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Abstract: Myrcauones A–D (1–4), four new phloroglucinol–terpene adducts were isolated from the leaves of Myrciaria cauliflora. Their structures with absolute configurations were elucidated by combination of spectroscopic analysis, single crystal X-ray diffraction, and electronic circular dichroism (ECD) calculations. Compound 1was a rearranged isobutylphloroglucinol–pinene adduct featuring an unusual 2,3,4,4a,10,11-hexahydro-1H-3,11a-methanodibenzo[b,f]oxepin backbone. Compound 4showed moderate antibacterial activity against Gram-positive bacteria including multiresistant strains. Graphic Abstract:

ABSTRACTThis study focused on the role of methionine (MET) in the autophagy of gastric cancer stem cells (GCSCs) and aims to elaborate its regulatory mechanism.In the present study, the GCSCs were isolated from human gastric cancer cell lines using an anti-CD44 antibody, and then cultured in MET+homocysteine (HCY)−or MET−HCY+medium.In MET+HCY–treated GCSCs, autophagy was suppressed, the methylation and phosphorylation of RAB37 were elevated, and miR-200b expression was down-regulated. Lentiviral vector (LV-) carrying methionine-γ lyase (an enzyme that could specifically lyse MET; Metase) promoted autophagy, reduced the methylation and phosphorylation of RAB37, and up-regulated miR-200b expression in MET+HCY–-treated GCSCs. Then, we found that miR-200b suppressed the expression of protein kinase C α (PKCα), a protein that could inactivate RAB37 through promoting its phosphorylation. LV-Metase down-regulated RAB37 phosphorylation via miR-200b/PKCα, thus promoting the RAB37-mediated autophagy and suppressing cell viability in MET+HCY–treated GCSCs. Finally, the in vivostudy proved that LV-Metase treatment inhibited tumor growth through up-regulating RAB37 expression.In conclusion, MET suppressed RAB37 expression via enhancing its methylation and suppressed RAB37 activity via miR-200b/PKCα axis, thus repressing RAB37-mediated autophagy in GCSCs. The supplementation of Metase lysed MET, thus inducing the autophagy of GCSCs and inhibiting tumor growth.

A pair of enantiomeric triketone–phloroglucinol hybrids, (+)- and (−)-myrtuspirone A (1), featuring an unprecedented 3-isopropyl-3H-spiro[benzofuran-2,1′-cyclohexane] backbone, were isolated from the leaves of Myrtus communis. The absolute configuration of each enantiomer of 1was determined by X-ray diffraction and chemical calculations. Furthermore, the gram-scale total syntheses of (±)-1and (−)-1were conducted in four steps using a Michael-N-iodosuccinimide (NIS)-mediated (3 + 2)-annulation reaction. Both (+)- and (−)-1exhibited antibacterial activities against Gram-positive bacteria including multidrug-resistant strains.

Callisretones A (1) and B (2), two rearranged phloroglucinol-monoterpenoid adducts featuring an unprecedented isopropylcyclopenta[b]benzofuran backbone, together with their postulated biosynthetic precursors (3–9), were isolated from Callistemon rigidus. The previously assigned absolute configurations of viminalins H (7), L (8), and N (9) were revised and unequivocally established by X-ray diffraction data. A putative biosynthetic pathway toward callisretones A and B involving the rearrangement of the terpenoid motif is proposed. In addition, 1and 2showed inhibitory effects on nitric oxide production with IC50values of 15.3 ± 1.0 and 17.7 ± 1.1 μM, respectively.

Objective To investigate the association between potentially functional MDM2 oncogene, E3 ubiquitin protein ligase (MDM2) T309G polymorphism and susceptibility to oesophageal or gastric cancer.Methods Two investigators independently searched the PubMed and Chinese National Knowledge Infrastructure databases for studies published before September 2013.Results Pooled results showed that the variant homozygous 309GG genotype (versus TT) was significantly associated with increased risk of both oesophageal (odds ratio [OR] 0.77; 95% confidence interval [CI] 0.65, 0.90) and gastric cancer (OR 0.52; 95% CI 0.38, 0.72). Subgroup analysis revealed a 309GG-associated increased risk for both cancer types in Asian populations, particularly among Chinese and Japanese ethnicity. When stratified for Helicobacter pyloriinfection and histological type of gastric cancer, the 309GG-related risk was higher in H. pylori-positive patients (T versus G: OR 0.37; 95% CI 0.22, 0.63) and the association was stronger with intestinal (TT + TG versus GG: OR 0.68; 95% CI 0.54, 0.87) rather than diffuse gastric-cancer type.Conclusions The MDM2T309G polymorphism may be significantly associated with increased susceptibility to oesophageal or gastric cancer, particularly among Eastern Asian populations.

Two new sapogenins, named (20S, 24R)-3β,20,21β,25-tetrahydroxy-21,24-cyclodammarane (1) and 3β-hydroxyetio-17β-dammaranic acid (2), were isolated from the alkaline hydrolysate of Gynostemma pentaphyllumsaponins. Their structures were elucidated by spectroscopic methods.

Two new cucurbitane-type triterpenoids, (23E)-5β,19-epoxycucurbita-6,23,25-triene-3β-ol (1) and (19R, 23E)-5β,19-epoxy-19-ethoxycucurbita-6,23-diene-3β,25-diol (2), together with three known compounds, have been isolated from the fruit of Momordica charantiaL. Their structures were determined on the basis of spectral analysis. Their cytotoxic activity was tested on 5 cancer cell lines, MCF-7, HepG2, Du145, Colon205 and HL-60 by MTT assay. Compounds 1, 3and 4showed weak cytotoxicity.

To study the chemical constituents in the acid-hydrolyzed ethanol extract from Momordica charantia.

One new triterpene saponin was isolated from Panax japonicusC. A. Meyer var major(Burk.) C. Y. Wu et K. M. Feng, and established as oleanolic acid 3-O-[β-d-glucopyranosyl-(1→2)-β-d-glucuronopyranosyl-6′-O-n-butyl ester] which showed moderate antitumor activities against the A2780 cells and OVCAR-3 cells. Its structure was established by means of spectral data, particularly NMR, including HSQC and HMBC techniques.

One new dammarane-type triterpene saponin, named (20S)-3β,20,21-trihydroxydammar-24-ene 3-O-[α-l- rhamnopyranosyl(1→2)][β-d-xylopyranosyl(1→3)]-β-d-glucopyranoside (1), was isolated from the aerial parts of Gynostemma pentaphyllum(Thunb.) Makino. Its structural elucidation was accomplished mainly on the basis of the interrelation of spectroscopic methods, such as IR, HR-TOF-MS, NMR.

Cunninghamella elegans has been employed for the biotransformation of cinobufagin (1) to afford one metabolites. The structure of the transformation product has been characterized as 7β,12β-dihydroxylcinobufagin (2). Product 2 is a new compound. In vitro cytotoxic activities of the biotransformation product and the substrate-cinobufagin have been assayed against HeLa; they all showed cytotoxic activities.

A new xanthene, named blumeaxanthene, was isolated from Blumea riparia DC. The structure was elucidated on the basis of the data of NMR, MS, IR.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.