Application of coordination agent in high-speed counter-current chromatography for the preparative separation and isolation ginkgolic acids from the sarcotesta of Ginkgo biloba L.

An efficient coordination high-speed counter-current chromatography method for the preparative separation of ginkgolic acids from the sarcotesta of Ginkgo biloba L was developed. The type, concentration, and mechanism of the coordination agent were investigated. Following the use of four types of metal salts including silver nitrate, copper chloride, ferric chloride, and aluminium nitrate, n-heptane/ethyl acetate/methanol/acetic acid 5:4:1:1, v/v with 0.20 mol/L silver nitrate as the coordination agent was chosen as the optimum two-phase solvent system. Five main ginkgolic acids including C13:0, C15:0, C15:1, C17:1, and C17:2 were successfully separated with purities greater than 98%. The sample loading was 500 mg, the flow-rate was 2.0 mL/min, rotation speed was 800 rpm and temperature was 20°C. The structures of the separated ginkgolic acids were identified by comparison with standard samples and electrospray ionization mass spectrometry. The introduction of coordination chemistry in high-speed counter-current chromatography is novel and effective for the preparative separation and isolation of ginkgolic acids from the sarcotesta of Ginkgo biloba L and could also be applied to separate compounds which form coordination bonds in other complex natural products.