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Flavonoid Production in a CO2-Enriched Medicinal Plant
Moghaddam, S.S., Jaafar, H.B., Aziz, M.A., Ibrahim, R., Rahmat, A.B. and Philip, E. 2011. Flavonoid and leaf gas exchange responses of Centella asiatica to acute gamma irradiation and carbon dioxide enrichment under controlled environment conditions. Molecules 16: 8930-8944.

Centella asiatica or Gotu Kola is a small herbaceous annual plant that has been used as a medicinal herb or nutraceutical in Ayurvedic, African and traditional Chinese medicine for more than 2000 years, where it is valued for its mildly antibacterial, antiviral and anti-inflammatory properties. It has been used a rejuvenating diuretic herb that is purported to clear toxins, to reduce inflammations and fevers, to improve healing and immunity, to improve memory, and to have a balancing effect on the nervous system, as well as a whole host of other uses to which it has been put over the ages and in different parts of the world.

What was done
Well watered and fertilized C. asiatica plants were grown for four to five weeks in individual polybags filled with a 1:1:1 mix of sand, coco dust and compost within controlled environment chambers, where CO2 concentrations of 400 and 800 ppm were maintained, in the words of the researchers, "for two hours every day between 8:30 to 10:30 am," at the ends of which four- to five-week periods the plants were harvested and their leaves assessed for total biomass and total flavonoid content, the latter of which set of substances is considered to be the source of the many health benefits attributed to the species.

What was learned
Moghaddam et al. report that the daily two-hour 400-ppm increase in the controlled environment chambers' atmospheric CO2 concentration led to a 193% increase in C. asiatica leaf biomass, a 264% increase in plant water use efficiency, as well as a 171% increase in leaf total flavonoid content.

What it means
The six Malaysian scientists conclude that "collectively, the enhancement in yield and quality provides an economic motivation to produce a consistent pharmaceutical-grade product for commercial purposes," via what they describe as "controlled environment plant production." And it also stands to reason that the ongoing rise in the atmosphere's CO2 concentration should gradually increase the medicinal potency of C. asiatica plants either growing wild or cultivated out-of-doors.

Reviewed 28 March 2012