Flavonoids contribute most to discriminating aged Guang Chenpi ( Citrus reticulata 'Chachi') by spectrum-effect relationship analysis between LC-Q-Orbitrap/MS fingerprint and ameliorating spleen deficiency activity

To further explore the mechanism of "the longer storage time, the better bioactivity" of aged Guang Chenpi, the dry pericarp of 'Chachi' (CRC), a series of activity assessments were performed on spleen deficiency mice. The constituents in CRC with different storage years were analyzed by LC-Q-Orbitrap/MS. A total of 53 compounds were identified, and CRC stored for more than 5 years showed higher flavonoid content, especially that of polymethoxyflavones. Anti-spleen deficiency bioactivity analysis among various CRC with different storage years showed aged CRC (stored for more than 3 years) could significantly alleviate fatigue and depression behaviors much better, increase D-xylose and gastrin secretion, and upregulate the expression of the linking protein occludin in the colon walls. Results from 16S rDNA sequencing showed that aged CRC could downregulate the abundance of , , , , and , which were significantly overrepresented in the model group. , , , , , , and were downregulated in the model group but enriched in the CRC groups. At last, the spectrum-effect relationship analysis indicated that flavonoids such as citrusin III, homoeriodictyol, hesperidin, nobiletin, and isosinensetin in aged CRC showed the highest correlation with better activity in ameliorating spleen deficiency by regulating gut microbiota. Flavonoids contribute most to discriminating aged CRC and could disclose the basis of "the longer storage time, the better bioactivity" of aged Guang Chenpi.