Extended Table 4. M/z ratios and retention times for 5-ASA in the IBDMDB and PRISM cohorts.

Identity of N-acetyl 5-ASA in PRISM and for N-propionyl 5-ASA and N-butyryl 5-ASA in the IBDMDB and PRISM cohorts were inferred using mass and retention time matching coupled with known mass shifts from functional groups. As further confirmation of these two possible 5-ASA derivatives, we searched publicly available MS² data from the Global Natural Product Social (GNPS) database (MassIVE MSV000084556) to generate molecular co-occurrence networks, inputting the known spectra of N-acetyl 5-ASA (46). In this analysis, we similarly found two unlabeled nodes linked with N-acetyl 5-ASA which matched the m/z of the compounds we identified, as well as a third node with an m/z of 238.11 which may correspond to yet another derivative of 5-ASA that has not been described, likely a 5-carbon acyl group plus 5-ASA given the additional mass shift (+12) from butyryl CoA.

	PRISM		IBDMDB
Compound	M/Z	Retention time	M/Z	Retention time
5-ASA	154.0493	3.98	154.0502	3.83
N-butyryl 5-ASA	224.0909	2.32	224.0922	2.24
N-acetyl 5-ASA	196.0599	2.97	196.0609	2.81
N-propionyl 5-ASA	210.0754	2.32	210.0764	2.52