In Vitro and in Silico Study of New Biscoumarin Glycosides from Paramignya trimera against Angiotensin-Converting Enzyme 2 (ACE-2) for Preventing SARS-CoV-2 Infection.

In Vietnam, the stems and roots of the Rutaceous plant Paramignya trimera (Oliv.) Burkill (known locally as "Xáo tam phân") are widely used to treat liver diseases such as viral hepatitis and acute and chronic cirrhosis. In an effort to search for Vietnamese natural compounds capable of inhibiting coronavirus based on molecular docking screening, two new dimeric coumarin glycosides, namely cis-paratrimerin B (1) and cis-paratrimerin A (2), and two previously identified coumarins, the trans-isomers paratrimerin B (3) and paratrimerin A (4), were isolated from the roots of P. trimera and tested for their anti-angiotensin-converting enzyme 2 (ACE-2) inhibitory properties in vitro. It was discovered that ACE-2 enzyme was inhibited by cis-paratrimerin B (1), cis-paratrimerin A (2), and trans-paratrimerin B (3), with IC50 values of 28.9, 68, and 77 µM, respectively. Docking simulations revealed that four biscoumarin glycosides had good binding energies (∆G values ranging from -10.6 to -14.7 kcal/mol) and mostly bound to the S1' subsite of the ACE-2 protein. The key interactions of these natural ligands include metal chelation with zinc ions and multiple H-bonds with Ser128, Glu145, His345, Lys363, Thr371, Glu406, and Tyr803. Our findings demonstrated that biscoumarin glycosides from P. trimera roots occur naturally in both cis- and trans-diastereomeric forms. The biscoumarin glycosides Lys363, Thr371, Glu406, and Tyr803. Our findings demonstrated that biscoumarin glycosides from P. trimera roots hold potential for further studies as natural ACE-2 inhibitors for preventing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection.

New Records of Potent In-Vitro Antidiabetic Properties of Dalbergia tonkinensis Heartwood and the Bioactivity-Guided Isolation of Active Compounds.

Alpha-glucosidase inhibitory activity has been commonly used for the evaluation of antidiabetic property in vitro. The aim of this study is to investigate and characterize Dalbergia tonkinensis as a potential source of antidiabetic compounds. The screening of the active parts used, such as trunk bark, heartwood, and the leaves of Dalbergia tonkinensis indicated that all these extracted parts used with methanol demonstrated potent α-glucosidase inhibitory activity. The in vitro antidiabetic property of Dalbergia tonkinensis was notably recorded for the first time and showed activity (EC50 = 0.17⁻0.78 mg/mL) comparable to those of reported potent herbal extracts (EC50 = 0.25⁻4.0 mg/mL) and higher activity than that of acarbose, a commercial antidiabetic drug (EC50 = 1.21 mg/mL). The stability tests revealed that the heartwood of Dalbergia tonkinensis extract (HDT) possesses high pH stability with relative activity in the range of 80⁻98%. Further bioassay-guided purification led to the isolation of 2 active compounds identified as sativanone and formononetin from the ethyl acetate fraction and water fraction of HDT, respectively. These α-glucosidase inhibitors (aGIs) show promising inhibition against various types of α-glucosidases. Remarkably, these inhibitors were determined as new mammalian aGIs, showing good effect on rat α-glucosidase. The results suggest that Dalbergia tonkinensis is a potent source of aGIs and suggest promise in being developed as functional food with antidiabetic efficacy. The results of this study also enrich our knowledge concerning current biological activity and constituents of Dalbergia tonkinensis species.

Purification and characterization of lignin peroxidase from white-rot fungi Pleurotus pulmonarius CPG6 and its application in decolorization of synthetic textile dyes.

From the biotechnological point of view, enzymes are powerful tools that help sustain a clean environment in several ways. The enzymatic biodegradation of synthetic dyes is a promising goal since it reduces pollution caused by textile dyeing factory wastewater. Lignin peroxidase (EC 1.11.1.14, LiP) has high redox potential; thus, it is great for application in various industrial fields (e.g., paper- waste treatment and textile dyeing wastewater treatment). In the present study, a LiP from an isolated strain Pleurotus pulmonarius CPG6 (PpuLiP) was successfully purified with a specific activity of 6.59 U mg -1. The enzyme was purified by using three-step column chromatography procedures including DEAE, Sephadex G-75, and HiTrapTM Q FF columns with 17.8-fold purity. The enzyme with a molecular weight of 40 kDa exhibited enhanced pH stability in the acidic range. The activity retention was over 75% at a pH of 3.0 for more than 6 hours. Purified PpuLiP was able to oxidize a variety of substrates including veratryl alcohol, 2,4-DCP, n propanol, and guaiacol. The effect of metal ions on PpuLiP activity was analyzed. The study will provide a ground to decolorize dyes from various groups of PpuLiP. Purified PpuLiP could decolorize 35% Acid blue 25 (AB25), 50% Acid red 129 (AB129), 72% Acid blue 62 (NY3), 85% Acid blue 113 (AB113), 55% Remazol Brilliant blue R (RBBR), and 100% Reactive red 120 (RR120) for 12 hours. Most of the dyes were decolorized, but the heat-denatured enzyme used as negative control obviously did not decolorize the tested dyes. These results indicate that the PpuLiP has potential application in enzyme-based decolorization of synthetic dyes. Keywords: Decolorization; lignin peroxidase; Pleurotus pulmonarius; textile dyes.

The wood rot ascomycete Xylaria polymorpha produces a novel GH78 glycoside hydrolase that exhibits α-L-rhamnosidase and feruloyl esterase activities and releases hydroxycinnamic acids from lignocelluloses.

Soft rot (type II) fungi belonging to the family Xylariaceae are known to substantially degrade hardwood by means of their poorly understood lignocellulolytic system, which comprises various hydrolases, including feruloyl esterases and laccase. In the present study, several members of the Xylariaceae were found to exhibit high feruloyl esterase activity during growth on lignocellulosic materials such as wheat straw (up to 1,675 mU g(-1)) or beech wood (up to 80 mU g(-1)). Following the ester-cleaving activity toward methyl ferulate, a hydrolase of Xylaria polymorpha was produced in solid-state culture on wheat straw and purified by different steps of anion-exchange and size-exclusion chromatography to apparent homogeneity (specific activity, 2.2 U mg(-1)). The peptide sequence of the purified protein deduced from the gene sequence and verified by de novo peptide sequencing shows high similarity to putative α-L-rhamnosidase sequences belonging to the glycoside hydrolase family 78 (GH78; classified under EC 3.2.1.40). The purified enzyme (98 kDa by SDS-PAGE, 103 kDa by size-exclusion chromatography; pI 3.7) converted diverse glycosides (e.g., α-L-rhamnopyranoside and α-L-arabinofuranoside) but also natural and synthetic esters (e.g., chlorogenic acid, hydroxycinnamic acid glycoside esters, veratric acid esters, or p-nitrophenyl acetate) and released free hydroxycinnamic acids (ferulic and coumaric acid) from arabinoxylan and milled wheat straw. These catalytic properties strongly suggest that X. polymorpha GH78 is a multifunctional enzyme. It is the first fungal enzyme that combines glycosyl hydrolase with esterase activities and may help this soft rot fungus to degrade lignocelluloses.

Bioconversion of Lignocellulosic Materials with the Contribution of a Multifunctional GH78 Glycoside Hydrolase from Xylaria polymorpha to Release Aromatic Fragments and Carbohydrates.

A bifunctional glycoside hydrolase GH78 from the ascomycete Xylaria polymorpha (XpoGH78) possesses catalytic versatility towards both glycosides and esters, which may be advantageous for the efficient degradation of the plant cell-wall complex that contains both diverse sugar residues and esterified structures. The contribution of XpoGH78 to the conversion of lignocellulosic materials without any chemical pretreatment to release the water-soluble aromatic fragments, carbohydrates, and methanol was studied. The disintegrating effect of enzymatic lignocellulose treatment can be significantly improved by using different kinds of hydrolases and phenoloxidases. The considerable changes in low (3 kDa), medium (30 kDa), and high (> 200 kDa) aromatic fragments were observed after the treatment with XpoGH78 alone or with this potent cocktail. Synergistic conversion of rape straw also resulted in a release of 17.3 mg of total carbohydrates (e.g., arabinose, galactose, glucose, mannose, xylose) per gram of substrate after incubating for 72 h. Moreover, the treatment of rape straw with XpoGH78 led to a marginal methanol release of approximately 17 µg/g and improved to 270 µg/g by cooperation with the above accessory enzymes. In the case of beech wood conversion, the combined catalysis by XpoGH78 and laccase caused an effect comparable with that of fungal strain X. polymorpha in woody cultures concerning the liberation of aromatic lignocellulose fragments.