“…Type III subtype IIa with C3/C4 double bond58,70,72,155,163,164,175,183,189,213,[215][216][217][218][219][220][221][222][223][224][225][226][227][228] (Table 16compounds 530-575 found in ESI †).A wide range of substituents are found on the decalin and butenolide moieties in type III subtype IIa compounds. With CO 2 H at the decalin C-4 position and OMe or H, respectively, at the butenolide C-4 position, limbatolides B (533) and C (534) from Otostegia limbata inhibited acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes in a concentration-dependent manner with IC 50 values of 47.2, 103.7 and 17.5, 14.2 mM, respectively.…”