Lepithiohydimerins A—D: Four Pairs of Neuroprotective Thiohydantoin Dimers Bearing a Disulfide Bond from Maca (Lepidium meyenii Walp.)

Main observation and conclusion An HPLC‐UV‐guided separation was performed and four pairs of unprecedented macathiohydantoin dimers, lepithiohydimerins A—D ( 1 — 4 ) bearing a rare disulfide bond were isolated from the tubers of Maca. Their structures were unambiguously confirmed by NMR spectroscopic, X‐ray crystallographic and electronic circular dichroism (ECD) analyses. At the concentration of 20 μmol/L, compounds 2‐1 , 2‐2 , and 4‐1 increased the viability of PC12 cells with the cell viability at (72.06 ± 1.14)%, (72.64 ± 1.49)%, and (70.93 ± 1.22)%, respectively. Furthermore, the serial concentration experiment showed that they can protect PC12 cells in a dose‐dependent manner.