Structure and absolute configuration of 20β-hydroxyprednisolone, a biotransformed product of predinisolone by the marine endophytic fungus penicilium lapidosum

• Published in: Molecules
• Main Author: Sultan S.; Zaimi Bin Mohd Noor M.; Anouar E.H.; Shah S.A.A.; Salim F.; Rahim R.; Trabolsy Z.B.K.A.; Weber J.-F.F.
• Format: Article
• Language: English
• Published: MDPI AG 2014
• Online Access: https://www.scopus.com/inward/record.uri?eid=2-s2.0-84908190263&doi=10.3390%2fmolecules190913775&partnerID=40&md5=1c51f2c7d7eb3b5eaa3dd83c636dc27e

The anti-inflammatory drug predinisolone (1) was reduced to 20β-hydroxyprednisolone (2) by the marine endophytic fungus Penicilium lapidosum isolated from an alga. The structural elucidation of 2 was achieved by 1D- and 2D-NMR, MS, IR data. Although, 2 is a known compound previously obtained through microbial transformation, the data provided failed to prove the C20 stereochemistry. To solve this issue, DFT and TD-DFT calculations have been carried out at the B3LYP/6-31+G (d,p) level of theory in gas and solvent phase. The absolute configuration of C20 was eventually assigned by combining experimental and calculated electronic circular dichroism spectra and 3JHH chemical coupling constants. © 2014 by the authors; licensee MDPI, Basel, Switzerland.