Abstract: To study the antioxidant activity of saccharides in jasmine stem of Guangxi.The separation and purification of the monomers were carried out by macroporous resin adsorption and preparative liquid chromatography.The structures were identified by spectroscopic analysis.The scavenging ability of the compounds against free radicals such as DPPH,O₂^-·and OH was measured,and the ability to reduce Fe³⁺ and chelate with metal ions (Fe²⁺) was determined.Four compounds were isolated from the stems of Guangxi Jasmine plants,namely molihuaside A,sambacoside A,sambacoside F and cycloolivil,respectively.The 4 compounds showed good activity in scavenging DPPH radical,O₂^-· radical,OH radical,reducing Fe³⁺ ability and chelating ability with metal ion (Fe²⁺).Four compounds were isolated for the first time of flowering plant stems from Guangxi jasmine,antioxidant activity has its sugar composition of scavenging free radicals,reducing Fe³⁺,and metal ions (Fe²⁺) on the chelating activity,and antioxidant activity and the structure of the number and position of hydroxyl glucoside and related to the steric hindrance.

Key words: Jasmine stems, chemical composition, polysaccharide, antioxidant activity, structure-activity relationship, action mechanism