Why is Firefly Oxyluciferin a Notoriously Labile Substance?

The chemistry of firefly bioluminescence is important for numerous applications in biochemistry and analytical chemistry. The emitter of this bioluminescent system, firefly oxyluciferin, is difficult to handle. The cause of its lability was clarified while its synthesis was reinvestigated. A side product was identified and characterized by NMR spectroscopy and X‐ray crystallography. The reason for the lability of oxyluciferin is now ascribed to autodimerization of the coexisting enol and keto forms in a Mannich‐type reaction.     

Natural product hybrids as new leads for drug discovery

Natural products play an important role in the development of drugs, especially for the treatment of infections and cancer, as well as immunosuppressive compounds. However, the number of natural products is limited, whereas millions of hybrids as combinations of parts of different natural products can be prepared. This new approach seems to be very promising in the development of leads for both medicinal and agrochemical applications, as the biological activity of several new hybrids exceeds that of the parent compounds. The advantage of this concept over a combinatorial chemistry approach is the high diversity and the inherent biological activity of the hybrids.     

The chemistry of the polycyclic polyprenylated acylphloroglucinols

With their fascinating biological profiles and stunningly complex molecular architectures, the polycyclic polyprenylated acylphloroglucinols (PPAPs) have long provided a fertile playing field for synthetic organic chemists. In particular, the recent advent of innovative synthetic methods and strategies together with C-C bond-forming reactions and asymmetric catalysis have revitalized this field tremendously. Consequently, PPAP targets which once seemed beyond reach have now been synthesized. This Review aims to highlight the recent achievements in the total synthesis of PPAPs, as well as notable methods developed for the construction of the bicyclo[3.3.1] core of these chemically and biologically intriguing molecules.     

新型海洋双吲哚类生物碱的研究进展

双吲哚类生物碱是近年来分离到的一类很重要的海洋天然产物。由于这类化合物具有新颖的化学结构和多种生理活性,因此它们引起了科学家极大的兴趣。本文综述了近年来新型海洋双吲哚类生物碱的研究进展。     

The Chemical Basis of Fungal Bioluminescence

Many species of fungi naturally produce light, a phenomenon known as bioluminescence, however, the fungal substrates used in the chemical reactions that produce light have not been reported. We identified the fungal compound luciferin 3‐hydroxyhispidin, which is biosynthesized by oxidation of the precursor hispidin, a known fungal and plant secondary metabolite. The fungal luciferin does not share structural similarity with the other eight known luciferins. Furthermore, it was shown that 3‐hydroxyhispidin leads to bioluminescence in extracts from four diverse genera of luminous fungi, thus suggesting a common biochemical mechanism for fungal bioluminescence.     

Anti-Inflammatory Dysidazirine Carboxylic Acid from the Marine Cyanobacterium Caldora sp. Collected from the Reefs of Fort Lauderdale,Florida

Dysidazirine carboxylic acid (1) was isolated from the lipophilic extract of a collection of the benthic marine cyanobacterium Caldora sp. from reefs near Fort Lauderdale, Florida. The planar structure of this new compound was determined by spectroscopic methods and comparisons between HRMS and NMR data with its reported methyl ester. The absolute configuration of the single chiral center was determined by the conversion of 1 to the methyl ester and the comparison of its specific rotation data with the two known methyl ester isomers, 2 and 3. Molecular sequencing with 16S rDNA indicated that this cyanobacterium differs from Caldora penicillata (Oscillatoriales) and represents a previously undocumented and novel Caldora species. Dysidazirine (2) showed weak cytotoxicity against HCT116 colorectal cancer cells (IC₅₀ 9.1 µM), while dysidazirine carboxylic acid (1) was non-cytotoxic. Similar cell viability patterns were observed in RAW264.7 cells with dysidazirine only (2), displaying cytotoxicity at the highest concentration tested (50 µM). The non-cytotoxic dysidazirine carboxylic acid (1) demonstrated anti-inflammatory activity in RAW264.7 cells stimulated with LPS. After 24 h, 1 inhibited the production of NO by almost 50% at 50 µM, without inducing cytotoxicity. Compound 1 rapidly decreased gene expression of the pro-inflammatory gene iNOS after 3 h post-LPS treatment and in a dose-dependent manner (IC₅₀ ~1 µM); the downregulation of iNOS persisted at least until 12 h.     

Chemical defence strategies of higher fungi

Like plants, fungi have evolved a variety of defence strategies in order to protect themselves against feeding mammals, insects and infection with parasitic fungi. In contrast to plants little is known on the chemical ecology of fruiting bodies of higher fungi, particularly those defence mechanisms which are induced upon wounding have only occasionally been recognised. Methods both for the detection of permanently present defence compounds and for the elucidation of wound-activated chemical defence mechanisms are discussed in this concept paper.     

Syntheses and X-Ray Crystal Structures of Cassiferaldehyde and Analogs

Cassiferaldehyde, a recently discovered naturally occurring tyrosinase inhibitor, and six of its analogs, in which the aldehyde group has been replaced by various other functionalities, have been synthesized by a short and simple sequence starting from 2,3-dihydroxybenzaldehyde. Single-crystal x-ray structures of cassiferaldehyde as well as its methyl ketone, nitrile, and carboxylic acid analogs are reported.     

Marine huge molecules: the longest carbon chains in natural products

Marine huge polyol and polyether compounds are remarkable molecules owing to their extraordinary structures and significant biological activities. Currently, palytoxin and maitotoxin are believed to have the longest carbon chains in nature (more than 100 Å in length), except for biopolymers. The structural properties of such marine huge molecules are highlighted, especially with regard to the length and shape of their carbon chains. © 2010 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 10: 000–000; 2010: Published online in Wiley InterScience ( www.interscience.wiley.com ) DOI 10.1002/tcr.200900030     

Recent Progress on the Synthesis and Bioactivity of Marine Naturally Occurring Dienamides and Related Derivatives

The diverse biological activities of many marine naturally occurring dienamides have made them privileged structures for the development of new drugs. This review highlights the different synthetic approaches for the preparation of the marine naturally occurring dienamides and related pharmaceutically active derivatives.     

Discovery,Total Synthesis and Key Structural Elements for the Immunosuppressive Activity of Cocosolide,a Symmetrical Glycosylated Macrolide Dimer from Marine Cyanobacteria

A new dimeric macrolide xylopyranoside, cocosolide ( 1 ), was isolated from the marine cyanobacterium preliminarily identified as Symploca sp. from Guam. The structure was determined by a combination of NMR spectroscopy, HRMS, X‐ray diffraction studies and Mosher's analysis of the base hydrolysis product. Its carbon skeleton closely resembles that of clavosolides A–D isolated from the sponge Myriastra clavosa, for which no bioactivity is known. We performed the first total synthesis of cocosolide ( 1 ) along with its [α,α]‐anomer ( 26 ) and macrocyclic core ( 28 ), thus leading to the confirmation of the structure of natural 1 . The convergent synthesis featured Wadsworth–Emmons cyclopropanation, Sakurai annulation, Yamaguchi macrocyclization/dimerization reaction, α‐selective glycosidation and β‐selective glycosidation. Compounds 1 and 26 potently inhibited IL‐2 production in both T‐cell receptor dependent and independent manners. Full activity requires the presence of the sugar moiety as well as the intact dimeric structure. Cocosolide also suppressed the proliferation of anti‐CD3‐stimulated T‐cells in a dose‐dependent manner.     

Chemical Diversity and Biological Activity of Secondary Metabolites Isolated from Indonesian Marine Invertebrates

Marine invertebrates have been reported to be an excellent resource of many novel bioactive compounds. Studies reported that Indonesia has remarkable yet underexplored marine natural products, with a high chemical diversity and a broad spectrum of biological activities. This review discusses recent updates on the exploration of marine natural products from Indonesian marine invertebrates (i.e., sponges, tunicates, and soft corals) throughout 2007–2020. This paper summarizes the structural diversity and biological function of the bioactive compounds isolated from Indonesian marine invertebrates as antimicrobial, antifungal, anticancer, and antiviral, while also presenting the opportunity for further investigation of novel compounds derived from Indonesian marine invertebrates.     

Synthesis and Pharmacological Studies on a Cyclooligopeptide from Marine Bacteria

A natural proline‐rich tetrapeptide cyclo‐prolyl‐leucyl‐prolyl‐phenylalanyl was prepared employing solution‐phase method of peptide synthesis through coupling of dipeptide fragments Boc‐l‐Pro‐l‐Leu‐OH and l‐Pro‐l‐Phe‐OMe which utilizes diisopropylcarbodiimide (DIPC) as coupling agent and N‐methylmorpholine (NMM) as the base. Deprotection of linear tetrapeptide unit followed by its cyclization provided a cyclopeptide, identical in all aspects to the natural molecule. Pharmacological evaluation showed cytotoxic, antifungal and antihelmintic potential of synthesized peptide against Dalton's Lymphoma Ascites (DLA) and Ehrlich's Ascites Carcinoma (EAC) cell lines, pathogenic dermatophytes and earthworms.     

海洋生物中的体化合物的研究进展

甾体化合物是一类具有显著生理活性且广泛存在于自然界中的天然化合物。本文对近年来从海洋生物中分离得到的甾体化合物,根据其结构特征对它们进行了分类总结,并对其生物活性进行了阐述,以期对甾体药物的研究开发提供有用的参考。