Chemical Constituents From The Aerial Parts Of Glycyrrhizu Uralensis And Glycyrrhiza Inflata

Licorice, a popular Chinese herbal medicine derived from the dried roots and rhizomes ofGlycyrrhiza species (Leguminosae family), contains about30species, and is widely distributed allover the world. In Chinese Pharmacopoeia, only three species, Glycyrrhiza uralensis, G. glabra,and G. inflate, are officially used as Gan-Cao medicine. Licorice has lots of usefulpharmacological properties such as antiulcer, antiviral, antioxidant, antibacterial, antifungal,antimalarial, antihepatotoxic, antispasmodic, and antiinflammatory and other activities. The chiefbioactive constituents of licorice are triterpene saponins and multifarious flavonoids. Previousphytochemical investigations on licorice led to find that The aerial parts of Licorice have alwaysbeen thrown away without any research. In order to find novel compounds with new structuresand significant activities, to explain the different chemical constituents in different parts of thesame plant, we conducted the chemical research to the90%ethanol extracts of the aerial parts ofLicorice.Based on a variety of chromatographic techniques such as silica gel chromatgraphy,Sephadex LH-20, HPLC, polyamide, and crystallization., thirteen compounds have been isolatedfrom an ethanol extract of the aerial parts of Glycyrrhiza uralensis. They are (2S)-3’-(2-hydroxy-3-methylbut-3-enyl)-4’,5,7-trihydroxy-dihydroflavanone （1*）， pinocembrin (2),sigmoidin B (3), licoflavanone (4),6-prenylnaringenin (5), pinobanksin (6), galangin (7), genistein(8), pratensein (9), kaempferol-3-O-β-D-rutinoside (10), rutin (11), α,α’-dihydro-3,5,3’-trihydroxy-4’-methoxy-5’-isopentenyl-stilbene (12) and D-1-O-methylinositol (13).Respectively. These compounds included five dihydroflavanones, one dihydroflavanol, oneflavonol, two isoflavones, two flavonoid glycosides, one dihydrostilbene and onepolyhydroxy-alcohol. Among them, compound1*was new, Compounds3,6,7,9and13wereobtained from the genus Glycyrrhiza for the first time.9compounds were obtained from an90%ethanol extract of the aerial parts of Glycyrrhiza inflata by the same way. Their structures were identified as2-(3-methyl-2-butenyl)-3,5,4’-trihydroxy-bibenzyl (14*) and (2S)-6-[(E)-3-hydroxymethyl-2-butenyl]-3’,4’,5,7-tetrahydroxy-dihydroflavanone (15*)，licoleafol (16),5,7,3’,4’-tetrahydroxy-8-(3’,3’-dimethylallyl)-flavanone(17),5,7,3’,4’-tetrahydroxy-6-(3’,3’-dimethylallyl)-flavanone (18),8-prenylnaringenin(19),6-prenylnaringenin (20),5,7-dihydroxy-8-(3’,3’-dimethylallyl)-flavanone(21),5,7-dihydroxy-6-(3’,3’-dimethylallyl)-flavanone (22), on the basis of spectroscopic analysis and by comparison oftheir spectroscopic data with those reported in the literature. Among them, Compounds14*and15*were new. And they were tested for their minimum inhibitory concentration (MIC) values ofinhibiting Staphylococcus aureus and Staphylococcus epidermidis.14*showed moderateantibacterial activities against both S. aureus (MIC of50.00μg/ml) and S. epidermidis (MIC of12.50μg/ml). The analysis of structure-activity relationships revealed that the antibacterial activityof dihydroflavanones (14*-22) was significantly affected by the position of prenyl group.