Structure elucidation and NMR assignments of two new pyrrolidinyl quinoline alkaloids from chestnut honey

The complete 1H, 13C and 15N NMR spectral assignments of two new alkaloids isolated from chestnut honey and structurally related to kynurenic acid have been made using 1-D and 2-D NMR techniques, including COSY, HMQC and HMBC experiments. The new compounds have been identified as 3-(2′-pyrrolidinyl)-kynurenic acid and its γ-lactam derivative.