Mannosylxylarinols A and B, Two New 3,4‐Seco‐ergostane‐type Steroidal Saponins From the Fungus Xylaria necrophora SZSS1‐2‐2

Two new 3,4‐ seco ‐ergostane‐type steroidal saponins ( 1  and  2 ) were isolated from the fermentation products of the fungus  Xylaria necrophora  SZSS1‐2‐2, together with four known compounds: 2‐hexylidene‐3‐methylsuccinic acid ( 3 ), xylcarpin C ( 4 ), (24 R )‐22,23‐dihydroxy‐ergosta‐4,6,8(14)‐trien‐3‐one 23‐ β ‐D‐glucopyranoside ( 5 ), and 5‐carboxymellein ( 6 ). The structures and absolute configurations of the new compounds were elucidated by comprehensive spectroscopic analyses, electronic circular dichroism (ECD), and GIAO 1 3 C NMR computational methods, and chemical hydrolysis followed by derivatization to determine the D‑mannose configuration of the sugar moiety. All isolated compounds ( 1–6 ) were evaluated for their biological activities. Only compound  5  showed selective inhibitory activity, inhibiting BV2 microglial cells with an IC 50 value of 17.10 ± 4.18 µM. Additionally, none of the compounds exhibited antimicrobial activity against the tested microorganisms. Two new 3,4‐seco‐ergostane saponins ( 1 – 2 ) and four known compounds were isolated from Xylaria necrophora . Structures were elucidated via spectroscopy, ECD, and computational NMR. Compound 5 selectively inhibited BV2 microglial cells (IC 5 0  = 17.10 µM), while all compounds showed no antimicrobial activity against tested microorganisms.