Improved synthesis, X-ray structure, and antifungal activity of a sugar-psoralen conjugate: 4,4′-Dimethylxanthotoxol 2,3,4,6-tetra-O-Acetyl-β-D-glucoside

Abstract

An improved synthesis for 4,4′-dimethylxanthotoxol 2,3,4,6-tetra-O-acetyl-β-D-glucoside (1) starting from resorcinol was developed. Crystallographic analysis of glucoside 1 indicated that the dihedral angles between the mean planes of the tricyclic ring system of adjacent molecules was 54.820(22)° probably due to the steric hindrance caused by the bulky O-glucoside moiety, which prevents the molecules from packing via π···π stacking between the tricyclic cores. The antifungal screening data revealed that glucoside 1 had higher inhibition than its parent compound 4,4′-dimethylxanthotoxol and azoxystrobin against Rhizoctonia solani, Pyricularia grisea, and Alternaria alternate Japanese pear pathotype, with the inhibitory rates of 75.4, 65.7 and 70.1%, respectively, at the 50 µg/mL concentration.