Bioassay-Guided Isolation And Its Use To Find New Drug Leads From Nature

Bioassay guided isolation is a procedure for finding new drugs from natural sources, such as plants, or other organisms. The method is started by preparing extracts from different organisms, which are then tested for their pharmacological activity in different test systems, depending on the aim. The compound where activity can be seen is then isolated, and if the chemical properties of this compound is not known all fractions in this compound is isolated and studied. If one of the compounds shows positive results then it is further studied and separated until the pure active compound is found. The bioassay guided isolation studies can be done in vivo, and in vitro. In the test model in vitro eggs from brine shrimp is used to test the toxicity of different compounds. It’s a model to study the effect on a compound under standard conditions were only an organ for example is tested.

And in the test model in vivo a whole organism is used to see the results of an injected compound or an extract, the most common test model for this type of study is the cypris larvae. In vivo studies is often a better way when studying bioassay guided isolation, this hence to when studies are done in vivo the whole organism is considered and different organs can be studied at the same time, but one advantage of it is also that all the metabolic pathways in the organism can be studied. One helpful assay that are useful when finding new drug leads is the toxicity assay. This method is used to determine toxicity of crude drugs, and factors such as developmental, neurotoxicity, mutagenicity, carcinogenicity but also the reproductive system is often considered. Therefore it’s better to perform some tests in vivo. When toxicity assays is studied there are guidelines to follow. The test should be performed on one or more species that are similar to man, and to use several dose levels. When the animal is being selected the behavior, life span, availability and other cost should be considered. Rats are often recommended for chronic, carcinogenicity, and reproduction studies. Rats and rabbits are also used for eye and skin irritation but also acute dermal studies.

For finding new drug leads with the help of a bioassay method there are High-throughput screening (HTS), which is a method that is well used in the pharmaceutical industry for this purpose. This method detects the pharmacological activity caused by a compound, and is a great method for isolating the active compound. I think you’re mixing up the words ‘compound’ and ‘fraction’.