PLANT SECONDARY METABOLITES (PSM)
The biological or therapeutic activity of a medicinal plant is closely related to the plant chemicals in it. As Plant Secondary Metabolites (PSM) are an extremely large group of compounds, a comprehensive overview of their biochemistry, bioactivity and chemistry is not possible in a relatively short paper. PSM, also known as phytochemicals, represent a diverse group of natural products, some of which may be nutritionally valuable but many of which have no nutritional value or antinutritional properties. Although precise numbers are at best an estimate, of the >100000 different compounds of natural origin that have been described >80000 are derived from plants. These chemicals can be classified into major groups of chemicals such as essential oils, alkaloids, acids, steroids, tannins, saponins and so forth. Each one of these classes of chemicals may have a preferred effective method of extraction.