Manginoids A–G: Seven Monoterpene–Shikimate-Conjugated Meroterpenoids with a Spiro Ring System from Guignardia mangiferae

Manginoids A–G (1–7), seven monoterpene–shikimate-conjugated meroterpenoids with a spiro ring system, were isolated from Guignardia mangiferae. Compounds 1–4 are four isomers with epimeric and double-bond isomeric features possessing a 6-oxaspiro­[bicyclo[3.2.1]­octane-3,5′-indene] ring, which represent the first examples of spiro meroterpenoids bearing a bridged spirocyclohexanedione moiety. Compounds 5 and 6 possess an unexpected 2,4-dioxatricyclo­[3.3.1.03,7]­nonane motif, which fuses with a 6-oxabicyclo[3.2.1]­octane moiety. Compound 1 exhibits inhibitory activities against 11β-hydroxysteroid dehydrogenase type 1 with an IC50 value of 0.84 μM.