Beshanzoides A–D, unprecedented cycloheptanone-containing polyketides from Penicillium commune P-4-1, an endophytic fungus of the endangered conifer Abies beshanzuensis. Issue 63 (14th December 2021) - Chen, Hao-Wei
Abstract : Four unprecedented cycloheptanone-containing and some related known bioactive polyketides were isolated from an endophytic fungus associated with the critically endangered conifer Abies beshanzuensis . Abstract : A number of previously undescribed (1–7 ) and structurally related known (8–17 ) isobenzofuran-type polyketides were obtained from the fermentation of Penicillium commune P-4-1, an endophytic fungus isolated from the fresh trunk bark of the critically endangered conifer Abies beshanzuensis . Beshanzoides A–D (1–4, resp.) feature a cycloheptanone-containing isobenzofuran ring system hitherto unknown, which might be biosynthesized via two steps of aldol reactions starting from a common co-occurring isobenzofuran-type polyketide as the precursor. The new structures were elucidated by spectroscopic methods, electronic circular dichroism data, and single crystal X-ray diffraction analyses. Beshanzoide E (5 ) showed antimicrobial activity (MIC: 16 μg mL −1 ) against Staphylococcus aureus, whereas (±)-strobide A (10 ) inhibited (MIC: 16 μg mL −1 ) Candida albicans . Cyclopaldic acid (12 ) and 3- O -methyl-cyclopaldic acid (13 ) exhibited inhibitory effects against acetyl-CoA carboxylase 1 (ACC1) with IC50 values of 0.96 and 11.77 μM, respectively. Compound 12 also inhibited (IC50 : 7.56 μM) ATP-citrate lyase (ACL).