Xanthone

About: Xanthone is a research topic. Over the lifetime, 1639 publications have been published within this topic receiving 25870 citations. The topic is also known as: 9-oxo-xanthene & Diphenyline ketone oxide.

Penicillanthone and penicillidic acids A–C from the soil-derived fungus Penicillium aculeatum PSU-RSPG105

Abstract: A new xanthone (penicillanthone, 1) and three new diphenyl ether derivatives (penicillidic acids A–C, 2–4) together with 14 known compounds (5–18) were isolated from the soil-derived fungus Penicillium aculeatum PSU-RSPG105. The structures were elucidated by spectroscopic analyses. The absolute configuration of compound 1 was determined using the Snatzke's method whereas those of compounds 2–4 was established by comparison of their optical rotations with those of structurally related compounds. Compound 5 exhibited mild antimycobacterial activity against Mycobacterium tuberculosis with an MIC value of 25 μg mL−1 and was noncytotoxic to noncancerous Vero cells. In addition, altenusin (12) displayed moderate antibacterial activity against methicillin-resistant Staphylococcus aureus with an MIC value of 32 μg mL−1 and mild activity towards Vero cells with an IC50 value of 19.46 μM.

An antiproliferative xanthone of Symphonia pauciflora from the Madagascar rainforest

Abstract: In our continuing search for biologically active natural products from tropical rainforests as part of an International Cooperative Biodiversity Group (ICBG) program [1,2] we obtained an ethanol extract of a plant identified as Symphonia pauciflora Baker (Clusiaceae) from Madagascar. The extract showed moderate antiproliferative activity against the A2780 human ovarian cancer cell line with an IC50 value of 19 μg/mL. On the basis of the activity and the absence of previous phytochemical study on this species, S. pauciflora was selected for further investigation under the guidance of our bioassay. Previous studies on the genus Symphonia reported guttiferone analogues [3–5] and xanthone derivatives [4–10], some of which showed anti-HIV [3], antioxidant [5], and anti-plasmodial [5,6,8,10] activities. The cytotoxicities of xanthones [9,11] and guttiferones [12,13] have been also studied. Bioassay-guided fractionation by applying C18 open column and HPLC on the dichloromethane fraction yielded a new xanthone 1 and two guttiferones 2 and 3. Herein we report the structural elucidation of the new xanthone and the antiproliferative properties (against the A2780 human ovarian cancer cell line) of the isolated compounds. Compound 1 was obtained as a yellow amorphous solid. Its positive ESI-MS revealed a pseudomolecular ion peak at m/z = 425.1590 [M+H]+ corresponding to a molecular formula of C24H25O7, (calcd for C24H25O7 425.1600). The 1H NMR spectrum showed signals for one aromatic proton singlet at δH 7.21 (s), one methoxyl group at δH 3.95 (s), an olefinic proton at δH 5.22 (t, J = 7.5 Hz), two methylene protons at δH 3.35 (d, J = 7.5Hz) and a pair of downfielded methyl singlets at δH 1.68 (s) and 1.82 (s) which corresponded to a 3-methyl-2-butenyl group. In addition a pair of cis-coupled olefinic doublets (δH 7.04, d, J = 10.0 Hz; 5.69, d, J = 10.0 Hz) and a pair of methyl singlets at δH 1.48 (s), which suggested the presence of 3-oxygenated-3-methyl-butenyl group. The 13C NMR spectrum of 1 exhibited 24 carbon signals (Table 1), including one resonance of a carbonyl at δC 181.7, one methoxyl group at δC 56.6, one 3-methyl-2-butenyl group (δC 22.0, δC 123.5, δC 131.9, δC 26.0, δC 18.1), and one 3-oxygenated-3-methyl-butenyl group (δC 116.6, δC 127.8, δC 79.1, δC 28.5, δC 28.5), as well as twelve aromatic carbons assignable to two isolated aromatic rings, seven of which were oxygenated due to their corresponding down field carbon chemical shifts (δC 160.8, δC 151.4, δC 159.0, δC 134.4, δC 143.8, δC 143.3, δC 147.3). The above data suggested that compound 1 was a xanthone similar to those previously isolated from the same genus Symphonia [4–10]. In order to satisfy the degree of unsaturation number (13) implied by the molecular formula C24H24O7, the 3-oxygenated-3-methyl-butenyl group must be cyclized with a hydroxyl group of the xanthone moiety to form a gem-dimethyl dihydropyran. Table 1 1H and 13C NMR Data (δ) in CD3OD for Compounds 1a To assign the attachment of the functionalities, 2D NMR experiments were carried out. HMQC (Heteronuclear Multiple Bond Coherence) allowed the assignment of all the signals observed in the 1D NMR spectra. Careful interpretation of the 1H–1H COSY, HMBC, ROESY and NOESY allowed us to confirm the xanthone nature of 1. 1H-1H COSY correlations between the signal of H-1″ (δH7.04) and H-2″ (δH 5.69) as well as the HMBC correlations between H-1″ and the two oxygenated aromatic carbons: C-3 δC 151.4, C-4a δC 159.0 led to conclude that the 3,3-dimethylpyrano ring was attached at C-3 and C-4. The allocation of the proton on the pentasubstituted aromatic ring was substantiated by the observation of 3J correlations between the singlet aromatic proton at H-8 (δH 7.21) and the carbonyl carbon C-9, the two overlapped aromatic carbon signals at C-5a (δC 143.8) and at C-6 (δC 143.3), and 2J correlations between H-8 (δH 7.21) and the aromatic carbon at C-8a (δC 112.3) and C-7 (δC 147.3). The location of a methoxyl group on C-7 was deduced from the cross peak on the ROESY spectrum between the signals at δH 3.95 and at H-8. This was confirmed by the observation of HMBC correlation between the signal of the methoxyl group and that of C-7. The hydrogen bonded proton observed at δH 13.30 in CDCl3 indicated a hydroxyl group must be attached on C-1. 1H-1H COSY correlations between the signal at δH 3.35 (H2-1′) and that at δH 5.22 (H-2′) as well as HMBC long-range correlations between the signal at H-2′ and those of two methyl groups (δC 18.1 and δC 26.0) confirm the presence of 3-methyl-2-butenyl group. The latter was assigned to be attached at the C-2 position due to the HMBC correlations observed from H-1′ to C-1 and to C-2. Furthermore, a clear NOESY coorelation was observed between the hydrogen-bonded proton and H2-1′ in the spectrum of 1 while measured in CDCl3. On the basis of the molecular formula of 1, the remaining two hydroxyl groups must be located at C-5 and C-6. From the above data, the structure of 1 was determined to be 2-(3,3-dimethylallyl)-1,5,6-trihydroxy-7-methoxy-2″,2″-dimethylpyrano(6″,5″:3,4) xanthone. Compound 1 showed a strong antiproliferative activitiy against the A2780 human ovarian cancer cell lines with an IC50 value of 3.8 μM. Lenta and co-workers isolated the similar compound [2-(3,3-dimethylallyl)-1,5-dihydroxy-6,7-dimethoxy-2″,2″-dimethylpyrano(6″,5″:3,4)xanthone] which showed good anti-plasmodial activity (1.3 μM) [5,8]. Although the cytotoxic activities of xanthones have been reported against several cell lines, including KB, MCF-7, HT-29, and HeLa [14–16], only a few reports have investigated the properties of xanthones against the A2780 human ovarian cancer cell line [10]. Compound 1 showed better antiproliferative activity than two xanthones previously reported in the literature [12].

Synthesis, Crystal Structure, DNA-binding Properties and Cytotoxic Activity of the Copper (II) Complex Involving Xanthone

Abstract: 1, 8-(3, 6, 9-Trioxaundecane-1, 11-diyldioxy)xanthone (L), and its new Cu (II) complex [Cu·L·(CH3CN)2](ClO4)2 have been synthesized and characterized by 1H NMR, electrospray mass spectra (ESI-MS), elemental analyses, infrared spectra (IR) and X-ray single crystal diffraction. The crystal structure of complex shows that Cu (II) ion is encapsulated within the macrocycle of L. The geometry around copper is a distorted square bipyramid with two acetonitrile molecules at axial position, and four macrocyclic oxygens including the carbonyl oxygen on the equatorial positions. The interaction of Cu (II) complex with calf thymus DNA (ct DNA) has been investigated by spectrophotometric titrations, ethidium bromide (EB) displacement experiments, circular dichroism (CD) spectra and viscosity measurements. Rresults indicate that Cu (II) complex can intercalate into the DNA base pairs by the plane of xanthone ring. Furthermore, the Cu (II) complex was tested against tumor cell lines including ECA109, SGC7901and GLC-82 by MTT (microculture tetrazolium) method. The studies of DNA-binding agree with the effects on the inhibition of tumor cells in vitro.