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Publication Details
AFRICAN RESEARCH NEXUS
SHINING A SPOTLIGHT ON AFRICAN RESEARCH
biochemistry, genetics and molecular biology
Tyrosinase activity of Greyia flanaganii (Bolus) constituents
Phytomedicine, Volume 18, No. 11, Year 2011
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Description
Hyper-pigmentation of the skin is a common problem that is prevalent in middle aged and elderly people. It is caused by over production of melanin. Tyrosinase is known to be the key enzyme in melanin production. Ethanolic extract of Greyia flanaganii leaves showed significant (P < 0.05) antityrosinase activity exhibiting the IC 50 of 32.62 μg/ml. The total extract was further investigated for its toxicity and effect on melanin production by melanocytes cells, and showed significant inhibition (P < 0.05) (20%) of melanin production at 6.25 μg/ml and low levels of cytotoxicity (IC 50 < 400 μg/ml). The amount of antioxidants necessary to decrease the initial DPPH absorbance by 50% (EC 50) by the total ethanolic extract was found to be 22.01 μg/ml. The effect of G. flanaganii against acne causing bacteria, Propionibacterium acnes, was investigated using microdilution assay. The MIC of the extract of G. flanaganii was found to be 250 μg/ml. Bioassay-guided fractionation led to the isolation of (3S)-4-hydroxyphenethyl 3-hydroxy-5-phenylpentanoate (1), 2′,4′, 6′-trihydroxydihydrochalcone (2), 2′,6′,4-trihydroxy-4′- methoxydihydrochalcone (3), 2′,6′-dihydroxy-4′- methoxydihydrochalcone (4), 5,7-dihydroxyflavanone [(2S)-pinocembrin] (5), 2′,6′-dihydroxy-4′,4-dimethoxy dihydrochalcone (6) and (2R,3R)-3,5,7-trihydroxy-3-O-acetylflavanone (7). The isolated compounds were tested for their antioxidant, cytotoxicity, tyrosinase inhibition and antibacterial activities. Compound 2 exhibited significant (P < 0.05) antityrosinase activity exhibiting the IC 50 of 69.15 μM. The isolated compounds showed low toxicity of the cells with reduction of melanin content of the cells. All compounds tested showed good radical scavenging activity. These data indicates that G. flanaganii extract and its isolated phenolic constituents could be possible skin lightening agents. © 2011 Elsevier GmbH. All rights reserved.
Authors & Co-Authors
Mapunya, Manyatja Brenda
South Africa, Pretoria
University of Pretoria
Hussein, Ahmed Abdel Fattah
South Africa, Pretoria
University of Pretoria
Egypt, Giza
National Research Centre
Rodrı́guez, Benjamı́n
Spain, Madrid
Csic - Instituto de Química Orgánica General Iqog
Lall, Namrita
South Africa, Pretoria
University of Pretoria
Statistics
Citations: 45
Authors: 4
Affiliations: 3
Identifiers
Doi:
10.1016/j.phymed.2011.03.013
ISSN:
09447113
e-ISSN:
1618095X