Bio-Inspiration- Turtle's Shell used as Chinese Medicine

Turtle shell has been used as both food and medicine since ancient time in China and is recorded in the Shennong Bencao Jing, which is a medical handbook that being used by the ancient physician for centuries as a standard guideline for chinese medicine practice. According to the chinese medicine, turtle shell is often use in rehmannia-based formulas that nourish the Yin and calm the Yang. In modern study, it found that turtle shell does provide a significant hormone effect to human body which caused by the nutritional components (calcium and protein) contains inside the turtle shell.  

Figure 1. The cover page of Shennong Bencao Jing. It is a medicinal handbook that commonly used in the chinese medicine practice

The bottom part of the turtle shell, which is also known as plastron, is the desire part which has significant pharmacological value instead of the top part of the shell (also known as carapace). Although study showed that there are twice the amount of gelatin (desired bioactive compound) as the plastron from the carapace, but the consumption of plastron is still higher than carapace for chinese medicine. The plastron is separated from the animal carcass and cook in 20% lime water in high temperature and the water is consumed by the patient. In addition, vinegar processing is consider another well known method that able to boil the collagen from plastron into gelatin.

Figure 2. Chemical structure of gelatin

The major chemical constituents of turtle shell (plastron and carapace) are calcium, collagen, gelatin, and a trace amount of fats, magnesium, zinc, vitamin D. The calcium compound make up the major part of the shell and  is able to cure calcium deficiency-related disease such as bone disease ricket, which is caused by impaired deposition of bone calcium. According to a case study, it was reported that calcium provided by the turtle shell has similar effect as the calcium supplement such as cod liver oil and calciferol. Moreover, the gelatin (make up 7% of the plastron) converted from collagen in boiled water is develop to inhibit arthritis, angiogenesis. In addition, the gelatin polypeptides (fragments that produced from digestion) is able to treat bleeding as well. Moreover, a turtle shell-based formula that combined with methimazole to treat Grave's disease showed that 14 out of 25 patients had complete remission of symptoms at the end of the treatment. The raw turtle shell is also reported to traditional use for treating vertigo, tinnitus, deafness, headache, and convulsion.     

Figure 3. Actual view of plastron of a turtle

References

1. S. Dorr, "Tortoise Shell: with Brief Reports on Treating Aplastic Anemia and Parkinson's Disease", Itmonline.org, 2016. [Online]. Available: http://www.itmonline.org/arts/tortois2.htm. [Accessed: 04- Jul- 2016].