Progress in Isoindolone Alkaloid Derivatives from Marine Microorganism: Pharmacology, Preparation, and Mechanism

Flavonoidal alkaloids: Emerging targets for drug discovery from Nature's bounty

This paper explores the potential of flavonoid alkaloids, a unique class of compounds that contain both flavonoid and alkaloid structures, as emerging targets for drug discovery. These compounds exhibit diverse biological activities, such as anti-inflammatory, anti-cancer, and anti-diabetic effects, which are attributed to the combination of different flavonoid scaffolds and alkaloid groups. Flavonoid alkaloids have attracted researchers' attention due to their diverse structures and important bio-activities. Therefore, this review summarizes recent advances in the extraction, purification, structural characterization, synthesis pathways and biological activities of flavonoid alkaloids from natural sources. Finally, the potential prospects and challenges associated with this class of compounds in pharmacological research are discussed along with details of a mechanistic investigation and future clinical applications in this research field.

Protection of Tight Junctional Complexes between hCMEC/D3 Cells by Deep-Sea Fibrinolytic Compound FGFC1

Tight junctional complexes (TJCs) between cerebral microvascular endothelial cells (CMECs) are essential parts of the blood-brain barrier (BBB), whose regulation closely correlates to the BBB's integrity and function. hCMEC/D3 is the typical cell line used to imitate and investigate the barrier function of the BBB via the construction of an in vitro model. This study aims to investigate the protective effect of the deep-sea-derived fibrinolytic compound FGFC1 against H2O2-induced dysfunction of TJCs and to elucidate the underlying mechanism. The barrier function was shown to decline following exposure to 1 mM H2O2 in an in vitro model of hCMEC/D3 cells, with a decreasing temperature-corrected transendothelial electrical resistance (tcTEER) value. The decrease in the tcTEER value was significantly inhibited by 80 or 100 µM FGFC1, which suggested it efficiently protected the barrier integrity, allowing it to maintain its function against the H2O2-induced dysfunction. According to immunofluorescence microscopy (IFM) and quantitative real-time polymerase chain reaction (qRT-PCR), compared to the H2O2-treated group, 80~100 µM FGFC1 enhanced the expression of claudin-5 (CLDN-5) and VE-cadherin (VE-cad). And this enhancement was indicated to be mainly achieved by both up-regulation of CLDN-5 and inhibition of the down-regulation by H2O2 of VE-cad at the transcriptional level. Supported by FGFC1's molecular docking to these proteins with reasonable binding energy, FGFC1 was proved to exert a positive effect on TJCs' barrier function in hCMEC/D3 cells via targeting CLDN-5 and VE-cad. This is the first report on the protection against H2O2-induced barrier dysfunction by FGFC1 in addition to its thrombolytic effect. With CLDN-5 and VE-cad as the potential target proteins of FGFC1, this study provides evidence at the cellular and molecular levels for FGFC1's reducing the risk of bleeding transformation following its application in thrombolytic therapy for cerebral thrombosis.

Fungi Fibrinolytic Compound 1 Plays a Core Role in Modulating Fibrinolysis, Altering Plasma Clot Structure, and Promoting Susceptibility to Lysis

Fibrin clot structure and function are major determinants of venous and arterial thromboembolic diseases, as well as the key determinants of the efficiency of clot lysis. Studies have revealed that fungi fibrinolytic compound 1 (FGFC1) is a novel marine pyranisoindolone natural product with fibrinolytic activity. Here, we explore the impacts of FGFC1 on clot structure, lysis, and plasminogen activation in vitro using turbidimetric, enzyme-linked immunosorbent assay, confocal and electron microscopy, urokinase, or plasmin chromogenic substrate. Clots formed in the presence of FGFC1 expressed reduced fibrin polymerization rate and maximum turbidity; however, they did not influence the lag phase of fibrin polymerization. In the absence of scu-PA (single-chain urokinase plasminogen activator), microscopy revealed that FGFC1 increased the number of protofibrils within fibrin fiber and the pore diameter between protofibrils, inducing clots to form a region of thinner and looser networks separated by large pores. The effects of FGFC1 on scu-PA-mediated plasma clot structure were similar to those in the absence of scu-PA. In addition, FGFC1 promoted the lysis of clots and increased the D-dimer concentration in lysate. FGFC1 increased the generation rate of p-nitroaniline in plasma. These results show that FGFC1 has fibrinolytic activity in plasma, leading to interference with the release of fibrinopeptide B to affect lateral aggregation of protofibrils and increase clot susceptibility to fibrinolysis by altering its structure.

The Rare Marine Bioactive Compounds in Neurological Disorders and Diseases: Is the Blood-Brain Barrier an Obstacle or a Target?

The blood-brain barrier (BBB) is a dynamic barrier separating neurocytes and brain tissues from blood that is extremely sealed and strictly regulated by transporters such as aquaporin-4 (AQP-4), glucose transporter (GLUT), and specialized tight junctional complexes (TJCs) including tight junctions (TJs), adherens junctions (AJs), and Zonulae occludens (ZOs). With specifically selective transcellular and paracellular permeability, the BBB maintains a homeostatic microenvironment to protect the central nervous system (CNS). In recent years, increasing attention has been paied to the importance of BBB disruption and dysfunction in the pathology of neurological disorders and diseases, such as Alzheimer's diseases (AD), Parkinson diseases (PD), stroke and cerebral edema. However, the further research on how the integral structure and function of BBB are altered under the physiological or pathological conditions is still needed. Focusing on the ultrastructural features of the BBB and combining the latest research on associated proteins and transporters, physiological regulation and pathological change of the BBB were elucidated. By summarizing the protective effects of known bioactive compounds derived from marine life on the BBB, this review aims to highlight the BBB as a key to the treatment of several major neurological diseases instead of a normally described obstacle to drug absorption and transport. Overall, the BBB's morphological characteristics and physiological function and their regulation provide the theoretical basis for the study on the BBB and inspire the diagnosis of and therapy for neurological diseases.

Marine Aspergillus: A Treasure Trove of Antimicrobial Compounds

Secondary metabolites from marine organisms are diverse in structure and function. Marine Aspergillus is an important source of bioactive natural products. We reviewed the structures and antimicrobial activities of compounds isolated from different marine Aspergillus over the past two years (January 2021-March 2023). Ninety-eight compounds derived from Aspergillus species were described. The chemical diversity and antimicrobial activities of these metabolites will provide a large number of promising lead compounds for the development of antimicrobial agents.

Bio-Active Products from Mangrove Ecosystems

Mangrove communities represent the coastal habitats located in intertidal zones or brackish waters of tropical and subtropical coastal areas in over 118 countries [...].

Isosteviol derivatives as protein tyrosine Phosphatase-1B inhibitors: Synthesis, biological evaluation and molecular docking

Protein tyrosine phosphatase (PTP1B) antagonizes insulin signaling and acts as a potential therapeutic target for insulin resistance associated with obesity and type II diabetes. In this work, a series of isosteviol derivatives 1-28 was synthesized and the inhibitory activity on PTP1B was evaluated by double antibody sandwich ELISA (DAS-ELISA) in vitro. Most isosteviol derivatives showed moderate PTP1B inhibitory activities. Among them, derivatives 10, 13, 24, 27 showed remarkable bioactivities with IC₅₀ values ranging from 0.24 to 0.40 µM. Particularly, derivative 24 exhibited the best inhibitory activity against PTP1B (IC₅₀ = 0.24 µM) in vitro; moreover, it showed 7-fold selectivity to PTP1B over T-cell protein tyrosine phosphatase (TCPTP) and 14-fold selectivity to PTP1B over cell division cycle 25 homolog B (CDC25B). Molecular docking studies demonstrated the hydrogen bond interaction between 24 and LYS-116 residue in PTP1B might be essential for the inhibitory activity. The results suggested that derivative 24 has great potential to be employed as drug candidate for the treatment of obesity and type II diabetes.

Microbial Natural Products with Wound-Healing Properties

Wound healing continues to pose a challenge in clinical settings. Moreover, wound management must be performed properly and efficiently. Acute wound healing involves multiple cell divisions, a new extracellular matrix, and the process of formation, such as growth factors and cytokines, which are released at the site of the wound to regulate the process. Any changes that disrupt the healing process could cause tissue damage and prolong the healing process. Various factors, such as microbial infection, oxidation, and inflammation, can delay wound healing. In order to counter these problems, utilizing natural products with wound-healing effects has been reported to promote this process. Several natural products have been associated with wound healing, most of which are from medicinal plants. However, secondary microbial metabolites have not been extensively studied for their wound-healing properties. Further, investigations on the wound-healing control of natural microbial products are required due to a lack of studies. This review discussed the in vivo and in vitro research on the wound healing activities of natural microbial products, which may assist in the development of better wound treatments in the future.

A Novel Marine Pyran-Isoindolone Compound Enhances Fibrin Lysis Mediated by Single-Chain Urokinase-Type Plasminogen Activator

Fungi fibrinolytic compound 1 (FGFC1) is a rare pyran-isoindolone derivative with fibrinolytic activity. The aim of this study was to further determine the effect of FGFC1 on fibrin clots lysis in vitro. We constructed a fibrinolytic system containing single-chain urokinase-type plasminogen activator (scu-PA) and plasminogen to measure the fibrinolytic activity of FGFC1 using the chromogenic substrate method. After FITC-fibrin was incubated with increasing concentrations of FGFC1, the changes in the fluorescence intensity and D-dimer in the lysate were measured using a fluorescence microplate reader. The fibrin clot structure induced by FGFC1 was observed and analyzed using a scanning electron microscope and laser confocal microscope. We found that the chromogenic reaction rate of the mixture system increased from (15.9 ± 1.51) × 10−3 min−1 in the control group to (29.7 ± 1.25) × 10−3 min−1 for 12.8 μM FGFC1(p < 0.01). FGFC1 also significantly increased the fluorescence intensity and d-dimer concentration in FITC fibrin lysate. Image analysis showed that FGFC1 significantly reduced the fiber density and increased the fiber diameter and the distance between protofibrils. These results show that FGFC1 can effectively promote fibrin lysis in vitro and may represent a novel candidate agent for thrombolytic therapy.