Natural Products Chemistry

A Quinoline Based bis-Urea Receptor for Anions: A Selective Receptor for Hydrogen Sulfate

by Bryan Wong

Natural Product Communications, 7, 301 (2012)

XXVIII

by A Nonomura

Co-authored with Andrew A. Benson and Barry A. Cullen
Published in Advances in Photosynthesis, 2012, Intech, ISBN 978-953-307-928-8

Clark_et_al_SupportingOnlineMaterial_JNP2012

by Valerie Clark

COLLECTING ARTHROPOD AND AMPHIBIAN SECRETIONS FOR CHEMICAL ANALYSES

by Valerie Clark

Evidence for An Enantioselective Pumiliotoxin 7-Hydroxylase In Dendrobatid Poison Frogs of the Genus Dendrobates

by Valerie Clark

Clark et al_JNP2012_sugar-bile frog secretion

by Valerie Clark

Influence of biflorin on the labelling of red blood cells, plasma protein, cell protein, and lymphocytes with technetium-99m: in vitro study

by Ulysses Albuquerque

Antimicrobial activity of three species of Phyllanthus (quebra-pedra) and its commercial product

by Ulysses Albuquerque

Atividade antimicrobiana de três espécies de phyllanthus (quebrapedra) e de seu produto comercial;/Antimicrobial activity of three species of phyllanthus ( …

by Ulysses Albuquerque

Mutant Malonyl-CoA Synthetases with Altered Specificity for Polyketide Synthase Extender Unit Generation

by Gavin Williams

Chembiochem, 2011

We have used structure-guided saturation mutagenesis followed by colorimetric screening to identify mutant malonyl-CoA... more We have used structure-guided saturation mutagenesis followed by colorimetric screening to identify mutant malonyl-CoA synthetases with altered substrate specificity. One particular mutant displayed a 240-fold shift in specificity (see graphic). These mutant enzymes will be useful tools for providing extender units to probe the activity of polyketide synthases.

Expanding the promiscuity of a natural-product glycosyltransferase by directed evolution.

by Gavin Williams

Nat Chem Biol, 2007

Natural products, many of which are decorated with essential sugar residues, continue to serve as a key platform for... more Natural products, many of which are decorated with essential sugar residues, continue to serve as a key platform for drug development. Adding or changing sugars attached to such natural products can improve the parent compound's pharmacological properties, specificity at multiple levels, and/or even the molecular mechanism of action. Though some natural-product glycosyltransferases (GTs) are sufficiently promiscuous for use in altering these glycosylation patterns, the stringent specificity of others remains a limiting factor in natural-product diversification and highlights a need for general GT engineering and evolution platforms. Herein we report the use of a simple high-throughput screen based on a fluorescent surrogate acceptor substrate to expand the promiscuity of a natural-product GT via directed evolution. Cumulatively, this study presents variant GTs for the glycorandomization of a range of therapeutically important acceptors, including aminocoumarins, flavonoids and macrolides, and a potential template for engineering other natural-product GTs.

Recombinant E. coli prototype strains for in vivo glycorandomization.

by Gavin Williams

ACS Chem Biol, 2011

In vitro glycorandomization is a powerful strategy to alter the glycosylation patterns of natural products and small... more In vitro glycorandomization is a powerful strategy to alter the glycosylation patterns of natural products and small molecule therapeutics. Yet, such in vitro methods are often difficult to scale and can be costly given the requirement to provide various nucleotides and cofactors. Here, we report the construction of several recombinant E. coli prototype strains that allow the facile production of a range of small molecule glycosides. This strategy relies on the engineered promiscuity of three key enzymes, an anomeric kinase, a sugar-1-phosphate nucleotidyltransferase, and a glycosyltransferase, as well as the ability of diverse small molecules to freely enter E. coli. Subsequently, this work is the first demonstration of "in vivo glycorandomization" and offers vast combinatorial potential by simple fermentation.

Combining two-directional synthesis and tandem reactions: a short formal synthesis of halichlorine

by Annabella Newton

Discorhabdin W, the first dimeric discorhabdin

by André Pinkert

Key achievements in the total synthesis of vibsane-type diterpenoids

by Jeffrey Y. W. Mak

Mak, J. Y. W.; Williams, C. M. Nat. Prod. Rep. 2012, DOI: 10.1039/C2NP00067A.

Vibsanins are rare, structurally dense diterpenes, which occur exclusively in the Viburnum species. Despite the first... more Vibsanins are rare, structurally dense diterpenes, which occur exclusively in the Viburnum species. Despite the first reported isolation 31 years ago, this natural product family has only attracted synthetic attention within the past decade. The aim of this article is to highlight the key accomplishments in the total synthesis of these unique natural products.

Enantioselective total synthesis of (−)-neovibsanin G and (−)-14-epi-neovibsanin G

by Jeffrey Y. W. Mak

Mak, J. Y. W.; Williams, C. M. Chem. Commun. 2012, DOI: 10.1039/C1CC15995J.

See also Synfacts, 2012, 8, 125.

The first total synthesis of vibsane-type diterpenoids neovibsanin G and 14-epi-neovibsanin G has been achieved. Key... more The first total synthesis of vibsane-type diterpenoids neovibsanin G and 14-epi-neovibsanin G has been achieved. Key to this endeavour was a late stage EtAlCl2 mediated skeletal rich cascade leading to the bicyclo[3.3.1]nonane core in one step.

Wound healing activity of jasminum sambac leaf extract

by Dr Syam Mohan

Chemical constituents from Zanthoxylum setulosum (Rutaceae)[Costituyentes químicos de Zanthoxylum setulosum (Rutaceae)]

by Max Chavarría

Soledad Mora, Victor Castro, Luis Poveda, Max Chavarría & Renato Murillo. BLACPMA. (2011) 10 (2): 155-158.

Following our phytochemical studies of Costa Rican plants, in this work we report the isolation and identification of... more Following our phytochemical studies of Costa Rican plants, in this work we report the isolation and identification of eight compounds from aerial parts of Zanthoxylum setulosum (Rutaceae). They were identified as the alkaloid skimmianine, the lignans savinin, kusunokinin, sesamin, syringaresinol and the isopentenyl ether of pluviatol, the amide aurantiamide acetate, and the triterpen lupeol. This is the first report of isolation of skimmianine from the leaves of Z. setulosum and its presence confirm that quinoline and benzophenanthridine alkaloids, can be considered as chemotaxonomic markers of this genus. All the isolated compounds were characterized by spectroscopic methods (including 1H-NMR, 13C-NMR, , HMQC, HMBC and NOESY) and comparison with the literature data.

Porpoisamides A and B, two novel epimeric cyclic depsipeptides from a Florida Keys collection of Lyngbya sp.

by Theresa Meickle

NMR-guided fractionation of a non-polar extract of a Florida Keys collection of Lyngbya sp. resulted in the isolation... more NMR-guided fractionation of a non-polar extract of a Florida Keys collection of Lyngbya sp. resulted in the isolation of two novel epimeric cyclic depsipeptides, porpoisamides A (1) and B (2). The planar structures of these compounds were determined using NMR spectroscopic techniques. The absolute configurations of amino and hydroxy acid subunits were assigned by enantioselective HPLC analysis. These compounds showed weak cytotoxicity towards HCT-116 colorectal carcinoma and U2OS osteosarcoma cells. The porpoisamides are a unique pair of cyclic depsipeptides that are epimeric at C-2 of the β-amino acid, 3-amino-2-methyloctanoic acid.

Bioassay-Guided Isolation and Identification of Desacetylmicrocolin B from Lyngbya cf. polychroa

by Theresa Meickle