Matthew Woll and Dr. Noel Owen, Chemistry and Biochemistry

Many important and useful biological compounds are found in plants. Extensive work has been done on evaluating anti-cancer 1, 2, anti-malarial 3, and anti-viral 4 properties of plants. The Yaqui Indians of northern Mexico have traditionally used many natural products to cure various diseases. Gloria Moroyoqui, the daughter of a Yaqui Indian shaman (medicine man) explained to us some of the plants and their uses as medicine. The Yaqui Indians have used Rhamnacae ziziphus obtusifolia, commonly known as graythorn, as a cancer chemotherapeutic agent.

The goal of my research project was to isolate and identify chemical compounds from graythorn that may make a significant contribution to the treatment of certain types of cancer. Upon receiving the plant from southern Arizona, I tested the crude extracts and found them to show significant activity against a cervical cancer cell line called HeLa cells. HeLa cells are a common in vitro standard used by many to evaluate the activity of anti-cancer agents.5

Further separation of the active crude extract compounds was accomplished through bioassay guided separations. This involves testing the fractions obtained from the separations on HeLa cells and then further separating the active fractions. Open column silica gel chromatography was used for the primary separations and then high performance liquid chromatography (HPLC) for the purification of individual compounds. Three pure compounds were isolated from the separations each weighing between 10-15 mg.

Using the purified compounds obtained from the separations I began the structural elucidation using molecular spectroscopy. Mass spectrometry and Nuclear Magnetic Resonance (NMR) spectroscopy were the primary techniques employed. Mass spectrometry gave me the physical data needed to determine the probable molecular formula of an unknown compound. One and two-dimensional NMR techniques such as 1H, 13C, DEPT, COSY, HETCOR, NOESY, HMBC, and INADEQUATE have been used and interpreted in determining the structure of the compound. Each compound looks to be some type of triterpenoid, but the exact structures are still being determined. All of the spectroscopy was done in the Brigham Young University Chemistry Department with the help of Bruce Jackson and Du Li.

My initial objective was to further test the isolated compounds on various cancer and noncancerous cell lines. I have not been able to accomplish the testing. The compounds that were isolated were active against the original cervical cancer line, but not active enough to be very interesting in further testing.

Graythorn still has many other compounds that have not been isolated that could be more active against cancer cells. Further work will need to be done in isolating these compounds. The compounds that I isolated will be identified and could be interesting novel compounds in chemistry.

References

1. Slichenmyer W., Von-Hoff D., J Clin Pharmacol 1990, 770-788.
2. Tsukagoshi S., Gan To Kagaku Ryoho 1993, 20, 425-431.
3. Carvalho L., Krettli A., Mem Inst Oswaldo Cruz 1991, 86, 181-184.
4. Houghton P., Trans R Soc Trop Med Hyg 1996, 90, 601-604.
5. Alley M., Scudiero D., Monks A., Hursey M., Czerwinski M., Fine D., Abbott B., Mayo J., Shoemaker R., Boyd M., Cancer Res 1988, 48, 589-601.