Effects of components extracted from crude drugs on the cell membrane

Saponins, which are important effective components extracted from crude drugs, have been reported to show various pharmacological actions: antiinflammatory action, effects on protein, lipid or carbohydrate metabolism and so on. Although these various pharmacological actions have been interpreted as the results of steroid hormone-like action or adrenal gland stimulating effect of saponins, there are a number of inconsistent points. We have found from previous experiments that a primary action site of saponin on a cell is the cell membrane, and we have been trying to analyze mechanisms showing various pharmacological actions from the effects of saponin on the cell membrane (target organelle theory). In general, saponin has a high affinity to the membrane and induces changes of membrane viscosity, fluidity or surface charge. These changes of the cell membrane might modify cell function. The modification of cell function in various organs could result in the various pharmacological actions. This hypothesis means that the target of a crude drug or saponin is not the organ but a cell organelle. In the present study, the various pharmacological actions of saikosaponin, as an example, and the characteristics of its action on the cell membrane have been reported, and the explanation for a variety of pharmacological actions has been proposed from this hypothesis.