Total synthesis of apios isoflavones and investigation of their tyrosinase inhibitory activity

Apios isoflavone glucosides 1 and 2 were synthesized for the first time via Friedel–Crafts reaction, Bischler–Napieralski-type cyclization, and phase-transfer catalyzed glycosylation as the key steps. In addition, aglycones 4 and 5 and related natural isoflavone cajanin (6) were synthesized in short steps. Evaluation of the inhibitory activity of these compounds toward tyrosinase indicated that all the compounds were active. In particular, the half-maximal inhibitory concentration of compound 1 toward tyrosinase was measured to be 729 μM.     

Unprecedented new nonadecyl para-hydroperoxycinnamate isolated from Erythrina excelsa and its cytotoxic activity

A new unprecedented cinnamate derivative (1) was obtained from Erythrina excelsa (Leguminosae) and identified as nonadecyl para-hydroperoxycinnamate. This compound was isolated together with three known compounds, namely lupeol (2), mixture of sitosterol and stigmasterol (3), and isoneorautenol (4). Their structures were established on the basis of NMR and mass spectroscopic data in conjunction with those reported in the literature. Compound 1 was evaluated for its capability of inhibiting cancer cell lines and growth of a panel of microbial strains. It turned out that 1 is moderately to significantly cytotoxic against six cancer cell lines and shows weak to no antimicrobial activity.     

Lactoquinomycin C and D,two new medermycin derivatives from the marine-derived Streptomyces sp. SS17A

Abstract

Lactoquinomycin C (1) and Lactoquinomycin D (2), two new medermycin derivatives together with six known compounds (3–8) were isolated from the rice solid fermentation of the marine-derived Streptomyces sp. SS17A. The intriguing structural features of the Lactoquinomycin D (2) which contains 5,14-epoxidation is relatively rare in medermycin derivatives. Compounds 1 and 2 exhibited no cytotoxicity against PC-3 and HCT-116 cancer cell lines, whereas compound 3 showed stronger cytotoxicity with IC₅₀ values of 0.02 and 0.04?μM, respectively. A structure-activity relationship was observed for the cytotoxicity of the medermycin derivatives with a γ-lactone unit is required for significant cytotoxicity based on compounds 1–3.     

Synthesis and cytotoxic activity of new indolylpyrrole derivatives

The current approach described the synthesis of a new series of indolylpyrrole derivatives through multicomponent reaction of α-cyano chalcones, appropriate aldehydes, and ammonium acetate in refluxed acetic acid. The chemical structures of the designed compounds were confirmed with spectroscopic data and elemental analysis and then tested for their in vitro cytotoxic activity by SRB assay method towards three cell lines involving human Prostate adenocarcinoma; metastatic cells (PC-3), human ovary adenocarcinoma (SKOV3) and human dukes' type B, colorectal adenocarcinoma (LS 174 T). Most significant activity provided with compounds 5c, 5h and, 5j against prostate cancer cells (PC-3) with IC50s of 3.30 ± 0.20, 3.60 ± 0.10, and 3.60 ± 0.90 µg/ml, respectively. In human ovarian carcinoma (SKOV3), the compounds 5a, and 5i have stronger cytotoxicity with IC50s of 1.20 ± 0.04, 1.90 ± 0.50 µg/ml, respectively than the standard doxorubicin (IC50 = 2.20 ± 0.02 µg/ml). On the other hand, only compound 5a has the ability to diminish the viability of LS174T cells in an active manner with IC50 2.80 ± 0.10 µg/ml. Consequently, this effort offers groundwork for additional examination of nominated indolylpyrroles as antiproliferative agents.     

Acylphloroglucinol derivatives from the twigs and leaves of Callistemon salignus

Three new acylphloroglucinol derivatives, callisalignones A–C (1–3), six new meroterpenoids, callisalignenes A–F (4–9), along with 18 known analogues (10–27) were isolated from the twigs and leaves of Callistemon salignus. Their structures and absolute configurations were established by comprehensive spectroscopic evidences (NMR, MS, amd electronic circular dichroism calculations). The absolute configurations of callistenones B (13) and H (14) were determined by comparison of their ECD spectra with that of callisalignone B (2). Callisalignones B and C are new adducts of β-triketone and acylphloroglucinol, whereas callisalignenes A–D are new meroterpenoids of acylphloroglucinol and α-phellandrene with different coupling models via hetero-Diels-Alder reaction, respectively. Myrtucommulone D (15) showed significant antibacterial activity against Staphylococcus aureus and three drug resistant S. aureus strains with MIC values of 1.953 and 0.975 μg/mL, respectively. Isomyrtucommulone B (17) displayed remarkable antibacterial activity against Escherichia coli with an MIC value of 0.122 μg/mL. Cytotoxic assay revealed that isomyrtucommulone B (17) was the most active against HCT116 with an IC₅₀ value of 2.09 ± 0.10 μM.     

Diazonamides C-E, new cytotoxic metabolites from the ascidian Diazona sp.

Three new macrocyclic peptides, diazonamides C-E (1-3), were isolated together with the previously reported diazonamides A (4) and B (5) from samples of the marine ascidian Diazona sp. collected in Indonesia. Their structures were assigned on the basis of detailed analysis of the 1D and 2D NMR and mass spectral data as well as Marfey’s analysis of the aminoacid residues. All the new compounds isolated displayed moderate cytotoxicity against a panel of three human tumor cell lines.     

Isolation and validated HPTLC analysis of four cytotoxic compounds,including a new sesquiterpene from aerial parts of Plectranthus cylindraceus

We report isolation of a new sesquiterpene (compound 2: plectranol A) along with three known compounds (1: maaliol, 3: penduletin and 4: chrysosplenol D) from the aerial parts of Plectranthus cylindraceus Hoechst. Ex. Benth ethyl acetate extract (PCEAE). Their structures were established by UV, IR, NMR (¹H & ¹³C), HRESIMS and HSQC methods. The MTT cell proliferation assay of the compounds and the extract performed on human breast, skin and cervical cancer cell lines showed high toxicity, and their IC₅₀ (μg/mL) values were determined. The validated HPTLC analyses of maaliol and PCEAE (method I) and, penduletin, chrysosplenol D and PCEAE (method II) furnished sharp and compact peaks. The estimated high contents (μg/mg) of maaliol (17.06), penduletin (39.36) and chrysosplenol D (31.66) in PCEAE approved the plant’s cytotoxic property. Since, P. cylindraceus contains a variety of cytotoxic terpenoids and flavonoids; our data warrant its further phytochemical and biological characterisation towards developing promising anti-cancer drugs.     

A new 12,17-cyclo-labdane diterpenoid from the twigs of Dacrycarpus imbricatus

A new 12,17-cyclo-labdane diterpenoid, podoimbricatin C (1), along with 15 known compounds was isolated from the twigs of Dacrycarpus imbricatus. Their structures were elucidated by means of extensive spectroscopic analysis. Compound 1 is the second example of the unusual 12,17-cyclo-labdane diterpenoids. It showed no inhibitory effects against five human tumour lines (HL-60, SMMC-7721, A-549, MCF-7 and SW-480).     

Two new polyhydroxylated triterpenoids from Salvia urmiensis and their cytotoxic activity

Two new polyhydroxylated triterpenoids were isolated from the acetone extract of the aerial parts of Salvia urmiensis Bunge. Their structures were elucidated by 1D and 2D NMR and HR-ESI-MS analyses as olean-12-ene-1β,3β,11α,22α-tetraol (1) and urs-12-ene-1β,3β,11β,22α-tetraol (2). The effect of these compounds on cell viability of MCF-7 cells was investigated by the MTT assay. Compounds 1 and 2 showed weak cytotoxicity with IC₅₀ values of 110.23 ± 0.12 and 88.35 ± 0.09 μM, respectively.     

A new cytotoxic cardenolide from the latex of Antiaris toxicaria

A new cardenolide,toxicarioside E(1),was isolated from the latex ofAntiaris toxicaria(Pers.) Lesch(Moraceae).Its structure was elucidated on the basis of spectral data and chemical evidence.Compound 1 showed significant cytotoxicity against K562 and SGC-7901 cell lines in vitro by MTT method with the IC_(50) value of 0.026 and 0.027μg/mL,respectively.     

A new compound from the fruit of Amorpha fruticosa and activity against acetaminophen-induced hepatotoxicity

A new isoflavone was obstained from the medicinal herb Amorpha fruticosa.It was elucidated asbenzopyran-12-one,1,4,10,11- tetrahydro-6′-[8′-(hydroxymethyl)ethenyl]-2,3-dimethoxy-8′-O-β-D-glucopyranosyl-O-α-D-arabinoside by spectroscopic methods including UV,IR,1D NMR and 2D NMR techniques.And the activity against acetaminophen-induced hepatotoxicity of this compound was also studied,and found this compound can protect liver obviously from hepatotoxicity induced by acetaminophen (AAP).     

Design and synthesis of novel cytotoxic podophyllotoxin derivatives

<正>In order to investigate the effect of different C4 linkage moieties on the cytotoxicity of podophyllotoxin derivatives,novel 4-Nand 4-C-substituted 4'-O-demethylepipodophyllotoxin derivatives were designed and synthesized.All the compounds were tested against A549 and MCF-7 tumor cells in vitro,and six compounds showed significant cytotoxicity.The most active compound 9f was superior to GL-331,and exhibited potent cytotoxicity with IC_(50) value at 10~(-7) mol/L level.     

Njaoamines A-F, new cytotoxic polycyclic alkaloids from the haplosclerid sponge Reniera sp.

Six new cytotoxic polycyclic alkaloids containing an 8-hydroxyquinoline moiety, njaoamines A-F (1-6), have been isolated from the 2-propanol extract of the sponge Reniera sp. collected in Tanzania. Their structures were determined by extensive analysis of their spectroscopic features, particularly 1D and 2D NMR spectra recorded in Py-d₅. Cytotoxicity of the compounds isolated was evaluated against a panel of three human tumor cell lines.     

Aplicyanins A-F, new cytotoxic bromoindole derivatives from the marine tunicate Aplidium cyaneum

Six new bromoindole derivatives, aplicyanins A-F (1-6), have been isolated from the CH₂Cl₂/MeOH extract of the tunicate Aplidium cyaneum collected in Antarctica. Their structures were determined by extensive analysis of their spectroscopic features, particularly 1D and 2D NMR spectra, and comparison with related compounds. Cytotoxic and antimitotic activities were found for compounds 2 and 4-6.     

Two new lignans from the stem bark of Magnolia obovata and their cytotoxic activity

Two new lignans, 4-methoxymagnaldehyde B (1) and coumanolignan (2), were isolated from the stem bark of Magnolia obovata, together with 11 known compounds (3-13). The structures of compounds 1 and 2 were determined to be 5'-allyl-2'-hydroxyphenyl-4-methoxy-3-cinnamic aldehyde (1) and 6-allyl-8-(5'-allyl-2'-hydroxyphenyl)coumarin (2) on the basis of spectroscopic and physicochemical analyses including 2D NMR and high-resolution EI-MS. Compounds 1-8, 11, 12, and 13 were tested in vitro for their cytotoxic activities against the HeLa, A549, and HCT116 cancer cell lines. Among the compounds tested, compound 1 showed the strongest cytotoxic activity against the HCT116 cancer cell line, with an IC(50) value of 1.3 microg/ml.     

Chemical characterization of constituents from Polygonatum cyrtonema Hua and their cytotoxic and antioxidant evaluation

Abstract

Twenty-four compounds were isolated from the roots of Polygonatum cyrtonema Hua, including a new octopamine dimer, named trans-bis(N-feruloyl)octopamine (1). The structure was established on the basis of spectroscopic and chemical methods. All the extracts and compounds were evaluated for cytotoxic and antioxidant activities by using MTT and chemiluminescence assay. The extracts showed activity against MCF-7 and HepG-2 cell lines from IC₅₀ 0.30 to 1.01 mg mL^?1. Compound 3 exhibited activity against HepG-2 cell lines with IC₅₀ 8.99?μM. Compound 7 exhibited activity against Hela cell lines with IC₅₀ 2.53?μM and BGC-823 cell lines with IC₅₀ 7.77?μM. Moreover, compound 7 showed antioxidant with IC₅₀ 12?µM compared to the positive control with IC₅₀ 77?µM. Compound 16 exhibited activity against HepG-2 cell lines with IC₅₀ 1.05?μM and MCF-7 cell lines with IC₅₀ 1.89?μM. These results indicated that this plant might be potential in natural medicine and healthy food.     

Synthesis and biological evaluation of isoflavone analogues from Dalbergia oliveri

Mucronulatol 1 and violanone 2 isolated from Dalbergia oliveri Gamble, and the corresponding isoflavone 3 were prepared by ligand coupling reactions involving organolead reagent. Biological studies have shown a significant cytotoxic effect against an HBL100 leukemia cell line only for isoflavan 1 with an IC₅₀ value amounting to 5.7 μM. All the drugs modestly inhibit the in vitro microtubule assembly, independently of the cytotoxic ability. Natural compounds 1 and 2 have no antibacterial activity, but are potent inhibitors of the Fusarium oxysporum phytopathogenic fungal growth.     

Two new clerodane-type diterpenoids from Bornean liverwort Gottschelia schizopleura and their cytotoxic activity

The Bornean liverwort Gottschelia schizopleura was investigated phytochemically for the first time. Two new and four previously known clerodane-type diterpenoids were isolated from the MeOH extract of G. schizopleura through a series of chromatographic techniques. The structures of the new metabolites were established by analyses of their spectroscopic data (1D NMR, 2D NMR, HRESIMS and IR). All the isolated compounds 1–6 were tested against human promyelocytic leukaemia (HL-60), human colon adenocarcinoma (HT-29) and Mus musculus skin melanoma (B16-F10). Compound 1 and 2 showed active inhibition against HL-60 and B16-F10 cells.     

A novel cytotoxic C-methylated biflavone,taiwanhomoflavone-B from the twigs of Cephalotaxus wilsoniana

A novel C-methylated biflavone, taiwanhomoflavone-B (1), together with known compounds, 7,4',7"-tri-O-methylamentoflavone, 6-C-methylnaringenin and apigenin-7-O-beta-glucoside were isolated from an ethanolic extract of Cephalotaxus wilsoniana. The structure of 1 was elucidated on the basis of spectroscopic analysis. Taiwanhomoflavone-B is cytotoxic with ED(50) values of 3.8 and 3.5 microg/ml, against KB oral epidermoid carcinoma and Hepa-3B hepatoma cells, respectively.     

Total synthesis and cytotoxic activity of dechlorogreensporones A and D

The first and convergent total syntheses of polyketide natural products dechlorogreensporones A and D have been accomplished in 17 longest linear steps with 2.8% and 5.4% overall yields, respectively, starting from known methyl 2-(2-formyl-3,5-dihydroxyphenyl)acetate and commercially available R-(+)-propylene oxide and 1,2-epoxy-5-hexene. Our synthesis exploited key Mitsunobu esterification and (E)-selective ring-closing metathesis (RCM) to assemble the macrocycles as well as a Jacobsen hydrolytic kinetic resolution to install the stereogenic centers. Both synthetic compounds were found to display significant cytotoxic activity against seven human cancer cell lines with the IC₅₀ ranges of 6.66–17.25?μM.