Isolation, Structural Elucidation, and Biological Evaluation of a 5‑Hydroxymethyl-2-furfural Derivative, Asfural, from Enzyme-Treated Asparagus Extract

Abstract

A novel 5-hydroxymethyl-2-furfural (HMF; <b>1</b>) derivative, which is named asfural (compound <b>2</b>), was isolated from enzyme-treated asparagus extract (ETAS) along with HMF (<b>1</b>) as a heat shock protein 70 (HSP70) inducible compound. The structure of compound <b>2</b> was elucidated on the basis of its spectroscopic data from HREIMS and NMR, whereas the absolute configuration was determined using chiral HPLC analysis, compared to two synthesized compounds, (<i>S</i>)- and (<i>R</i>)-asfural. As a result, compound <b>2</b> derived from ETAS was assigned as (<i>S</i>)-(2-formylfuran-5-yl)­methyl 5-oxopyrrolidine-2-carboxylate. When compound <b>2</b>, synthesized (<i>S</i>)- and (<i>R</i>)-asfural, and HMF (<b>1</b>) were evaluated in terms of HSP70 mRNA expression-enhancing activity in HL-60 cells, compound <b>2</b> and (<i>S</i>)-asfural significantly increased the expression level in a concentration-dependent manner. HMF (<b>1</b>) also showed significant activity at 0.25 mg/mL