Viridin

[1] Belonging to a class of molecules known as furanosteroids, it has a characteristic highly strained electrophilic furan ring fused between C-4 and C-6 of the steroid framework.

[4] Although the mechanisms and order of the remaining steps from lanosterol to viridin are not certain, these include the formation of the furan ring, the loss of C-13 and C-14 methyl groups, aromatization of the C-ring, removal of the side chain, and oxidation of the A-ring.

Loss of a hydrogen atom from C-15 during removal of the C-14 methyl group suggests a pathway similar to that of other steroid biosyntheses.

[7] It likely follows the pathway of androstenedione and oxidatively removes the side chain as acetic acid, resulting in a ketone on the D-ring.

[5] In the biosynthesis of viridiol by Gliocladium deliquescens, the 3β-OH reduced form of viridin, the incorporation of squalene, lanosterol, dehydroxydemethoxyviridin, and demethoxyviridin was reported.

Removal of C-14 methyl
Oxidative removal of side chain
Removal of C-4 methyl