Date Published: March 6, 2019
Publisher: Public Library of Science
Author(s): Yuqian Zhang, Yunchen Zhao, Yaoying Lu, Qiming Cao, Wenzhong Chen, Yuru Chen, Vijai Gupta.
A fungus identified as Aspergillus aculeatus was used to biotransform genistein and glycosides to polyhydroxylated isoflavones. The strain was identified on the basis of colony morphology features and ITS rDNA sequence analysis. Phylogenetic tree was constructed to determine its taxonomic status. Genistein and glycosides were transformed by Aspergillus aculeatus to 5,7,8,4’- tetrahydroxyisoflavone. The chemical structure of the product was identified by high performance liquid chromatography(HPLC), liquid chromatography-mass spectrometry(LC/MS), Infrared spectroscopy (IR) and NMR spectrometer methods. The ITS rDNA sequence of the strain had 100% similarity with Aspergillus. Furthermore, it was ultimately identified as Aspergillus aculeatus. The metabolite of genistein and glycosides was identified as 5,7,8,4’-tetrahydroxyisoflavone. 120 mg 5,7,8,4’-tetrahydroxyisoflavone was made from 20 g fructus sophorae, which was bioconverted unconditionally by Aspergillus aculeatus for 96 h, and the purity was 96%. On the basis of the findings, Aspergillus aculeatus was a novel strain with specific ability to convert genistein and glycosides into 5,7,8,4’-tetrahydroxyisoflavone which had potential applications.
Isoflavones are a class of organic compounds and bio-molecules related to the flavonoids. They are thought of by some as useful in treating cancer. They are also very strong antioxidants. Genistin, genistein, rutin, quercetin and kaempferol are the main effective components of flavones and isofavonoids [1–2]. In recent years, the metabolic process of isoflavones and flavones has drawn more attention. Isoflavones such as genistein and daidzein are found in a number of plants including lupin, fava beans, soybeans, Kudzu, and psoralea being the primary food source[3–4], also in the medicinal plants[5–7], coffee and Maackia amurensis cell cultures. Fructus sophorae, Chinese name as “Huaijiao”, is widely used to treat heart diseases in China. It is effective against neoplasms, inflammation and hyperlipidemia. Besides, it can be used for curing senile osteoporosis, reducing uric acid concentration[10–11]. Studies showed that fructus sophorae contains flavonoids, isoflavonoids, alkaloids, terpenoids, amino acid, saccharide and phospholipids et al.
Our study has screened and identified a strain named Aspergillus aculeatus on the basis of colony morphology features and ITS rDNA sequence analysis. Phylogenetic tree was constructed to determine its taxonomic status.