Cardenolides from the methanolic extract of Nerium oleander leaves possessing central nervous system depressant activity in mice.

Two new cardenolides, 3 beta-O-(D-2-O-methyldigitalosyl)-14 beta-hydroxy-5 beta-carda-16,20(22)-dienolide (1) and 3 beta-hydroxy-8,14-epoxy-5 beta-carda-16,20(22)-dienolide (2), and two known cardenolides, 3 beta-O-(D-digitalosyl)-14 beta-hydroxy-16 beta-acetoxy-5 beta-card-20(22)-enolide (3) and 3 beta-O-(D-digitalosyl)-14 beta-hydroxy-5 beta-card-20(22)-enolide (4), have been isolated from the leaves of Nerium oleander following a bioactivity-directed isolation of the MeOH extract, which showed central nervous system (CNS) depressant activity in mice at a dosage of 50 mg/kg i.p. Their structures were established on the basis of chemical and spectral data. Compounds 1, 3, and 4 were found to exhibit sedation in mice at a dosage of 25 mg/kg, although 2 had no effect on the CNS of mice at a dosage of up to 50 mg/kg.