Arabincosides A-D, pregnane glycosides isolated from Caralluma arabica

The aqueous remained fraction after partitioning the crude ethanol extract with ether and methylene chloride of the aerial parts of Caralluma arabica yielded six pregnane glycosides, four of them were found to be new pregnane glycosides and were identified using spectral analysis (MS, 1D and 2DNMR) as 3β,14β, dihydroxypregn-5-en-20-one-3-O-β-d-glucopyranosyl-(1 → 4)-O-β-d-digitalopyranoside (arabincoside A), 3β,14β-dihydroxypregn-5-en-20-one-3-O-β-d-glucopyranosyl-(1 → 6)-O-β-d-glucopyranosyl-(1 → 4)-O-β-d-digitalopyranoside (arabincoside B), 12-β-O-benzoyl-3β, 12β, 14β, 20-tetrahydroxy-(20R)-pregn-5-ene-3-O-β-d-glucopyranosyl-(1 → 4)-β-d-cymaropyranosyl-(1 → 4)-β-d-cymaropyranoside (arabincoside C) and 12-β-O-benzoyl-3β, 12β, 14β, 20-tetrahydroxy-(20R)-pregn-5-ene-3-O-β-d-glucopyranosyl-(1 → 4)-β-d-glucopyranosyl-(1 → 4)-β-d-cymaropyranosyl-(1 → 4)-β-d-cymaropyranoside (arabincoside D). In addition, two known pregnane glycosides were also isolated and identified as russelioside D and russelioside C, previously isolated from C. russelliana. [Display omitted] •Caralluma arabica is a succulent herb and endemic to Arabian Peninsula.•It is used traditionally for the treatment of liver diseases, diabetes and hypertension.•C. arabica afforded yielded six pregnane glycosides, including four ones.•The structure of the new aarabincosides A-D were elucidated with 2DNMR and MS.•The known pregnane glycosides were identified as russeliosides C and D.