1,3,6-Trihydroxy-5-methoxyxanthone

Planta Med. 2002 Jan;68(1):49-54.

Natural products inhibiting Candida albicans secreted aspartic proteases from Tovomita krukovii.[Pubmed: 11842327]

METHODS AND RESULTS:
Assay-guided fractionation of the ethanol extract of Tovomita krukovii resulted in the identification of four new xanthones (1 - 4) and ten known compounds (5 - 14). The structures of compounds 1 - 14 were determined by spectral data to be 3,5-dihydroxy-4-methoxyxanthone (1), 1,3,5,7-tetrahydroxy-8-isoprenylxanthone (2), 1,3,5-trihydroxy-8-isoprenylxanthone (3), 1,5,7-trihydroxy-8-isoprenylxanthone (4), 1,3,7-trihydroxy-2-isoprenylxanthone (5), 1,5-dihydroxyxanthone (6), 1,6-dihydroxy-5-methoxyxanthone (7), 1,3,5-trihydroxyxanthone (8), 1,3,6-Trihydroxy-5-methoxyxanthone (9), 1,6-dihydroxy-3,5-dimethoxyxanthone (10), 1,3,7-trihydroxyxanthone (11), 3-geranyl-2,4,6-trihydroxybenzophenone (12), betulinic acid (13), and 3,4-dihydroxybenzoic acid (14).
CONCLUSIONS:
Compounds 2, 3, 12 and 13 showed inhibitory effects against Candida albicans secreted aspartic proteases (SAP) with IC50 values of 15 microg/ml, 25 microg/ml, 40 microg/ml, and 6.5 microg/ml, respectively, while the other compounds were inactive. In addition, compound 12 showed activity against C. albicans, C. neoformans, S. aureus and methicillin resistant S. aureus (MRS).

J Asian Nat Prod Res. 2015;17(4):377-83.

Synthesis and antitumor activity evaluation of a novel series of xanthone derivatives.[Pubmed: 25628155]

METHODS AND RESULTS:
A natural xanthone, 1,3,6-Trihydroxy-5-methoxyxanthone, was totally synthesized for the first time by six steps in 31% overall yield. The xanthone skeleton was formed by a one-step synthesis in 80% yield, and five of its novel derivatives were also obtained by this approach. This synthetic strategy and all the derivatives could be further used for the preparation of other natural xanthones. All the xanthones were characterized by NMR and ESI-MS, and the cytotoxicity of these xanthones was evaluated against HepG2 and HT-29 cells, and the preliminary structure-activity relationship was evaluated from the results.
CONCLUSIONS:
It was proved that the presence of 3-OH group in the molecule is crucial for its biological activity, while the presence of substituents at C-5 and C-6 may also be beneficial.

Nat Prod Res. 2015;29(13):1217-21.

A new flavonoid from Cudrania cochinchinensis.[Pubmed: 25571958 ]

METHODS AND RESULTS:
Chemical investigation of the ethanol extract of the roots of Cudrania cochinchinensis led to the isolation of a new flavonoid, (6S,12S,13R)-1-methoxy cyanomaclurin (1), together with seven known compounds, 1,3,5-trihydroxy-4-(3'-hydroxy-3'-methylbutyl)xanthone (2), 1,3,6-trihydroxy-4-prenylxanthone (3), 1,3,6,7-tetrahydroxyxanthone (4), 1,3,5,6-tetrahydroxyxanthone (5), 1,3,6-Trihydroxy-5-methoxyxanthone (6), resveratrol (7) and oxyresveratrol (8).
CONCLUSIONS:
The structure of compound 1 was elucidated on the basis of 1D and 2D NMR spectra and the HR-ESI-MS data. The absolute stereochemistry was deduced via Rh2(OCOCF3)4-induced CD and NOESY spectra.