Xanthones with Potential Anti-Inflammatory and Anti-HIV Effects from the Stems and Leaves of Cratoxylum cochinchinense

Four new xanthones, cratocochinones A-D (1-4), together with eight known analogues (5-12), were isolated from the stems and leaves of Cratoxylum cochinchinense. The chemical structures of cratocochinones A-D (1-4) were elucidated by comprehensive spectroscopic analyses and the known compounds were identified by comparisons with the spectral data reported in the literature. All isolated compounds 1-12 were evaluated for their anti-inflammatory activities and anti-HIV-1 activities. Compounds 1-12 showed remarkable inhibitory activities on nitric oxide (NO) production induced by lipopolysaccharide in mouse macrophage RAW 264.7 cells in vitro, with IC50 values in the range of 0.86 ± 0.05 to 18.36 ± 0.21 µM. Meanwhile, compounds 1-12 exhibited significant anti-HIV-1 activities with EC50 which ranged from 0.22 to 11.23 µM. These findings indicate that the discoveries of these xanthones, isolated from the stems and leaves of C. cochinchinense, showing significant anti-inflammatory and anti-HIV-1 effects could be of great importance to the research and development of new natural anti-inflammatory and anti-HIV agents.

Chemopreventive Effect of Cratoxylum formosum (Jack) ssp. pruniflorum on Initial Stage Hepatocarcinogenesis in Rats

Cratoxylum formosum ssp. pruniflorum (Kurz) Gogelein (CP) is an indigenous plant found mainly in southeast Asia. Several in vitro studies have confirmed its activity against hepatocellular carcinoma; however, in vivo studies of the effect of CP on liver cancer are needed. This study investigated the effect of CP on early-stage hepatocarcinogenesis in rat liver when using diethylnitrosamine (DEN) as a carcinogen. Immunohistochemistry was used to detect (a) upregulation of glutathione S-transferase placental (GST-P) positive foci, (b) the proliferating cell nuclear antigen PCNA, and (c) apoptotic cells in the liver as indicators of early-stage carcinogenesis. Immunohistochemical parameters were observed in rats given CP orally following DEN injection. Rats given DEN presented overexpression of GST-P positive foci, PCNA, and apoptotic cells, indicating the formation of cancerous tissues, and these effects were diminished by CP treatment. CP thus inhibited hepatocarcinogenic effects in an animal model. These results could help plan further in vivo studies and support the use of CP to prevent processes that promote the pathogenesis of hepatocellular carcinoma in humans.

Modified tetra-oxygenated xanthones analogues as anti-MRSA and P. aeruginosa agent and their synergism with vancomycin

Five isolated xanthones from the C. cochinchinense and G. mangostana were evaluated and tested for antibacterial activities. Isolated 4 and 5 exhibited potent anti-MRSA and P. aeruginosa activity, but showed poor pharmacokinetic properties via ADMET prediction. It led us to improve pharmacokinetic properties of 4 and 5 by partially modifying them in acidic condition yielding fourteen analogues. It was found that analogues 4b, 4d and 5b possessed proper pharmacokinetic properties, while only 4b exhibited the best anti-MRSA and P. aeruginosa activity. The SEM results indicated that 4b may interact with or damage the cell wall of MRSA and P. aeruginosa. Moreover, a combination of 4b and vancomycin exhibits synergistic effect against both MRSA and P. aeruginosa at MIC value of 4.98 (MIC = 18.75 μg/mL for 4b) and 9.52 μg/mL (MIC = 75 μg/mL for 4b), respectively.

Cytotoxic phenolic constituents from Hypericum japonicum

Nine undescribed compounds, including five xanthone derivatives, two flavonoids, one 2-pyrone derivative, and one undescribed naturally occurring compound, along with 30 known phenolic compounds, were isolated from Hypericum japonicum. In addition, hyperjaponols A and B were identified as racemates. The structures and absolute configurations of the undescribed compounds were determined by comprehensive MS, NMR spectroscopy, and electronic circular dichroism (ECD) calculations. The cytotoxic effects of the isolated compounds on two human tumour cell lines (HEL and MDA-MB-231) were evaluated by the MTT assay. Eighteen compounds showed good inhibitory activities against the HEL cell line, with IC₅₀ values of 3.53-18.7 μM, while nine compounds exhibited moderate cytotoxicity against the MDA-MB-231 cancer cell line, with IC₅₀ values ranging from 4.92 to 10.75 μM. Their preliminary structure-activity relationship of the isolated compounds was also discussed.

A pair of new enantiomers of xanthones from the stems and leaves of Cratoxylum cochinchinense

Background

The simple and caged xanthones from Clusiaceae showed significant antineoplastic activity. This study aims to identify structural diverse xanthones and search for novel antitumor natural products from this family plants.

Methods

The structures of new compounds 1a and 1b were elucidated mainly through comprehensive NMR and MS spectroscopic data, and their absolute configurations were determined by the comparison of the experimental and calculated electronic circular dichroism.

Results

A pair of new xanthone enantiomers, (+)- and (-)-cracochinxanthone A (1a and 1b), along with thirty known analogues (2-31), were isolated from extracts of the stems and leaves of C. cochinchinense. Preliminary biological assay of some isolates against HL-60, PC-3, and MDA-MB-231 cancer cell lines.

Conclusion

Some isolated xanthones exhibited high sensitivity against three human malignant cell lines and the structure-activity relationship study showed that the prenyl and geranyl units may play an important role in antitumor activity.

Highly Cytotoxic Xanthones from Cratoxylum cochinchinense Collected in Myanmar

Eight xanthones and one anthraquinone, together with four common triterpenoids, have been isolated from the barks of Cratoxylum cochinchinense, collected in Myanmar. The structures of the metabolites were elucidated by spectroscopic data analysis and their antiproliferative activities were measured against six human tumor cell lines, by using the MTT assay. Pruniflorone N (1) showed a significant cytotoxicity against all cancer cells with IC50 values in the range 3-9 μM, on average higher than the anticancer drug cisplatin. Instead, compounds 2 and 3 exhibited high antiproliferative activity against some specific cell lines.

New Benzophenones and Xanthones from Cratoxylum sumatranum ssp. neriifolium and Their Antibacterial and Antioxidant Activities

Two new benzophenones (1 and 2) and four new xanthones (4-6 and 17) together with 24 known compounds (3, 7-16, and 18-30) were isolated from the roots and twigs of Cratoxylum sumatranum ssp. neriifolium. Their structures were elucidated by spectroscopic methods. Compounds 5 and 26 showed antibacterial activity against Micrococcus luteus, Bacillus cereus, and Staphylococcus epidermis with minimum inhibitory concentrations ranging from 4 to 8 μg/mL, whereas compounds 7, 20, and 26 displayed selective antibacterial activities against Staphylococcus aureus (8 μg/mL), Salmonella typhimurium (4 μg/mL), and Pseudomonas aeruginosa (4 μg/mL), respectively. The radical scavenging effects of some isolated compounds were investigated. Compounds 11 and 21 exhibited potent activity against 2,2-diphenyl-1-picrylhydrazyl (DPPH) with IC₅₀ values of 7.0 ± 1.0 and 6.0 ± 0.2 μM, respectively.

Bioactive Xanthones from Cratoxylum cochinchinense

Chemical investigation of Cratoxylum cochinchinense stem bark has led to the isolation and identification of a new xanthone, cochinchinone M (1), together with 12 known compounds. Their structures were elucidated on the basis of spectroscopic methods, including UV, IR, NMR and MS. Some compounds were evaluated for their antibacterial and acetylcholinesterase inhibitory activities.

Bioactive prenylated xanthones from the stems of Cratoxylum cochinchinense

Cochinchinones M-U (1-9), together with 12 known compounds (10-21), were isolated from the stems of Cratoxylum cochinchinense (Lour.) Blume. Their structures were determined on the basis of extensive spectroscopic data analyses. In addition, their retinoid X receptor-α transcriptional activities were evaluated using an in vitro assay.

Phenolic constituents from the leaves of Cratoxylum formosum ssp. pruniflorum

One (formosumone A, 1) new and fifteen (2-16) known phenolic compounds were isolated from the leaves of Cratoxylum formosum ssp. pruniflorumm, a substitute for the popular bitter nail tea ("Kuding Tea") generally used in Southeast Asia. Their structures were determined by extensive spectroscopic analysis and by comparison with literature data. Compound 1 possesses a rare scaffold of a flavanone coupled with a phloroglucinol moiety, representing the first example of such a scaffold from the Clusiaceae family. Among the isolates, toxyloxanthone B (11) and vismione D (12) were found to show remarkable anti-neuroinflammatory effects by inhibiting nitric oxide (NO) production in lipopolysaccharide (LPS)-stimulated murine BV-2 microglial cells. Additionally, toxyloxanthone B (11) exhibited significant neuroprotective effect against β-amyloid(25-35) (Aβ(25-35))-induced cell viability decrease in SH-SY5Y neuroblastoma cells.

Inhibition of nitric oxide production in lipopolysaccharide-activated RAW264.7 macrophages by isolated xanthones from the roots of Cratoxylum formosum ssp. pruniflorum

The inhibitory activity of extract and compounds isolated from the roots of Cratoxylum formosum ssp. pruniflorum against nitric oxide (NO) was evaluated using RAW264.7 cells. Isolation of the CH2Cl2 extract of C. formosum ssp. pruniflorum roots afforded ten known xanthones including six tri-oxygenated xanthones (1-6) and four tetra-oxygenated xanthones (7-10), respectively. Compound 7 showed the highest inhibitory activity against NO release with an IC50 value of 3.9 μM, followed by compound 8 with an IC50 value of 4.3 μM, respectively. In order to understand the mechanism of this anti-inflammatory activity, the transcriptional level of 7 was found to down regulate mRNA expressions of iNOS and COX-2 in dose-dependent manners, whereas 8 inhibited only iNOS mRNA expression but did not affect on that of COX-2 gene. Xanthones might be the main anti-inflammatory components in C. formosum ssp. pruniflorum.

Racemic 2'-hydroxy-4',4'-dimethylpyran-1,5-dihydroxyxanthone monohydrate

The title xanthone (systematic name: 3,6,11-trihy­droxy-1,1-dimethyl-2,3-di­hydro­chromeno[2,3-f]chromen-7-one monohydrate), known as pruniflorone N, crystallized as a monohydrate, C₁₈H₁₆O₆·H₂O. The three ring systems of the xanthone skeleton are approximately coplanar, with an r.m.s. deviation of 0.0270 (1) Å from the plane through the 14 non-H atoms. The O atoms of the two hy­droxy substituents on the benzene rings also lie close to this plane, with deviations of 0.019 (1) and 0.070 (1) Å. The 2′-hy­droxy-4′,4′-di­methyl­pyran ring is disordered over two positions with a 0.798 (3):0.202 (3) site-occupancy ratio. An intra­molecular O—H⋯O hydrogen bond generates an S(6) ring motif. In the crystal, the xanthone and water mol­ecules are linked into a three-dimensional network by O—H⋯O hydrogen bonds and weak C—H⋯O inter­actions. π–π inter­actions, with centroid–centroid distances of 3.5982 (7), 3.6081 (7) and 3.6456 (7) Å, are also observed.

Sphenostylisins A-K: bioactive modified isoflavonoid constituents of the root bark of Sphenostylis marginata ssp. erecta

Sphenostylisins A-C (1-3), three complex dimeric compounds representing two novel carbon skeletons, along with an additional eight new compounds, sphenostylisins D-K (4-11), were isolated from the active chloroform-soluble extract of the root bark of Sphenostylis marginata ssp. erecta using a bioactivity-guided isolation approach. The structures were elucidated by means of detailed spectroscopic analysis, including NMR and HRESIMS analysis, and tandem MS fragmentation was utilized to further support the structures of 1-3. The absolute configuration of sphenostylisin C (3) was established by electronic circular dichroism analysis. Plausible biogenetic relationships between the modified isoflavonoids 1-11 are proposed, and a cyclization reaction of 9 was conducted to support one of the biogenetic proposals made. All of these pure isolates were evaluated against a panel of in vitro bioassays, and among the results obtained, sphenostylisin A (1) was found to be a very potent NF-κB inhibitor (IC50 = 6 nM).

Coumarins from roots of Clausena excavata

Two new coumarins, clauexcavatins A (1) and B (2), along with seven known ones (3-9), were isolated from the roots of Clausena excavata Burm. f. (Rutaceae). Their structures were elucidated on the basis of spectral data.