Synergistic activities crude extracts

Vfe noticed that stepwise purification of the crude extracts resulted in gradually diminishing activity. When several of the identified phenolic compounds were individually tested, none of them exhibited biological activity. Wfe concluded that the biological activity was associated with either the threshold levels of chemicals in the crude extracts or synergistic effect of sane chemicals. Similar observations were made by others, and it needs to be verified by further experimentation (17, 48). 

However, we have observed that values obtained with crude extracts were only qualitative. Often, they did not accurately estimate the quantities of the individual enzymes present. Inhibitors were typically present that caused the underestimation of certain enzymes ie.g., ligninases Table II) and that could potentially mask less dominant enzymes. Also, certain polysaccharidases e.g., hemicellulases) were often overestimated due to the action of non-specific or synergistic enzymes e.g., other hemicellulases or cellulases) (9,14), This artifact resulted in low apparent recovery of a given activity and only moderate increases in specific activity upon purification of the major corresponding enzyme present, in spite of the fact that SDS polyacrylamide gels indicated good recovery and substantial removal of contaminants (14),... 

Biological effects, e.g., mutagenicity in a short-term test, of a crude material (or a crude extract or leachate) may be difficult to detect because of overall toxicity of the mixture or the very low concentrations of the active components, or both. Therefore, it is desirable to subdivide the materials into fractions that can be tested much more accurately and that lend themselves to chemical analyses for identification of the active compounds much more readily than does the starting test material. Possible disadvantages include the loss or modification of specific components or the loss of potential for synergistic effects. Various approaches to fractionation by chemical class are discussed in the following sections. 

It is worth remembering that these advances are enjoyed only by a privileged few. The WHO estimates that 80% of the world s population still relies on traditional medicines for their primary health care needs. These are invariably crude natural product extracts, with potentially large variations in composition from one batch to another, and that are not subjected to controlled clinical trials. It is also true that many of these traditional medicines, although consumed by millions of people who vouch for their efficacy, have not succumbed to Western-style inquisitions to determine their mechanism of action. Traditional medicines, contend their proponents, work by complex synergistic interactions between their constituents. Consequently, reductionist approaches that identify single active pharmaceutical ingredients are doomed to failure. 

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