Phenylpropanoid Glycoside Esters: Leucine Aminopeptidase Inhibitors from Hebe stricta var. Atkinsonii

Abstract

Screening of New Zealand native plants for inhibitors of leucine aminopeptidase led to the isolation of a new phenylpropanoid glycoside ester, 2-O-caffeoyl-D-glucopyranose (1) from Hebe stricta var. atkinsonii (Scrophulariaceae). (1) is a competitive inhibitor of leucine aminopeptidase (K_j=10.5 μM). Two other compounds isolated, 3-methyl-3-(6′-O-caffeoyl-β-D-glucopyranosyloxy)-pentan-5-olide (2) and forsythiaside, 3′″, 4′″-dihydroxy-β-phenethyl-O-α-L-rhamnopyranosyl-(1′ → 6)-4-O-caffeoyl-β-D-glucopyranoside (3), were also shown to be competitive inhibitors with K_j values of 3.75 and 8.C μM respectively.

Key Words:

• Leucine aminopeptidase
• phenylpropanoid
• glycoside
• Hebe stricta