Fig. 6: Bioactivity-based discovery of GPCR ligands from complex biological samples.

The high sensitivity of the biosensor enables the discovery of GPCR ligands from complex mixtures. a The bioprospecting workflow consists of (1) selection of biological material, (2) preparation of extract, (3) fractionation of extract using the chromatographic method of interest, (4) assaying the fractions using the biosensor strain, and (5) structure determination of compounds in the fraction. Depending on the degree of separation of the compounds in the initial fractionation, one or more additional fractionation and biosensor assay steps can be performed to ensure purity of the target compound. b Assaying 71 plant extracts with the biosensor strain KM206 revealed two plant extracts that clearly activate CB₂. c In order to purify main cannabinoid compound from the R. columnifera extract, this was fractionated into 16 fractions (red lines) by preparative HPLC (UV trace in black) and each fraction was assayed with the biosensor to find the cannabinoid-containing fractions. d The biosensor strain KM206 was incubated with a 10 nM to 100 µM dilution series of dugesialactone (structure determined by NMR in insert). The resulting dose–response curve (black) indicates an EC50 of 2 µM. A control curve produced by incubating dugesialactone with KM207 (gray) shows no non-CB₂-specific effect of dugesialactone on KM206 in the specified range). For (b) and (d), data presented as mean + /− standard deviation. n = 3 biologically independent samples. Source data are provided in the Source Data file.