A bromopyrrole-containing diterpene alkaloid from the Okinawan marine sponge Agelas nakamurai activates the insulin pathway in Huh-7 human hepatoma cells by inhibiting protein tyrosine phosphatase 1B

Potential Therapeutic Targets for the Management of Diabetes Mellitus Type 2

Diabetes is one of the lifelong chronic metabolic diseases which is prevalent globally. There is a continuous rise in the number of people suffering from this disease with time. It is characterized by hyperglycemia, which leads to severe damage to the body's system, such as blood vessels and nerves. Diabetes occurs due to the dysfunction of pancreatic β -cell which leads to the reduction in the production of insulin or body cells unable to use insulin produce efficiently. As per the data shared International diabetes federation (IDF), there are around 415 million affected by this disease worldwide. There are a number of hit targets available that can be focused on treating diabetes. There are many drugs available and still under development for the treatment of type 2 diabetes. Inhibition of gluconeogenesis, lipolysis, fatty acid oxidation, and glucokinase activator is emerging targets for type 2 diabetes treatment. Diabetes management can be supplemented with drug intervention for obesity. The antidiabetic drug sale is the second-largest in the world, trailing only that of cancer. The future of managing diabetes will be guided by research on various novel targets and the development of various therapeutic leads, such as GLP-1 agonists, DPP-IV inhibitors, and SGLT2 inhibitors that have recently completed their different phases of clinical trials. Among these therapeutic targets associated with type 2 diabetes, this review focused on some common therapeutic targets for developing novel drug candidates of the newer generation with better safety and efficacy.

Deep-Sea Sponges and Corals off the Western Coast of Florida-Intracellular Mechanisms of Action of Bioactive Compounds and Technological Advances Supporting the Drug Discovery Pipeline

The majority of natural products utilized to treat a diverse array of human conditions and diseases are derived from terrestrial sources. In recent years, marine ecosystems have proven to be a valuable resource of diverse natural products that are generated to defend and support their growth. Such marine sources offer a large opportunity for the identification of novel compounds that may guide the future development of new drugs and therapies. Using the National Oceanic and Atmospheric Administration (NOAA) portal, we explore deep-sea coral and sponge species inhabiting a segment of the U.S. Exclusive Economic Zone, specifically off the western coast of Florida. This area spans ~100,000 km2, containing coral and sponge species at sea depths up to 3000 m. Utilizing PubMed, we uncovered current knowledge on and gaps across a subset of these sessile organisms with regards to their natural products and mechanisms of altering cytoskeleton, protein trafficking, and signaling pathways. Since the exploitation of such marine organisms could disrupt the marine ecosystem leading to supply issues that would limit the quantities of bioactive compounds, we surveyed methods and technological advances that are necessary for sustaining the drug discovery pipeline including in vitro aquaculture systems and preserving our natural ecological community in the future. Collectively, our efforts establish the foundation for supporting future research on the identification of marine-based natural products and their mechanism of action to develop novel drugs and therapies for improving treatment regimens of human conditions and diseases.

Recent advances in the chemo-biological characterization of decalin natural products and unraveling of the workings of Diels-Alderases

The Diels-Alder (DA) reaction refers to a [4 + 2] cycloaddition reaction that falls under the category of pericyclic reactions. It is a reaction that allows regio- and stereo-selective construction of two carbon-carbon bonds simultaneously in a concerted manner to generate a six-membered ring structure through a six-electron cyclic transition state. The DA reaction is one of the most widely applied reactions in organic synthesis, yet its role in biological systems has been debated intensely over the last four decades. A survey of secondary metabolites produced by microorganisms suggests strongly that many of the compounds possess features that are likely formed through DA reactions, and most of them are considered to be catalyzed by enzymes that are commonly referred to as Diels-Alderases (DAases). In recent years, especially over the past 10 years or so, we have seen an accumulation of a substantial body of work that substantiates the argument that DAases indeed exist and play a critical role in the biosynthesis of complex metabolites. This review will cover the DAases involved in the biosynthesis of decalin moieties, which are found in many of the medicinally important natural products, especially those produced by fungi. In particular, we will focus on a subset of secondary metabolites referred to as pyrrolidine-2-one-bearing decalin compounds and discuss the decalin ring stereochemistry and the biological activities of those compounds. We will also look into the genes and enzymes that drive the biosynthetic construction of those complex natural products, and highlight the recent progress made on the structural and mechanistic understanding of DAases, especially regarding how those enzymes exert stereochemical control over the [4 + 2] cycloaddition reactions they catalyze.

Secondary metabolites from marine sponges of the genus Agelas: a comprehensive update insight on structural diversity and bioactivity

As one of the most common marine sponges in tropical and subtropical oceans, the sponges of the genus Agelas, have emerged as unique and yet under-investigated pools for discovery of natural products with fabulous molecular diversity and myriad interesting biological activities. The present review highlights the chemical structure and biological activity of 355 compounds that have been isolated and characterized from the members of Agelas sponges, over the period of about five decades (from 1971 to November 2021). For a better understanding, these numerous compounds are firstly classified and presented according to their carbon skeleton as well as their biosynthetic origins. Relevant summaries focusing on the source organism and the associated bioactivity of these compounds belonging to different chemical classes are also provided. This review highlights sponges of the genus Agelas as exciting source for discovery of intriguing natural compounds.

The diterpenoid alkaloids

The diterpenoid alkaloids are a family of extremely important natural products that have long been a research hotspot due to their myriad of intricate structures and diverse biological properties. This chapter systematically summarizes the past 11 years (2009-2019) of studies on the diterpenoid alkaloids, including the "so-called" atypical ones, covering the classification and biogenetic relationships, phytochemistry together with 444 new alkaloids covering 32 novel skeletons and the corrected structures, chemical reactions including conversion toward toxoids, synthetic studies, as well as biological activities. It should be noted that the synthetic studies, especially the total syntheses of various diterpenoid alkaloids, are for the first time reviewed in this treatise. This chapter, in combination with our four previous reviews in volumes 42, 59, 67, and 69, will present to the readers a more completed and updated profile of the diterpenoid alkaloids.

Structural diversity, bioactivities, and biosynthesis of natural diterpenoid alkaloids

Covering: 2009 to 2018. Diterpenoid alkaloids, originating from the amination of natural tetracyclic diterpenes, are a diverse class of compounds having complex structural features with many stereocenters. The important pharmacological activities and structural complexity of the diterpenoid alkaloids have long interested scientists due to their medicinal uses, infamous toxicity, and unique biosynthesis. Since 2009, 373 diterpenoid alkaloids, assigned to 46 skeletons, have been isolated and identified from plants mostly in the Ranunculaceae family. The names, classes, molecular weight, molecular formula, NMR data, and plant sources of these diterpene alkaloids are collated here. This review will be a detailed update of the naturally occurring diterpene alkaloids reported from the plant kingdom from 2009-2018, providing an in-depth discussion of their diversity, biological activities, pharmacokinetics, toxicity, application, evolution, and biosynthesis.

Exploration of marine natural resources in Indonesia and development of efficient strategies for the production of microbial halogenated metabolites

Nature is a prolific source of organic products with diverse scaffolds and biological activities. The process of natural product discovery has gradually become more challenging, and advances in novel strategic approaches are essential to evolve natural product chemistry. Our focus has been on surveying untouched marine resources and fermentation to enhance microbial productive performance. The first topic is the screening of marine natural products isolated from Indonesian marine organisms for new types of bioactive compounds, such as antineoplastics, antimycobacterium substances, and inhibitors of protein tyrosine phosphatase 1B, sterol O-acyl-transferase, and bone morphogenetic protein-induced osteoblastic differentiation. The unique biological properties of marine organohalides are discussed herein and attempts to efficiently produce fungal halogenated metabolites are documented. This review presents an overview of our recent work accomplishments based on the MONOTORI study.

Marine Pharmacology in 2016-2017: Marine Compounds with Antibacterial, Antidiabetic, Antifungal, Anti-Inflammatory, Antiprotozoal, Antituberculosis and Antiviral Activities; Affecting the Immune and Nervous Systems, and Other Miscellaneous Mechanisms of Action

The review of the 2016-2017 marine pharmacology literature was prepared in a manner similar as the 10 prior reviews of this series. Preclinical marine pharmacology research during 2016-2017 assessed 313 marine compounds with novel pharmacology reported by a growing number of investigators from 54 countries. The peer-reviewed literature reported antibacterial, antifungal, antiprotozoal, antituberculosis, and antiviral activities for 123 marine natural products, 111 marine compounds with antidiabetic and anti-inflammatory activities as well as affecting the immune and nervous system, while in contrast 79 marine compounds displayed miscellaneous mechanisms of action which upon further investigation may contribute to several pharmacological classes. Therefore, in 2016-2017, the preclinical marine natural product pharmacology pipeline generated both novel pharmacology as well as potentially new lead compounds for the growing clinical marine pharmaceutical pipeline, and thus sustained with its contributions the global research for novel and effective therapeutic strategies for multiple disease categories.

[Search for Protein Tyrosine Phosphatase 1B Inhibitors from Marine Organisms and Induced Production of New Fungal Metabolites by Modulating Culture Methods]

Marine environments offer a rich source of natural products with potential therapeutic applications because the ocean covers 70% of the earth's surface and approximately 80% of all living organisms live in the sea. Therefore we have investigated bioactive compounds from marine organisms such as marine sponges, ascidians, and marine-derived microorganisms. This review consists of two topics based on marine natural product chemistry. (1) Protein tyrosine phosphatase (PTP) 1B plays a key role as a negative regulator in the insulin and leptin signaling pathways. Accordingly, the development of PTP1B inhibitors is expected to provide new drugs for type 2 diabetes and obesity. We have been searching for new types of PTP1B inhibitors among marine organisms and identified various PTP1B inhibitors from marine sponges and fungi. This review presents their structural diversities and unique biological properties. (2) In the course of our studies on the induced production of new fungal metabolites, the Palauan marine-derived fungus, Trichoderma cf. brevicompactum TPU199, was found to produce the unusual epipolythiodiketopiperazines, gliovirin and pretrichodermamide A. Long-term static fermentation of the strain induced production of a new dipeptide, dithioaspergillazine A, whereas fermentation of the strain with NaCl, NaBr, and NaI produced the Cl and Br derivatives of pretrichodermamide A and a new iodinated derivative, iododithiobrevamide, respectively. Moreover, DMSO-added seawater medium induced the production of diketopiperazine with the unprecedented trithio-bridge, chlorotrithiobrevamide. This fermentation study on the strain as well as the structures of the metabolites obtained are described in this review.

Nuclear Theranostics in Taiwan

Boron neutron capture therapy and Y-90 radioembolization are emerging therapeutic methods for uncontrolled brain cancers and hepatic cancers, respectively. These advanced radiation therapies are heavily relied on theranostic nuclear medicine imaging before the therapy for the eligibility of patients and the prescribed-dose simulation, as well as the post-therapy scanning for assessing the treatment efficacy. In Taiwan, the Taipei Veterans General Hospital is the only institute performing the BNCT and also the leading institute performing Y-90 radioembolization. In this article, we present our single institute experiences and associated theranostic nuclear medicine approaches for these therapies.

Absolute Structures of Wedelolide Derivatives and Structure-Activity Relationships of Protein Tyrosine Phosphatase 1B Inhibitory ent-Kaurene Diterpenes from Aerial Parts of Wedelia spp. Collected in Indonesia and Japan

Two sesquiterpene lactones with the (9R)-eudesman-9,12-olide framework, wedelolides I and J, have been isolated together with five eudesmanolide sesquiterpenes and twelve ent-kaurene diterpenes from the aerial parts of Indonesian Wedelia prostrata. The absolute configurations of wedelolides I and J, proposed in the previous communication, were proven by comparing their experimental Electronic Circular Dichroism (ECD) spectra with the calculated ECD spectrum of wedelolide I. The phytochemical study on the aerial parts of Okinawan Wedelia chinensis led to the isolation of three other eudesmanolide sesquiterpenes in addition to the three sesquiterpenes and eleven diterpenes isolated from the Indonesian W. prostrata as above. However, the wedelolide derivatives found in the Indonesian plant were not detected. Among these compounds, most of the diterpenes inhibited protein tyrosine phosphatase (PTP) 1B activity, and a structure-activity relationship study revealed that the cinnamoyl group enhanced inhibitory activity. Therefore, two ent-kaurene derivatives with and without a cinnamoyl group were examined for the ability to accumulate phosphorylated-Akt (p-Akt) because PTP1B dephosphorylates signal transduction from the insulin receptor such as phosphorylated Akt, a key downstream effector. However, neither compound enhanced insulin-stimulated p-Akt levels in two human hepatoma cell lines (Huh-7 and HepG2) at non-cytotoxic doses.

Current anti-diabetic agents and their molecular targets: A review

Diabetes mellitus is a medical condition characterized by the body's loss of control over blood sugar. The frequency of diagnosed cases and consequential increases in medical costs makes it a rapidly growing chronic disease that threatens human health worldwide. In addition, its unnerving statistical projections are perilous to both the economy of the nation and man's life expectancy. Type-I and type-II diabetes are the two clinical forms of diabetes mellitus. Type-II diabetes mellitus (T2DM) is illustrated by the abnormality of glucose homeostasis in the body, resulting in hyperglycemia. Although significant research attention has been devoted to the development of diabetes regimens, which demonstrates success in lowering blood glucose levels, their efficacies are unsustainable due to undesirable side effects such as weight gain and hypoglycemia. Over the years, heterocyclic scaffolds have been the basis of anti-diabetic chemotherapies; hence, in this review we consolidate the use of bioactive scaffolds, which have been evaluated for their biological response as inhibitors against their respective anti-diabetic molecular targets over the past five years (2012-2017). Our investigation reveals a diverse target set which includes; protein tyrosine phosphatase 1 B (PTP1B), dipeptidly peptidase-4 (DPP-4), free fatty acid receptors 1 (FFAR1), G protein-coupled receptors (GPCR), peroxisome proliferator activated receptor-γ (PPARγ), sodium glucose co-transporter-2 (SGLT2), α-glucosidase, aldose reductase, glycogen phosphorylase (GP), fructose-1,6-bisphosphatase (FBPase), glucagon receptor (GCGr) and phosphoenolpyruvate carboxykinase (PEPCK). This review offers a medium on which future drug design and development toward diabetes management may be modelled (i.e. optimization via structural derivatization), as many of the drug candidates highlighted show promise as an effective anti-diabetic chemotherapy.

Marine Alkylpurines: A Promising Group of Bioactive Marine Natural Products

Marine secondary metabolites with a purine motif in their structure are presented in this review. The alkylpurines are grouped according to the size of the alkyl substituents and their location on the purine ring. Aspects related to the marine source, chemical structure and biological properties are considered together with synthetic approaches towards the natural products and bioactive analogues. This review contributes to studies of structure–activity relationships for these metabolites and highlights the potential of the sea as a source of new lead compounds in diverse therapeutic fields.