Potent Inhibitory Activity Research Articles

Triterpenoid Saponins and Flavonoid Glycosides from the Flower of Camellia flavida and Their Cytotoxic and α-Glycosidase Inhibitory Activities

Camellia flavida var. flavida, commonly known as “Jinhua Tea”, has its flowers and leaves traditionally utilized as tea and functional food sources. However, there is limited knowledge about its bioactive components and their biological activities. This study isolated ten previously unidentified glycoside compounds from the flowers of Camellia flavida, including three oleanane-type triterpenoid saponins (compounds 1–3) and seven flavonoid glycosides (compounds 4–10), collectively named flavidosides A–J. This study assessed the cytotoxicity of these compounds against a panel of human cancer cell lines and their α-glucosidase inhibitory activities. Notably, flavidoside C showed significant cytotoxicity against BEL-7402 and MCF-7 cell lines, with IC50 values of 4.94 ± 0.41 and 1.65 ± 0.39 μM, respectively. Flavidoside H exhibited potent α-glucosidase inhibitory activity, with an IC50 value of 1.17 ± 0.30 mM. These findings underscore the potential of Camellia flavida in the development of functional foods.

Synthesis, α-Glucosidase, α-Amylase, and Aldol Reductase Inhibitory Activity with Molecular Docking Study of Novel Imidazo[1,2-a]pyridine Derivatives.

Inhibition ofaldose reductase (AR), α-glycosidase (α-GLY), and α-amylase (α-AMY) are some of the essential targets in diabetes mellitus (DM). Here, a series of imidazo[1,2-a]pyridine-based 1,3,4-thiadiazole derivatives (8a-k) were successfully synthesized and characterized using 1H NMR, 13C NMR, and HRMS spectroscopic techniques. The inhibition effects of the synthesized derivatives against AR, α-GLY, and α-AMY were evaluated using both in vitro and in silico methods. In vitro studies revealed that the derivatives (8a-k) showed significant inhibition activity. The results showed that the novel derivatives (8a-k) demonstrated potential inhibitory activity, with K I values covering the following ranges: 23.47 ± 2.40 to 139.60 ± 13.33 nM for AR and 6.09 ± 0.37 to 119.80 ± 12.31 μM for α-GLY, with IC50 values 81.14 to 153.51 μM for α-AMY. Furthermore, many of these compounds exhibited high inhibition activity, while some of them showed higher potency than the reference compounds. Molecular docking of the target compounds was carried out in the active sites of AR (PDB ID: 4JIR) and α-GLY (PDB ID: 5NN8).

Targeting PARP-1 and DNA Damage Response Defects in Colorectal Cancer Chemotherapy with Established and Novel PARP Inhibitors.

The DNA repair protein PARP-1 emerged as a valuable target in the treatment of tumor entities with deficiencies of BRCA1/2, such as breast cancer. More recently, the application of PARP inhibitors (PARPi) such as olaparib has been expanded to other cancer entities including colorectal cancer (CRC). We previously demonstrated that PARP-1 is overexpressed in human CRC and promotes CRC progression in a mouse model. However, acquired resistance to PARPi and cytotoxicity-mediated adverse effects limit their clinical applicability. Here, we detailed the role of PARP-1 as a therapeutic target in CRC and studied the efficacy of novel PARPi compounds in wildtype (WT) and DNA repair-deficient CRC cell lines together with the chemotherapeutics irinotecan (IT), 5-fluorouracil (5-FU), and oxaliplatin (OXA). Based on the ComPlat molecule archive, we identified novel PARPi candidates by molecular docking experiments in silico, which were then confirmed by in vitro PARP activity measurements. Two promising candidates (X17613 and X17618) also showed potent PARP-1 inhibition in a CRC cell-based assay. In contrast to olaparib, the PARPi candidates caused no PARP-1 trapping and, consistently, were not or only weakly cytotoxic in WT CRC cells and their BRCA2- or ATR-deficient counterparts. Importantly, both PARPi candidates did not affect the viability of nonmalignant human colonic epithelial cells. While both olaparib and veliparib increased the sensitivity of WT CRC cells towards IT, no synergism was observed for X17613 and X17618. Finally, we provided evidence that all PARPi (olaparib > veliparib > X17613 > X17618) synergize with chemotherapeutic drugs (IT > OXA) in a BRCA2-dependent manner in CRC cells, whereas ATR deficiency had only a minor impact. Collectively, our study identified novel lead structures with potent PARP-1 inhibitory activity in CRC cells but low cytotoxicity due to the lack of PARP-1 trapping, which synergized with IT in homologous recombination deficiency.

Immunosuppressive Breviane Spiroditerpenoids from Penicillium bialowiezense Isolated from a Medicinal Plant.

Breviane spiroditerpenoids are a small group of structurally interesting and complex meroterpenoids. This work focused on an endophytic fungus Penicillium bialowiezense ZBWPQ-27 that was isolated from a medicinal plant Euphorbia neriifolia, leading to the isolation of 15 breviane spiroditerpenoids with four types of polycyclic systems (1-6 and 9-17), and two new carotane sesquiterpenoids (7 and 8). The structures including absolute configurations of the new compounds 1-8 were elucidated by spectroscopic data analysis and electronic circular dichroism (ECD) calculations. In addition, the misassigned NMR data of several resonances of the 5-methyl-TAL motif (E ring) in those of known brevianes (9-15) were corrected by spectroscopic data analysis. Biological tests revealed that brevianes with the type A ring system (6/6/6/5/6) showed moderate to significant immunosuppressive activities, and compound 11 displayed the most potent inhibitory activities against concanavalin A (ConA)-induced T cell proliferation (IC50 4.1 ± 0.2 μM) and lipopolysaccharide (LPS)-induced B cell proliferation (IC50 4.6 ± 0.2 μM), with good SI values of 28 ± 2 and 25 ± 4, respectively.

Design, synthesis and biological evaluation of novel benzocoumarin derivatives as potent inhibitors of MAO-B activity

The continued research of novel reversible inhibitors targeting monoamine oxidase (MAO) B remains crucial for effectively symptomatic treatment of Parkinson’s disease. In this study we synthesized and evaluated a new series of 3-aryl benzo[g] and benzo[h] coumarin derivatives as MAO-B inhibitors. Compound A6 has been found to display the most potent inhibitory activity and selectivity against the MAO-B isoform (IC50 = 13 nM and SI = >7693.31 respectively). Inhibition mode of A6 on MAO-B was predicted as mixed reversible inhibition with a Ki value of 3.274 nM. Furthermore, in order to elaborate structure–activity relationships, the binding mode of A6 was investigated by molecular docking simulations.

Design, Synthesis, and Study of Novel Memantine Schiff Base Derivatives Against Targeted Enzymes in Alzheimer’s Disease

Introduction: According to WHO, Alzheimer’s disease was estimated at 74.4 million cases in 2023, which will increase by 152.8 million cases in 2050. The therapeutic options available in the market for the treatment of AD are only capable of reducing the symptoms of dementia but not preventing progressive degeneration. Memantine is a non-competitive NMDAR antagonist used for the treatment of patients with moderate-to-severe AD, but it has a high toxicity profile. To counter this, the Memantine Schiff base derivatives were designed as simple and lowtoxicity compounds. Materials and Methods: Molecular docking was performed against the targeted enzymes Acetylcholinesterase and Butyrylcholinesterase using AUTODOCK 1.5.7 software. A series of novel Memantine derivatives of Schiff base were synthesized by condensing Memantine with various aryl aldehydes and screened for their invitro-cholinesterase inhibitory activity towards Acetylcholinesterase (AChE) and Butyrylcholinesterase (BChE) by Ellman’s method. Results and Discussion: Among the designed compounds, compounds LMV and LMC showed maximum binding scores of -10.35 kcal/mol and -10.12 kcal/mol, respectively, than the standard Donepezil (-8.78 kcal/mol) against Acetylcholinesterase. The compounds LMONB and LMDMB produced significant binding scores of -9.31 kcal/mol and -9.11 kcal/mol, respectively, compared to the standard Donepezil (-7.57 kcal/mol) against Butyrylcholinesterase. Also, compounds LMV (30.9 ± 2.13 μM) and LMDMB (13.51 ± 1.12 μM) showed potent inhibitory activity against the AChE and BChE. These compounds possess drug-like characteristics and are also capable of crossing the Blood Brain Barrier (BBB). Conclusion: The studied compounds LMV and LMDMB, being non-toxic, obey Lipinski’s rule of 5 and are potential inhibitors against targeted enzymes, which may be promising clinical candidates for treating Alzheimer’s disease.

Synthesis, optimization and antitumor activity evaluation of sulfonyl benzoyl hydrazide derivatives as novel human LSD1 inhibitors

A new set of compounds known as sulfonyl benzoyl hydrazide derivatives were synthesized and tested using cellular assays. Through systematic optimization starting from general structure S-1, compound 10e emerged as highly promising. It exhibited potent inhibitory activity with an IC50 value of 0.8 nM and possessed moderate clogP. Compounds 10e significantly inhibited solid tumor cells proliferation. Additionally, 10e induced apoptosis and arrested the cell cycle. Furthermore, in vivo studies using an HCT116 xenograft model showed substantial growth inhibition of tumors, accompanied by a favorable safety profile. These findings underscored compound 10e as a novel LSD1 inhibitor with robust efficacy both in vitro and in vivo, establishing it as a promising lead compound for further anticancer drug development.

Design and synthesis of triazolopyridine derivatives as potent JAK/HDAC dual inhibitors with broad-spectrum antiproliferative activity

A series of triazolopyridine-based dual JAK/HDAC inhibitors were rationally designed and synthesised by merging different pharmacophores into one molecule. All triazolopyridine derivatives exhibited potent inhibitory activities against both targets and the best compound 4-(((5-(benzo[d][1, 3]dioxol-5-yl)-[1, 2, 4]triazolo[1, 5-a]pyridin-2-yl)amino)methyl)-N-hydroxybenzamide (19) was dug out. 19 was proved to be a pan-HDAC and JAK1/2 dual inhibitor and displayed high cytotoxicity against two cancer cell lines MDA-MB-231 and RPMI-8226 with IC50 values in submicromolar range. Docking simulation revealed that 19 fitted well into the active sites of HDAC and JAK proteins. Moreover, 19 exhibited better metabolic stability in vitro than SAHA. Our study demonstrated that compound 19 was a promising candidate for further preclinical studies.

Benzoxaborinine, New Chemotype for Carbonic Anhydrase Inhibition: Ex Novo Synthesis, Crystallography, In Silico Studies, and Anti-Melanoma Cell Line Activity.

The benzoxaborinine scaffold, a homologue of benzoxaborole with an additional carbon atom in the boracycle, shows significant potential in developing new therapeutic agents. This study reports the synthesis, inhibition assays against four human carbonic anhydrase (hCA, EC 4.2.1.1) isoforms, and anti-melanoma evaluation of 7-aryl(thio)ureido-substituted benzoxaborinines. Some derivatives, particularly compound 11, exhibited potent inhibitory activity (below 65 nM) against hCA IX and XII and stronger antiproliferative effects than SLC-0111 on human melanoma cells under hypoxia. Crystallographic studies of benzoxaborinine 3 adducts with hCA I and II demonstrated the binding mode of this chemotype, revealing that although both benzoxaborinine 3 and benzoxaborole 10 share a similar zinc-binding mode, the expanded ring in benzoxaborinine led to a different orientation within the active site. These findings suggest that benzoxaborinines hold promise for designing novel carbonic anhydrase inhibitors.

Investigating the inhibition of xanthine oxidase by five catechins: Kinetic studies, spectroscopy, molecular docking, and dynamics simulations

Catechins compounds from tea have demonstrated significant inhibitory effects on xanthine oxidase (XOD). However, the precise inhibitory mechanisms of the main catechins on XOD remain to be fully elucidated. This study explored the inhibition mechanisms and binding characteristics of five catechins (GC, EGC, EC, EGCG, and ECG) on XOD through a combination of inhibition kinetics, multi-spectroscopy analysis, molecular docking, and dynamics simulations. Among the catechins, EGCG and ECG exhibited the most potent inhibitory activities against XOD. All five catechins were found to exhibit mixed inhibition, affecting the hydrophobic groups and secondary structure of XOD predominantly through hydrophobic interactions and hydrogen bonding. Molecular dynamics simulations revealed that a 3,4,5-trihydroxybenzoic acid moiety at C3 position significantly enhances the binding affinity of EGCG and ECG to XOD. Additionally, the decrease of β-sheet and random coil induced by EGCG and ECG was found to be crucial for enhancing inhibitory activity of XOD. In vitro cell experiments showed that EGCG and ECG significantly reduced high uric acid levels of BRL-3A cell. This study elucidates the inhibitory mechanisms of catechins on XOD, paving the way for their application as XOD inhibitors to combat hyperuricemia.

Discovery of CZL-046 with an (S)-3-Fluoropyrrolidin-2-one Scaffold as a p300 Bromodomain Inhibitor for the Treatment of Multiple Myeloma.

E1A binding protein (p300) is a promising therapeutic target for the treatment of cancer. Herein, we report the discovery of a series of novel inhibitors with an (S)-3-fluoropyrrolidin-2-one scaffold targeting p300 bromodomain. The best compound 29 (CZL-046) shows potent inhibitory activity of p300 bromodomain (IC50 = 3.3 nM) and antiproliferative activity in the multiple myeloma (MM) cell line (OPM-2 IC50 = 51.5 nM). 29 suppressed the mRNA levels of c-Myc and IRF4 and downregulated the expression of c-Myc and H3K27Ac. Compared to the lead compound 5, 29 exhibits significantly improved in vitro and in vivo metabolic properties. Oral administration of 29 with 30 mg/kg achieved a TGI value of 44% in the OPM-2 xenograft model, accompanied by good tolerability. The cocrystal structure of CREB binding protein bromodomain with 29 provides an insight into the precise binding mode. The results demonstrate that 29 is a promising p300 bromodomain inhibitor for the treatment of MM.

Identification of Bioactive and Anticancer Properties of Bidens Pilosa in-vitro Evidence.

Bidens pilosa and Trianthema portulacastrum are noteworthy weeds with a series of bioactive flavonoid constituents, hence, they can be utilized as potential health supplements and readily available sources of natural antioxidants, as well as effective constituents in medicinal applications. The current study aims to assess the anti-proliferative activity of B. pilosa and T. portulacastrum extracts using the HepG2 cell line. Methods The prepared extracts were evaluated for their cytotoxic influence and their potential CC50 in HepG2 cell lines and normal hepatocytes using the MTT assay. Using quantitative real-time polymerase chain reaction (qRT-PCR), the relative gene expression of Raf-1, MEK-1, LC3B, and Atg12 was quantified in treated cells to detect the expression levels of cell proliferation factors and autophagy-related genes. The quantification analysis of the released interleukin-1beta (IL-1β) and interleukin-1alpha (IL-1α) was also done using an ELISA assay. The activities of B. pilosa extract showed an anti-proliferative influence on HepG2 cell lines upon treatment as compared to normal cells. It was assessed for cytotoxicity using molecular studies against both Raf-1 and MEK-1 as proposed anticancer mechanisms and showed promising inhibitory activity against Raf-1 and MEK-1 gene expression. Likewise, the reduction of autophagy-related genes, Atg12 and LC3B, in HepG2 cells pre-treated with B. pilosa extract, further confirmed its influence in the induction of programmed cell death (PCD). The ELISA assay revealed a substantial elevation of the pro-inflammatory cytokines IL-1α and IL-1β upon treatment. This study found that B. pilosa extract, without any detectable cytotoxic effects, had potential inhibitory activities against both Raf-1 and MEK-1 gene expression, and a significant reduction in autophagic machinery upon treatment.<br /><br />.

Enhancer reprogramming underlies therapeutic utility of a SMARCA2 degrader in SMARCA4 mutant cancer.

Genomic studies have identified frequent mutations in subunits of the SWI/SNF (switch/sucrose non-fermenting) chromatin remodeling complex including SMARCA4 and ARID1A in non-small cell lung cancer (NSCLC). Genetic evidence indicates that the paralog SMARCA2 is synthetic lethal to SMARCA4 suggesting SMARCA2 is a valuable therapeutic target. However, the discovery of selective inhibitors of SMARCA2 has been challenging. Here, we utilized structure-activity relationship (SAR) studies to develop YD23, a potent and selective proteolysis targeting chimera (PROTAC) targeting SMARCA2. Mechanistically, we show that SMARCA2 degradation induces reprogramming of the enhancer landscape in SMARCA4-mutant cells with loss of chromatin accessibility at enhancers of genes involved in cell proliferation. Furthermore, we identified YAP/TEADas key partners to SMARCA2 in driving growth of SMARCA4-mutant cells. Finally, we show that YD23 has potent tumor growth inhibitory activity in SMARCA4-mutant xenografts. These findings provide the mechanistic basis for development of SMARCA2 degraders as synthetic lethal therapeutics against SMARCA4-mutant lung cancers.

Synthesis, Molecular Modeling and Biological Evaluation of Novel Trifluoromethyl Benzamides as Promising CETP Inhibitors.

Hyperlipidemia is considered a major risk factor for the progress of atherosclerosis. Cholesteryl ester transfer protein (CETP) facilitates the relocation of cholesterol esters from HDL to LDL. CETP inhibition produces higher HDL and lower LDL levels. Synthesis of nine benzylamino benzamides 8a-8f and 9a-9c was performed. In vitro biological study displayed potential CETP inhibitory activity, where compound 9c had the best activity with an IC50 of 1.03 μM. Induced-fit docking demonstrated that 8a-8f and 9a-9c accommodated the CETP active site and hydrophobic interaction predominated ligand/ CETP complex formation. Pharmacophore mapping showed that this scaffold endorsed CETP inhibitors features and consequently elaborated the high CETP binding affinity.

Discovery of a novel thiophene carboxamide analogue as a highly potent and selective sphingomyelin synthase 2 inhibitor for dry eye disease therapy

Dry eye disease (DED) is a prevalent and intractable ocular disease induced by a variety of causes. Elevated sphingomyelin (SM) levels and pro-inflammatory cytokines were detected on the ocular surface of DED patients, particularly in the meibomian glands. Sphingomyelin synthase 2 (SMS2), one of the proteins involved in SM synthesis, would light a novel way of developing a DED therapy strategy. Herein, we report the design and optimization of a series of novel thiophene carboxamide derivatives to afford 14l with an improved highly potent inhibitory activity on SM synthesis (IC50, SMS2 = 28 nmol/L). Moreover, 14l exhibited a notable protective effect of anti-inflammation and anti-apoptosis on human corneal epithelial cells (HCEC) under TNF-α-hyperosmotic stress conditions in vitro, with an acceptable ocular specific distribution (corneas and meibomian glands) and pharmacokinetics (PK) profiles (t1/2, cornea = 1.11 h; t1/2, meibomian glands = 4.32 h) in rats. Furthermore, 14l alleviated the dry eye symptoms including corneal fluorescein staining scores and tear secretion in a dose-dependent manner in mice. Mechanically, 14l reduced the mRNA expression of Tnf-α, Il-1β and Mmp-9 in corneas, as well as the proportion of very long chain SM in meibomian glands. Our findings provide a new strategy for DED therapy based on selective SMS2 inhibitors.

Studi Molecular Docking dan Evaluasi Farmakokinetik Senyawa Analog Pirazol Turunan Benzen-Sulfonilurea sebagai Inhibitor Enzim Aldose Reduktase and α-Glukosidase Menggunakan Pendekatan In Silico

The pyrazole scaffold modification in various chemical structures on several studies has shown various biopharmacological activities. This study aims to predict the potential inhibition of pyrazole analogs derived benzene-sulfonylurea (4A, 4B, 4E, 5A, 5C, 5D) against the α-glucosidase (3A4A) and aldose reductase (3RX2) enzymes based on a molecular docking approach using Molecular Operating Environment (MOE) 2020.0102 software and evaluate pharmacokinetic profile (ADMET). In this study, the six test compounds were obtained from previous studies that have been proven antihyperglycemic. The results showed that all the 3,5-disubstituted benzene-sulfonylurea derivative pyrazole analogs are predicted to have low inhibitory activity against the α-glucosidase enzyme. Further, all compounds showed good aldose reductase inhibitor activity and had lower binding free energy values ​​than tolrestat as the positive control (-6.82 kcal/mol). Compound 5C has the best potential inhibitory activity against the aldose reductase enzyme compared to the other test compounds, because it has the lowest binding free energy value (-8.76 kcal/mol) and interacts with important residues on the receptor forming four hydrogen bonds, namely the carbonyl group of SO2 with residues Trp111 and His110, and the carbonyl group of the amide with residues His110 and Tyr48, as well as 3 hydrophobic bonds, namely a pyrazole ring with residues Leu300, Trp219 and a furan ring with Phe122. ADMET properties of the compounds are also predicted. This information provides an opportunity for a 5C compound as an aldose reductase inhibitor agent to develop drug candidates with better and safer activities.

Systemic administration of a potent mouse monoclonal antibody provides multisite protection against HPV16 infection

Although preventive vaccines for Human Papillomaviruses (HPV) are available, a definitive cure for the viral infection itself is currently lacking. There is a sizable population that remains inaccessible to HPV vaccination due to reasons such as high costs or lack of availability of the vaccines. Therefore, there remains a significant population susceptible to HPV infection. Persistent multisite infections with high-risk HPV types can cause cancer at several different anatomic sites.Especially HPV16 is a key etiologic factor for cervical, other ano-genital and oropharyngeal cancers. Therefore, it is imperative to develop pharmaceutical interventions for the treatment of viral infections. In this study, a panel of 9 neutralizing antibodies was screened using the hybridoma technique, with 20F6 being identified as the representative antibody. The purified 20F6 exhibited an IC50 of 0.0011 μg/ml against HPV16, demonstrating potent viral inhibitory activity. Moreover, it displayed cross-neutralizing efficacy towards other Alphapapillom 9 subtypes including HPV31, HPV33, HPV52, and HPV58 with respective IC50 values of 2.0 μg/ml, 7.3 μg/ml, 1.7 μg/ml, and 3.0 μg/ml. 20F6 recognizes the linear epitope MSLW, the first four amino-acids located at the very N-terminus of the HPV16 L1 protein. Administration of 20F6, 24 h prior to and following HPV16 pseudo-virion (PSV) challenge, conferred protection against infection in mice at doses as low as 1 mg/kg. Following intraperitoneal administration of 20F6, neutralizing antibodies were consistently detected at both oral and vaginal sites, indicating that prophylactic systemic administration of 20F6 may confer efficient protection against multiple susceptible mucosal sites.

Design, Synthesis, and Biological Evaluation of HDAC Inhibitors Containing Natural Product-Inspired N-Linked 2-Acetylpyrrole Cap.

Drawing inspiration from the structural resemblance between a natural product N-(3-carboxypropyl)-2-acetylpyrrole and phenylbutyric acid, a pioneer HDAC inhibitor evaluated in clinical trials, we embarked on the design and synthesis of a novel array of HDAC inhibitors containing an N-linked 2-acetylpyrrole cap by utilizing the pharmacophore fusion strategy. Among them, compound 20 exhibited potential inhibitory activity on HDAC1, and demonstrated notable potency against RPMI-8226 cells with an IC50 value of 2.89 ± 0.43 μM, which was better than chidamide (IC50 = 10.23 ± 1.02 μM). Western blot analysis and Annexin V-FTIC/propidium iodide (PI) staining showed that 20 could enhance the acetylation of histone H3, as well as remarkably induce apoptosis of RPMI-8226 cancer cells. The docking study highlighted the presence of a hydrogen bond between the carbonyl oxygen of the 2-acetylpyrrole cap group and Phe198 of the HDAC1 enzyme in 20, emphasizing the crucial role of introducing this natural product-inspired cap group. Molecular dynamics simulations showed that the docked complex had good conformational stability. The ADME parameters calculation showed that 20 possesses remarkable theoretical drug-likeness properties. Taken together, these results suggested that 20 is worthy of further exploration as a potential HDAC-targeted anticancer drug candidate.

Potential MRSA inhibitory activity of some new benzofuran-pyrazolo[1,5-a]pyrimidine hybrids attached to arene units via methylene or azo linkage

MRSA, a resistant bacteria causing severe infections, is targeted by researchers developing new anti-resistance compounds. The study aimed to investigate the MRSA inhibitory activity of two series of benzofuran-pyrazolo[1,5-a]pyrimidines 1 and 2, attached to arene units via methylene or azo linkage, respectively. The desired products were prepared, in 82–92% yields, by reacting benzofuran-based enaminone 4 with the appropriate 1H-pyrazole-3,5-diamines 5 in pyridine at reflux for 5–6 h. The new hybrids showed a wide spectrum of antibacterial activity against different ATCC strains. Products with azo linkage and para-substituted arene units with electron-releasing groups demonstrated higher antibacterial activity. 3-((4-Methoxyphenyl)diazenyl)-linked pyrazolo[1,5-a]pyrimidine 2e demonstrates activity that exceeded the reference ciprofloxacin with MIC/MBC values of 1.8/3.6 µM against S. aureus and E. coli strains. Also, it demonstrated more effective MRSA inhibitory activity than the reference linezolid, with MIC/MBC values of 3.6/14.4 and 1.8/7.2 µM against MRSA ATCC:33591 and ATCC:43300 strains, respectively.

Biosynthesis of the α-D-Mannosidase Inhibitor (-)-Swainsonine.

(-)-Swainsonine is a polyhydroxylated indolizidine alkaloid with potent inhibitory activity against α-D-mannosidases. In this work, we successfully reconstituted swainsonine biosynthetic pathway both in vivo and in vitro. Our study unveiled a surprising epimerization mechanism involving an imine reductase (SwnN) and two non-heme iron and α-ketoglutarate-dependent oxygenases (SwnH2 and SwnH1). SwnH2 is a multifunctional enzyme responsible for both C2-hydroxylation and amine desaturation, while SwnN completes the oxidation-reduction sequence to achieve the net redox neutral epimerization. Notably, SwnN exhibits substrate-dependent stereospecificity and the stereochemical outcome of SwnN-catalyzed iminium reduction is determined by SwnH1-catalyzed C8-hydroxylation. We also discovered that an O -acetyl ester can serve as a detachable protecting/directing group, altering the site-selectivity of SwnH2-catalyzed hydroxylation while maintaining the stereoselectivity. Insights gained from the biochemical characterization of these tailoring enzymes enabled biocatalytic synthesis of a new polyhydroxylated indolizidine alkaloid, opening doors to the biosynthesis of diverse natural product-based glycosidase inhibitors.