A chemical derived from plants in Africa has been shown to stop the spread of tumors caused by multidrug-resistant forms of cancer.

A study conducted at Johannes Gutenberg University Mainz determined that medicinal plants from the Republic of Cameroon in Central Africa contain a chemical substance, known as benzophenones (an active ingredient in most sunscreen products), with possible therapeutic benefits.

"The benzophenones investigated are potentially cytotoxic substances that need to be more extensively investigated with the aim of developing new cancer drugs that are effective against susceptible and resistant cancers," claims the study.

Biochemist Dr. Victor Keute of the University of Dschang in Cameroon and fellow researcher Professor Thomas Efferth at Mainz University oversaw four years of experimentation probing the possible medical benefits of various plant species including the giant globe thistle, wild pepper, speargrass, and Ethiopian pepper. Efferth has also conducted research dealing with medicinal plants used in traditional Chinese medicine.

"The active substances present in African medicinal plants may be capable of killing off tumor cells that are resistant to more than one drug. They thus represent an excellent starting point for the development of new therapeutic treatments for cancers that do not respond to conventional chemotherapy regimens," said Efferth.

Findings produced by the research team's cellular models focused on three different resistant mechanisms:

1. Transporter-mediated resistance - Resistant protein known as P-glycoprotein inhibits the effectiveness of most cancer drugs.

2. Tumor-suppressor-gene-mediated resistance - Cancerous cells are intensified by a mutation in the protein p53.

3. Oncogene-mediated resistance - Tumors continue to spread through signals produced by the epidermal growth factor receptor (EGFR).

Efferth and his colleagues established that four types of naturally-occurring benzophenones in African medicinal plants were able to prevent the spread of tumor-producing cancer cells. These substances will undergo further laboratory examination to confirm their remedial effects.

"We have already found an entire series of benzophenones and other phytochemicals that are able to elude resistance mechanisms and thus offer many new opportunities for continued research," explained Efferth.

"We are now looking for substances that can both break down tumor resistance and not produce side effects."

Source: Efferth T, Keute V. Substances from African medicinal plants could help stop tumor growth. Phytomedicine. 2013.