Discovery of amide-bridged pyrrolo[2,3-d]pyrimidines as tumor targeted classical antifolates with selective uptake by folate receptor α and inhibition of de novo purine nucleotide biosynthesis

We previously showed that classical 6-substituted pyrrolo[2,3-d]pyrimidine antifolates bind to folate receptor (FR) α and the target purine biosynthetic enzyme glycinamide ribonucleotide formyltransferase (GARFTase) with different cis and trans conformations. In this study, we designed novel analogs of this series with an amide moiety in the bridge region that can adopt both the cis and trans lowest energy conformations. This provides entropic benefit, by restricting the number of side-chain conformations of the unbound ligand to those most likely to promote binding to FRα and the target enzyme required for antitumor activity. NMR of the most active compound 7 showed both cis and trans amide bridge conformations in ~1:1 ratio. The bridge amide group in the best docked poses of 7 in the crystal structures of FRα and GARFTase adopted both cis and trans conformations, with the lowest energy conformations predicted by Maestro and evidenced by NMR within 1 kcal/mol. Compound 7 showed ~3-fold increased inhibition of FRα-expressing cells over its non-restricted parent analog 1 and was selectively internalized by FRα over the reduced folate carrier (RFC), resulting in significant in vitro antitumor activity toward FRα-expressing KB human tumor cells. Antitumor activity of 7 was abolished by treating cells with adenosine but was incompletely protected by 5-aminoimidazole-4-carboxamide (AICA) at higher drug concentrations, suggesting GARFTase and AICA ribonucleotide formyltransferase (AICARFTase) in de novo purine biosynthesis as the likely intracellular targets. GARFTase inhibition by compound 7 was confirmed by an in situ cell-based activity assay. Our results identify a “first-in-class” classical antifolate with a novel amide linkage between the scaffold and the side chain aryl L-glutamate that affords exclusive selectivity for transport via FRα over RFC and antitumor activity resulting from inhibition of GARFTase and likely AICARFTase. Compound 7 offers significant advantages over clinically used inhibitors of this class that are transported by the ubiquitous RFC, resulting in dose-limiting toxicities.     

Synthesis of guanine nucleosides by fusion,and a mechanistic aspect of the reaction

N²-Acetylguanine (1) was condensed by fusion with the fully acetylated derivatives of the following sugars: β-D-ribofuranose (2), β-D-ribopyranose (3), α-D-xylopyranose (4), β-D-xylopyranose (5), α-D-glucopyranose (6), and β-D-gluco-pyranose (7). The reaction of 1 with either 2 or 3 gave a mixture of 7-β, 9-α, and 9-β isomers, whereas only the 7-β and 9-β isomers, and virtually no 9-α isomer, were obtained when 4, 5, 6, and 7 were used. When each isomeric acetylated ribofuranosylguanine was heated in the presence of an acidic catalyst, a mixture of 7-β, 9-α, and 9-β nucleosides was formed. Close examination of the product ratios showed that the ratio of 7:9 isomers remained unchanged throughout the reactions, but the anomeric nature of the 9-substituted nucleoside was dependent on the sugar used.     

Comparison of intestinal folate carrier clone expressed in IEC-6 cells and in Xenopus oocytes

We recently identified a cDNA clone frommouse small intestine, which appears to be involved in folate transportwhen expressed in Xenopus oocytes. Theopen reading frame of this clone is identical to that of the reducedfolate carrier (RFC) (K. H. Dixon, B. C. Lanpher, J. Chiu, K. Kelley,and K. H. Cowan. J. Biol. Chem. 269: 17-20,1994). The characteristics of this cDNA clone [previously referred toas intestinal folate carrier 1 (IFC-1)] expressed inXenopus oocytes, however, were foundto be different from the characteristics of folate transport in nativesmall intestinal epithelial cells. To further study these differences,we determined the characteristics of RFC when expressed in anintestinal epithelial cell line, IEC-6, and compared the findings toits characteristics when expressed inXenopus oocytes. RFC was stablytransfected into IEC-6 cells by electroporation; its cRNA wasmicroinjected into Xenopus oocytes.Northern blot analysis of poly(A)⁺RNA from IEC-6 cells stably transfected with RFC cDNA (IEC-6/RFC) showed a twofold increase in RFC mRNA levels over controls. Similarly, uptake of folic acid and 5-methyltetrahydrofolate (5-MTHF) by IEC-6/RFCwas found to be fourfold higher than uptake in control sublines. Thisincrease in folic acid and 5-MTHF uptake was inhibited by treatingIEC-6/RFC cells with cholesterol-modified antisense DNAoligonucleotides. The increase in uptake was found to be mainly mediated through an increase in the maximal velocity(V_max) of theuptake process [the apparent Michaelis-Menten constant(K_m) alsochanged (range was 0.31 to 1.56 µM), but no specific trend wasseen]. In both IEC-6/RFC and control sublines, the uptake of bothfolic acid and 5-MTHF displayed 1)pH dependency, with a higher uptake at acidic pH 5.5 compared with pH7.5, and 2) inhibition to the sameextent by both reduced and oxidized folate derivatives. Thesecharacteristics are very similar to those seen in native intestinalepithelial cells. In contrast, RFC expressed inXenopus oocytes showed1) higher uptake at neutral andalkaline pH 7.5 compared with acidic pH 5.5 and2) higher sensitivity to reducedcompared with oxidized folate derivatives. Results of these studiesdemonstrate that the characteristics of RFC vary depending on the cellsystem in which it is expressed. Furthermore, the results may suggestthe involvement of cell- or tissue-specific posttranslationalmodification(s) and/or the existence of an auxiliary proteinthat may account for the differences in the characteristics of theintestinal RFC when expressed inXenopus oocytes compared with whenexpressed in intestinal epithelial cells.

     

Synthesis and biological evaluation of 2-quinolineacrylamides

A series of C6-substituted N-hydroxy-2-quinolineacrylamides (3–15), with four types of bridging groups have been synthesized. Most of these compounds exhibit antiproliferative activity against A549 and HCT116 cells and Western blot analysis revealed that they are able to inhibit HDAC. Measurement of the HDAC isoform activity of ether-containing compounds showed that compound 9 has distinct HDAC6 selectivity, more than 300-fold over other isoforms. This paper describes the development of 6-aryloxy-N-hydroxy-2-quinolineacrylamides as potential HDAC6 inhibitors.     

Cytotoxic monoterpenoid indole alkaloids from the leaves and twigs of Tabernaemontana bovina

Phytochemical investigation of the leaves and twigs of Tabernaemontana bovina led to the isolation of 10 monoterpenoid indole alkaloids, including two new taberbovinines A (1) and B (2) along with eight known analogs: mehranine (3), 14α,15β-dihydroxy-N-methylaspidospermidine (4), (16S*)− 15-epi-E-isositsirikine (5), (16R*)− 15-epi-E-isositsirikine (6), 16 R*-19,20-E-isositsirikine acetate (7), hecubine (8), voafinidine (9), and voacangarine (10). Taberbovinine B (2) represents the first case of an unusual ring C/D cleavage among the natural Corynanthe-type alkaloids. Compounds 2 and 8 exhibited weak cytotoxicity against five human cancer cell lines, including SK-LU-1, HepG2, MCF-7, SK-Mel-2, and LNCaP, with IC₅₀ values ranging from 42.9 to 66.3 μM, whereas compounds 4 − 6 and 9 were cytotoxic toward MCF-7, SK-LU-1 and LNCaP cells, with IC₅₀ values in a range of 51.6–93.3 μM.     

Optimisation of estrogen receptor subtype-selectivity of a 4-Aryl-4H-chromene scaffold previously identified by virtual screening

4-Aryl-4H-Chromene derivatives have been previously shown to exhibit anti-proliferative, apoptotic and anti-angiogenic activity in a variety of tumor models in vitro and in vivo generally via activation of caspases through inhibition of tubulin polymerisation. We have previously identified by Virtual Screening (VS) a 4-aryl-4H-chromene scaffold, of which two examples were shown to bind Estrogen Receptor α and β with low nanomolar affinity and <20-fold selectivity for α over β and low micromolar anti-proliferative activity in the MCF-7 cell line. Thus, using the 4-aryl-4H-chromene scaffold as a starting point, a series of compounds with a range of basic arylethers at C-4 and modifications at the C3-ester substituent of the benzopyran ring were synthesised, producing some potent ER antagonists in the MCF-7 cell line which were highly selective for ERα (compound 35; 350-fold selectivity) or ERβ (compound 42; 170-fold selectivity).     

Enhanced estrogen receptor beta (ERβ) selectivity of fluorinated carborane-containing ER modulators

We previously showed that fluorination of the carborane-containing selective estrogen receptor modulator (SERM) BE360 altered the agonist/antagonist activity balance and the estrogen receptor (ER) α/β subtype selectivity. Here, we designed and synthesized a series of fluorinated carboranyl phenols as candidate ERβ-selective ligands. Introduction of a fluorine atom onto the carborane cage commonly reduced the binding affinity for ERα, to an extent that depended on the other substituents present. The B-fluorinated m-carboranyl phenol 4a showed fourfold more potent ERβ-binding affinity than the parent non-fluorinated compound 7. 1-Iodo-9-fluoro-m-carboranyl phenol 4f showed high ERβ-binding affinity with an ERβ/ERα selectivity ratio of 8.2. Among the compounds tested, 6 showed the highest ERβ selectivity (10.1-fold) and the highest ER-agonistic activity (EC₅₀: 5.1 × 10^?10 M) in MCF-7 cell proliferation assay.     

Synthesis and evaluation of new N6-substituted adenosine-5′-N-methylcarboxamides as A3 adenosine receptor agonists

A number of N⁶-substituted adenosine-5′-N-methylcarboxamides were synthesised and their pharmacology, in terms of their receptor affinity, selectivity and cardioprotective effects, were explored. The first series of compounds, 4a–4f and 5a–5f, showed modest receptor affinity for the A₃AR with K_i values in the low to mid μM range. However, the incorporation of a 4-(2-aminoethyl)-2,6-di-tert-butylphenol group in the N⁶-position (in compounds 4g and 5g) significantly improved the affinity with K_i values of 30 and 9 nM, respectively. Improvements in affinity, as well as selectivity were seen when a functionalised linker was introduced. The N⁶-phenyl series, compounds 7a–7d, demonstrated low to mid nanomolar receptor affinities (K_i = 2.3–45.0 nM), with 7b displaying 109-fold selectivity for the A₃AR (vs A₁). The N⁶-benzyl series 9a–9c also proved to be potent and selective A₃AR agonists and the longer chain length linker 13 was tolerated at the A₃AR without abrogation of affinity or selectivity. Cardioprotection was demonstrated by a simulated ischaemia cell culture assay, whereby 7b, 7c, 9a, 9b and 9c all showed cardioprotective effects at 100 nM comparable or better than the benchmark A₃AR agonist IB-MECA, but which were indistinguishable by statistical analysis. For example, compound 9c reduced cell death by 68.0 ± 3.6%.     

The anti-cancer,anti-inflammatory and tuberculostatic activities of a series of 6,7-substituted-5,8-quinolinequinones

A variety of 6,7-substituted-5,8-quinolinequinones were synthesised and assessed for their anti-tumour and anti-inflammatory activities, and their ability to inhibit the growth of Mycobacterium bovis BCG. In particular, the introduction of a sulfur group at the 7-position of the quinolinequinone led to the discovery of two compounds, 6-methylamino-7-methylsulfanyl-5,8-quinolinequinone (10a) and 6-amino-7-methylsulfonyl-5,8-quinolinequinone (12), that exhibited selectivity for leukemic cells over T-cells, a highly desirable property for an anti-cancer drug. A number of anti-inflammatory (AI) compounds were also identified, with 6,7-bis-methylsulfanyl-5,8-quinolinequinone (18a) exhibiting the highest AI activity (0.11 μM), while 6,7-dichloro-5,8-quinolinequinone (7a), 6,7-dichloro-2-methyl-5,8-quinolinequinone (7b), and 6,7-bis-phenylsulfanyl-quinoline-5,8-diol (19) also exhibited good AI activity and specificity. Several quinolinequinone TB-drug candidates were identified. Of these, 6-amino-7-chloro-5,8-quinolinequinone (11) and 6-amino-7-methanesulfinyl-5,8-quinolinequinone (14), exhibited low MICs (1.56–3.13 μg/mL) for the 100% growth inhibition of M. Bovis BCG. Some general trends pertaining to the functional group substitution of the quinolinequinone core and biological activity were also identified.     

Two new metabolites from Portulaca oleracea and their anti-inflammatory activities

Two new metabolites, identified as 6-phenylbenzofuran-4-ol, named olerabenzofuran (1), and 2-(furan-2-yl)− 6-hydroxy-1 H-inden-1-one, named oleraindenone (2), together with eight furan compounds obtained for the first time, (+)-pinoresinol (3), (-)-syringaresinol (4), (+)-diasyringaresinol (5), (+)-episyringaresinol (6), (2 S)− 1-[2-(furan-2-yl)− 2-oxoethyl]− 5-oxopyrrolidine-2-carboxylic acid (7), methyl (2 S)− 1[2-(furan-2-yl)− 2-oxoethyl]− 5-oxopyrrolidine-2-carboxylate (8), drynaran (9), and 2-furoic acid (10), were isolated from Portulaca oleracea L., and spectroscopic methods, including 1D and ²D NMR and UHPLC-ESI-QTOF/MS spectrometry techniques, were employed to determine their structures. It was suggested that both olerabenzofuran (1) and oleraindenone (2) could significantly inhibit inflammatory factor interleukin-1β (IL-1β) in RAW 264.7 cells induced by LPS.     

Chemical constituents from Gentianella turkestanorum (Gentianaceae)

Phytochemical investigation of Gentianella turkestanorum (Gentianaceae) afforded nineteen compounds, including six xanthones (1–6), two triterpenoids (7–8), eight flavones (9–16) and three iridoids (17–19). Here, we firstly reported that 1-hydroxy-3,5-dimethoxyxanthone (4), 1, 8-dihydroxy-3-methoxyxanthone (5), apigenin (9), quercetin (10), luteolin-7-O-glucoside (12) and three other compounds (1, 8-dihydroxy-3-methoxyxanthone (5), apigenin-7-O-gluco (1″ → 3‴) glucoside (15) and luteolin-7-O-gluco (1″ → 3‴) glucoside (16)) could be isolated from G. turkestanorum. The occurrence of chemical data and the sequence data might be employed as common constituents of the genera Gentianella, Lomatogonium and Swertia.     

Rothmanniamide and other constituents from the leaves of Rothmannia hispida (K.Schum.) fagerl. (Rubiaceae) and their chemophenetic significance

The chemical investigation of the CH₂Cl₂/MeOH (1:1) extract of the leaves of Rothmannia hispida (K. Schum.) Fagerl. (Rubiaceae) led to the isolation of a new ceramide rothmanniamide (1) and a naturally isolated alkyl cinnamate derivative n-heptadecyl-4-hydroxy-trans-cinnamate (2), along with fifteen known compounds including lupeol palmitate (3), lupeol (4), a mixture of uvaol (5) and erythrodiol (6), ursolic acid (7), 30-nor-2α,3β-dihydroxyurs-12-ene (8), hederagenin (9), stigmast-22-en-3-ol (10), a mixture of β-sitosterol (11) and stigmasterol (12), stigmast-4,22-dien-3-ol (13), stigmasterol 3-O-β-D-glucoside (14), triacontan-1-ol (15), kaempferol 3-O-β-D-glucopyranoside (16) and D-mannitol (17). Their structures were elucidated with the help of MS and NMR data. Compounds 8, 10 and 15 were isolated for the first time from the Rubiaceae family. The crude extract and the isolates were assessed in vitro for their antileishmanial activity against Leishmania donovani 1 S (MHOM/SD/62/1 S) promastigotes and cytotoxicity on RAW 264.7 macrophage cells. Compounds 7 and 8 exhibited a highly potent antileishmanial activity with IC₅₀ values of 0.88 and 1.75 μg/mL, respectively, with good selectivity indexes (SI > 57). The chemophenetic significance of these compounds is also discussed.     

Gynostemosides A–E,megastigmane glycosides from Gynostemma pentaphyllum

Megastigmane glycosides (1–5) together with seven (6–12) related known compounds were isolated from the whole plants of Gynostemma pentaphyllum. The structures were elucidated by means of spectroscopic methods, including 2D NMR, HR-ESIMS, and circular dichroism (CD), as well as chemical transformations to be (3R, 4R, 5S, 6S, 7E)-3,4,6-trihydroxymegastigmane-7-en-9-one-3-O-β-d-glucopyranoside (gynostemoside A, 1), (3S, 4S, 5R, 6R, 7E, 9R)-3,4,6,9-tetrahydroxymegastigmane-7-en-3-O-β-d-glucopyranoside (gynostemoside B, 2), (3S, 4S, 5S, 6S, 7E, 9R)-3,4,9-trihydroxymegastigmane-7-en-9-O-β-d-glucopyranoside (gynostemoside C, 3), (3S, 4S, 5S, 6S, 7E, 9R)-3,4,9-trihydroxymegastigmane-7-en-3-O-β-d-glucopyranoside (gynostemoside D, 4), and (3S, 4S, 5S, 6S, 7E, 9R)-3,4,9-trihydroxymegastigmane-7-en-4-O-β-d-glucopyranoside (gynostemoside E, 5), respectively.     

Synthesis and structure–activity relationships of 1-benzylindane derivatives as selective agonists for estrogen receptor beta

The estrogen receptor beta (ERβ) selective agonist is considered a promising candidate for the treatment of estrogen deficiency symptoms in ERβ-expressing tissues, without the risk of breast cancer, and multiple classes of compounds have been reported as ERβ selective agonists. Among them, 6-6 bicyclic ring-containing structures (e.g., isoflavone phytoestrogens) are regarded as one of the cyclized analogues of isobutestrol 5b, and suggest that other cyclized scaffolds comprising 5-6 bicyclic rings could also act as selective ERβ ligands. In this study, we evaluated the selective ERβ agonistic activity of 1-(4-hydroxybenzyl)indan-5-ol 7a and studied structure–activity relationship (SAR) of its derivatives. Some functional groups improved the properties of 7a; introduction of a nitrile group on the indane-1-position resulted in higher selectivity for ERβ (12a), and further substitution with a fluoro or a methyl group to the pendant phenyl ring was also preferable (12b, d, and e). Subsequent chiral resolution of 12a identified that R-12a has a superior profile over S-12a. This is comparable to diarylpropionitrile (DPN) 5c, one of the promising selective ERβ agonists and indicates that this indane-based scaffold has the potential to provide better ERβ agonistic probes.     

A new phenylpropanoid and an alkylglycoside from Piper retrofractum leaves with their antioxidant and α-glucosidase inhibitory activity

Two new compounds, piperoside (1) and isoheptanol 2(S)-O-β-d-xylopyranosyl (1→6)-O-β-d-glucopyranoside (11), along with 10 known compounds 3,4-dihydroxyallylbenzene (2), 1,2-di-O-β-d-glucopyranosyl-4-allylbenzene (3), tachioside (4), benzyl-O-β-d-glucopyranoside (5), icariside F₂ (6), dihydrovomifoliol-3′-O-β-d-glucopyranoside (7), isopropyl O-β-d-glucopyranoside (8), isopropyl primeveroside (9), n-butyl O-β-d-glucopyranoside (10), isoheptanol 2(S)-O-β-d-apiofuranosyl-(1→6)-O-β-d-glucopyranoside (12), were isolated from the leaves of Piper retrofractum. Their structures were determined from 1D-NMR, 2D-NMR, and HR-ESI-MS spectral, a modified Mosher’s method, and comparisons with previous reports. All of the isolated compounds showed modest α-glucosidase inhibitory (4.60 ± 1.74% to 11.97 ± 3.30%) and antioxidant activities under the tested conditions.     

Lignan glycosides from the Rhizomes of Smilax trinervula and their Biological activities

Phytochemical investigation of the rhizomes of Smilax trinervula led to isolation and structure elucidation of eight lignan glycosides, including five new lignans, namely, (7S, 8R, 8′R)-4, 4′, 9-trihydroxy-3, 3′, 5, 5′-tetramethoxy-7, 9′-epoxylignan-7′-one 4′-O-β-d-glucopyranoside (1), (7S, 8R, 8′R)-4, 4′, 9-trihydroxy-3, 3′, 5, 5′-tetramethoxy-7, 9′-epoxylignan-7′-one 4-O-β-d- glucopyranoside (2) (7S, 8R)-4, 9, 9′-trihydroxy-3, 3′, 5-trimethoxy-4′, 7-epoxy-8, 5′-neolignan 9′-O-β-d-glucopyranoside (3), (7R, 8R)-4, 9, 9′-trihydroxy-3, 5-dimethoxy-7.O.4′, 8.O.3′- neolignan 9′-O-β-d-glucopyranoside (4), and (7S, 8R)-4, 9, 9′-trihydroxy-3, 3′, 5-trimethoxy-8, 4′-oxy-neolignan 4-O-β-d-glucopyranoside (5), along with three known compounds (6-8). Their structures were established mainly on the basis of 1D and 2D NMR spectral data, ESI–MS and comparison with the literature. Compounds 1-8 were tested in vitro for their cytotoxic activity against four human tumor cell lines (SH-SY5Y, SGC-7901, HCT-116, Lovo). Compounds 3 and 5 exhibited cytotoxic activity against Lovo cells, with IC₅₀ value of 10.4 μM and 8.5 μM, respectively.     

Characterization of a xylose containing oligosaccharide,an inhibitor of multidrug resistance in Staphylococcus aureus,from Ipomoea pes-caprae

Pescaprein XVIII (1), a type of bacterial efflux pump inhibitor, was obtained from the CHCl₃-soluble resin glycosides of beach morning glory (Ipomoea pes-caprae). The glycosidation sequence for pescaproside C, the glycosidic acid core of the lipophilic macrolactone 1 containing d-xylose and l-rhamnose, was characterized by means of several NMR techniques and FAB mass spectrometry. Recycling HPLC also yielded eight non-cytotoxic bacterial resistance modifiers, the two pescapreins XIX (2) and XX (3) as well as the known murucoidin VI (4), pecapreins II (6) and III (7), and stoloniferins III (5), IX (8) and X (9), all of which contain simonic acid B as their oligosaccharide core. Compounds 1–9 were tested for in vitro antibacterial and resistance-modifying activity against strains of Staphylococcus aureus possessing multidrug resistance efflux mechanisms. All of the pescapreins potentiated the action of norfloxacin against the NorA over-expressing strain by 4-fold (8 μg/mL from 32 μg/mL) at a concentration of 25 μg/mL.     

Betaine or folate can equally furnish remethylation to methionine and increase transmethylation in methionine-restricted neonates

Methionine partitioning between protein turnover and a considerable pool of transmethylation precursors is a critical process in the neonate. Transmethylation yields homocysteine, which is either oxidized to cysteine (i.e., transsulfuration), or is remethylated to methionine by folate- or betaine- (from choline) mediated remethylation pathways. The present investigation quantifies the individual and synergistic importance of folate and betaine for methionine partitioning in neonates. To minimize whole body remethylation, 4–8-d-old piglets were orally fed an otherwise complete diet without remethylation precursors folate, betaine and choline (i.e. methyl-deplete, MD-) (n=18). Dietary methionine was reduced from 0.3 to 0.2 g/(kg∙d) on day-5 to limit methionine availability, and methionine kinetics were assessed during a gastric infusion of [¹³C₁]methionine and [²H₃-methyl]methionine. Methionine kinetics were reevaluated 2 d after pigs were rescued with either dietary folate (38 μg/(kg∙d)) (MD + F) (n=6), betaine (235 mg/(kg∙d)) (MD + B) (n=6) or folate and betaine (MD + FB) (n=6). Plasma choline, betaine, dimethylglycine (DMG), folate and cysteine were all diminished or undetectable after 7 d of methyl restriction (P<.05). Post-rescue, plasma betaine and folate concentrations responded to their provision, and homocysteine and glycine concentrations were lower (P<.05). Post-rescue, remethylation and transmethylation rates were~70–80% higher (P<.05), and protein breakdown was spared by 27% (P<.05). However, rescue did not affect transsulfuration (oxidation), plasma methionine, protein synthesis or protein deposition (P>.05). There were no differences among rescue treatments; thus betaine was as effective as folate at furnishing remethylation. Supplemental betaine or folate can furnish the transmethylation requirement during acute protein restriction in the neonate.     

Gout prophylactic constituents from the flower buds of Lonicera japonica

Two new sesquiterpene glycosides (R)-dehydroxyabscisic alcohol β-d-apiofuranosyl-(1″ → 6′)-β-d-glucopyranoside (1) and (−)-(1S,2R,6R,7R)-1,2,6-trimethyl-8-hydroxy methyltricyclic[5.3.1.0^2,6]-undec-8-en-10-one β-d-apiofuranosyl-(1″ → 6′)-β-d-glucopyranoside (2), were isolated from the flower buds of Lonicera japonica. Their structures were determined by spectroscopic and chemical methods. Compound 2 could significantly decrease monosodium urate-mediated cytokine production from activated macrophage through lowering IL-1β and TNFα.     

Cytotoxic terpenoids from the stem bark of Taxus wallichiana

Chemical study of the stem bark of Taxus wallichiana Zucc. afforded the isolation of two new cyclopenta[b]naphthalene terpenoids, wallichianones A (1) and B (2) and 13 taxane diterpenoids, baccatin III (3), 10-deacetylbaccatin III (4), baccatin IV (5), 1-dehydroxybaccatin IV (6), 1-deoxybaccatin VI (7), taxol (8), 10-deacetyltaxol (9), 7-epi-10-deacetyltaxol (10), taxol-7-xyloside (11), 7-xylosyl-10-deacetyltaxol C (12), cephalomannine (13), 10-deacetylcaphalomannine (14), and 7-epi-10-deacetylcephalomannine (15). Their structures were identified by comprehensive analyses of the spectroscopic methods, including NMR and mass spectra. The absolute configurations of 1 and 2 were clarified by time-dependent density functional theory (TD-DFT) electronic circular dichroism (ECD) spectroscopic analyses. Compounds 3 and 7–15 showed cytotoxicity against all five human cancer cell lines, including lung (SK-LU-1), liver (HepG2), breast (MCF7), skin (SK-Mel-2), and prostate (LNCaP), with IC₅₀ values ranging from 1.4 ± 0.2 to 88.1 ± 5.8 μM. Compounds 9–11, 14, and 15 were additionally cytotoxic against human embryonic kidney (HEK-293A) cell line (IC₅₀ = 14.5 ± 1.0–48.4 ± 1.0 μM), however, 13 was noncytotoxic toward this cell line. The positive control, ellipticine showed cytotoxicity against all the cell lines, with IC₅₀ values in a range of 1.5 ± 0.1–2.0 ± 0.3 μM. Preliminary analysis of the structural and cytotoxicity relationship of compounds 3–15 suggested that the phenylalanine substituent at C-13 may contribute an important role for the cytotoxicity of the taxane diterpenoids.