Screening of bioactive flavour compounds targeting muscarinic-3 acetylcholine receptor from Siraitia grosvenorii and evaluation of their synergistic anti-asthmatic activity

Siraitia grosvenorii (Swingle) C. Jeffrey (SG) is widely used as a natural sweetener and traditional medicine for respiratory diseases. The anti-respiratory compounds in the plant and their mechanism remain elusive due to the lack of a high-throughput screening method. In this work, immobilization of the muscarinic-3 acetylcholine receptor (M3R) was used to establish an affinity chromatographic strategy for synchronously recognizing the flavour components in the SG extract binding to this receptor and evaluating their anti-asthmatic effect. The accuracy of the method was assessed by in vivo experiments. Mogroside V (Mog V) and 11-oxomogroside V (11-O MogV) were identified as functional flavour compounds binding to M3R. Their association constants were determined to be 3.32 × 104 and 2.40 × 104 M−1 by the injection amount-dependent method. The binding energies of the two compounds to M3R were calculated to be −80.52 and −48.20 kJ/mol by molecular dynamics simulation. The synergistic application of the two flavour compounds exhibited stronger anti-asthma activity than the original SG extract. These results indicated that immobilized M3R is a powerful alternative for the identification of flavour compounds in plants. Mog V and 11-O Mog V are the main functional flavour compounds contributing to SG's anti-asthma function. We reasoned that the two compounds have the potential to become functional food additives. This work has the possibility to contribute considerably to the pursuit of functional flavour compounds from natural plants in the field of functional food development.