iso-PsE, a new pseudopterosin

We describe the discovery of a new member of the pseudopterosin class of marine natural products. Its structure is isomeric with that of pseudopterosin E and has therefore been given the name iso-PsE.     

In vivo and in vitro investigations into the biosynthetic relatedness of the pseudopterosins

[formula: see text] Both in vivo and in vitro techniques have been developed to test putative intermediates in the biosynthetic pathway to the pseudopterosins, antiinflammatory compounds isolated from Pseudopterogorgia elisabethae. Furthermore, specific activity data we have obtained indicate that pseudopterosin A is a precursor to pseudopterosins B, C, and D. We conclude that in the biosynthesis xylose is attached to the diterpene skeleton to produce pseudopterosin A and is then aceylated to form pseudopterosins B-D.     

New Antibacterial Diterpenes from Pseudopterogorgia elisabethae

From the MeOH extract of Pseudopterogorgia elisabethae, collected from the Bahamas, four new diterpenes, elisabethin E ( 1 ), elisabethin F ( 2 ), pseudopterosin P ( 3 ), and pseudopterosin Q ( 4 ), were isolated and their structures established with the aid of extensive spectroscopic studies. Compounds 3 and 4 showed antibacterial activity selectively against the Gram‐positive bacteria Streptococcus pyogenes, Staphylococcus aureus, and Enterococcus faecalis.     

Syntheses and stereochemical revision of pseudopterosin G-J aglycon and helioporin E

Revised structures are proposed for pseudopterosin G-J aglycon and helioporin E.     

Identification of amphilectosins as key intermediates in pseudopterosin biosynthesis

Amphilectosins A and B have been identified from the organic extract of Pseudopterogorgia elisabethae collected in the Florida Keys, along with seco-pseudopterosins and pseudopterosins. The structures of the amphilectosins, "C-12-C-13 dehydro seco-pseudopterosins", suggested that these metabolites provide the biosynthetic link between the seco-pseudopterosins (serrulatane diterpenes) and pseudopterosins (amphilectane diterpenes). This biosynthetic relationship was confirmed through various radiolabeling experiments. Incubation studies with the amphilectosins revealed the selective transformation of amphilectosin A to pseudopterosin Y and the transformation of amphilectosin B to pseudopterosin F, which suggests that the alpha/beta stereochemistry for the isobutenyl group in the pseudopterosins arises from the selective ring closure of the cis- and trans-amphilectosins.     

Pseudopterosin biosynthesis in Symbiodinium sp., the dinoflagellate symbiont of Pseudopterogorgia elisabethae

Investigations are reported that identify the biosynthetic source and origins of the pseudopterosins, pharmacologically important diterpene glycosides, in the gorgonian coral Pseudopterogorgia elisabethae. We report here the isolation of physiologically significant levels of endogenous pseudopterosins A, B, C, and D from purified symbionts identified as the dinoflagellate Symbiodinium sp. Biosynthetic studies in photosynthesizing symbiont isolates utilizing 14C-labeled inorganic carbon and the tritiated intermediate geranylgeranyl diphosphate yielded radiochemically pure pseudopterosins A through D and the first committed intermediate, elisabethatriene. The 14CO(2) uptake into the pseudopterosin pathway occurred at low levels compared to the 14CO(2) uptake into total lipids, suggesting a large reserve pool of the compounds. These results reveal for the first time that pseudopterosin biosynthesis is occurring within the algal symbiont and suggests the physiological implications of this biosynthesis.     

Oxidations of erogorgiaene in pseudopterosin biosynthesis

Pseudopterosins are potent anti-inflammatory diterpene glycosides initially isolated from the gorgonian coral Pseudopterogorgia elisabethae. In continuation of pathway elucidation studies focused on this family of terpenes, we report the isolation of 7-hydroxyerogorgiaene and 7,8-dihydroxyerogorgiaene from P. elisabethae and confirm the intermediacy of these compounds in pseudopterosin biosynthesis by in vitro incubation experiments with these metabolites in radiolabeled form.     

Assessing calcareous sponges and their associated bacteria for the discovery of new bioactive natural products

An overview of the chemistry and microbiology of calcareous sponges (Calcispongiae) is provided, highlighting the potential of these sessile filter-feeding marine invertebrates and their associated bacteria for the discovery of new bioactive natural products. 103 compounds are presented and 116 references cited.     

Integrating social and environmental justice into the chemistry classroom: a chemist’s toolbox

ABSTRACT

Although the chemical enterprise has provided numerous contributions to humanity, unintended consequences contribute to a disproportionate exposure of hazardous chemicals to certain populations based on race and socioeconomic status. Integrating concepts of social and environmental justice within chemistry curriculum provides an educational framework to help mitigate these impacts by training the next generation of chemists with justice-centered and green chemistry principles to guide their future work. Green and sustainable chemistry technologies can contribute to social equity and environmental justice. However, equity and social justice have only recently become a significant part of the green chemistry conversation. This article summarizes how the authors have explored issues of equity and environmental justice with the green and sustainable chemistry community. It offers a toolbox for college and university instructors containing foundational language, research, and idea-generation that can be used to strengthen the transition of a traditional chemistry curriculum toward a justice-centered one.     

Emerging supramolecular chemistry of gases

Molecular recognition of gases is an emerging area of chemistry. Supramolecular chemistry helps us to understand how gases interact with biological molecules and offers delicate insights into the mechanisms of their physiological activity. Principles of molecular recognition have been used for gas sensing, and have provided fundamental knowledge about the structure and dynamics of receptor-analyte complexes, and novel materials for gas sensing and storage have been developed. Supramolecular chemistry is also enabling us to learn how to transform gases into synthetically useful reagents. The rational design of novel catalysts for gas conversion and, more recently, encapsulation complexes with gases open novel directions in preparative synthetic chemistry.     

Synthesis and an evaluation of the bioactivity of the C-glycoside of pseudopterosin A methyl ether

The Suzuki-Miyaura cross-coupling protocol was applied to the synthesis of 1a, the C-glycoside analogue of PsA methyl ether. This marks the first construction of a C-glycoside for this class of marine natural products, thereby offering an opportunity to compare its bioactivity to the natural substances. Its activity profile resembled that of PsA (1) and PsA O-methyl ether (1b) when assayed for its anti-inflammatory activity and its ability to inhibit phagocytosis. We conclude that the intact structure is present when a pseudopterosin expresses its anti-inflammatory and phagocytosis inhibitory properties and that they are, therefore, not likely to be prodrugs. Results show that 1a is an effective binding agent toward the A2A and A3 adenosine receptors, displaying IC50 values of 20 and 10 microM, respectively.     

Identification of anti-inflammatory diterpenes from the marine gorgonian Pseudopterogorgia elisabethae

Analysis of the terpene metabolites of Pseudopterogorgia elisabethae collected from the Florida Keys has resulted in the identification of a novel hydroxyquinone, elisabethadione (1), as well as new pseudopterosins and seco-pseudopterosins. Anti-inflammatory assays indicate that elisabethadione is more potent than the well characterized pseudopterosin A and E. This report also describes the co-occurrence of pseudopterosins and seco-pseudopterosins, diterpenes with amphilectane and serrulatane skeletons, respectively. This together with our previously described isolation of elisabethatriene as the sole diterpene cyclase product in P. elisabethae suggests that the amphilectane and serrulatane families of diterpenes are derived from the same geranylgeranyl diphosphate cyclase product.     

Chemistry,Biology, and Medicine of the Glycopeptide Antibiotics

The war against infectious bacteria is not over! Although vancomycin and glycopeptide antibiotics have provided a strong last line of defence against many drug-resistant bacteria, their overuse has given rise to more dangerous strains of bacteria. An understanding of the chemistry and biology of these highly complex glycopeptides are destined to play a crucial role in the discovery of new antibiotics.     

Insight into the construction of open-framework aluminophosphates

Over the past twenty five years, a class of open-framework aluminophosphates, denoted AlPOs, has been prepared with neutral zeolitic frameworks and anionic frameworks showing wonderfully complex structural and compositional diversity. An insight into the construction of open-framework AlPOs revealing their general structural features and topological chemistry is provided in this tutorial review, and the role of templating and the designed construction and synthesis of AlPOs are discussed.     

基于点击化学的色谱分离材料研究新进展

自诺贝尔奖获得者Sharpless教授2001年首次提出点击化学概念以来,该类反应凭借条件温和、反应迅速、产量高、副产物少、分离提纯简单等优势,迅速拓展至材料和生命等诸多科学领域,成为一种强大的模块化合成工具。目前,点击化学反应已成为设计制备分离材料的重要手段,展现出蓬勃发展的现状。本文首先简要地回顾了点击化学的发展历程并介绍了其独特优势,然后聚焦于柱色谱和膜色谱两大分离领域,系统地综述了近5年发表的基于点击化学的色谱分离材料相关报道,重点归纳了叠氮-炔、巯基-烯和巯基-炔这3种常见点击反应类型在色谱分离材料研究中的最新进展,最后对点击化学在开发高效分离材料方面的发展前景进行了展望。     

浅谈P4的生长

P_4(白磷的分子式)及其衍生物的结构是化学竞赛的热点之一。本文简介了P_4的生长,对近年与本知识相关的几道竞赛题进行了解析,并提出了几点教学建议。     

Toward universal substituent constants: Model chemistry sensitivity of descriptors from the quantum theory of atoms in molecules

The quantum theory of atoms in molecules (QTAIM) provides a theoretical foundation to determine the properties of functional groups through additive atomic contributions. Many studies have used QTAIM in their analyses with a variety of electronic structure methods, but it is unknown if the properties measured using one model chemistry, the combination of the electronic structure method and basis set, can be compared to those measured by another. Here, we evaluate the sensitivity of QTAIM functional group and bond critical point properties using six functionals and seven basis sets. High-level B2PLYPD3-BJ/aug-cc-pV5Z reference values are provided for 116 functional groups and the property sensitivity with respect to these values are evaluated based on absolute deviations and by assessing linear relationships. Functional group properties, including charges, dipoles, quadrupoles and volumes, were found to be mostly insensitive to choice of computational model chemistry. However, due to structural and topological inconsistencies, the 6-31G(d) basis set is not recommended for use. Bond critical point properties varied with choice of model chemistry, but models incorporating hybrid functionals and triple-ζ basis sets provided values suitable for use in regression studies.     

Chemistry of two-dimensional MXene nanosheets in theranostic nanomedicine

Transition metal carbide,carbonitride and nitride MXenes,as the emerging two-dimensional(2D)nanomaterials,have aroused burgeoning research interest in a broad range of applications ranging from energy conversion to biomedicines attributing to their distinctive planar nanostructure,physiochemical properties and biological effects.They are featured with fascinating electronic,optical,magnetic,mechanical and thermal properties,which exert significant roles in biomedical applications of 2D MXenes.In this review,we briefly summarize the recent research progress of 2D MXenes and highlight their intrinsic chemistry in theranostic nanomedicines,focusing on the synthetic chemistry for MXenes construction,surface chemistry for surface engineering,physiochemical property for theranostic application and biological chemistry for biosafety evaluation.Furthermore,based on the current achieve ments on MXenes,their potential research directio n,critical challenges and future development in biomedicine are also discussed.It is highly expected that 2D MXene-based nanosystems would have a broad application prospect in theranostic biomedicine provided the current facing critical issues and challenges are adequately solved.     

Oxidative spirocyclization of phenolic sulfonamides: scope and applications

A full account of the oxidative dearomatization of para- and ortho-phenolic sulfonamides is provided together with an overview of the chemistry of the products and their elaboration to building blocks for spirocyclic alkaloids. A concise total synthesis of putative lepadiformine complements the discussion.     

Internet上有机化学资源的检索与利用

Internet上丰富的有机化学资源为从事有机化学的研究人员检索文献提供了一条方便快捷的途径。介绍了化学文摘(CA)、专利及其它与有机化学相关的数据库检索,并给出了一些有用的域名地址。