Phycomysterols and Other Sterols from the Fungus Phycomyces blakesleeanus

In the search for novel bioactive products from filamentous fungi, sterols and triterpenoids found in Phycomyces blakesleeanus were analyzed using semipreparative HPLC, GC−MS, and NMR techniques. Structures proposed for the three new compounds identified, phycomysterol A (<BO>1</BO>), phycomysterol B (<BO>2</BO>), and neoergosterol (<BO>3</BO>), were confirmed by chemical synthesis. Phycomysterols possess a new natural 19-norergostane skeleton with an aromatic B ring. Phycomysterol A showed anti-HIV activity.