中药桑叶固体发酵前后抗氧化活性的研究

目的 探讨桑叶固体发酵前后70％乙醇提取物的体外抗氧化活性.方法 应用“药用真菌固体发酵工程”的原理和方法,以桑叶为药性基质,冠突散囊菌为发酵菌种,在一定条件下进行固体发酵,对发酵物用70％乙醇进行提取.并以维生素C（Vc）和乙二胺四乙酸（EDTA）为阳性对照,以清除1,1-二苯基-2-三硝基苯肼（DPPH）、2,2-联氮-二（3-乙基-苯并噻唑-6-磺酸）二铵盐（ABTS）、＆#183;OH自由基、铁还原能力及与Fe2＋螯合能力5个指标对发酵前后桑叶体外抗氧化活性进行评价;同时对发酵前后总黄酮、总酚酸含量进行测定.结果 未发酵桑叶70％乙醇提取物清除自由基能力及铁还原能力优于固体发酵7d后桑叶的70％乙醇提取物,但对于Fe2＋螯合能力而言,发酵后的桑叶70％乙醇提取物较未发酵前有所升高.其中未发酵桑叶70％乙醇提取物DPPH、ABTS、Fe2＋螯合能力的IC50值分别为：4.69、2.03、20.89 mg/mL,而固体发酵7d后的桑叶70％乙醇提取物三者的IC50值分别为：17.63、1.87、9.20 mg/mL;同时含量测定结果显示,发酵后桑叶中总多酚含量较发酵前明显下降,而发酵后桑叶中总黄酮含量却高于发酵前总黄酮含量.其中发酵前桑叶中总黄酮、总酚酸含量分别为4.39、3.95 mg/mL,而发酵后桑叶中总黄酮含量上升至5.37 mg/g,总酚酸下降为1.55 mg/g.结论 固体发酵7d,能够降低桑叶清除自由基的能力及铁还原能力,但却能升高其螯合能力.

Study on antioxidant activities of the solid fermentation and non-fermentation products in mulberry leaves

Objective To investigate the in vitro antioxidant activities between solid fermentation and non-fermentation products in mulberry leaves. Methods Guided by the theory of medicinal fungi solid fermentation engineering, with mulberry leaves used as medicinal matrix and the activated eurotiumcristatumas inoculated fungi, the activity of its total extract （70% ethanol） was evaluated by several in vitro experiments including DPPH assay, ABTS assay, ~ OH radicals assay, ferric-reducing power （FRAP） assay and ion-chelating assay using ascorbic acid and EDTA as positive controls. At the same time, the contents total flavonoids and total phenolic in fermentation and non-fermentation were determinated. Results The 70% ethanol extract of non-fermented mulberry leaves had stronger free radical scavenging capacity and FRAP than that of the fermented one. In a while, the 70% ethanol extract of fermented mulberry leaves was found stronger ion-chelating ability. For example, the total extract of the non-fermented one had capacity of scavenging DPPH, ABTS and ion-chelating ability with IC5o values of 4.69, 2.03 and 20.89 mg/mL, respectively. On thecontrary, the total extract of the fermentation of mulberry leaves showed capacity of scavenging DPPH, ABTS and ion-chelating ability with IC5o values of 17.63, 1.87 and 9.20 mg/mL, respectively. At the same time, the result of contents determination displayed that the total phenolic contents of the fermented one was significantly lower than that of the non-fermented one, while the total flavonoids of the fermented content was increased thanthat of the non-fermented one. For example, the total flavonoids and phenolic content of the non-fermentation products were 4.39 and 3.95 mg/g, but that of fermentation were 5.37 and 1.55 mg/g. Conclusion The capacities of free radical scavenging and FRAP decline after 7 days fermentation, while the ion-chelating ability increases.