ABSTRACT
Stereospecific oxidation of diacetoxyheterobetulin with ozone and dimethyldioxirane led to 3ß,28-diacetoxy-18α,19ßH-urs-20α,21α-epoxide with yields of 79% and 87%, respectively. Oxidation with ozone was not selective and gave two minor products containing 2lα-hydroxy-20(30)-ene and 21a-hydroxy-20ß,28-epoxy-fragments in ring E. The structures of 3ß,28-diacetoxy-18α,19ßH-urs-20α,21α-epoxide and 3ß-diacetoxy-21α-hydroxy-20ß,28-epoxy-18α,19ßH-ursane were confirmed by X-ray analysis for the first time.
Subject(s)
Epoxy Compounds/chemistry , Epoxy Compounds/chemical synthesis , Triterpenes/chemistry , Triterpenes/chemical synthesis , Oxidation-Reduction , Ozone/chemistry , StereoisomerismABSTRACT
A variety of new and earlier synthesized lupane, oleanane, ursane and dammarane triterpenoids have been investigated for their inhibitory activity against α-glucosidase. 2,3-Indole-21 ß-acetyl-20ß,28-epoxy-18α,19ßH-ursane and 3-oxo-3A-homo-3a-aza-20(S)-hydroxydammar-24(25)-ene were synthesized for the first time. The compounds 3, 4, 8-11 and 14 demonstrated strong in vitro inhibitory activity towards α-glucosidase with IC50 values of 37.5-115.1 µM. 3-Deoxy-3a-homo-3a-aza-28-cinnamoyloxy-20(29)-lupene, with an IC50 of 6.67 µM was 60-fold more active than the market drug acarbose.
