8-deoxygartanin and mangostin

MutT homologue 1 (MTH1) protects the nucleotide pool from oxidative stress by hydrolyzing oxidized nucleoside triphosphates and prevents their incorporation into DNA. Cancer cells are dependent on the MTH1 activity for survival due to the high-level of reactive oxygen species in cancer cells; therefore, MTH1 is considered to be a novel target for treatment of various cancers. Here, we show by X-ray crystallographic screening using an in-house cocktail library that α-mangostin, a natural xanthone from mangosteen pericarp, binds to the active site of MTH1. A subsequent inhibition assay revealed that 3-isomangostin, a cyclized derivative of α-mangostin, was the most potent MTH1 inhibitor, with an IC

Topics: Catalytic Domain; Crystallography, X-Ray; DNA Repair Enzymes; Drug Discovery; Drug Evaluation, Preclinical; Enzyme Inhibitors; Garcinia mangostana; Phosphoric Monoester Hydrolases; Protein Binding; Xanthones

Somatic heterozygous mutations of isocitrate dehydrogenase-1 (IDH1) are abundantly found in several types of cancer and strongly implicate altered metabolism in carcinogenesis. In the present study, we have identified α-mangostin as a novel selective inhibitor of mutant IDH1 (IDH1-R132H). We have observed that α-mangostin competitively inhibits the binding of α-ketoglutarate (α-KG) to IDH1-R132H. The structure-relationship study reveals that α-mangostin exhibits the strongest core inhibitor structure. Finally, we have observed that α-mangostin selectively promotes demethylation of 5-methylcytosine (5mC) and histone H3 trimethylated lysine residues in IDH1 (+/R132H) MCF10A cells, presumably via restoring the activity of cellular α-KG-dependent DNA hydroxylases and histone H3 lysine demethylases. Collectively, we provide evidence that α-mangostin selectively inhibits IDH1-R132H.

Topics: Binding, Competitive; Drug Discovery; Humans; Isocitrate Dehydrogenase; MCF-7 Cells; Molecular Structure; Mutation; Recombinant Proteins; Structure-Activity Relationship; Xanthones

Garcinia mangostana is a well-known tropical plant found mostly in South East Asia. The present study investigated acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory activities of G. mangostana extract and its chemical constituents using Ellman's colorimetric method. Cholinesterase inhibitory-guided approach led to identification of six bioactive prenylated xanthones showing moderate to potent cholinesterases inhibition with IC50 values of lower than 20.5 μM. The most potent inhibitor of AChE was garcinone C while γ-mangostin was the most potent inhibitor of BChE with IC50 values of 1.24 and 1.78 μM, respectively. Among the xanthones, mangostanol, 3-isomangostin, garcinone C and α-mangostin are AChE selective inhibitors, 8-deoxygartanin is a BChE selective inhibitor while γ-mangostin is a dual inhibitor. Preliminary structure-activity relationship suggests the importance of the C-8 prenyl and C-7 hydroxy groups for good AChE and BChE inhibitory activities. The enzyme kinetic studies indicate that both α-mangostin and garcinone C are mixed-mode inhibitors, while γ-mangostin is a non-competitive inhibitor of AChE. In contrast, both γ-mangostin and garcinone C are uncompetitive inhibitors, while α-mangostin is a mixed-mode inhibitor of BChE. Molecular docking studies revealed that α-mangostin, γ-mangostin and garcinone C interacts differently with the five important regions of AChE and BChE. The nature of protein-ligand interactions is mainly hydrophobic and hydrogen bonding. These bioactive prenylated xanthones are worthy for further investigations.

Topics: Cholinesterase Inhibitors; Garcinia mangostana; Molecular Docking Simulation; Molecular Structure; Prenylation; Structure-Activity Relationship; Xanthones

Twelve xanthone constituents of the botanical dietary supplement mangosteen (the pericarp of Garcinia mangostana) were screened using a noncellular, enzyme-based microsomal aromatase inhibition assay. Of these compounds, garcinone D (3), garcinone E (5), alpha-mangostin (8), and gamma-mangostin (9) exhibited dose-dependent inhibitory activity. In a follow-up cell-based assay using SK-BR-3 breast cancer cells that express high levels of aromatase, the most potent of these four xanthones was gamma-mangostin (9). Because xanthones may be consumed in substantial amounts from commercially available mangosteen products, the consequences of frequent intake of mangosteen botanical dietary supplements require further investigation to determine their possible role in breast cancer chemoprevention.

Topics: Anticarcinogenic Agents; Aromatase Inhibitors; Dietary Supplements; Dose-Response Relationship, Drug; Garcinia mangostana; Molecular Structure; Xanthones