Study On The Alkaline-degradation Method Under High Temperature And High Pressure For Panax Quinquefolium Saponin And The Antioxidant Activity Of Degradation Products

Ginsenosides are the main chemical component of Araliacede panax botany which includes Panax ginseng C.A.Mey,Panax quinquefolium L.,Panax notoginseng etc.Some researches showed that secondary ginsenosides containing less glycosyl had stronger biological activity than common ginsenosides.However,the secondary ginsenosides and sapogenins are rare in Panax plants,therefore they were usually obtained by degrading common ginsenosides.In the literatures,there are many degradation methods,such as acid degradation,alkali degradation,enzyme degradation,microbial degradation and microwave degradation.These methods have many disadvantages,including low degradation efficiency,more by-products and structural change.In order to find more efficient preparation methods,in this paper,studied on the alkaline-degradation method under high temperature and high pressure for panax quinquefolium saponins?PQSs?.Firstly,Taking temperature,time,alkalinity and solid-liquid ratio as reference factors,Theoptimaldegradationconditionsof20?S?-ginsenosideRg₃,20?S?-ginsenoside Rh₂,20?S?-ginsenoside PPD and their mixture were determined under high temperature,high pressure and alkaline conditions respectively through single factor and orthogonal experiment.The experimental results are as follows.a)The optimal degradation conditions of 20?S?-ginsenoside Rg₃:the degradation temperature is 180°C,the concentration of NaOH is 80 mg/mL,the solid-liquid ratio is1:100,and the duration is 6 hours.Under these conditions,the conversion rate of20?S?-ginsenoside Rg₃ is 24.66%.b)The optimal degradation conditions of20?S?-ginsenoside Rh₂:the degradation temperature is 200°C,the concentration of NaOH is 60 mg/m L,the duration is 10 hours,and the solid-liquid ratio is 1:100.Under these conditions,the conversion rate of 20?S?-ginsenoside Rh₂ is 25.93%.c)The optimaldegradationconditionsof20?S?-protopanoxatriol[20?S?-PPD]:the degradation temperature is 220°C,the duration is 10 hours,the solid-liquid ratio is1:100,and the concentration of NaOH is 60 mg/m L.Under these conditions,the conversion rate of 20?S?-PPD is 45.71%.d)The optimal degradation conditions of total amount of three secondary products that include 20?S?-ginsenoside Rg₃,Rh₂ and PPD:the degradation temperature is 200°C,the concentration of NaOH is 40 mg/m L,the solid-liquid ratio is 1:200,and the duration is 10 hours.Under these conditions,the conversion rate is 65.82%.In addition,a HPLC method was established to detect the component of 20-?S?-Rg₃,Rh₂ and PPD in the degradation products.The chromatographic conditions are optimized as follows:The chromatographic column is Agilent-ZORBAX SB-C18?4.6×250 mm,5 m?;the condition of gradient elution of mobile phase is that 0-20min and A accounts for 40-50%,20-40min and A accounts for 50-70%,40-60min and A accounts for 70-95%.,where A is acetonitrile and surplus is water;the mobile rate is0.8 mL/min;the column temperature sets up 30°C;the wavelength of detection is 203nm.Experimental results of methodology show that the linear range of Rg₃,Rh₂ and PPD is wide,and the analytical method has high sensitivity,precision and accuracy.Secondly,Twelve compounds were separated from the degradation products at the optimal degradation conditions of their mixture of 20?S?-ginsenoside Rg₃,Rh₂ and PPD.their structures were identified by means of NMR,they were 20?S?-ginsenoside Rg₂?compound 1?,ginsenoside Rk₂?compound 2?,ginsenoside Rh₃?compound 3?,ginsenoside Rk₁?compound 5?,ginsenoside Rg₅?compound 6?,20?S?-ginsenoside Rh₂?compound 7?,ginsenoside Rk₃?compound 8?,20?S?-ginsenoside PPT?compound9?,20?S?-ginsenoside PPD?Compound 10?,20?S?-ginsenoside Rg₃?compound 11?,ginsenoside Rh₄?compound 12?,and 20?S?-ginsenoside Rh₁?compound 13?.On the basis of the above researches,the degradation mechanism of ginsenosides was also analyzed.Finally,It explores the biological activity of three degradation products under optimal degradation conditions,which were prepared from the total saponins of Panax ginseng?G?,Panaxquinquefolium?Q?andPanaxnotoginseng?N?,respectively.Biological activity was studied which includes scavenging hydroxyl radical?·OH?and superoxide anion?·O₂^-?and inhibiting L-tyrosinase..The results show that three degradation products have good scavenging radical ability,and the order is Q>N>G.Moreover,three degradation products have the effect of inhibiting tyrosinase,suggesting that they may have whitening effect.In conclusion,this paper deeply studied alkaline-degradation method of 20?S?-ginsenoside Rg₃,Rh₂ and PPD under high temperature and high pressure and the antioxidant activity of degradation products.The results of this study provide a new scientific basis for further development and utilization of ginseng resources.