Ginkgo seed extracts show antibacterial activity on skin pathogens

Ginkgo biloba seed extracts show antibacterial activity on pathogens that can cause skin infections such as acne, psoriasis, dermatitis and eczema, reveals a study from Emory University . Frontiers in Microbiology publishes the results of laboratory experiments showing that the extracts inhibit the growth of Cutibacterium acnes, Staphylococcus aureus and Streptococcus pyogenes.

A nearly 200-year-old copy of a 16th-century text on traditional Chinese medicine, the Ben Cao Gang Mu, guided the researchers in their experiments. "It was like eliminating the dust of knowledge and rediscovering something that had always existed," said Xinyi (Xena) Huang, co-first author of the newspaper.

Huang, originally from China, started the main thesis project in biology at Emory. She has since graduated from Emory and is now studying at the Faculty of Pharmacy at the University of Maryland.

"To our knowledge, this is the first study to demonstrate the antibacterial activity of ginkgo seeds on skin pathogens," says Cassandra Quave, lead author of the journal and assistant professor at the Emory Center. for the study of human health and school. of the Department of Dermatology of Medicine. "This paper is just one more example of what we still need to learn about the pharmacological potential of complex plant chemistry."

Quave is an ethnobotanist who studies how indigenous peoples use plants in their healing practices to discover promising candidates for new drugs.

"Our results confirm the validity of the use of ginkgo seeds as a topical antimicrobial, as prescribed in this text of the sixteenth century," says François Chassagne, co-first author of the article and pharmacist at the Quave laboratory.

He adds that many obstacles remain before ginkgo seed extracts can be considered for use in a modern medical setting. In its concentrated form, ginkgolic acid C15: 1, the main compound that a statistical analysis identified as probably responsible for antibacterial activity, was shown to exhibit skin toxicity.

"A possible strategy in the search for new antibiotics would be to investigate ways to modify the structure of ginkgolic acid related to antibacterial activity, to try to improve its effectiveness and reduce its toxicity to human skin cells, "said Chassagne. .

James Lyles, a chemist from Quave Lab, is another co-author of the study.

Ginkgo, native to China, is one of the oldest tree species, at least 270 million years old. The tree is known for its distinctive fan-shaped leaves and long history in traditional Chinese medicine. Modern researchers have studied ginkgo extensively in search of medical benefits, ranging from memory enhancement to macular degeneration, but there is still "no conclusive evidence that the Ginkgo is useful in all disease states, "according to the National Institutes of Health National Health Center's webpage for Complementary and Integrative Health.

Most previous studies have focused on ginkgo leaves.

While crossing the campus, wondering what to focus on for his main thesis, a ginkgo tree caught Huang's attention. She knew that the tree was used in traditional Chinese medicine, even though she knew no details, so she decided to look for it.

Huang's interest grows when she learns that Emory owns an 1826 version of Ben Cao Mu Gang, or Compendium of Materia Medica. Regarded as the most comprehensive book on traditional Chinese medicine, it was compiled and written in the 16th century by Li Shi-zhen during the heyday of the Ming Dynasty. The original collection is large and includes dozens of volumes, but Huang has only seen very condensed versions sold in Chinese bookstores.

Emory's copy is at the Pitts Theology Library of the Candler School of Theology. The 1826 version was adopted at one point by a London bookseller. The unnumbered pages are printed in bulk in Chinese characters, but at one point were bounced in 10 volumes with covers denominated in English.

Huang never imagined touching such an ancient copy of Ben Cao Gang Mu. "You can feel the story in it," she says. "The paper is so yellow, lean and fragile that I was afraid to break the pages by turning them."

A volume entitled "Grains, Vegetables, Fruits" describes 17 traditional uses of ginkgo seed, including eight for skin conditions such as chapped hands and feet, rosacea, itching caused by crab lice, abscess and the pustules of dog bites. Li Shi-Zhen recommended preparing a paste of crushed seeds mixed with rice wine or other alcohol, or dipping the crushed seeds into rapeseed oil. The dough could then be applied to the affected area.

An earlier study showed that ginkgo seed casts demonstrated antibacterial activity against some intestinal bacterial pathogens. And ginkgo leaves showed antibacterial activity on both some intestinal bacteria and on the pathogen of the skin S. aureus.

Huang, however, wanted to check the information she had learned from the ancient text regarding the use of ginkgo seeds as a topical treatment for skin disorders. Skin pathogens are of particular interest to the Quave laboratory, which focuses on finding new approaches to treating antibiotic-resistant bacteria.

Huang collected ginkgo samples to test them. The extractions from the seeds were treated as closely as possible in accordance with the recommendations of Ben Cao Gang Mu, using water, ethanol or rapeseed oil. Huang and Chassagne conducted microbial experiments, including evaluation of ginkgo extracts from walnut, immature seeds and integument, on 12 different bacterial strains.

The results showed that ginkgo and immature seeds had antibacterial activity on three of the strains tested: C. acnes, S. aureus and S. pyogenes. Statistical analysis also found a positive correlation between the antimicrobial activity of ginkgo samples and the concentration of ginkgolic acid C15: 1, suggesting that he was involved in the activity.

"Our discovery is still at an early stage – these extracts have not yet been tested in animal or human studies – but I'm always delighted to learn that this ancient story of Ben Cao Gang Mu seems to be real Huang said. "As a student pharmacist, it gives me a better idea of ​​the value of using ancient herbal remedies to guide modern research."