West African Plants Studied for Inflammation and Cancer Prevention

Division of Cancer Prevention

Research findings about the harmful effects of chronic inflammation on human health – plus the extensive expe­rience with studying the effects of aspirin and other nonsteroidal anti-inflammatory drugs – have led researchers to suspect a link between chronic inflammation and cancer. In particular, cyclo­oxygenase (COX) enzymes were found to be turned on by the body in response to long-term inflammation and in the early signs of cancer activity. One class of drugs to reduce pain and inflammation, called COX-2 inhibitors, have shown preliminary signs of success in reducing the development of adenomas that are known to lead to colorectal cancer.

However, problems arose when the most celebrated of these drugs rofecoxib (Vioxx) was pulled off the market in 2004, because it posed an increased risk of heart attack, stroke, and gastrointestinal bleeding. A similar drug celecoxib (Celebrex) is still in use but also carries the same risks. This led Michael Wargovich, Ph.D., F.A.C.N., to wonder “if there might be natural products that would hit these same targets but hopefully without the significant side effects.”

Dr. Wargovich, a professor of Cell and Molecular Pharmacology at the Medical University of South Carolina, said his interest in ethnobotany is long-standing and started during a visit to Conakry, capital of the Republic of Guinea in West Africa. An official in the Republic of Guinea’s Ministry of Health provided Dr. Wargovich with a catalog of traditional African medicines. He subsequently developed a short-list of plants that practicing native healers use for pain and inflammation. Dr. Wargovich eventually returned to his laboratory with five promising West African plant extracts from the neem and baobab trees, African basil, the kinkrissi bush, and the bark of the Senegal mahogany tree.

With NCI funding*, Dr. Wargovich is studying these natural products in rigorous detail. “There are a number of important steps we need to go through, but eventually, we hope to find the active inhibitors of the pathways leading to inflammation, polyps, and colon cancer,” he explained. This entails exposing cancer cells to the isolates and extracts, which Dr. Wargovich and his colleagues develop from the African plants. The researchers also test these plants for specific kinds of anticancer activity, especially COX inhibition, on colon cancer cell lines. Once the active ingredients are isolated and characterized, they hope to learn more about the mechanisms that appear to be working against cancer and test them in animal models.

If successful, the work may eventually progress to human studies, Dr. Wargovich said. “The current COX-drugs are expensive,” he commented. “It would be helpful to develop an alternative that was derived from traditional medicine which could be more cheaply available as a preventive in Africa and the developing world.”

NCI Division of Cancer Prevention Program Director Vernon Steele, Ph.D., M.P.H., commented, “This is a interesting and potentially very important study on West African medicinal plants to prevent cancer. These plant extracts should present a much lower toxicity profile (necessary for cancer prevention-type drugs) based on generations of use in the African people. There are currently few studies of traditional herbal medicines worldwide to prevent cancer.”