Science News
from research organizations

Orange lichens are potential source for anticancer drugs

Parietin pigment kills leukemia cells, combats Warburg effect

October 19, 2015
Emory Health Sciences
An orange pigment found in lichens and rhubarb called parietin may have potential as an anti-cancer drug because it interferes with the metabolic enzyme 6PGD, scientists have discovered.


An orange pigment found in lichens and rhubarb called parietin may have potential as an anti-cancer drug, scientists at Winship Cancer Institute of Emory University have discovered.

The results are scheduled for publication on October 19 in Nature Cell Biology.

Parietin, also known as physcion, could slow the growth of and kill human leukemia cells obtained directly from patients, without obvious toxicity to human blood cells, the authors report. The pigment could also inhibit the growth of human cancer cell lines derived from lung and head and neck tumors when grafted into mice.

A team of researchers led by Jing Chen, PhD, discovered the properties of parietin because they were looking for inhibitors for the metabolic enzyme 6PGD (6-phosphogluconate dehydrogenase). 6PGD is part of the pentose phosphate pathway, which supplies cellular building blocks for rapid growth. Researchers have already found 6PGD enzyme activity increased in several types of cancer cells.

"This is part of the Warburg effect, the distortion of cancer cells' metabolism," says Chen, professor of hematology and medical oncology at Emory University School of Medicine and Winship Cancer Institute. "We found that 6PGD is an important metabolic branch point in several types of cancer cells."

This work represents a collaboration among three laboratories at Winship led by Chen, Sumin Kang, PhD, assistant professor of hematology and medical oncology, and Jun Fan, PhD, assistant professor of radiation oncology. Co-first authors are postdoctoral fellows Ruiting Lin, PhD, and Changliang Shan, PhD, and former graduate student Shannon Elf, PhD, now at Harvard.

The Winship team obtained cancer cells from a patient with acute lymphoblastic leukemia, and found doses of physcion/parietin that could kill half the leukemia cells in culture within 48 hours, while the same doses left healthy blood cells unscathed. A more potent derivative of the pigment called S3 could cut the growth of a lung cancer cell line by a factor of three over 11 days, when the cells were implanted into mice.

Although 6PGD inhibitors appear to be nontoxic to healthy cells, more toxicology studies are needed, both to assess potential side effects and to see whether people with inherited conditions would be more sensitive to the drugs. Parietin is present in some natural food pigments, but has not been tested as a drug in humans.


Story Source:

Materials provided by Emory Health Sciences. Note: Content may be edited for style and length.

Journal Reference:

  1. Ruiting Lin, Shannon Elf, Changliang Shan, Hee-Bum Kang, Quanjiang Ji, Lu Zhou, Taro Hitosugi, Liang Zhang, Shuai Zhang, Jae Ho Seo, Jianxin Xie, Meghan Tucker, Ting-Lei Gu, Jessica Sudderth, Lei Jiang, Matthew Mitsche, Ralph J. DeBerardinis, Shaoxiong Wu, Yuancheng Li, Hui Mao, Peng R. Chen, Dongsheng Wang, Georgia Zhuo Chen, Selwyn J. Hurwitz, Sagar Lonial, Martha L. Arellano, Hanna J. Khoury, Fadlo R. Khuri, Benjamin H. Lee, Qunying Lei, Daniel J. Brat, Keqiang Ye, Titus J. Boggon, Chuan He, Sumin Kang, Jun Fan, Jing Chen. 6-Phosphogluconate dehydrogenase links oxidative PPP, lipogenesis and tumour growth by inhibiting LKB1–AMPK signalling. Nature Cell Biology, 2015; DOI: 10.1038/ncb3255

Cite This Page:

Emory Health Sciences. "Orange lichens are potential source for anticancer drugs." ScienceDaily. ScienceDaily, 19 October 2015. <>.
Emory Health Sciences. (2015, October 19). Orange lichens are potential source for anticancer drugs. ScienceDaily. Retrieved October 1, 2023 from
Emory Health Sciences. "Orange lichens are potential source for anticancer drugs." ScienceDaily. (accessed October 1, 2023).

Explore More
from ScienceDaily