红曲橙色素的发酵制备及其在红曲红色素化学半合成中的应用

以红色红曲菌M7为菌株,采用pH 3的两步发酵法,结合结晶分离步骤,制备高纯度红曲橙色素,并以红曲橙色素和氨基酸为前体物,利用亲氨基反应在体外进行红曲红色素的化学半合成。结果显示,在该发酵条件下,所产生的色素在300 nm~600 nm范围内只有一个吸收峰,最大吸收波长为472 nm,表明该色素产物的主要成分为红曲橙色素,产量达(7.9±0.2)×10⁴U/L;结晶分离步骤能显著提高红曲橙色素的纯度,当向70%乙醇的色素提取液中加入0.5倍体积的水进行结晶分离时,每升发酵培养基可获得(0.63±0.04)g高纯度红曲橙色素晶体,含红斑红曲素和红曲玉红素两种橙色素组分,未检出桔霉素;体外亲氨基反应成功合成色氨酸和谷氨酸衍生红曲红色素,且橙色素向2种衍生红曲红色素的转化效率无显著差异。

Orange Monascus Pigments Preparation and Application in the Semi-synthesis of Red Monascus Pigments

Orange Monascus pigments were produced by a two-stage fermentation process under pH 3 with Monascus ruber M7,followed by the purification of pigments by a fractional crystallization method.The purified orange Monascus pigments,along with amino acids,were used as precursors for the semi-synthesis of amino acid-derived red Monascus pigments in vitro based on the aminophilic reaction.Results suggested that in the range of 300 nm-600 nm,the pigments had only one absorption peak and theλmax was approximately 472 nm,indicating that this pigment product was dominant with orange Monascus pigments,with a yield of(7.9±0.2)×10⁴U/L.The following fractional crystallization step significantly increased the purity of orange Monascus pigments.After adding 0.5 volume of water to 70%ethanolic pigment extract,(0.63±0.04)g of crystallized orange Monascus pigments were obtained with high purity from 1 L fermentation medium,and no citrinin was detected.The crystallized orange Monascus pigments mainly comprised two orange compounds,rubropunctatin and monascorubrin.Trp-and Glu-derived red Monascus pigments were successfully synthesized with the purified orange Monascus pigments by aminophilic reaction,and there were no obvious differences in the efficiency of converting orange Monascus pigments to the Trp-and Glu-derived red Monascus pigments.