A new study, published in the journal Science Advances, has revealed how the popular Chinese herbal remedy Huang-Qin (Scutellaria baicalensis) — also known as the Chinese skullcap — produces compounds which may help to treat cancer and liver diseases.

The Chinese skullcap is cultivated in China, Siberia, Mongolia and Korea. It is an herb used in traditional Chinese medicine to treat a variety of conditions including epilepsy, hepatitis, infections, and cancer. It is often used in combination with other botanicals such as PC-SPES and sho-saiko-to.

Previous research on cells cultured in the lab has shown that certain compounds called flavones — found in the roots of the Chinese skullcap — not only have beneficial anti-viral and anti-oxidant effects, but they can also kill human cancer cells while leaving healthy cells untouched.

In live animal models, these flavones have also halted tumor growth, offering hope that they may one day lead to effective cancer treatments, or even cures.

As a group of compounds, the flavones are relatively well understood. But the beneficial flavones found in the roots of the Chinese skullcap — such as wogonin and baicalin — are different: a missing hydroxyl (-OH) group in their chemical structure left scientists scratching their heads as to how they were made in the plant.

“Many flavones are synthesized using a compound called naringenin as a building block,” said study senior author Prof. Cathie Martin, from the John Innes Centre in Norwich, UK.

“But naringenin has this -OH group attached to it, and there is no known enzyme that will remove it to produce the flavones we find in the Chinese skullcap roots.”

Prof. Cathie and her colleagues explored the possibility that Chinese skullcap’s root-specific flavones (RSFs) were made via a different biochemical pathway.

Step-by-step, they unraveled the mechanism involving new enzymes that make RSFs using a different building block called chrysin.

“We believe that this biosynthetic pathway has evolved relatively recently in Scutellaria roots, diverging from the classical pathway that produces flavones in leaves and flowers, specifically to produce chrysin and its derived flavones,” Prof. Martin said.

“Understanding the pathway should help us to produce these special flavones in large quantities, which will enable further research into their potential medicinal uses.”

“It’s exciting to consider that the plants which have been used as traditional Chinese remedies for thousands of years may lead to effective modern medicines,” she added.

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Qing Zhao et al. 2016. A specialized flavone biosynthetic pathway has evolved in the medicinal plant, Scutellaria baicalensis. Science Advances, vol. 2, no. 4, e1501780; doi: 10.1126/sciadv.1501780