Effective Forms, Additive Effect, and Toxicities Scattering Effect of Pharmacodynamic Substances of TCMs Some Reflections Evoked by the Study on the Metabolic Disposition of Traditional Chinese Medicines (TCM) / 世界科学技术-中医药现代化

ABSTRACT

The blood concentrations of the pharmacodynamic substances of traditional Chinese medicines (TCMs) are usually very low. How can they exert pharmacological actions, in which forms (original form, metabolite or the both) do they exert the actions. To answer these questions, we proposed a new concept ofEffective Formsof pharmacodynamic substances of TCMs and a hypothesis of additive effect of multiple constituents of TCMs. The hypothesis includes that the aggregate or summation of Effective Forms of pharmacodynamic substances of TCMs is the core material base of the effi-cacy of TCMs, and the additive effect of the blood concentrations of different Effective Forms is one part of the action mechanism. The additive effect of the different Effective Forms of a TCMs means an additive effect of numerous con-stituents or/and metabolites on a same target, and therefore the efficacy brought by the addition of the concentrations of all these compounds, which different from the synergy effect of multi-constituents on multi-targets. Studies on the disposition of TCMs showed that a constituent can be biotransformed to many metabolites (up to more than 50 metabolites);different constituents can produce the same metabolites;many metabolites (up to 10 compounds for each metabolite) are isomers or homologues; some constituents can be converted to each other in vivo; and some metabolites are bioactive. These com-pounds having the similar structure are likely to have the same pharmacological effects on the same target, which could provide experimental evidences for the concept ofEffective Formsand the hypothesis ofAdditive Effect. We suggest that the Effective Forms and Additive Effects of the pharmacodynamic substances of TCMs should be extensively investi-gated in the future, and the results of such researches will help us further understand the pharmacodynamic substances and action mechanism of TCMs, and give a new explanation 'Toxicities Scattering Effect' for 'Why the toxicities of TCMs are low', and propose a new strategy for quality control of TCMs.