Glabranin

Food Chem. 2013 Aug 15;139(1-4):87-92.

Antioxidant activity-guided separation of coumarins and lignan from Melicope glabra (Rutaceae).[Pubmed: 23561082 ]

METHODS AND RESULTS:
The ethyl acetate and methanol bark extracts of Melicope glabra were evaluated for their antioxidant capacities by 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging activity and β-carotene bleaching/linoleic acid system. Both extracts exhibited strong inhibition against the DPPH radical (IC50 values of 24.81 and 13.01 μg ml(-1), respectively) and strong antioxidant activity in β-carotene bleaching assay. Both samples were found to have high phenolic content with values of 39 and 44 mg GAE/g as indicated by Follin-Ciocalteau's reagent. Antioxidant TLC assay-guided isolation on the methanol extract led to the isolation of a new pyranocoumarin, Glabranin (1), umbelliferone (2), scopoletin (3) and sesamin (4), and their structures were determined by spectroscopy.
CONCLUSIONS:
Compounds (1-3) showed significant activities on DPPH free radical with the IC50 of 240.20, 810.02 and 413.19 μg ml(-1), respectively. However, in β-carotene bleaching assay, sesamin (4) showed higher inhibitory activity (1 mg ml(-1), 95%) than Glabranin (1) (1 mg ml(-1), 74%), whilst umbelliferone (2) and scopoletin (3) were slightly pro-oxidant.

Molecules. 2015 Apr 20;20(4):7143-55.

Inhibition of Oxidative Stress and Skin Aging-Related Enzymes by Prenylated Chalcones and Other Flavonoids from Helichrysum teretifolium.[Pubmed: 25903365]

METHODS AND RESULTS:
Ten flavonoid-related structures viz. heliteretifolin (1), isoxanthohumol (2), 2',4',6'-trihydroxy-3'-prenylchalcone (3), isoGlabranin (4), Glabranin (5), 7-methoxy-isoGlabranin (6), quercetin (7), 4'-methoxyquercetin (8), 4'-methoxykaempferol (9) and mosloflavone (10) were isolated from a H. teretifolium methanolic extract and identified. One of them (compound 1) is reported for the first time from a natural source, while compounds 6, 8-10 were isolated for the first time from the genus Helichrysum. The total extract of H. teretifolium showed potent antioxidant activity. When tested for total antioxidant capacity compound 3 possesses moderate biological activity compared to 2, which displayed some of the highest TEAC values (4529.01 ± 2.44; 4170.66 ± 6.72) µM TE/g, respectively. Compounds 7 and 8 demonstrated the highest inhibitory activities on Fe2+-induced lipid peroxidation (IC50 = 2.931; 6.449 µg/mL); tyrosinase (8.092; 27.573) and elastase (43.342; 86.548). Additionally, the total antioxidant capacities measured as FRAP (4816.31 ± 7.42; 3584.17 ± 0.54) µM AAE/g, and ORAC for hydroxyl radical (7.265 ± 0.71; 6.779 ± 3.40) × 106 and peroxyl radical (17.836 ± 2.90; 12.545 ± 5.07) × 103 µM TE/g were also observed for compounds 7 and 8, respectively.
CONCLUSIONS:
In conclusion, H. teretifolium total extract represents a rich source of bioactive constituents with potent antioxidant and moderate anti-tyrosinase and anti-elastase activities that can help to avert accumulation of free radicals in the body, and could therefore be good candidates for the prevention and/or treatment of skin-related conditions, such as aging. This is the first scientific report on the chemical and biological profile of H. teretifolium.

Phytother Res. 2000 Mar;14(2):89-92.

Antiviral effect of flavonoids on the dengue virus.[Pubmed: 10685103]

METHODS AND RESULTS:
In the present study we analysed the possible antiviral effect on dengue viruses of different flavonoids extracted and identified at the Chemistry Institute, UNAM, from the Mexican plants Tephrosia madrensis, Tephrosia viridiflora and Tephrosia crassifolia. The flavonoids Glabranine and 7-O-methyl-Glabranine presented 70% inhibition on the dengue virus at a concentration of 25 microM, while methyl-hildgardtol A, hildgardtol A and elongatine had no effect on viral growth.
CONCLUSIONS:
Our results show that Glabranine and 7-O-methyl-Glabranine isolated from Tephrosia s.p. exert a dose-dependent inhibitory effect in vitro on the dengue virus.

Phytochemistry, 1983, 22(2):573-6.

Antimicrobial agents from higher plants: Prenylated flavonoids and other phenols from Glycyrrhiza lepidota.[Reference: WebLink]

METHODS AND RESULTS:
Bioassay directed fractionation of extracts of American licorice, Glycyrrhiza lepidota (Leguminosae), resulted in identification of the known bibenzyl, 3,5-dihydroxy-4-(3-methyl-2-butenyl)-bibenzyl, and the known flavanones, Glabranin and pinocembrin, as well as the isolation and structure determination of the new flavonol, glepidotin A and the new dihydroflavonol, glepidotin B as antimicrobial agents.

J Nat Prod. 2005 Jul;68(7):1099-102.

Dihydrostilbene derivatives from Glycyrrhiza glabra leaves.[Pubmed: 16038558]

METHODS AND RESULTS:
Four new dihydrostilbenes, alpha,alpha'-dihydro-3,5-dihydroxy-4'-acetoxy-5'-isopentenylstilbene (1), alpha,alpha'-dihydro-3,3',4'-trihydroxy-5-O-isopentenyl-6-isopentenylstilbene (2), alpha,alpha'-dihydro-3,5,3'-trihydroxy-4'-methoxystilbene (3), and alpha,alpha'-dihydro-3,3'-dihydroxy-5beta-d-O-glucopyranosyloxy-4'-methoxystilbene (4), together with seven known flavonoids, Glabranin isomer, naringenin, lupiwighteone, pinocembrin 7-O-glucoside, astragalin, isoquercitrin, vicenin II, and the inositol, pinitol, were isolated from the leaves of Glycyrrhiza glabra grown in Sicily. The structures of 1-4 were elucidated by spectroscopic methods.