcriptome of two H. cordata accessions (6# and 7#) with distinct flavonoids contents. In total 397 metabolites, i.e., 220 flavonoids, 92 amino acids and derivatives, 20 vitamins, and 65 saccharides were abundant in aboveground part. Cyanidin-3-O-rutinoside and quercetin-3-O-galactoside were the most abundant flavonoids, which can be categorized into seven classes, namely anthocyanidins, chalcones, flavanols, flavanones, flavanonols, flavones, and flavonols. Flavonols was the most abundant group. Contents of 112 flavonoids differed significantly between the two accessions, with catechin-(7,8-bc)-4α-(3,4-dihydroxyphenyl)-dihydro-2-(3H)-one, cinchonain Id, and cinchonain Ic being the dominant flavonoid metabolites among them. Pinocembrin-7-O-neohesperidoside, pinocembrin-7-O-rutinoside, and kaempferol-3-O-galactoside-4'-O-glucoside were uniquely abundant in accession 7. Transcriptome data revealed a total of 110 different expressed genes related to flavonoid metabolism, with more highly expressed genes observed in 7#. We annotated a total of 19 differential flavonoid metabolites and 34 differentially expressed genes that are associated with the flavonoid metabolic network. Based on the transcriptome and qPCR data a total of 8 key candidate genes involved in flavonoid metabolism were identified. The ANS gene were found to play an important role in the synthesis of cyanidin-3-O-glucoside, while the CHI, F3'H and FLS genes were mainly responsible for controlling the levels of flavanones, flavones, and flavonols, respectively. Collectively, the present study provides important insights into the molecular mechanism underlying flavonoid metabolism in H. cordata.

Unveiling Chemical, Antioxidant and Antibacterial Properties of Fagonia indica Grown in the Hail Mountains, Saudi Arabia

The Aja and Salma mountains in the Hail region are home to a variety of indigenous wild plants, some of which are used in Bedouin folk medicine to treat various ailments. The purpose of the current study was to unveil the chemical, antioxidant and antibacterial properties of Fagonia indica (Showeka) grown widely in these mountains, as data on the biological activities of this plant in this remote area are scarce. XRF spectrometry indicated the presence of some essential elements, which were in the order of Ca > S > K > AL > CL > Si > P > Fe > Mg > Na > Ti > Sr > Zn > Mn. Qualitative chemical screening revealed the presence of saponins, terpenes, flavonoids, tannins, phenols and cardiac glycosides in the methanolic extract (80% v/v). GC-MS showed the presence of 2-chloropropanoic acid 18.5%, tetrahydro-2-methylfuran 20.1%, tridecanoic acid 12-methyl-, methyl ester 2.2%, hexadecanoic acid, methyl ester 8.6%, methyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate 13.4%, methyl linoleate 7.0%, petroselinic acid methyl ester 15%, erucylamide 6.7% and diosgenin 8.5%. Total phenols, total tannins, flavonoids, DPPH, reducing power, -carotene and ABTS IC₅₀ (mg/mL) scavenging activity were used to measure the antioxidant capabilities of Fagonia indica, which exhibited prominent antioxidant properties at low concentrations when compared to ascorbic acid, butylate hydroxytoluene and beta-carotene. The antibacterial investigation revealed significant inhibitory effects against Bacillus subtilis MTCC121 and Pseudomona aeruginosa MTCC 741 with inhibition zones of 15.00 ± 1.5 and 12.0 ± 1.0 mm, respectively. The MIC (minimum inhibitory concentration) and MBC (minimum bactericidal concentration) ranged between 125 to 500 μg/mL. The MBC/MIC ratio indicated possible bactericidal efficacy against Bacillus subtilis and bacteriostatic activity against Pseudomona aeruginosa. The study also showed that this plant has anti-biofilm formation activity.

Phenolic Profile and Antioxidant Properties in Extracts of Developing Açaí (Euterpe oleracea Mart.) Seeds

We investigated changes in the phenolic profile and antioxidant properties in the extracts of developing seeds of açaí (Euterpe oleracea). Four developmental stages were evaluated, with earlier stages displaying higher antioxidant activity and polyphenols content, while mass spectrometry analysis identified procyanidins (PCs) as the major components of the extracts in all stages. B-type PCs varied from dimers to decamers, with A-type linkages in a smaller number. Extracted PCs decreased in average length from 20.5 to 10.1 along seed development. PC composition indicated that (-)-epicatechin corresponded to over 95% of extension units in all stages, while (+)-catechin presence as the starter unit increased from 42 to 78.8% during seed development. This variation was correlated to the abundance of key enzymes for PC biosynthesis during seed development. This study is the first to report PC content and composition variations during açaí seed development, which can contribute to studies on the plant's physiology and biotechnological applications.

Linking metabolites in eight bioactive forage species to their in vitro methane reduction potential across several cultivars and harvests

An in vitro Hohenheim gas test was conducted to analyze the fermentation end-products from 17 cultivars of eight polyphenol containing forage species. The polyphenol composition and proanthocyanidin (PA) structural features of all the cultivars were analyzed with UPLC-MS/MS in leaves of vegetative or generative plants. The samples were incubated with and without polyethylene glycol (PEG, a tannin-binding agent) to separate the tannin-effect on methane (CH4, ml/200 mg DM) production from that of forage quality. Sulla and big trefoil, two particularly PA rich species, were found to have the highest CH4 reduction potential of up to 47% when compared to the samples without PEG. However, concomitant reduction in gas production (GP, ml/200 mg DM) of up to 44% was also observed. An increase in both GP and CH4 production under PEG treatments, confirms the role of tannins in CH4 reduction. Moreover, PA structural features and concentration were found to be an important source of variation for CH4 production from PA containing species. Despite having low polyphenol concentrations, chicory and plantain were found to reduce CH4 production without reducing GP. Additionally, interspecies variability was found to be higher than intraspecies variability, and these results were consistent across growth stages, indicating the findings' representativeness.

Isolation and Quantification of the Hepatoprotective Flavonoids From Scleromitron diffusum (Willd.) R. J. Wang With Bio-Enzymatic Method Against NAFLD by UPLC-MS/MS

Flavonoids were the major phytochemicals against hepatic peroxidative injury in Scleromitron diffusum (Willd.) R. J. Wang with an inventive bio-enzymatic method by our group (LU500041). Firstly, the total flavonoids from Scleromitron diffusum (Willd.) R. J. Wang were extracted by reflux, ultrasonic, ultrasound-assisted enzymatic methods (TFH), and the bio-enzymatic method (Ey-TFH). Then 24 flavonoid compounds were isolated and quantified in the extracts by UPLC-MS/MS. Next, six representative differential compounds in Ey-TFH were further screened out by multivariate statistical analysis compared with those in TFH. In a further step, Ey-TFH presented a higher protective rate (59.30 ± 0.81%) against H2O2-damaged HL-02 hepatocytes than TFH. And six representative differential compounds at 8 and 16 μmol/L all exerted significant hepatoprotective effects (p < 0.05 or p < 0.01). Finally, the therapeutic action of Ey-TFH for nonalcoholic fatty liver disease (NAFLD) was processed by a rat's model induced with a high-fat diet. Ey-TFH (90, 120 mg/kg) significantly ameliorated the lipid accumulation in the rat model (p < 0.05). Meanwhile, Ey-TFH relieved liver damage. The levels of ALT, ALP, AST, LDH, and γ-GT in rats' serum were also significantly reduced (p < 0.05 or p < 0.01). In addition to this, the body's antioxidant capacity was improved with elevated SOD and GSH levels (p < 0.05) and down-regulated MDA content (p < 0.01) after Ey-TFH administration. Histopathological observations of staining confirmed the hepatic-protective effect of Ey-TFH.