Abstract: The content,stability and antioxidant activity of anthicyanins from Dendrobium officinale by different extraction methods were studied,and the content of anthocyanin was determined by pH differential method.The anthocyanins were extracted from Dendrobium officinale by organic solvent,microwave and ultrasonic wave.The effects of temperature,sunlight,metal ions and food additives on the stability of anthocyanins were investigated,and the antioxidant activity was investigated by scavenging hydroxyl radical,DPPH radical and ABTS⁺ radical.The result showed that:Microwave-assisted extraction made the highest yields (9.63 mg/100 g),followed by ultrasonic-assisted extraction (9.12 mg/100 g) and organic solvent extraction (7.56 mg/100 g);the Stability experiments showed that the change of temperature had great effect on the anthocyanins of Dendrobium officinale.As the temperature rose,the color gradually deepened.The anthocyanins were extremely unstable when exposed to sunlight.However,the anthocyanins extracted from the three extraction methods under sunlight were more stable than under natural and indoor natural light.Metal ions such as Mg²⁺ and Al³⁺ had hyperchromic effect on the anthocyanins,while Cu²⁺,Pb²⁺,Zn²⁺ and Fe³⁺ could result in fading of the color,Ca²⁺ had little influence on the stability of the anthocyanins.Ascorbic acid and sucrose significantly faded the anthocyanins,but sodium benzoate could exert negative effects;In vitro antioxidant system experiments showed that the IC₅₀ of anthocyanins from Dendrobium officinale extracted by organic solvent,microwave-Assisted and ultrasonic-assisted extraction was 3.349、3.155、3.338 mg/L for scavenging hydroxyl radical,0.119、0.71、0.088 mg/L for scavenging DPPH radical and 0.571、0.455、0.482 mg/L for scavenging ABTS⁺ radical.The content of anthocyanins extracted from Dendrobium officinale by microwave is the highest and the antioxidant ability is higher.

Key words: Dendrobium officinale, anthocyanins, stability, antioxidant activity