Chinese herbal medicine’s anti-ageing role

In modern terms, energy tonics such as Codonopsis pilosula (Dang Xin) can strengthen central and sympathetic nervous systems. They can also increase production of cAMP, the intercellular second messenger at the cellular level. The yin tonics such as Polygonatum odoratum (Yu Ju) can increase secretion of yin hormones including growth hormones and estrogen, strengthen the para-sympathetic nervous system and increase production of cGMP at the cellular level. The adrenal yang tonics such as Cuscuta chinensis (Tu Si Zhi) can increase secretion of yang hormones including androgen, epinephrine and sex hormones, and increase the metabolic rate.

Based on the TCM theories, direct causes of ageing of skin and the human body are the deterioration and imbalance of the five viscera. These are the TCM “anatomical terminologies” for human internal organs and systems. For example, the TCM viscera “heart” is actually referring to the cardiovascular system, “lung” the respiratory system, “liver” the hepatic and autonomous systems, “kidney” the endocrine and reproductive systems, and “spleen” the digestive system. The central theme of TCM theory for maintaining good health including the skin is to sustain the dynamic balance of yin and yang particularly within the five viscera. The functionality of these viscera is both complementary and antagonistic according to TCM literature. In modern biological language, it means the dynamic balance of the interplay of many separated organs, enzymes and cellular activities has to be in place. For example, the balance of anabolism (yin) and catabolism (yang) processes throughout the body where synthesis and breakdown of organic molecules are in equilibrium. The acid base and electrolyte balance of the renal function has to be stable. The homeostatic control system, where a collection of body components work to keep a physical or chemical property of the internal environment relatively constant, has to function properly.

A brief summary of the linkages of active components of Chinese herbal medicine with anti-ageing functionalities is also necessary before discussing the recent findings on mechanisms for delaying skin ageing. Many research papers showed that there are three major active categories which have positive actions on eliminating free radicals inside the body, enhancing anti-oxidation capabilities, improving skin micro-circulation, increasing production of skin collagen fibre and protein, and enhancing immunity. They are polyphenols including flavonoids, lignans, coumarins and tannins; polysaccharides including D-galactose, D-fructose; and sucrose; saponins and glycosides.

Flavonoids have long been recognised to process anti-allergic, anti-inflammatory, anti-viral, anti-proliferative and anticarcinogenic activities as well as to affect some aspects of mammalian and human metabolism. Its subclass isoflavonoids is particularly important in studying the delaying of skin ageing. Almost entirely restricted to the subfamily Papilionoidase of the Leguminosae, isoflavonoid, having similar chemical structure as 17 estradial, can effectively initiates phyto-estrogenic activities on human skin.

Tannins usually exist in roots, stems leaves and fruits. They are known to be good antioxidants, and can effectively increase SOD activities.

Lignans, usually present in the wooden part of the plant, are known to have anti-carcinogenic activities and are able to provide protection against free radical attack.

Polysaccharides are commonly found in most of the adrenal yang tonics. These include Huang Qi, Ren Xin, Huang Jing and many others. Polysaccharides are known to have positive actions on improving immunity, enhancing cellular metabolism, and increasing anti-oxidation. Saponins and glycosides have multiple bioactivities. They are known to be able to accelerate protein synthesis, to improve anti-inflammatory activities and to regulate the central nervous system.

Having briefly covered the physiological and chemical aspects of Chinese herbal medicines on the ageing process, presented in the following section of the article is a summary of key research findings on how herbal medicines delay skin ageing.

Free radical scavenging action

Free radicals including superoxide and hydroxyl radicals having strong oxidising power are responsible for the ageing of skin and body. At the cellular level, for example, superoxide attacks enzymes and the cell membrane. It focuses on unsaturated fatty acids in the cell membrane causing them to break down to form an amorphous yellow complex called lipofuscin. This gives the skin an ugly yellow colour as people grow old. The attack of superoxide on the fatty acid produces lipid peroxide. This process is known as lipid peroxidation (LPO). During this process, one of the reactive by-products is known as malonyldialdehyde (MDA) which is used as a marker of lipid peroxidation. MDA is a strong crosslinker which could react with cellular proteins, nuclei acids and lipids to form insoluble substances which stiffen the cellular membrane. The cell will then rupture and die.

Other cellular organelles including mitochondria, peroxisome and nucleus re constantly subjected to the attack by peroxide, superoxide, and hydroxyl radicals. Even cellular proteins are attacked by all reactive oxygen species. Available in the cell, an antioxidant defence system is available. For example, in the mitochondria, there are two major enzymes that control the level of peroxides. One is called catalase (CAT) and the other is called glutathione peroxidase. Other antioxidants include SOD, tocopherol and ubiquinol-10. In the cell membrane, vitamine E, thioredoxin, glutathione peroxidase, uric acid, and beta carotene are effective antioxidants. However, with age, the level of these antioxidants will go down. External help is necessary to strengthen the defence. Experimental data showed that many Chinese herbal medicines have a strong antioxidant function. Powder of Pteria martensii, for example, can reduce the level of LPO and MDA and increase SOD activity. Polysaccharide of Astragalus membranaceus including astraglan I, II, III and its flavonoids, saponins and glycosides including astragaloside VIII can inhibit lipid peroxidation. Data showed that with higher concentration the scavenging power of free radicals will increase. Experimental findings showed that actives of Astragalus membranaceus can increase the synthesis of SOD and GSH-PX enzymes which in turn reduce the LPO.

Other experimental data showed that flavonoids of bamboo leaf extract can improve the proliferation of fibroblasts and keratinocytes of skin, reduce MDA content in keratinocytes and enhance SOD activity. Cistanche salsa (Rou Cong Yong), another popular adrenal yang tonic, is also a powerful antioxidant. Data showed that its glycosides including cistanoside A, B, C, D, E, F can significantly increase SOD activity.

Another study showed that a TCM prescription comprising more than 10 herbs including Panax ginseng (Ren Xin), Ligustri lucidi (Nu Zhen Zi), Lycium barbarum (Gou Qi Zi), and Rhodiola sachalinensis (Hong Jing Tian), as principal herbs can significantly inhibit MDA production in liver and brain cells, and increase SOD activity in the brain. This prescription obviously comprises of thousands of actives including different types of flavonoids, glycosides, coumarins, alkaloids, terpenes, saponins, polysaccharides and amino acids working collectively on multiple targets. Again these principal herbs are used in popular traditional adrenal yang tonics. Other studies showed many haemostatics and emmenagogues including Angelica sinensis (Dang Guai), Morus alba (Sang Zhen), Hippophae rhamnoides (Sha Ji), Paeonia lactiflora (Bai Shao) and Dimocarpus longan (Long Yan Rou) can promote immunity and inhibit free radicals.

Collagen repair action

Collagen is the most abundant of all body proteins which make up 25% of the total as an important component of the dermis. It is an insoluble protein which is found mainly in skin, teeth, bones, and tendons. Collagen consists of many fibres which are made up of many fibrils which, in turn, are made up of smaller microfibrils. The microfibrils are made up of molecules which consist of polypeptide chains which are wrapped around one another as a triple helix providing rigidity to the molecule.

Hydroxyproline comprises 10% of the total amino acid content of collagen. It is so important that without it no triple helix is formed.

With age, the ability of collagen to respond to physical stress will decrease since hydroxyproline is the most important and stable amino acid in skin (dermis) collagen. Its relative content indirectly reflects the collagen content in the skin. This also reflects the degree of ageing of the dermis.

Studies have shown that many traditional herbal medicines have collagen repair capability in addition to free radical scavenging. For example, Poria cocos (Fu Ling) extract in high dose can increase hydroxyproline content and inhibits crosslinking of collagen protein molecules. A prescription consisting of Polygonatum sibirlcum (Huang Jing) and Lycium barbarum (Gou Qi Zi) can effectively increase hydroxyproline content and promote fibroblast production. Magnolia ficinalis (Hou Po) extract inhibits enzymatic activities of elastase, collagenase and hyaluronidase.

Danshen, Salvia miltiorrhiza, a popular emmenagogue contains actives called danshensuan B and salvianolic acid C which are potent free radical scavengers, and LPO and platelet aggregation inhibitors. It also enhances SOD activity, increases hydroxyproline content, and improves skin elasticity.

Immunity regulation

The epidermis of the skin is the natural defence against antigens invasion. Studies have shown that it contains half of the circulating T cells. In the epidermis, the first layer is the stratum corneum, next to the lipid bilayers. Within these, the natural defence tools are the low hostile PH and the langerhan cell (LC).

The langerhan cell is also known as the dendritic cell which has many spidery projections call dendrites. The LC is also known as macrophage since it can ingest and process antigens. Some scientists also believe that LC controls the division of epidermal cells and is responsible for all types of complex cellular growth. Once the LC is stimulated, it can activate macrophages in the dermis. The activated macrophages then release a series of compounds that can produce the stimulation of fibroblasts to produce collagen or elastin. When the immune system is not working well, the negative impact on collagen and elastin will delay wound healing. With ageing, there is a decreased response in many of the immune functions.

Among Chinese herbal medicines, Schisandra chinensis (Wu Wei Zi) extract can increase macrophage activity and at the same time increase SOD action. Another example is Sanqi, Panax notoginseng. Its major active, saponin glycosides, not only exhibits strong free radical scavenging ability but also can regulate skin immunity. Extract of Cuscuta chinensis on the other hand can increase production of interleulin-2 (IL-2) which improves immunity.

Skin microcirculation Improvement

Skin microcirculation can facilitate efficient nutrient supply to support cellular metabolism and regulate body temperature which is vital for skin care and to delay skin ageing. Studies showed that Danshen extract can improve capillary blood vessel circulation. The extract of Donguai and Carthamus tinctorius (Bai Zhi), is not only a powerful antioxidant because of its flavonoids, but also can effectively improve blood circulation which delays skin ageing.

Conclusion

Based on the above discussions, it is obvious that a lot of work has been done in the past decade on identifying and developing Chinese herbal actives to delay skin ageing.

However, it is also apparent that more work needs to be done on validation of TCM multi-herb prescriptions. The challenge ahead is to design methodologies to study the interactions of hundred of actives present in a prescription. The complexities of tracing chemical reactions are mind bogging if one adopts only the Western style of analysis. Many scientists in China recommended treating the whole prescription as one single unit. The ultimate therapeutic benefits are the integrative result of the actives’ interactions. In other words, the in vivo and clinical test results are more indicative of the functional value of the prescription. Some scientists, on the other hand, still believe that searching the molecular targets of specific herbal ingredients is worthwhile. A survey showed that the combination of both approaches will be the research direction in the years ahead to define both the cosmetic and therapeutic benefits generated by synergy created by TCM prescriptions.

On addressing cosmetic benefits based on TCM actives, there is another frontier that requires more research efforts. While scientists are busy defining and harnessing the power of phyto-synergy, it appears that there are only limited studies into developing the effective delivery systems for the actives. There is more documentation on how the TCM prescriptions work when taking orally in both modern and classical literatures. When the prescription applies to the skin, the transdermal behaviour and dynamics of these actives has yet to be studied.

References

1 Qian Wang and Linning Cai: The research status of Traditional Chinese Medicine on Delaying Skin Senility.

2 Arthur Vander, James Sherman & Dorothy Luciano: Human Physiology.

3 Peter To Pugliese: Physiology of the Skin II.

4 Tijun Zhang and Changqin Chen: Anti-aging and Anti-fatigue Traditional Chinese Medicine – Research and Application.

5 Qi Wang, Yu Shi, C. Viennet, Ni Li and P. Humbert: Effects of Astragaloside on Growth Activity and Apoptosis of Fibroblasts From Human Skin.

6 Qian Wang: Free Radical Theory and The Research Status of Traditional Chinese Medicine on Delaying Skin Senility.

7 Shouying Yu, Jingyao Huang, Pang Xu, et al: Anti-Aging Mechanism of Polygonatum Sibirlcum and Lycium Barbarum.