The traditional Chinese herb Scutellaria (called skullcaps in the West) contains a combination of plant chemicals that together can significantly slow the growth of several different cancers, according to a study published in the January 2009 issue of Planta Medica.
The authors say this herb might prove an important addition to current cancer treatments. “On the basis of our preliminary results, we expect maximum benefit from Scutellaria…in combination with standard therapy such as surgery, chemotherapy, and immunotherapy,” says Prahlad Parajuli, PhD, assistant professor in the Department of Neurosurgery at Wayne State University and Karmanos Cancer Institute in Detroit, Michigan.
Past studies have shown that Scutellaria has potent antibacterial, anti-inflammatory, and anti-cancer properties, which come primarily from natural plant chemicals (phytochemicals) called flavonoids. Most of the research conducted on Scutellaria so far has focused on the roots of the herb, which are rich in the flavonoid wogonin. However, the leaves and stems are also thought to be high in cancer-fighting phytochemicals, according to study co-author Nirmal Joshee, PhD, assistant professor of Plant Science at Fort Valley State University in Georgia.
To learn more about this herb and how it might combat cancer, the researchers analyzed leaf, stem, and root extracts from 13 different Scutellaria species. They found that each extract contained different combinations of six flavonoids: apigenin, baicalein, baicalin, chrysin, scutellarein, and wogonin. Most extracts contained three or four different flavonoids. Two extracts contained all six flavonoids.
They then treated human breast, prostate, and brain cancer cells, as well as non-cancerous cells, with the Scutellaria extracts. Nine of the extracts significantly halted the spread of cancer cells. The higher the dose and longer the duration of treatment, the more effectively the extracts killed cancer cells. Four extracts—all from the Scutellaria leaf—were particularly effective at triggering the death (apoptosis) of brain cancer cells.
The researchers also looked at how the flavonoids in Scutellaria—both individually and in combination—affected cancer cells. A combination of four flavonoids, each at a low dose, blocked the growth of brain cancer cells by almost 50 percent. However, when those same flavonoids were given individually at the same dose, they had no effect on the cancer, which suggests that each one possesses a different anti-cancer mechanism and the effects are amplified when the different flavonoids work together.
Future studies will help determine which combination, or combinations of phytochemicals have the greatest cancer-fighting ability. “Combining phytochemicals with synergistic anti-cancer activity would allow use of individual components at a very low dose, which would eliminate or reduce toxicity,” explains Dr. Parajuli.
Certain flavonoids in Scutellaria also appeared to target specific types of cancer. For example, baicalein significantly slowed the growth of brain cancer cells. This may be because individual flavonoids affect mechanisms that are unique to each cancer, the authors say.
Based on the promising results of studies done so far, the researchers say they may launch a human clinical study to investigate Scutellaria as an adjuvant cancer treatment within a few years.
Parajuli P, Joshee N, Rimando AM, Mittal S, Yadav AK. In vitro antitumor mechanisms of various Scutellaria extracts and constituent flavonoids. Planta Medica. 2009;75:41-48.