Biological activities of selected 1-Oxo-tetrahydroisoquinolinone alkaloids.

Natural products continue to represent a compelling resource for uncovering chemical scaffolds characterised by significant structural variability and diverse biological activities. These compounds possess the potential to be directly utilised or to serve as initial templates for further refinement, ultimately leading to the development of innovative pharmaceutical agents. Among natural products, isoquinoline alkaloids stand out as one of the most extensively researched groups. 1-Oxo-tetrahydroisoquinolinones (1 O-THIQ), isolated from a variety of natural sources, exhibit valuable biological properties. This review investigates the bioactivities of specific 1 O-THIQ alkaloids, which have not been reviewed to the same depth in previous studies.

The occurrence and bioactivity of tetrahydronaphthoquinoline-diones (THNQ-dione).

Natural products have been important in the discovery of new drugs, but their use is limited due to issues with accessibility and synthesis. Tetrahydronaphthoquinoline-dione (THNQ-dione) is a key structural feature found in several natural and synthetic compounds that exhibit notable biological properties. The unique properties of THNQ-diones can be attributed to the fusion of tetrahydroquinoline and anthraquinone moieties. These alkaloids are synthesised through various biosynthetic pathways, leading to diverse structures and bioactivities. Despite their significance, THNQ-diones have not been extensively covered in the review literature, highlighting the importance of this article in discussing their natural occurrence and biological activities. This article explores the distribution of THNQ-dione alkaloids in different organisms and their potential as a source of novel bioactive natural products.

Biological activity of natural 2-quinolinones.

While natural products have undeniably played a crucial role in drug discovery, challenges such as limited availability and complex synthesis methods have hindered the identification of lead compounds. At the core of numerous natural and synthetic compounds, each displaying distinct biological behaviours, lies the foundational structure of 2-quinolinone. Compounds with this structural motif exhibit a broad range of effects in different tissues. Furthermore, specific members showcase therapeutic potential for various disorders. Despite the significance of these compounds, the current review literature has not provided a comprehensive overview, underscoring the essential contribution of this article in exploring their biological functions. This study examines the biological activity of selected 2-quinolinone alkaloids across diverse organisms, unveiling their potential as a source of innovative bioactive natural products.

Natural 3,4-dihydro-2(1H)-quinolinones- Part I: plant sources.

While natural products have undoubtedly played a pivotal role in drug discovery, their potential as lead compounds has been hindered by challenges such as limited accessibility and complex synthesis processes. At the core of numerous natural and synthetic compounds, each exhibiting remarkable biological traits, lies the foundational structure of 3,4-dihydro-2(1H)-quinolinone, also known as 2-oxo-tetrahydroquinoline (2 O-THQ). This article extensively examines the occurrence of 2 O-THQ alkaloids across the plant kingdom, exploring their capacity to serve as a source for innovative bioactive natural products. Despite the undeniable significance of these compounds, the existing body of review literature has yet to provide comprehensive coverage, underscoring the pivotal contribution of this present article in investigating their prevalence in nature.

Natural 3,4-Dihydro-2(1H)-quinolinones - part III: biological activities.

Natural products have played a crucial role in drug discovery, but their development is hindered by challenges such as inadequate availability and complex synthesis methods. However, both natural and synthetic compounds that have the core structure of 3,4-dihydro-2(1H)-quinolinone, also known as 2-oxo-1,2,3,4-tetrahydroquinoline (2O-THQ), display a diverse array of effects in both central and peripheral tissues, with some showing therapeutic potential in treating various disorders. Despite the significance of this family of compounds, the current literature lacks comprehensive coverage of their biological functions. This article aims to address this gap by extensively reviewing the biological activities of 2O-THQ alkaloids from diverse organisms and exploring their potential to serve as a source of innovative bioactive natural products.

Natural 3,4-dihydro-2(1h)-quinolinones- Part II: animal, bacterial, and fungal sources.

While natural products have undoubtedly played a pivotal role in drug discovery, their potential as lead compounds has been hindered by challenges such as limited accessibility and complex synthesis processes. At the core of numerous natural and synthetic compounds, each exhibiting remarkable biological traits, lies the foundational structure of 3,4-dihydro-2(1H)-quinolinone, also recognised as 2-oxo-tetrahydroquinoline (2 O-THQ). This article extensively examines the occurrence of 2 O-THQ alkaloids across diverse organisms including animals, fungi, and bacteria, exploring their capacity to serve as a source for innovative bioactive natural products. Despite the undeniable significance of these compounds, the existing body of review literature has yet to provide comprehensive coverage, underscoring the pivotal contribution of this present article in investigating their prevalence in nature.

Tetrahydroquinoline-containing natural products discovered within the last decade: occurrence and bioactivity.

Although natural products have played a crucial role in drug discovery, limited accessibility and difficult synthesis restrict their use as leads. Tetrahydroquinoline is an essential structural feature in many natural and synthetic compounds with notable biological properties. This article covers the distribution of tetrahydroquinoline alkaloids in different organisms and their potential as a source of new bioactive natural products. These alkaloids are produced through various biosynthetic pathways, resulting in diverse structures and bioactivities. While some tetrahydroquinolines have therapeutic potential, their toxicity against predators and pathogens presents challenges for drug development. Despite their significance, tetrahydroquinolines have not been thoroughly covered in review literature, making this article essential for discussing their natural occurrence, biosynthetic pathways, and biological activities from 2011 to mid-2023.

Chromone and flavonoid alkaloids: occurrence and bioactivity.

The chromone and flavonoid alkaloids represent an unusual group of structurally diverse secondary metabolites, derived from the convergence of multiple biosynthetic pathways that are widely distributed through the plant and animal kingdoms. Many of them have been discovered through bioassay-guided chemical investigations of traditional medicines, suggesting potential therapeutic significance. Their unique structures and varied pharmacological activities may provide important new leads for the discovery of drugs with novel mechanisms of action. Potential therapeutic indications are as diverse as cancer and viral infections, inflammation and immunomodulation, neurological and psychiatric conditions, and diabetes.

Monocyclic phenolic acids; hydroxy- and polyhydroxybenzoic acids: occurrence and recent bioactivity studies.

Among the wide diversity of naturally occurring phenolic acids, at least 30 hydroxy- and polyhydroxybenzoic acids have been reported in the last 10 years to have biological activities. The chemical structures, natural occurrence throughout the plant, algal, bacterial, fungal and animal kingdoms, and recently described bioactivities of these phenolic and polyphenolic acids are reviewed to illustrate their wide distribution, biological and ecological importance, and potential as new leads for the development of pharmaceutical and agricultural products to improve human health and nutrition.

Part 1. modular approach to obtaining diverse tetrahydroquinoline-derived polycyclic skeletons for use in high-throughput generation of natural-product-like chemical probes.

A practical synthesis of a tetrahydroaminoquinoline scaffold (12) was developed that used a stereocontrolled aza Michael as the key reaction. Three tetrahydroquinoline alkaloid-like, tricyclic derivatives 16, 18, and 19 with different medium to macrocyclic ring skeletons were obtained, using this scaffold as the starting material, in a modular manner. The macrocyclic compounds with an isolated olefin and an electron-deficient olefin were obtained by ring-closing metathesis approaches. Compounds 16 and 18 are unique and contain bridged 10- and 12-membered functionalized rings. The NMR studies of these compounds revealed interesting information on the conformation of the bicyclic scaffolds that was dependent on the nature and the size of the macrocyclic rings. Finally, this modular methodology, using compound 21 anchored onto the solid support, successfully led to the generation of different macrocyclic derivatives, 23, 25, and 27 in solid-phase synthesis. The solid-phase synthesis approach outlined in this article has the potential to generate tetrahydroquinoline-based tricyclic compounds containing different medium to macrocyclic architectures.

A solution- and solid-phase approach to tetrahydroquinoline-derived polycyclics having a 10-membered ring.

With the goal of library generation using a polycyclic derivative 5 having an enamide functional group, a simple and practical, enantioselective synthesis of tetrahydroquinoline derivative 2 was achieved. The phenolic hydroxyl group in compound 2 was utilized as an anchoring site for solid-phase synthesis. The ring closing metathesis approach yielded the desired polycyclic product 5 on solid phase in five steps (overall 40% yield). Compound 5 is a novel scaffold for the library generation of natural product-like polycyclics having a functionalized medium ring for obtaining a new class of small molecules to be utilized as chemical probes.