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CO2 Enrichment of a Highly-Prized Chinese Medicinal Herb
Hao, X., Li, P., Feng, Y., Han, X., Gao, J., Lin, E. and Han, Y. 2013. Effects of fully open-air [CO2] elevation on leaf photosynthesis and ultrastructure of Isatis indigotica Fort. PLOS ONE 8: e74600.

The authors write that the highly-valued Chinese herb Isatis indigotica (Chinese Woad) "has multiple pharmacological properties such as anti-viral, anti-cancer, anti-bacterial and immune enhancement (Kong et al., 2008; Shin et al., 2010)" and that "it can reduce fever, detoxify and benefit the pharynx (Qing, 2009)." In addition, they say that the adenosine contained in its tissues "can be used as a cardio-protective and therapeutic agent for chronic heart failure (Guo et al., 2006; Ding et al., 2008)" and that it also "shows anti-inflammatory efficacy (Asako et al., 1993)," while "the most popular medicine form of the herb is indigowoad root infusion, which is used for treating flu." And in light of these many benefits of the plant to human health, they state that the amount of adenosine contained by the herb "is an indicator of the quality of indigowoad root (Ding et al., 2008)."

What was done
At a Free-Air CO2 Enrichment (FACE) facility located in Changping, Beijing, China, Hao et al. measured a number of physical and physiological properties of I. indigotica plants grown from seed in pots filled with a clay loam soil and at atmospheric CO2 concentrations of either 411 ppm (ambient) or 550 ppm (elevated) under well-watered and fertilized conditions for a period of 84 days, after which root adenosine contents were extracted and assessed.

What was learned
The seven Chinese scientists report that the net photosynthesis rates of fully-expanded upper leaves at 36, 53 and 84 days after planting were increased, respectively, by 13.1, 22.8 and 27.1%, while plant water use efficiencies were increased by 1.3, 28.9 and 20.7%, with the end result that total weight per plant was enhanced by 8.8% in the elevated CO2 treatment. However, they go on to say that "elevated CO2 increased the weight of root per plant by 17.4%," which for a 300-ppm increase in the air's CO2 concentration would translate into to an increase of 37.6% for the root-derived adenosine.

What it means
As the air's CO2 content continues to rise, the abundance of health-promoting adenosine derived from the roots of the Chinese Woad plant should grow right along with it, to the benefit of many people with a number of different health problems.

Asako, H., Wolf, R.E. and Granger, D.N. 1993. Leukocyte adherence in rat mesenteric venules: effects of adenosine and methotrexate. Gastroenterology 104: 31-37.

Ding, Y., Zhang, T. and Tao, J.S. 2008. The research of effective components in radix isatidis. Chinese Traditional Patent Medicine 30: 1697-1701.

Guo, L., Liang, H.X., Zhao, B. and Fang, S.G. 2006. The measure of adenosine content in the radix isatidis and folium isatidis. Chinese Traditional Patent Medicine 28: 1064-1066.

Kong, W., Zhao, Y., Shan, L., Xiao, X. and Guo, W. 2008. Thermochemical studies on the quantity-antibacterial effect relationship of four organic acids from Radix isatidis on Escherichia coli growth. Biological & Pharmaceutical Bulletin 31: 1301-1305.

Qing, C. 2009. Pharmacological effects and clinical application of Radix isatidis. Chinese Pharmaceutical Affairs 23: 607-608.

Shin, E.K., Kim, D.H., Lim, H., Shin, H.K. and Kim, J.K. 2010. The anti-inflammatory effects of a methanolic extract from Radix isatidis in murine macrophages and mice. Inflammation 33: 110-118.

Reviewed 12 February 2014