By Maria M. Lameiras

New research on using controlled environment agriculture (CEA) to grow plants with medicinal properties could lead to production methods that will increase one anti-cancer compound naturally produced by certain species of plants.

The study, led by doctoral student Rebekah Maynard, was designed to identify crops to be used in medical treatments and to develop strategies to increase the concentration of an anti-cancer compound produced by the plants.

Using controlled environment agriculture to grow medicinal plants

Working with Rhuanito Ferrarezi, associate professor of CEA crop physiology, Maynard grew compact crops with a short life cycle — chamomile (Matricaria chamomilla) and parsley (Petroselinum crispum) — in a vertical farming environment. The researchers measured the plants’ production of apigenin, a natural anti-inflammatory compound with promising anti-cancer effects.

“Beyond citrus, which is a naturally high-yielding producer of apigenin, but wouldn’t be a good option for a vertical farm, parsley was listed as the No. 1 producer of apigenin,” Maynard explained. “While chamomile was reported to produce less apigenin than parsley, we wanted to experiment with it because it is a compact plant that could be grown in a vertical farm.”

In the study published in the journal HortScience, two cultivars of chamomile — ‘Bodegold’ and ‘Zloty Lan’ — and three cultivars of parsley — ‘Darki’, ‘Giant of Italy’ and ‘Wega’ — were grown in an indoor vertical farm to see how the indoor environment affected apigenin production and plant size. 

Chamomile and parsley as natural sources of an anti-cancer compound

After 15 weeks, mature parsley leaves and unopened chamomile flowers were harvested for analysis. While the parsley cultivar ‘Giant of Italy’ produced the largest plants of any of the cultivars, total apigenin accumulation was higher in the ‘Bodegold’ chamomile compared to any parsley cultivar, also generating more usable biomass.

“Apigenin can also be chemically synthesized, but the current approach is a multi-day, four-step process that does not produce a great yield,” said Maynard. “We found that we can grow these crops year-round in a vertical farm, so this is a feasible growing environment alternative.”

With an increase in investment in vertical farming across the nation, identifying crops — both for consumption and other applications — is an important line of research for the industry.

“Everyone is looking for an alternative crop to guarantee that all of that expensive infrastructure is profitable. We not only looked into the crops themselves but into finding a compound of interest in those crops. These were the species chosen for the purpose,” Ferrarezi said.

“If we could prove that we could grow them and then extract the compound of interest, that could increase the profitability of vertical farms and make them financially feasible.”

An initial study, specifically targeting biopharmaceuticals, served to find fast-growing, efficient crops that could be produced on a massive scale, an important consideration for the profitability of controlled-environment agriculture.

How UV light influences apigenin production

While the growth of most of the plants was successful, Maynard was surprised to find that the plants produced less apigenin than expected. “Since secondary metabolites are often produced as a stress response, we thought the lower levels may be because there was no UV light in the vertical farm,” she said. Secondary metabolites are organic compounds produced by organisms that are not essential for their growth, development or reproduction.

In a follow-up study, Maynard added UV lighting to growth chambers when repeating the experiment. While those findings have not yet been published, Maynard said apigenin production increased significantly in the parsley cultivars.

“This is an exciting result, but there is a lot more work that needs to be done to get this optimized to the point that we could create recommendations for a grower for optimized procedures,” added Ferrarezi, whose lab is also conducting similar research to extract alkaloid anti-cancer compounds from Madagascar periwinkle (Catharanthus roseus).

“We are identifying the stressors that could increase the concentration of those alkaloids. Because UV is such a stressor to plants, the idea is to use it to screen other crops and molecules,” he added.

Vertical farming for future biopharmaceuticals

Maynard, whose undergraduate degree was in chemistry, is focusing her doctoral dissertation on the accumulation of secondary metabolites, specifically apigenin, in specific herbs grown in controlled environments.

This is the first publication on biopharmaceuticals released from Ferrarezi’s lab. Maynard is working on the publication of a second paper on the research before defending her thesis in March.

“We learned quite a lot about these compounds and how they are triggered by different physiological processes. We don’t do a lot of biochemistry in CEA, but the core of the research is to find production methods for plants that can be used to increase the production of those compounds. We focused on the plant science aspect of it,” Ferrarezi said.