The research developed out of Rutgers' Lilium species breeding program, which develops hybrid lilies as potted plants for holiday sales and as plants for the garden. According to Thomas Gianfagna, lead researcher and professor of plant biology in RU's Plant Biology & Pathology department, lily bulbs are used in China as a food and medicine to treat coughs and upper respiratory infections.
Although the lily's active compounds are unknown, lily bulbs contain significant quantities of steroidal glycosides and polyphenols that may be responsible for biological activity. Further, plants in the lily family contain steroidal saponins, which are cytotoxic to cancer cells. "We decided to try and identify the steroidal glycosides from our bulbs to determine if they have medicinal or cosmetic value," professor Gianfagna said.
The team's preliminary experiments with several lines of human cancer cells showed that extracts from the bulbs were "very cytotoxic" to MCF-7 breast cancer cells and HL-60 leukemia cells. "We have now identified steroidal saponins and steroidal alkaloids in lily bulbs that may contribute to the cytotoxicity of bulb extracts to human cancer cells, as well as to other medicinal uses of this plant," commented professor Gianfagna, who credited graduate student Nimmi Rajmohan with beginning the work.
One of the steroidal alkaloids identified is a new structure and the other has been identified in L. brownii bulbs. In addition, they identified three steroidal saponins that differ slightly in structure from the saponins identified by researchers in 1992. "Our compounds are all furastanols and have a free hydroxyl group at the C-22 position whereas the saponins reported by Mimaki et al (1992) are methoxylated at C-22," professor Gianfagna said. The presence of a methoxy group at C-22 may be due to the extraction method, which the team plans to test.
"The identifications of the steroidal glycosides were completed by NMR spectrometry of the purified compounds," he explained. "We used solvent partitioning of a freeze-dried bulb extract with pentanes and ethyl acetate to remove lipids, and other non polar compounds, followed by partitioning of the steroidal glycosides into butanol. The butanol fraction was purified by preparative HPLC using a reverse phase column."
In total, the researchers have identified a total of five pure compounds-four new compounds, and one compound that is new to the species Lilium longiflorum-in mg quantities to test alone and in combination in the cancer cell growth assays. "The compounds are steroidal glycosides, two are steroidal glycoalkaloids and three are furostanols," said professor Gianfagna. "This work was done by another of my graduate students, John Munafo."
The five compounds will serve as the basis for the next stage of their research. "If these groups of compounds are responsible for the cytotoxic activity of the bulb extract, we will continue on to studies designed to understand their mechanism of action," he said. "We will be testing our extracts and pure compounds in a variety of studies to determine if they may be used as nutritional supplements to reduce risks of disease from cancer to type 2 diabetes.
"The lily bulb itself is edible and is prepared in stir-fry dishes or in soups," he continued. "We may offer lily bulbs as a functional food. We also hope to test our extracts in skin care assays. I think people would love to use products like body washes and skin creams containing these beautiful plants. Our cancer cell experiments will continue for another year. Right now we are busy purifying enough of our new compounds to test along with our extracts."
The results of the research are currently being written up for publication in the journal Phytochemistry.
Functional Fast Track
One company ready to jump into the realm of lily bulbs as functional foods is Harbor, OR-based WF Holding LLC, whose parent company, Winharbor Farms, has been a commercial grower of the field-grown bulbs for more than 30 years. "Until recently, our primary market was growing the bulbs for the green house/potted plant market for the Easter season; however our cultivation is very much in keeping with food crops, such as potatoes," said Donna Freeman, of WF Holding. "Our bulbs are Lilium longiflorum, as are the imported bulbs from China, referenced in Traditional Chinese Medicine for centuries. Lilium longiflorum are in the Lily family, as are onion, garlic, kale, aloe and asparagus."
Ms. Freeman said the company has long known that its bulbs are considered a food in Japan, China and even in some upscale restaurants throughout the U.S., which feature entrees such as red snapper and lily bulb broth on their menus.
She said recent university and medical research regarding the health benefits have made the whole food market a real possibility in the U.S., especially when it comes to fresh and pureed bulbs for use in soups. "We plan to be in the functional whole food market this fall, with our bulbs being commercially processed and packaged. Presently, I am working with a regional soup company in Portland, OR, to develop soup and menu entrees for breast health, with our primary consumers being women."
Ms. Freeman said the growing and harvesting process of lily bulbs is much like that of other vegetables. Low temperature storage is important to preserve the saponins. "In food processing and cooking, blanching is preferred, as high temperatures do compromise the health benefits, as does boiling of any fruit or vegetable," she said.
Following the harvest of its 2009 crop in late August, the company will be offering its lily bulb product in fresh, pureed and freeze-dried varieties.