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The Pharmacological Activity of Scutellaria Plants
Volume 12, Number 24: 17 June 2009

Scutellaria plants are herbaceous perennials that possess numerous medicinal properties. According to Stutte et al. (2009), they are "rich in physiologically active flavonoids that have a wide spectrum of pharmacological activity." In this regard, for example, they say leaf extracts of Scutellaria barbata have been found "to be limiting to the growth of cell lines associated with lung, liver, prostate, and brain tumors (Yin et al., 2004)," and that "extracts of S. lateriflora and the isolated flavonoids from the extracts have been shown to have antioxidant, anticancer, and antiviral properties (Awad et al., 2003)." Hence, it is only natural to wonder how the growth of these important plants -- and their significant medicinal properties -- might be affected by the ongoing rise in the air's CO2 content.

In an attempt to shed further light on the subject, Stutte et al. conducted experiments with both S. barbata and S. lateriflora, where they measured effects of elevated atmospheric CO2 concentrations (1200 and 3000 ppm vs. a control value of 400 ppm) on total plant biomass production and plant concentrations of six bioactive flavonoids -- apigenin, baicalin, baicalein, chrysin, scutellarein and wogonin -- all of which substances, in their words, "have been reported to have anticancer and antiviral properties," as described in the review papers of Joshee et al. (2002) and Cole et al. (2007). These experiments were conducted in a large step-in controlled-environment chamber that provided a consistent light quality, intensity and photoperiod to six smaller plant growth chambers that had "high-fidelity control of relative humidity, temperature, and CO2 concentration," each of which chambers was also designed to monitor nutrient solution uptake by six individual plants that they grew from seed for a period of 49 days.

With respect to plant productivity, i.e., fresh and dry weight production, the three U.S. researchers determined that in the case of S. barbata, increasing the air's concentration of CO2 from 400 to 1200 ppm resulted in a 36% increase in shoot fresh weight and a 54% increase in shoot dry matter, with no further increases between 1200 and 3000 ppm CO2. In the case of S. lateriflora, on the other hand, the corresponding increases in going from 400 to 1200 ppm CO2 were 62% and 44%, while in going all the way to 3000 ppm CO2, the total increases were 122% and 70%, respectively.

With respect to total flavonoid concentrations in the plants' vegetative tissues, Stutte et al. report that in the case of S. barbata, "the combined concentration of the six flavonoids measured increased by 48% at 1200 and 81% at 3000 ppm CO2," while in S. lateriflora they say "the total flavonoid content increased by over 2.4 times at 1200 and 4.9 times at 3000 ppm CO2." Thus, in consequence of the compounding effect of increases in both plant biomass and flavonoid concentration, the total flavonoid content in S. barbata rose by 72% in going from 400 to 1200 ppm CO2, and by 128% in going all the way to 3000 ppm CO2, while in S. lateriflora the corresponding increases were a huge 320% and a mind-boggling 1,270%.

In the concluding sentence of their paper's abstract, Stutte et al. say their results indicate that "the yield and pharmaceutical quality of Scutellaria species can be enhanced with controlled environment production and CO2 enrichment," and massively so, we would add. In addition, since they indicate that over 200 substances -- of which over 80% are flavonoids -- have been found in a total of 65 Scutellaria species, it would appear that "increased concentration of flavonoids through CO2 enrichment," as they describe it, "has the potential to enhance the production and quality of [many, we would add] medicinal plants."

Sherwood, Keith and Craig Idso

Awad, R., Arnason, J.T., Trudeau, V., Bergeron, C., Budziinski, J.W., Foster, B.C. and Merali, Z. 2003. Phytochemical and biological analysis of skullcap (Scutellaria lateriflora L.): A medicinal plant with anxiolytic properties. Phytomedicine 10: 640-649.

Cole, I.B., Sacena, P.K. and Murch, S.J. 2007. Medicinal biotechnology in the genus Scutellaria. In Vitro Cellular & Developmental Biology - Plant 43: 318-327.

Joshee, N., Patrick, T.S., Mentreddy, R.S. and Yadav, A.K. 2002. Skullcap: Potential medicinal crop. In: Janick, J. and Whipkey, A. (Eds.). Trends in New Crops and New Uses. ASHS Press, Alexandria, VA, USA, pp. 58-586.

Stutte, G.W., Eraso, I. and Rimando, A.M. 2008. Carbon dioxide enrichment enhances growth and flavoniod content of two Scutellaria species. Journal of the American Society for Horticultural Science 133: 631-638.

Yin, X., Zhou, J., Jie, C., Xing, D. and Zhang, Y. 2004. Anticancer activity and mechanism of Scutellaria barbata extract on human lung cancer cell line A549. Life Science 75: 2233-2244.