Phytochemical investigation of the fruits of Paliurus spina-christi Mill.

Paliurus spina-christi Mill. (Rhamnaceae) is a much-branched, deciduous, thorny shrub with green fruits that become brown during maturation. The shrub is found in dry slopes in Mediterranean, Southwest and Central Asia and North America. Its common name is ‘Christ’s thorn’ because it is said that its spiny branches were used to make the crown of thorns which had been placed on Christ’s head before his crucifixion. P. ramosissimus Lour., P. orientalis Franch. and P. hemsleyanus Rehder are well known species of the Eastern Asia [1]. Traditionally, P. spina-christi is used for its diuretic and anti-hypercholesterolemic properties, as well as a palliative against gastrointestinal pain [2]-[5]. Thus, it was decided to investigate the shrub’s fruits phytochemically.

Powdered mature fruits were exhaustively extracted with cyclohexane, dichloromethane, methanol and water. In order to remove fats and sugars, the dried methanolic extract was subjected to liquid-liquid extraction with c-Hex., EtOAc and water. The EtOAc fraction was initially chromatographed on Si-gel using Vacuum Liquid Chromatography (NP-VLC), followed by prepTLC and NP-HPLC for the final separations and isolation of the pure secondary metabolites. The water phase was treated using adsorption resin technology and the obtained fractions were further chromatographed using Reversed Phase-Solid Phase Extraction (RP-SPE) and RP-HPLC. Structure determination was based on NMR spectroscopy and LC-MS.

So far, there have been isolated and identified 12 secondary metabolites, 1 flavonoid-diglycoside, 2 phenolics, 2 triterpenoids, 1 lignan, 3 phytosterols and 3 cyclopeptide alkaloids (CPAs). One of the CPAs, metabolite 8, has been recognized as a new natural product.

• References

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