Mannosylxylarinols A and B, Two New 3,4‐ Seco ‐ergostane‐type Steroidal Saponins From the Fungus Xylaria necrophora SZSS1‐2‐2
Qian Luo, Yu Yang, Rui Xu, Xue Zhao, Hui‐Fang Tan, Yu‐Ying Wei, Er‐Wei Li, Li‐Xia Chen, You‐Zhi Zhang, Chang‐Wei LiABSTRACT
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.