Dimeric chromenes and mixed dimers of a chromene with euparin from Encelia canescens

The investigation of Encelia canescens afforded, in addition to several known compounds, four new dimeric p-hydroxyacetophenone derivatives, two epimeric chromene dimers and two epimeric mixed dimers of euparin and encecalin. Furthermore, derivatives of tremetone and of encecalin were present. The structures were elucidated hy high field ¹H NMR spectroscopy.     

A dehydrofarnesol derivative from Stomanthaes africanus

Stomanthes africanus afforded several p-hydroxyacetophenone and dehydronerolidol derivatives. Furthermore, a new dehydrofarnesol was isolated. The chemotaxonomy is discussed briefly.     

Ein neues germacren-derivat sowie ein diterpenmalonat aus Baccharis-arten

The investigation of the aerial part of B. scandens afforded a new ketone, a germacrene derivative. The aerial parts of B. tricuneata var. lineata yielded, in addition to known ent-clerodane derivatives, a malonate of a further diterpene of this type. The structures are elucidated by spectroscopic methods.     

Nitrogen-containing derivatives of O-tetramethylquercetin: Synthesis and biological profiles in prostate cancer cell models

Forty-eight nitrogen-containing quercetin derivatives were synthesized from readily available rutin or quercetin for the in vitro evaluation of their biological profiles. The WST-1 cell proliferation assay data indicate that thirty-nine out of the forty-eight derivatives possess significantly improved antiproliferative potency as compared with quercetin and fisetin, as well as the parent 3,3′,4′,7-O-tetramethylquercetin toward both androgen-sensitive (LNCaP) and androgen-insensitive (PC-3 and DU145) human prostate cancer cell lines. 5-O-Aminoalkyl-3,3′,4′,7-O-tetramethylquercetins were established as a better scaffold for further development as anti-prostate cancer agents. Among them, 5-O-(N,N-dibutylamino)propyl-3,3′,4′,7-O-tetramethylquercetin (44) was identified as the optimal derivative with IC₅₀ values of 0.55–2.82 µM, being over 35–182 times more potent than quercetin. The flow cytometry-based assays further demonstrate that 44 effectively activates PC-3 cell apoptosis.     

2-Oxo-labda-8(17),13-dien-15-OL from Ophryosporus chilca

The aerial parts of Ophryosporus chilca afforded several prenylated p-hydroxyacetophenones, two labdane derivatives and a cinnamyl ester. Ophryosporus peruvianus also contains prenylated p-hydroxyacetophenones. Three compounds were isolated for the first time; their structures were established by ¹H NMR spectroscopy.     

An epoxygermacranolide and further constituents from Mikania species

Mikania purpurascens afforded in addition to known compounds a 5,10-epoxygermacranolide, while M. arrojadoi gave only known ent-kaurene derivatives.     

Types of sesquiterpenes from Artemisia filifolia

The roots of Artemisia filifolia afforded in addition to known compounds an oxo-longipinane, a longibornan endoperoxide, two seco-longibornane derivatives and a himachalene derivative. The structures of the new sesquiterpenes were elucidated by several chemical transformations and by NMR spectroscopic investigations. Possible biogenetic pathways are discussed briefly.     

A daucanolide further farnesene derivatives from Ageratum fastigiatum

A reinvestigation of Ageratum fastigiatum afforded, in addition to known compounds, several new farnesene derivatives including some tetrahydropyrane derivatives. Furthermore a sesquiterpene lactone derived from daucane and a minor derivative of the ent-labdanes isolated previously were isolated. The structures were elucidated by spectroscopic methods.     

A simple, mild, and regioselective method for the benzylation of carbohydrate derivatives promoted by silver carbonate

A simple, mild, and regioselective method has been developed for the selective benzylation and p-methoxybenzylation of carbohydrate derivatives in high yields using Ag₂CO₃ as the promoter. Benzylation of base-labile substrates, for which other reported methods are of little use, has been performed in high yields.     

Seven furanoeremophilanes from three Senecio species

The investigation of two further Senecio species and the re-investigation of S. inaequidens afforded, in addition to known compounds, seven new furanoeremophilane derivatives. Six of these are closely related to cacalol, a sesquiterpene type which predominates in the species investigated.     

Dimeric 1,4-benzoquinone derivatives and a resorcinol derivative from Ardisia gigantifolia

Naturally occurring dimeric 1,4-benzoquinone derivatives, belamcandaquinones F, G, H, and I, as well as one resorcinol derivative and four known compounds, were isolated from rhizomes of Ardisia gigantifolia. Their structures were established by means of spectroscopic analyses. All compounds were tested against cell lines PC-3, EMT6, A549, Hela, RM-1, and SGC7901 for cytotoxicity in vitro. In comparison with cisplatin, compounds 5 and 6 showed a strong cytotoxicity with IC₅₀ values less than 30 μM for most cell lines tested.     

Synthesis and biological evaluation of water-soluble derivatives of chiral gossypol as HIV fusion inhibitors targeting gp41

A series of novel or known water-soluble derivatives of chiral gossypol were synthesized and screened in vitro for their anti-HIV-1 activity. (?)-gossypol derivative was more active against HIV-1 than the corresponding (+)-gossypol derivative, respectively. Among these derivatives, d-glucosamine derivative of (?)-gossypol, oligopeptide derivative of (?)-gossypol and taurine derivative of (?)-gossypol, such as compounds 1a, 3a and 14a, showed significant inhibitory activities against HIV-1 replication, HIV-1 mediated cell-cell fusion and HIV gp41 6-helix bundle formation as some amino acid derivatives of (?)-gossypol.     

Labdane derivatives from hemizonia species

The investigation of three Hemizonia species afforded in addition to known compounds seven new labdane derivatives, all derived from labd-13-en-15-ol. The absolute configuration of these diterpenes was determined by degradation of the triol by periodate cleavage, which afforded a known norditerpene ketone. From H. fitchii two new chromene esters and the cis-isomer of a known coumarate were isolated. H. congesta afforded in addition to labdane derivatives a hydroxycubebol.     

Presence of di- and polyamines covalently bound to protein in rat liver

Acid hydrolysis of trichloroacetic acid precipitate from rat tissue (liver, kidney and testis) homogenate released significant amounts of acid-insoluble putrescine, spermidine and spermine. Following incubation of liver homogenate with [1,4-¹⁴C]putrescine, 1.4% of total radioactivity and 1.0% of labelled diamine were recovered in the acid-insoluble fraction. Exhaustive digestion of acid-precipitable material with proteinases (Pronase, aminopeptidase M, carboxipeptidase A, B and Y) revealed the presence of di- and polyamines and of N¹-(γ-glutamyl)spermidine, N¹-(γ-glutamyl)sperminine and N¹, N¹²-bis(γ-glutamyl)spermine. These derivatives were identified both by chromatographic analysis and by enzymatic digestion with purified γ-glutamylamine cyclotransferase. The finding of di- and polyamine γ-glutamyl derivatives in the proteinase-digested acid-insoluble fraction of homogenate may be considered as a proof of the in vivo transglutaminase-catalyzed binding of polyamines to proteins. This evidence suggests that di- and polyamines might have an important role in mammalian tissues through covalent binding to proteins by either one or both the primary amino groups.     

3-Anhydro-6-hydroxy-ophiobolin A,a new sesterterpene inhibiting the growth of methicillin-resistant Staphylococcus aureus and inducing the cell death by apoptosis on K562, from the phytopathogenic fungus Bipolaris oryzae

A new ophiobolin derivative, 3-anhydro-6-hydroxy-ophiobolin A (1), as well as two known ophiobolin derivatives 3-anhydro-ophiobolin A (2) and 3-anhydro-6-epi-ophiobolin A (3) were isolated from the PDB culture of a phytopathogenic fungus Bipolaris oryzae. The structure of 1 was elucidated through 2D NMR and other spectroscopic techniques. Compound 1 exhibited strong antimicrobial activity against Bacille Calmette–Guerin, Bacillus subtilis, Staphylococcus aureus, and methicillin-resistant Staphylococcus aureus with MIC value of 12.5 μg/mL, and potent antiproliferative activity against cell lines HepG2 and K562 with IC₅₀ of 6.49 μM and 4.06 μM, respectively. Further studies on the cytotoxicity of compound 1 against K562 cells demonstrated that it induced apoptosis, observed by flow cytometric method. Preliminary structure–activity relationships of these ophiobolins and the mechanism of apoptosis induced by 1 were analyzed.     

A tetracyclic sesquiterpene,further isocedrene and guaiene derivatives from Jungia stuebelii

The aerial parts of Jungia stuebelii afforded, in addition to known compounds, two guaiene derivatives, a pseudoguaiane derivative, nine isocedrene     

Synthesized oversulfated and acetylated derivatives of polysaccharide extracted from Enteromorpha linza and their potential antioxidant activity

Sulfated polysaccharide extracted from blue algae Enteromorpha linza is proved to possess excellent antioxidant activities. Two derivatives by means of oversulfated and acetylated coupling were synthesized and investigated their antioxidant activities including scavenging effect of superoxide, hydroxyl and 1,1-diphenyl-2-picrylhydrazyl radicals. And then the relationship between antioxidant activity and chemical characteristics was characterized. The results of chemical analysis and FT-IR showed that the modification of polysaccharide was successful. In addition, it was found that certain derivatives exhibited stronger antioxidant activity than raw material. They could serve as free-radical inhibitors or scavengers, acting possibly as primary antioxidants.     

A germacranolide and a longipinene derivative from Eupatoriadelphus purpureus

The roots of Eupatoriadelphus purpureus contain tridecapentaynene, β-pinene and five p-hydroxyaecetophenone derivatives. By contrast, the aerial parts have germacrene D, lupeol and its isomers, coumarin, a new sesquiterpene tiglate and a new germacranolide.     

Labdane derivatives from Planaltoa lychnophoroides

The investigation of a representative of the small Brazilian genus Planaltoa afforded, in addition to known compounds, a new toxol derivative and two ent-labdane derivatives, closely related to austrofolin. The structures were elucidated by high field ¹H NMR spectroscopy. The chemotaxonomic situation is discussed briefly.     

Spiramine derivatives induce apoptosis of Bax−/−/Bak−/− cell and cancer cells

Spiramine C–D, the atisine-type diterpenoid alkaloids isolated from the Chinese herbal medicine Spiraea japonica complex, are shown to have anti-inflammatory effects in vitro. In this study, we report that spiramine derivatives of spiramine C–D bearing α,β-unsaturated ketone induce apoptosis of Bax^−/−/Bak^−/− MEFs cell, which is positively corresponding their cytotoxicity of tumor cell lines including multidrug resistance MCF-7/ADR. The results indicated that oxazolidine ring is necessary, and derivatives bearing double ‘Michael reaction acceptor’ group would significantly increased activities both of inducing apoptosis of Bax^−/−/Bak^−/− cells and cytotoxicity of tumor cells. The result indicated that spiramine derivative with α,β-unsaturated ketone group is a new anti-cancer agent with a capability of inducing apoptosis of cancer cells in Bax/Bak-independent manner.