Tscheschamine — A New Cyclopeptide Alkaloid from the Bark of Zizyphus sativa Gaertn

A new minor 13-membered cyclopeptide alkaloid tscheschamine -ha8 been isolated from the bark of Zizyphus sativa and its structure was determined on the basis of spectral studies and hydrolysis.Ziryphus speeiea (Rhamnaceae) are used Lo traditional medicine for treating insomnia1, healing of wounds and ulcers2 and bronchit18~.They are a rich source of cyclopeptide alkaloids4.Cyelopepride alkaloids are polyamtde plant bases containing a styrylamine unit in a 13-, 14-, or 15-membered maeroeyelic ring system5.It is interesting to note that from 2. sative6 just like Z. arnph~bia~.~,L. n ~m m u l a r i a ~-~~ and L. jujuba13 only 13-and 14-membered cyclopeptide alkaloids were Lsolated.The 13-and 15-membered cyclopeptide alkaloids were found in Z. oenoplia14 end &.mucronata15.g. abyssinica16 possessed only 15-membered eyelopeptide alkaloids while L. m a ~r i r i e n a ~~ and Z. ~o i n a -c h r i s r i ~~* ~~ mere found t o eonrain only 14-membered alkaloids of this class.Recently we reported the isolation of nine new alkaloids from Z.In this communication we report the isolation and structure determination of a new minor alkaloid, tscheschamine ( I ) , from the bark of this plant.EXPERIMENTAL Zizyphus sativa Gaertn bark was collected from Hazara district of Pakistan.The stem back ( 5 kg)was repeatedly extracted with a mixture of C6H6-EtOH-~on~.NH40H q. (100:Z:l) and solvent evaporated.The residue was dieeolved in 7% citric acid and filtered.The aq. layer was basified with NH40H to pH 10, and extracted with CHC13 to give crude alkaloids (2.1 g).The mixture of crude baaea was chromatographed on silica gel (90 g) column, eluting with increasingly polar CHZClZ-HeOH mixtures into 10 main fractions.The collected fractions were analysed by TLC proving in every ease to be mixture of two or three compounds.The pure compounds were separated by prep.TLC using chromatotron-7924.