Traditional Processing of Arum maculatum L. and Apparent α-Amylase Inhibition: An Exploratory In Vitro and In Silico Study

Arum maculatum L. is a traditionally consumed but toxic and irritant plant that must be processed before use. This exploratory study examined whether three preparations—an ethanol:water (80:20, v/v) extract of dried material (E1), a corresponding extract of fresh material (E2) and an aqueous decoction of fresh material (E3) mirroring traditional boiling—differ in apparent α-amylase inhibition, and whether their previously reported phenolic marker profiles (high-performance liquid chromatography with photodiode array detection, HPLC–PDA) account for these differences. Inhibition of Aspergillus oryzae α-amylase was measured by the starch–iodine method at a single extract concentration and two enzyme loadings, using one extract per preparation and analytical triplicates. All extracts gave higher apparent inhibition values (75.13–90.80%) than the assay-internal acarbose control (67.28–68.15%) at the same nominal mass concentration (40 µg/mL), with E3 highest at the higher enzyme loading. The previously quantified markers did not account for this pattern. Docking against fungal (3VX0, 7TAA) and human (2QV4, 4GQR) α-amylases placed all markers in the catalytic cleft, a hypothesis-generating result that does not establish binding affinity. These descriptive differences indicate that processing is associated with different apparent α-amylase inhibition, whereas the active constituents, possible assay interference and the safety of the preparations remain to be established.