Identification of Anticancer Compounds in Gallnuts Through PCA-constructed Secondary Metabolite Map

Background and Objective: Gallnuts have been traditionally used as a source of drugs for the treatment of cancerous diseases in folk medicinal system around world.To reveal the anticancer phytochemical foundation of Gallnuts, the secondary metabolite maps were constructed to correlate the chemistry with the cytotoxicity of crude extracts on human cancer cells.Materials and Methods: The growth inhibition activities were determined by MTT assay of 8 solvent extracts of gallnuts Galla Chinensis and Galla Turcica in the human liver cancer cell line 7721.The activities were then mapped onto the secondary metabolite profile of crude extracts by principal components analysis (PCA) of HPLC-UV data.The top five PCA components of the map discriminated extract activity mainly based on the differential content of five compounds, which two of them were then tested individually using MMT assay on cancer cells in vitro.Results: PCA-constructed secondary metabolite mapping quickly identified functional compounds from crude gallnuts extracts.Galla Chinensis and Galla Turcica constituents gallic acid and 1, 2, 3, 4, 6-O-pentagalloyl glucose inhibited the growth of human liver cancer cell line growth with activities (IC 50 : 36.44±8.75 and 55.59±14.96µg mLG 1 , respectively) comparable to that of cisplatin (IC 50 : 35.12±1.74µg mLG 1 ).Conclusion: Gallic acid and 1, 2, 3, 4, 6-O-pentagalloyl glucose are identified as the anticancer constituents of Gallnuts.It thus strongly underpins a fundamental understanding of anticancer activities of gallnuts medicine and supports their ongoing clinical uses in China.Moreover, this work may confirm the potential of HPLC-PCA analysis as a tool for quick identification of functional compounds of plant extracts.