Aplysinoplides A-C, cytotoxic sesterterpenes from the marine sponge Aplysinopsis digitata

Sesterterpenoids: sources, structural diversity, biological activity, and data management

Reviewing the literature published up to October 2024.Sesterterpenoids are one of the most chemically diverse and biologically promising subgroup of terpenoids, the largest family of secondary metabolites. The present review article summarizes more than seven decades of studies on isolation and characterization of more than 1600 structurally novel sesterterpenoids, supplemented by biological, pharmacological, ecological, and geographic distribution data. All the information have been implemented in eight tables available on the web and a relational database https://sesterterpenoids.unige.net/. The interface has two sections, one open to the public for reading only and the other, protected by an authentication mechanism, for timely updating of published results.

The Kornblum DeLaMare rearrangement in natural product synthesis: 25 years of innovation

Covering: 1998 up to the end of 2023Since its initial disclosure in 1951, the Kornblum DeLaMare rearrangement has proved an important synthetic transformation and has been widely adopted as a biomimetic step in natural product synthesis. Utilising the base catalysed decomposition of alkyl peroxides to yield a ketone and alcohol has found use in many syntheses as well as a key strategic step, including the unmasking of furans, as a biomimetic synthetic tool, and the use of the rearrangement to install oxygen enantioselectively. Since ca. 1998, its impact as a synthetic transformation has grown significantly, especially given the frequency of use in natural product syntheses, therefore this 25 year time period will be the focus of the review.

Catalytic Cross-Metathesis Reactions That Afford E- and Z-Trisubstituted Alkenyl Bromides: Scope, Applications, and Mechanistic Insights

Stereochemically defined trisubstituted alkenes with a bromide and a methyl group at a terminus can be readily and stereoretentively derivatized through catalytic cross-coupling, affording unsaturated fragments found in many bioactive natural products. A direct method for generating such entities would be by stereocontrolled catalytic cross-metathesis (CM). Such methods are scarce however. Here, we present a stereoretentive strategy for CM between tri-, Z- or E-di, or monosubstituted olefins and Z- or E-2-bromo-2-butene, affording an assortment of E- or Z-trisubstituted alkenyl bromides. The majority of the transformations were catalyzed by two Mo monoaryloxide pyrrolide (MAP) complexes, one purchasable and the other accessible by well-established protocols. Substrates, such as feedstock trisubstituted olefins, can be purchased; the alkenyl bromide reagents are commercially available or can be prepared in two steps in a multigram scale. The catalytic process can be used to generate products that contain polar moieties, such as an amine or an alcohol, or sterically hindered alkenes that are α- or β-branched. The utility of the approach is highlighted by a brief and stereocontrolled synthesis of an unsaturated fragment of phomactin A and a concise total synthesis of ambrein. An unexpected outcome of these investigations was the discovery of a new role for the presence of a small-molecule alkene in an olefin metathesis reaction. DFT studies indicate that this additive swiftly reacts with a short-lived Mo alkylidene and probably helps circumvent the formation of catalytically inactive square pyramidal metallacyclobutanes, enhancing the efficiency of a transformation.

Total Synthesis of Terpenes and Their Biological Significance: A Critical Review

Terpenes are a group of natural products made up of molecules with the formula (C5H8)n that are typically found in plants. They are widely employed in the medicinal, flavor, and fragrance industries. The total synthesis of terpenes as well as their origin and biological potential are discussed in this review.

Cytotoxic Manoalide-Type Sesterterpenes from the Sponge Luffariella variabilis Collected in the South China Sea

Thirteen new linear terpenes, including 11 rare acyclic manoalide derivatives (1-11), one polyprenylphenol derivative (12), and one polyprenylbenzaldehyde derivative (13), together with three known compounds (14-16) were isolated from the sponge Luffariella variabilis collected in the South China Sea. The planar structures were resolved by NMR and MS analyses, while the absolute configurations were fully elucidated by NOESY experiments, combined with experimental and calculated ECD spectra, acetal formation, empirical rules of ¹H and ¹³C NMR shifts, DP4+ probability analyses, and Mosher's method. Compounds 1-7, 10, and 13 demonstrated cytotoxic activities against several human cancer cell lines with IC₅₀ values ranging from 2 to 10 μM.

γ-Hydroxybutenolide Containing Marine Natural Products and Their Synthesis: A Review

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γ-Hydroxybutenolides (γ-HB) is an important structural core found in many bioactive marine natural products (MNPS). The γ-HB core containing NPS served as an inspiration to medicinal chemists to undertake designing of the new synthetic strategies to construct γ-HB core. Subsequently, it further results in the development of novel physiological and therapeutic agents. The most notable example includes manoalides, cacospongionolides, petrosaspongioide M and dysidiolide from marine sponges possessing anti-inflammatory properties. γ-HB containing MNPS were known to possess various pharmacological properties such as antimicrobial (acantholide B), cytotoxic (acantholide A-E, spongianolide A), inhibitors of secretory phospholipase A2 (cladocorans A and B), BACE inhibitors (ianthellidone G), etc. Moreover, the γ-HB moiety was explored as antifouling agents as well. Owing to their numerous biological activities and attractive molecular structures, there are lots of advances in the synthetic methodology of these compounds. This review gives the account on isolation and biological studies of MNPS with γ-HB skeleton as a core unit. Furthermore, the synthesis of selective γ-HB containing bioactive MNPS like manoalide, secomanoalide, cacospongionolides, luffarielloide and dysidiolide were highlighted in the article.

Total synthesis of sesterterpenoids

Total syntheses of biologically and structurally fascinating sesterterpenoids published between Jan. 2012 and Jan. 2018 are summarized and discussed here.

Sesterterpenoids with Anticancer Activity

Terpenes have received a great deal of attention in the scientific literature due to complex, synthetically challenging structures and diverse biological activities associated with this class of natural products. Based on the number of C5 isoprene units they are generated from, terpenes are classified as hemi- (C5), mono- (C10), sesqui- (C15), di- (C20), sester- (C25), tri (C30), and tetraterpenes (C40). Among these, sesterterpenes and their derivatives known as sesterterpenoids, are ubiquitous secondary metabolites in fungi, marine organisms, and plants. Their structural diversity encompasses carbotricyclic ophiobolanes, polycyclic anthracenones, polycyclic furan-2-ones, polycyclic hydroquinones, among many other carbon skeletons. Furthermore, many of them possess promising biological activities including cytotoxicity and the associated potential as anticancer agents. This review discusses the natural sources that produce sesterterpenoids, provides sesterterpenoid names and their chemical structures, biological properties with the focus on anticancer activities and literature references associated with these metabolites. A critical summary of the potential of various sesterterpenoids as anticancer agents concludes the review.

Targeting cancer with sesterterpenoids: the new potential antitumor drugs

Cancer remains a major cause of death in the world to date. A variety of anticancer drugs have been used in clinical chemotherapy, acting on the particular oncogenic abnormalities that are responsible for malignant transformation and progression. Interestingly, some of these anticancer drugs are developed from natural sources such as plants, marine organisms, and microorganisms. Over the past decades, a family of naturally occuring molecules, namely sesterterpenoids, has been isolated from different organisms and they exhibit significant potential in the inhibition of tumor cells in vitro, while the molecular targets of these compounds and their functional mechanisms are still obscure. In this review, we summarize and discuss the functions of these sesterterpenoids in the inhibition of cancer cells. Moreover, we also highlight and discuss chemical structure–activity relationships of some compounds, demonstrating their pervasiveness and importance in cancer therapy.

Recent advances in deep-sea natural products

Covering: 2009 to 2013. This review covers the 188 novel marine natural products described since 2008, from deep-water (50->5000 m) marine fauna including bryozoa, chordata, cnidaria, echinodermata, microorganisms, mollusca and porifera. The structures of the new compounds and details of the source organism, depth of collection and country of origin are presented, along with any relevant biological activities of the metabolites. Where reported, synthetic studies on the deep-sea natural products have also been included. Most strikingly, 75% of the compounds were reported to possess bioactivity, with almost half exhibiting low micromolar cytotoxicity towards a range of human cancer cell lines, along with a significant increase in the number of microbial deep-sea natural products reported.

Recent advances in deep-sea natural products

Review of deep-sea natural products covering the five-year period 2009–2013.

Heterocyclic terpenes: linear furano- and pyrroloterpenoids

This review of furano- and pyrroloterpenoids covers the literature, 180 articles in all, published from January 2006 to December 2013.

Structures and potential antitumor activity of sesterterpenes from the marine sponge Hyrtios communis

The extract of marine sponge Hyrtios communis was found to inhibit activation of the transcription factor hypoxia-inducible factor-1 (HIF-1) in T47D human breast tumor cells. Bioassay-guided isolation led to the identification of six new (1-6) and five previously reported (7-11) sesterterpene analogues and two unrelated sesterterpenes. Two new sesterterpenes, thorectidaeolide A (1) and 4-acetoxythorectidaeolide A (2), and luffariellolide (11) were among the most potent inhibitors of hypoxia (1% O₂)-induced HIF-1 activation (IC₅₀ values of 3.2, 3.5, and 3.6 μM, respectively). Luffariellolide (11) exhibited a significant level of cytotoxicity that mirrored its HIF-1 inhibitory activity. Neither compound 1, compound 2, nor any of the other less active sesterterpenes suppressed breast tumor T47D or MDA-MB-231 cell viability.

Recent advances in marine drug research

Structures and properties of promising marine anti-cancer, anti-inflammation and anti-infectious (HIV, HSV, malaria, leishmania) compounds reported during 2008-2011 are discussed. Wherever possible, attempts have also been made to highlight their possible biogenesis or structure-activity relationships (SAR). Since the stress is on identifying and short-listing potential drug molecules, this review is restricted to only those compounds exhibiting promising in vitro activity, the arbitrary cut off being IC50<15 μM, reported during the above period.

The Chemistry of Marine Sponges∗

Marine sponges continue to attract wide attention from marine natural product chemists and pharmacologists alike due to their remarkable diversity of bioactive compounds. Since the early days of marine natural products research in the 1960s, sponges have notoriously yielded the largest number of new metabolites reported per year compared to any other plant or animal phylum known from the marine environment. This not only reflects the remarkable productivity of sponges with regard to biosynthesis and accumulation of structurally diverse compounds but also highlights the continued interest of marine natural product researchers in this fascinating group of marine invertebrates.

Among the numerous classes of natural products reported from marine sponges over the years, alkaloids, peptides, and terpenoids have attracted particularly wide attention due to their unprecedented structural features as well as their pronounced pharmacological activities which make several of these metabolites interesting candidates for drug discovery. This chapter consequently highlights several important groups of sponge-derived alkaloids, peptides, and terpenoids and describes their biological and/or pharmacological properties.

Hippolides A-H, acyclic manoalide derivatives from the marine sponge Hippospongia lachne

Eight new acyclic manoalide-related sesterterpenes, hippolides A-H (1-8), together with two known manoalide derivatives, (6E)-neomanoalide (9) and (6Z)-neomanoalide (10), were isolated from the South China Sea sponge Hippospongia lachne. The absolute configurations of 1-8 were established by the modified Mosher's method and CD data. Compound 1 exhibited cytotoxicity against A549, HeLa, and HCT-116 cell lines with IC50 values of 5.22×10(-2), 4.80×10(-2), and 9.78 μM, respectively. Compound 1 also showed moderate PTP1B inhibitory activitiy with an IC50 value of 23.81 μM, and compound 2 showed moderate cytotoxicity against the HCT-116 cell line and PTP1B inhibitory activity with IC50 values of 35.13 and 39.67 μM, respectively. In addition, compounds 1 and 5 showed weak anti-inflammatory activity, with IC50 values of 61.97 and 40.35 μM for PKCγ and PKCα, respectively.

Bioactive sesterterpenes and triterpenes from marine sponges: occurrence and pharmacological significance

Marine ecosystems (>70% of the planet's surface) comprise a continuous resource of immeasurable biological activities and immense chemical entities. This diversity has provided a unique source of chemical compounds with potential bioactivities that could lead to potential new drug candidates. Many marine-living organisms are soft bodied and/or sessile. Consequently, they have developed toxic secondary metabolites or obtained them from microorganisms to defend themselves against predators [1]. For the last 30-40 years, marine invertebrates have been an attractive research topic for scientists all over the world. A relatively small number of marine plants, animals and microbes have yielded more than 15,000 natural products including numerous compounds with potential pharmaceutical potential. Some of these have already been launched on the pharmaceutical market such as Prialt (ziconotide; potent analgesic) and Yondelis (trabectedin or ET-743; antitumor) while others have entered clinical trials, e.g., alpidin and kahalalide F. Amongst the vast array of marine natural products, the terpenoids are one of the more commonly reported and discovered to date. Sesterterpenoids (C(25)) and triterpenoids (C(30)) are of frequent occurrence, particularly in marine sponges, and they show prominent bioactivities. In this review, we survey sesterterpenoids and triterpenoids obtained from marine sponges and highlight their bioactivities.

24-O-ethylmanoalide, a manoalide-related sesterterpene from the marine sponge Luffariella cf. variabilis

A new manoalide-related sesterterpene, 24-O-ethylmanoalide (3), was isolated from the Indian Ocean sponge Luffariella cf. variabilis, together with the known compounds manoalide (1), seco-manoalide, manoalide monoacetate and 24-O-methyl-manoalide (2). The structure of compound 3 was elucidated by interpretation of its spectroscopic data.