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Pure Appl. Chem., Vol. 70, No. 11,
pp. 2122, 1998
Strategy for the biological and chemical evaluation
of plant extracts*
K. Hostettmann
Institut de Pharmacognosie et Phytochimie, Université
de Lausanne, BEP, CH- I 0 1 5 Lausanne-Dorigny, Switzerland
E-mail: [email protected]
Abstract: Only a small percentage of the 400'000 to 500'000
species in the plant kingdom has been investigated phytochemically.
Even fewer species have been studied simultaneously for their biological
and pharmacological properties. For these reasons, it is essential
to have efficient systems available for the rapid chemical and biological
screening of plant extracts.
Different techniques can be used for the chemical
evaluation of plants. Thin-layer chromatography (TLC) is the simplest
and cheapest method but new hyphenated HPLC systems are now available
which provide improved on-line information about the composition
of extracts, with good selectivity and sensitivity : LC/UV, LC/MS
and LC/NMR (1). By these means, it is possible to avoid known or
trivial compounds during searches for new lead compounds.
The biological testing requires simple, fast and
reproducible methods in order to allow the screening of a large
number of extracts. The test targets are of various nature. Thin-layer
chromatography is also ideal for biological screening. The technique
of bioautography combines TLC with a bioassay in situ and
allows localization of active constituents in a complex matrix (2).
Antifungal, antibacterial, pesticide and antioxidant activities
can all be investigated by TLC bioautography. These and other benchtop
bioassays are rapid and simple to perform. They provide efficient
methods for activity-guided isolation of natural products.
Examples will be given of the strategies employed
to obtain new bioactive compounds from plant sources, including
initial screening and subsequent preparative chromatography of extracts
selected for study.
-
K. Hostettmann, J.-L. Wolfender, S. Rodriguez,
Planta Med. 6.3 2-10 (1997).
-
K. Hostettmann, A. Marston, Pure Appl. Chem.
6.6 2231-2234 (1994).
* Invited lecture presented at the International
Conference on Bioversity and Bioresources: Conservation and
Utilization, 23-37 November 1997, Phuket, Thailand.
Page last modified 15 April 1999.
Copyright ©1997, 98, 99 International Union of Pure and Applied
Chemistry.
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