Physiological and Chemical Studies on the Bioconversion of Glycyrrhizin by Aspergillus niger NRRL595

Abstract

Glycyrrhizin (GL), the well-known sweet saponin of licorice, has been used as a food-additive and as a medicine. Its aglycone, glycyrrhetic acid (GA) showed antiinflamatory, antiulcer and antiviral properties. GA is now produced form GL by acid hydrolysis. However, it is difficult to obtain GA in a good yield by using this method, because many by-products are also produced. Screening of different microorganisms (13 bacteria, 2 yeasts and 23 fungi) for production of GA from GL revealed that Aspergillus niger NRRL 595 produced the highest yield of GA. The bioconversion of GL by A. niger NRRL 595 for 96 h, followed by isolation and purification of the transformation products led to the separation of two conversion products, namely: GA and 3-oxo-GA. Confirmation of the identity of these products was established by determination of their Rf values, m.p., and IR, UV, MS and NMR spectra. The conditions for cultivation of this fungus with the maximum hydrolytic activity for the maximum yield of GA were investigated. Based on the results, A. niger NRRL 595 was cultivated with a medium composed of 1.75 % GL, 0.5 % glucose, 0.8 % corn steep liquor at pH 6.5 at 32 °C for 96 h. The cultivation of fungal cells under the latter conditions afforded GA and 3-oxo-GA in a yield of 65 % and 22 %, respectively.

Chemoenzymatic synthesis of new derivatives of glycyrrhetinic acid with antiviral activity. Molecular docking study

“…2.1. Amidation of 3-acetyl glycyrrhetinic acid (2) Six commercial lipases from different sources were evaluated for enzymatic amidation with ethanolamine: from the yeasts Candida rugosa (CRL), Candida antarctica B (CAL B) and Candida antarctica lipase B (CAL B immo plus); from the fungus Rhizomucor miehei (LIP), Rhizopus oryzae lipase (ROL) and Thermomyces lanuginosus (TLL).…”

“…The pentacyclic triterpenoid glycyrrhetinic acid (GA) is the major bio-active constituent isolated from the roots of Glycyrrhiza glabra, which is a sweet-tasting material and has greater sweetening power than sugar, making it a widely used as additive in the food industry [1][2][3]. GA has been used as a lead compound to search more potent derivatives with different pharmacological properties.…”

Synthesis and Antiviral and Antitumor Activities of Novel 18β-Glycyrrhetinic Acid Derivatives

“…Licorice (Glycyrrhiza glabra) is a medicinal plant widely used in traditional Chinese medicine (TCM). Its major active ingredient, glycyrrhetinic acid (GA), is a pentacyclic triterpenoid with a broad spectrum of pharmacological activities [1][2][3]. GA has been shown to possess anticancer [4][5][6][7], antiviral [8][9][10], antioxidant [11], antibacterial [12], and antiinflammatory [13] functions.…”