Based on ancient Chinese philosophy, the Yin-Yang theory believes that matter has opposing Yin and Yang aspects. These aspects are mutually controlled and inhibited by each other resulting in a state of dynamic equilibrium. If this equilibrium is disturbed, one component may become excessive and this can cause serious problems, such as diseases. According to Chinese Medicine theory, the interaction between Yin and Yang can generate Qi, which then circulates for the Meridian to nourish various organs in a time-dependent and synchronized pattern. The application of Yin-Yang theory spans ancient to modern times. Professor Sutherland described the antagonistic action of cyclic AMP and cyclic GMP in regulating cellular function in a fashion similar to the Yin-Yang concept, and this earned him a Nobel Prize in Physiology of Medicine in 1971. In neuroscience, the Yin Yang phenomenon is actually exemplified by the long-known antagonistic relationship between parasympathetic and sympathetic neural activities in the body. Consistently, a recent psychophysiological investigation in human subjects has revealed an association of decreased parasympathetic and sympathetic activities with deficiencies in Yin and Yang, respectively, in the body. My laboratory at the Hong Kong University of Science and Technology has investigated the opposing relationship between antioxidation and oxidation in the cell. Cellular antioxidants such as GSH - reduce glutathione, ascorbic acid - vitamin C, and alpha-tocopherol - vitamin E, are able to scavenge reactive oxygen species - ROS, and reactive nitrogen species - RNS, generated through energy metabolism and other cellular activities. In a healthy cell, Yin and Yang activites are in balance. When Yang activity are higher than those of Yin, cellular oxidative stress is increased. With regard to the Yin in relation to a cellular antioxidant defense, we believe that the glutathione-driven antioxidant network plays a crucial role in preventing the detrimental effects of ROS. Cellular GSH levels are maintained by the de-novo synthesis, meaning being built from scratch using amino acids and gluthathione redox cycling, meaning the regeneration of the reduced form from the oxidized form. In addition, GSH work synergistically with ascorbic acid and alpha-tocopherol by regenerating their reduced form from oxidized forms. In so doing, antioxidant protection can be sustained by cellular metabolic processes through the supply of ATP, meaning energy, for gluthathione synthesis and NADPH, meaning reducing power for gluthathione redox cycling. On the other hand, energy metabolism related to Yang is dependent on the intake of foodstuffs, with the digested and absorbed nutrients undergoing biochemical oxidation to generate ATP, which is the universal energy fuel required to support cellular activities and hence, body functions. Under physiological conditions, approximately 98% of electrons produce a tetravalent reduction of the oxygen molecule to form water. About 2% of the electron leak out during the transport process. These combine with oxygen molecules to form ROS in the mitochondrial matrix or the extra mitochondrial space. A healthy mitochondrial cell can handle oxidant challenges by virtue of an effective antioxidant defense system. The leakage of electrons during electron transport is increased when mitochondrial function is compromised, as occurs, for example, during the aging process. The increased production of ROS can overwhelm antioxidant defense components and cause oxidative damage in mitochondria that can favor the development of age-associated diseases. The practice of Chinese Medicine emphasizes the prevention of age- associated diseases. With the use of various categories of Chinese tonifying herbs, it is possible to restore the Yin/Yang balance in body function and hence a healthy body status. In terms of "Modern Medicine", we hypothesize that Yang tonifying herbs can activate energy metabolism and increase ATP production, whereas Yin tonifying herbs can produce immunomodulatory action, meaning either stimulatory or suppressive in action. On the other hand, Qi and Blood tonifying herbs can produce hormone-like actions and affect neuroendocrinological regulation and or stress responses. This wraps up the first part of the seminar. In the second part, I'm going to discuss the pharmacological action of Yin and Yang tonifying herbs.
