Antimicrobial activity and structure-activity relationships of molecules containing mono- or di- or oligosaccharides: An update.

Bacterial infections are the second leading cause of death worldwide, and the evolution and widespread distribution of antibiotic-resistance elements in bacterial pathogens exacerbate the threat crisis. Carbohydrates participate in bacterial infection, drug resistance and the process of host immune regulation. Numerous antimicrobials derived from carbohydrates or contained carbohydrate scaffolds that are conducive to an increase in pathogenic bacteria targeting, the physicochemical properties and druggability profiles. In the paper, according to the type and number of sugar residues contained in antimicrobial molecules collected from the literatures ranging from 2014 to 2024, the antimicrobial activities, action mechanisms and structure-activity relationships were delineated and summarized, for purpose to provide the guiding template to select the type and size of sugars in the design of oligosaccharide-based antimicrobials to fight the looming antibiotic resistance crisis.

Synthesis and evaluation of coumarin derivatives on antioxidative, tyrosinase inhibitory activities, melanogenesis, and in silico investigations.

New coumarin derivatives were designed using a 2-(2-oxo-2H-chromen-4-yl)acetic acid scaffold conjugated with amino acid esters or tyramine. The anti-tyrosinase and anti-lipid peroxidation activities of the synthesized compounds were investigated. Coumarin derivatives 7,9, 11-13, 15-18 showed strong anti-lipid peroxidation activity. Compound 13 exhibited uncompetitive tyrosinase inhibitory activity with an IC50 value of 68.86 µM. Compound 14 (% activity = 123.41) showed stronger tyrosinase activating activity than 8-methoxypsolaren (8-MOP, % activity = 109.46). In silico studies revealed different poses between the inhibitors and activators near the tyrosinase catalytic site. Compounds 13 (25-50 µM) and 14 (25-100 µM) did not show cytotoxicity against B16F10 cells. In contrast to the tyrosinase inhibition assay, compound 13 (50 µM) suppressed melanogenesis in B16F10 cells with two times higher potency than KA (100 µM). Compound 14 at 100 µM showed melanogenesis enhancement in B16F10 cells in a dose-dependent manner, however, inferior to the 8-MOP. Based on the findings, compound 13 and 14 offer potential for development as skin-lightening agents and vitiligo therapy agents, respectively.

A Comparative Study of Chemical Profiling and Bioactivities between Thai and Foreign Hemp Seed Species (Cannabis sativa L.) Plus an In-Silico Investigation.

Hemp (Cannabis sativa L.) is a plant widely used by humans for textiles, food, and medicine. Thus, this study aimed to characterize the chemical profiling of 12 hemp seed extracts from Thai (HS-TH) and foreign (HS-FS) samples using gas chromatography-mass spectrometry (GC-MS). Their antibacterial activity and α-glucosidase inhibitory activity were assayed. Linoleic acid (17.63-86.53%) was a major component presented in Thai hemp seed extracts, while α,ß-gluco-octonic acid lactone (30.39%), clionasterol (13.42-29.07%), and glyceryl-linoleate (15.12%) were detected as the main metabolites found in foreign hemp seed extracts. Furthermore, eight extracts from both Thai and foreign hemp seed exhibited antibacterial activity against Staphylococcus aureus, Staphylococcus epidermidis, Methicillin-resistant Staphylococcus aureus, and Cutibacterium acnes, with MIC values ranging from 128 to 2048 µg/mL. Interestingly, the ethanol extract of Thai hemp seed (HS-TH-2-M-E) showed superior α-glucosidase inhibition (IC50 value of 33.27 ug/mL) over foreign species. The combination between Thai hemp species (HS-TH-2-M-E) and acarbose showed a synergistic effect against α-glucosidase. Furthermore, the docking investigation revealed that fatty acids had a greater impact on α-glucosidase than fatty acid esters and cannabinoids. The computational simulation predicts a potential allosteric binding pocket of guanosine on glucosidase and is the first description of gluco-octonic acid's anti-glucosidase activity in silico. The findings concluded that Thai hemp seed could be used as a resource for supplemental drugs or dietary therapy for diabetes mellitus.

Water Extract of Mungbean (Vigna radiata L.) Inhibits Protein Tyrosine Phosphatase-1B in Insulin-Resistant HepG2 Cells.

The present study aimed to investigate the effects of mungbean water extract (MWE) on insulin downstream signaling in insulin-resistant HepG2 cells. Whole seed mungbean was extracted using boiling water, mimicking a traditional cooking method. Vitexin and isovitexin were identified in MWE. The results showed that MWE inhibited protein tyrosine phosphatase (PTP)-1B (IC50 = 10 µg/mL), a negative regulator of insulin signaling. MWE enhanced cellular glucose uptake and altered expression of genes involved in glucose metabolism, including forkhead box O1 (FOXO1), phosphoenolpyruvate carboxykinase (PEPCK), and glycogen synthase kinase (GSK)-3ß in the insulin-resistant HepG2 cells. In addition, MWE inhibited both α-amylase (IC50 = 36.65 mg/mL) and α-glucosidase (IC50 = 3.07 mg/mL). MWE also inhibited the formation of advanced glycation end products (AGEs) (IC50 = 2.28 mg/mL). This is the first study to show that mungbean water extract increased cellular glucose uptake and improved insulin sensitivity of insulin-resistant HepG2 cells through PTP-1B inhibition and modulating the expression of genes related to glucose metabolism. This suggests that mungbean water extract has the potential to be a functional ingredient for diabetes.

Synthetic oligosaccharides can replace animal-sourced low-molecular weight heparins.

Low-molecular weight heparin (LMWH) is used clinically to treat clotting disorders. As an animal-sourced product, LMWH is a highly heterogeneous mixture, and its anticoagulant activity is not fully reversible by protamine. Furthermore, the reliability of the LMWH supply chain is a concern for regulatory agencies. We demonstrate the synthesis of heparin dodecasaccharides (12-mers) at the gram scale. In vitro experiments demonstrate that the anticoagulant activity of the 12-mers could be reversed using protamine. One of these, labeled as 12-mer-1, reduced the size of blood clots in the mouse model of deep vein thrombosis and attenuated circulating procoagulant markers in the mouse model of sickle cell disease. An ex vivo experiment demonstrates that the anticoagulant activity of 12-mer-1 could be reversed by protamine. 12-mer-1 was also examined in a nonhuman primate model to determine its pharmacodynamic parameters. A 7-day toxicity study in a rat model showed no toxic effects. The data suggest that a synthetic homogeneous oligosaccharide can replace animal-sourced LMWHs.

De novo synthesis of a narrow size distribution low-molecular-weight heparin.

Heparin, a commonly used anticoagulant drug, is a mixture of highly sulfated polysaccharides with various molecular weights (MWs). The unique sulfation pattern dictates the anticoagulant activity of heparin. Commercial heparins are categorized into three forms according to their average MW: unfractionated heparin (UFH, MWavg 14,000), low-MW heparin (LMWH, MWavg 3500-6500) and the synthetic pentasaccharide (fondaparinux, MW 1508.3). UFH is isolated from porcine intestine while LMWH is derived from UFH by various methods of depolymerization, which generate a wide range of oligosaccharide chain lengths. Different degradation methods result in structurally distinct LMWH products, displaying different pharmacological and pharmacokinetic properties. In this report, we utilized a chemoenzymatic method to synthesize LMWH with the emphasis on controlling the size distribution of the oligosaccharides. A tetrasaccharide primer and a controlled enzyme-based polymerization were employed to build a narrow size oligosaccharide backbone. The oligosaccharide backbones were further modified by a series of sulfation and epimerization steps in order to obtain a full anticoagulation activity. Determination of the anticoagulation activity in vitro and ex vivo indicated that the synthetic LMWH has higher potency than enoxaparin, a commercial LMWH drug in clinical usage.

Homogeneous low-molecular-weight heparins with reversible anticoagulant activity.

Low-molecular-weight heparins (LMWHs) are carbohydrate-based anticoagulants clinically used to treat thrombotic disorders, but impurities, structural heterogeneity or functional irreversibility can limit treatment options. We report a series of synthetic LMWHs prepared by cost-effective chemoenzymatic methods. The high activity of one defined synthetic LMWH against human factor Xa (FXa) was reversible in vitro and in vivo using protamine, demonstrating that synthetically accessible constructs can have a critical role in the next generation of LMWHs.

Expression of heparan sulfate sulfotransferases in Kluyveromyces lactis and preparation of 3'-phosphoadenosine-5'-phosphosulfate.

Heparan sulfate (HS) belongs to a major class of glycans that perform central physiological functions. Heparin is a specialized form of HS and is a clinically used anticoagulant drug. Heparin is a natural product isolated from pig intestine. There is a strong demand to replace natural heparin with a synthetic counterpart. Although a chemoenzymatic approach has been employed to prepare synthetic heparin, the scale of the synthesis is limited by the availability of sulfotransferases and the cofactor, 3'-phosphoadenosine-5'-phosphosulfate (PAPS). Here, we present a novel method to produce secreted forms of sulfotransferases in the yeast cells, Kluyveromyces lactis. Five sulfotransferases including N-sulfotransferase, 2-O-sulfotransferase, 3-O-sulfotransferase 1 and 6-O-sulfotransferases 1 and 3 were expressed using this method. Unlike bacterial-expressed sulfotransferases, the yeast proteins can be directly used to modify polysaccharides without laborious purification. The yeast-expressed sulfotransferases also tend to have higher specific activity and thermostability. Furthermore, we demonstrated the possibility for the gram-scale synthesis of PAPS from adenosine 5'-triphosphate at only 1/5000th of the price purchased from a commercial source. Our results pave the way to conduct the enzymatic synthesis of heparin in large quantities.