Purification of total flavonoids from Ginkgo biloba flowers with resin column chromatography and evaluation of antioxidant activities in vitro

Purification of total flavonoids from Ginkgo biloba flowers (GBF) extracts were studied using six resins. Adsorption-desorption experiments indicated that polyamide resin is the most suitable resin. The optimal purification process of total flavonoids of GBF was as follows: a loading concentration of 5.85 mg/mL, a loading volume of 1 bed volume (BV), a loading flow rate of 2 BV/h, a water volume of 2.67 BV, and a desorption solution of 40% ethanol. Under these conditions, the maximum purity of total flavonoids was 37.1 ± 1.1%. The antioxidant activity of purified flavonoids was further evaluated in vitro. It showed that the 40% ethanol purified fraction (Fr. B) group had the strongest antioxidant activity of the 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity concentration for 50% of maximal effect (EC₅₀, 145.4 ± 13.8 µg/mL) and ferric reducing ability (2.5 ± 0.2 mM FeSO₄ equivalent mg^-1Fr. B). In addition, at the concentration of 160 µg/mL, the Fr. B strikingly increased the viability rate of hydrogen peroxide stimulated PC-12 cells to normal levels (***p < 0.001). This method provides a basis for the application and development of GBF resources. It indicated that the purified GBF flavonoids can be used as a source of potential antioxidant.

An Effective Chromatography Process for Simultaneous Purification and Separation of Total Lignans and Flavonoids from Valeriana amurensis

An effective chromatography process was developed and validated for simultaneous purification and separation of total lignans and flavonoids from Valeriana amurensis. The total lignans and flavonoids in Valeriana amurensis extract were prepurified with macroporous resin column chromatography, and the conditions were optimized as follows: 40 mg/mL Valeriana amurensis extract (2.0 g) solution was loaded onto an AB-8 resin column with a diameter-to-height ratio of 1:7, followed by adsorption for 6 h; then, the column was eluted successively with 5 BV water and 10% and 50% ethanol at a flow rate 2 BV/h. The obtained 50% ethanol fraction was further repurified and separated by polyamide resin column chromatography to obtain the total lignans and flavonoids, respectively. The chromatography conditions were optimized as follows: a 50% ethanol fraction (1.0 g) was mixed with 1.0 g polyamide resin and loaded onto a polyamide resin (60-100 mesh) column with a diameter-to-height ratio of 1:3; then, the column was eluted successively with 6 BV water and 40% and 80% ethanol at a flow rate of 4 BV/h. The total lignans and flavonoids were obtained from water and 80% ethanol fraction, respectively. The content and recovery of standard compounds in total lignans and flavonoids were analyzed with HPLC-PDA, and the feasibility of the process was confirmed.