Determination of Contents of the Main Nutritional Components, Functional Components of Akebia trifoliata Pericarp and the Antioxidant Activity of Its Extracts

In order to explore the nutritional value and active function of Akebia trifoliata pericarp, the main nutritional components contents of protein, fat, total sugar, reducing sugar, 8 mineral elements, total flavonoids, total phenols and total saponins were determined by using Kjeldahl method, acid hydrolysis, phenol sulfuric acid method, 3,5-dinitrosalicylic acid method, ICP-AES method, NaNO₂-AlCl₃ method, Folin-ciocalten and vanillin-perchloric acid. The antioxidant capacity of pericarp extracts was also evaluated. The results showed that the contents of protein (8.16%±0.11%), reducing sugar (19.31%±0.21%) and total sugar (32.61%±0.18%) in the peel of Akebia trifoliata were high, and the pectin content determined by gravimetric method was (20.08%±0.20%). Among the eight nutrient elements measured, K content was the richest (14061.17 μg/g DW), followed by Ca (4959.28 μg/g DW). The orders of the contents of eight mineral elements were K>Ca>Mg>Fe>Mn>Na>Cu>Zn. The contents of total flavonoids, polyphenolics and saponins were (20.58±0.12), (31.53±0.18) and (45.20±12.04) mg/g DW, respectively. The scavenging capabilities of extraction on the free radicals of DPPH and ABTS⁺ were also investigated. When the scavenging rate reached to 50%, the IC₅₀ values on DPPH and ABTS⁺ free radicals scavenging were 0.049, 0.052 mg/mL, respectively. The scavenging ability of extracts in Akebia trifoliata pericarp was dose-dependent. The contents of total flavonoids, total polyphenols and total saponins had strong and positive correlations with antioxidant activity (P<0.01). In summary, Akebia trifoliata pericarp should be new resources with high nutritional values and strong antioxidant activities worth for in-depth development.