Traditional Chinese Medicinal Plant Shows Promise as Safe Insecticide

(CN) – Bet you never tried killing aphids with cough medicine. Research published Wednesday isolated 10 new insect-killing compounds from bai bu, an herb long used by traditional Chinese medicine to treat everything from dry coughs to lice.

Led by Xiachang Wang, the team of Chinese researchers at the Nanjin University of Chinese Medicine used Stemona sessilifolia plants from Jiangjun Mountain, but they weren’t interested in the plants as much as the things living inside the plants: endophytes.

Stemona sessilifolia, from which the Chinese herbal remedy bai bu is derived.

Endophytes are the tiny fungus or bacteria that live in between plant cells and depending on the type, can either have a symbiotic or pathogenic relationship with their host. Researchers carefully isolated the microbes at the heart of this study, Streptomyces clavuligerus, from the bai bu samples. Then using mass spectrometry separated out 10 new pyrrole-2-carboxylic ester derivatives, chemical compounds produced by the endophytes which proved to be toxic to insects.

“Endophytes have now become the potential sources of novel secondary metabolites which could serve as new medicines and agrichemicals because of their biological effects to help defending host plants from herbivorous insects, mammals, disease organisms, and environmental stresses,” the researchers explained in the paper.

Dubbing the compounds endostemonine A through endostemonine J, researches tested the lethalness of each against insects on cucumber and pea plants by dipping the leaves in each of the compounds. Results indicate the endostemonines were deadly to aphids, and pretty effective against red spider mites as well. Some of them also work as antibiotics.

Of course, a mixture of endostemonine A through endostemonine J works better than any one chemical on its own.

The research indicates bai bu is not only an effective home remedy but may also help protect crops from insects.

“The discovery of new, safe and effective pesticides is one of the main means for modern crop protection and parasitic disease control,” the researchers wrote. “This research highlighted the discovery of pesticide natural products from insecticidal medicinal plant endophytes for the first time, paving a new pathway for the development of pest control.”

As for the safety of the wide use of pyrrole alkaloids on plants – the substance often comes up in health articles warning against the overconsumption of tea – Wang said they’re already being used as insecticides.

“Some of the S. sessilifolia products are now widely used as insecticide in China market, for example, stemona sprays,” Wang told Courthouse News. “There are some pyrrole alkaloids used in the market as an insecticide, such as chlorfenapyr. Chlorfenapyr was registered by EPA in January 2001 for use on nonfood crops in greenhouses, and it can be also used as a wool insect-proofing agent, and introduced as an alternative to synthetic pyrethroids due to a lower toxicity to mammalian and aquatic life.”

The researchers published their findings in the American Chemical Society’s Journal of Agricultural and Food Chemistry.

The National Key R&D Program and the Nature Science Foundation of Jiangsu Higher Education Institutions of China funded the research.

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