Illuminating Landscapes: Discovering Potential Pharmaceuticals from a Mobile Darkroom

An integral part of the biomedical field is drug discovery. Since prehistory, natural products have been a major source of drugs used by humans. However, research into natural products can be hindered by the time and cost of collecting and screening large numbers of randomly selected plant samples. One solution is the development of instrumentation that can rapidly identify plants with the highest potential for bioactivity in the field. We hypothesize that a field portable, mobile darkroom can be used to identify the species of plants with chemical profiles avoided by herbivores and therefore more likely to have bioactive chemicals. Currently, field based identification is often based on morphological phenotypes (plant size, leaf shape, etc.), leading to the misidentification of sagebrush known to have chemical profiles that are potentially toxic. One simple test to differentiate between palatable and toxic species is a UV fluorescence assay. Recent work demonstrated that sagebrush subspecies selected by herbivores (black, early, and mountain big sagebrush) have lower concentrations of potentially toxic chemicals and have a fluoresce blue in water when exposed to a UV light. In contrast, basin, and Wyoming big sagebrush are generally avoided by herbivores, have more diverse and higher concentration of chemicals and do not have a UV signal. The mobile darkroom provides a controlled environment to visualize the plant’s UV fluorescence. A custom made 395 nm - 400 nm UV light array powered by a universal power bank was used to excite the samples. A small window allowed visual assessment and capture of the UV fluorescence image with a smartphone for downstream semi-quantification of UV signals. The mobile darkroom allows field researchers to identify fluorescent compounds and allow a more targeted collection of individual plants with the highest potential of chemical diversity and bioactivity, which will save time and resources in the drug discovery process.