In silico studies of bis-spiro- and Furano-Labdane diterpenoids from Rydingia persica Scheen ( Otostegia persica ) as α-glucosidase enzyme inhibitor.

The inhibition potential of α-glucosidase enzyme by crude- dichloromethane, methanol, and ethanol -extracts of Rydingia persica were evaluated using colorimetric method. We have isolated four labdane diterpenoids: 15, 16- epoxy-3α, 7β, 9α -trihydroxylabdan-13- (16), 14-dien-6-one ( 1 ), 15, 16- epoxy-3α, 7α, 9α -trihydroxylabdan-13- (16), 14-dien-6-one ( 2 ), 9, 13, 15, 16-diepoxy- 3α, 7β, 15α (β)- trihydroxy-labdan- 6 one ( 3 , 4 ) from the most potent enzyme inhibitor fraction; the ethyl acetate soluble part of ethanol extract of the aerial parts of R. persica . The structures of the compounds were elucidated by their 1 H and 13 C NMR and ESIMS spectral data analyses. The enzyme inhibition potential of the compounds was evaluated against acetylcholine esterase (AChE) and α-glucosidase by simulation studies. The predicted binding energy of most diterpenes towards mouse AChE enzyme was low, while the binding energy of diterpenes towards α-glucosidase enzyme was moderate to potent.