Cyclodepsipeptides from a Kenyan marine cyanobacterium

Dzeha, Thomas Mwambire

Title: Cyclodepsipeptides from a Kenyan marine cyanobacterium
Creator: Dzeha, Thomas Mwambire
ThesisAdvisor: Davies-Coleman, Mike
Subject: Cyanobacteria
Subject: Stereochemistry
Subject: Natural products -- Kenya
Date: 2003
Type: Thesis
Type: Masters
Type: MSc
Identifier: vital:4303
Identifier: http://hdl.handle.net/10962/d1004961
Identifier: Cyanobacteria
Identifier: Stereochemistry
Identifier: Natural products -- Kenya
Description: An examination of an organic extract of the cyanobacterium Lyngbya majuscula collected from Wasini Island off the southern Kenyan coast led to the isolation of the known cyclodepsipeptide antanapeptin A (7), recently isolated from a Madagascan collection of L. majuscula, and a new bioactive cyclodepsipeptide, homodolastatin 16 (42). Although L. majuscula is a common, pantropical cyanobacterium this study represents the first investigation of the natural product chemistry of a Kenyan population of L. majuscula. The structures of the two cyclodepsipeptides were determined from 2D NMR and mass spectrometry data. The L- stereochemistry of the proline, valine, and N-methylphenylalanine amino acids in 7 and the L – proline configuration in 42, was confirmed by Marfey’s HPLC method. Chiral GC was used to determine the absolute stereochemistry of the hydroxyisovaleric acid moiety in 7 and 42, the lactate residue in 42 and tentatively propose an L-stereochemistry for the Nmethylisoleucine amino acid in 42. Homodolastatin 16, a higher homologue of the potential anti-cancer agent, dolastatin 16, exhibited moderate activity against two oesophageal cancer cell lines.
Format: 108 p., pdf
Publisher: Rhodes University, Faculty of Science, Chemistry
Language: English
Rights: Dzeha, Thomas Mwambire

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