Influence of environmental abiotic factors on the content of saponins in plants

Saponins are a large group of secondary metabolites occurring in significant amounts in many plant species. However, the saponin content of plants is variable and it can be influenced by the surrounding environment. The local geoclimate, seasonal changes, external conditions such as light, temperature, humidity and soil fertility, as well as cultivation techniques, affect both the quantitative amount and qualitative composition of saponins. Such variation substantially impacts on the quality and properties of wild and cultivated plants exploited for pharmaceutical, nutritional and industrial applications. This review summarizes the available data on the effects of abiotic environmental factors on saponin level in plants, especially those of considerable economic importance, highlighting current problems such as the reduction in natural plant resources, over-exploitation and destruction of wild habitats, climate shifts as well as the consequences of the growing demand for plant-derived medicinal and industrial products. The need for a theoretical basis for a reasonable harvest, attempts at the domestication of wild plant species and the development of new agricultural technologies allowing high production under optimized conditions are also discussed.