Sulfur-Containing Phenolic Compounds from the Cave Soil-Derived GZWMJZ-152.

Six new sulfur-containing phenolic compounds (-) and their putative metabolic precursors (-) were isolated from the cave soil-derived fungus GZWMJZ-152. Compound represents an unusual benzophenone-diketopiperazine hybrid via a thioether linker, while compound contains a naturally rare sulfoxide group. Both compounds and were initially isolated as racemic mixtures and then purified as the enantiomerically pure (+)-, (-)-, (+)-, and (-)-, respectively. Their structures, including absolute configurations, were elucidated by spectroscopic analysis, X-ray diffraction, and the calculations of electronic circular dichroism. The antioxidant activity of compounds - was evaluated based on oxygen radical absorbance capacity, 2,2-diphenyl-1-picrylhydrazyl radical scavenging, and the protective effect on the PC12 cell line against HO-induced damage. Compounds - and showed radical-scavenging activity against 2,2-diphenyl-1-picrylhydrazyl free radicals with the IC values of 3.45 ± 0.02, 23.73 ± 0.08, 18.90 ± 0.16, and 17.27 ± 0.15 μM, respectively. Compounds (±)-, , , and exhibited potent antioxidant capacity with oxygen radical absorbance capacity values of 1.73 ± 0.13, 1.65 ± 0.03, 6.14 ± 0.35, and 1.55 ± 0.04 μmol TE/μmol, respectively. Compounds (±)- and (±)- also exhibited protective effects on oxidative injury of PC12 cells induced by HO.