A vegetable that glows in ultraviolet light could help us see inside cells

Plants that glow in ultraviolet light aren’t just the stuff of science fiction. The roots of a traditional medicinal plant called the orange climber, or Toddalia asiatica, can radiate an ethereal blue fluorescence. And now, researchers have identified two substances that could be the cause of this phenomenon.

These substances, naturally occurring coumarins, have unique fluorescent properties, and one of the compounds could potentially be used for medical imaging.

The study is the work of a team made up of, among others, Shan-Shan Chen and Xiao-Dong Luo, from the Kunming Institute of Botany, attached to the Chinese Academy of Sciences, as well as Ben Zhong Tang and Zheng Zhao, from the University Hong Kong Chinese,

Fluorescent substances absorb ultraviolet light directed at them and release intensely colored visible light. Some of them glow even brighter when they are close to others, a phenomenon seen in compounds called cluster-induced emission luminogens. These are key components in some optical devices, cell imaging diagnostic techniques, and environmental sensors. However, these molecules are usually made in a laboratory, and many are toxic. Some plants already have this ability, so Shan-Shan Chen and his colleagues turned to nature to find natural and safer clump-induced emission luminogens.

The researchers dried roots of the orange climber, ground them into a powder, and then isolated and identified the coumarin compounds with cluster-induced emission properties: 5-methoxyseselin (5-MOS) and 6-methoxyseselin (6- MOS). When diluted in an organic solvent, 5-MOS glowed blue-green and 6-MOS gave a slightly dimmer blue glow. In addition, both cluster-induced emission luminogens presented low cytotoxicity and good biocompatibility.

A fluorescent compound from the root of a plant could help to image cells very quickly. (Image: Adapted from ACS Central Science 2023, DOI: 10.1021/acscentsci.3c00012. CC BY)

Then, in a final series of experiments, the team found that mitochondria could be clearly identified in 5-MOS-stained live cells without any additional processing, making cell imaging faster and easier compared to most current methods. . According to the researchers, the new compound is a natural option of plant origin that could contribute to the advancement of biodiagnostic imaging.

The study is titled “Natural Coumarin Isomers with Dramatically Different AIE Properties: Mechanism and Application”. And it has been published in the academic journal ACS Central Science. (Source: American Chemical Society)