FIG 3.

HPLC purification of the Fe³⁺-reducing compound secreted by the ECM fungus P. involutus during the decomposition of organic matter. (A) Chromatogram of the MH7 SP_EtOAc eluate (see Fig. 1) separated by isocratic reverse-phase chromatography. Fractions were collected according to peaks (λ = 254 nm). Fe³⁺-reducing activity was detected in one peak, indicated by the arrow, and the compound was identified as involutin by HRESIMS (see Fig. 2 inset). (B) ¹H NMR spectrum of HPLC-purified involutin (>90% pure). The red lines/numbers represent the integrator trace. (Inset) Chemical structure of involutin.