3-Oxyanthranilic acid derivatives from Actinomadura sp. BCC27169

Eight new compounds including 9′-[2-amino-3-(4″-O-methyl-α-rhamnopyranosyloxy) phenyl]nonanoic acid (1), 9′-[2-amino-3-(4″-O-methyl-α-ribopyranosyloxy)phenyl] nonanoic acid (2), 11′-[2-amino-3-(4″-O-methyl-α-rhamnopyranosyloxy)phenyl]undecanoic acid (3), 11′-[2-amino-3-(4″-O-methyl-α-ribopyranosyloxy)phenyl]undecanoic acid (4), 8-(4′-O-methyl-α-rhamnopyranosyloxy)-3,4-dihydroquinolin-2(1H)-one (5), 8-(4′-O-methyl-α-ribopyranosyloxy)-3,4-dihydroquinolin-2(1H)-one (6), 8-(4′-O-methyl-α-rhamnopyranosyloxy)-2-methyquinoline (7), and 8-(4′-O-methyl-α-ribopyranosyloxy)-2-methylquinoline (8) were isolated from Actinomadura sp. BCC27169. The chemical structures of these compounds were determined based on NMR and high-resolution mass spectroscopy. The absolute configurations of these monosaccharides were revealed by the hydrolysis of compounds 7 and 8. Compounds 3 and 8 exhibited antitubercular activity at MIC 50 μg/mL. Only compound 3 showed cytotoxicity against KB cell at IC₅₀ 18.63 μg/mL, while other isolated compounds were inactive at tested maximum concentration (50 μg/mL).     

Antimicrobial and antiquorum-sensing activity of Ricinus communis extracts and ricinine derivatives

Ricinine (1), a known major alkaloid in Ricinus communis plant, was used as a starting compound for the synthesis of six ricinine derivatives; two new and four known compounds. The new derivatives; 3-amino-5-methyl-1H-pyrazolo[4,3-c]pyridin-4(5H)-one (2), and 3-amino-5-methyl-1-(phenylsulfonyl)-1H-pyrazolo[4,3-c]pyridin-4(5H)-one (3), as well as the previously prepared derivatives (4–7) were subjected for antimicrobial and antiquorum-sensing evaluation in comparison to different R. communis extracts. Acetyl ricininic acid derivative (5) showed the highest antimicrobial activity among all tested derivatives against Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeuroginosa and Candida albicans. However, compound 7 (4-methoxy-1-methyl-2-oxo-1,2-dihydropyridine-3-carboxamide) showed the highest antiquorum-sensing activity among all tested compounds and extracts. These findings proved the usefulness of ricinine as a good scaffold for the synthesis of new antimicrobial and antiquorum-sensing derivatives in spite of its poor contribution to the antimicrobial activity of the plant extracts.     

N-Hydroxypyridone alkaloids,chromone derivatives,and tetrahydroxanthones from the scale-insect pathogenic fungus Orbiocrella sp. BCC 33248

Six new compounds, an N-hydroxypyridone glucoside, orbiocrellin A (1), its aglycone orbiocrellin B (2), chromone glucosides 3 and 4, a dihydrochromone 5a/5b, and a chromone 6, were isolated from the scale-insect pathogenic fungus Orbiocrella sp. BCC 33248. Orbiocrellin A (1) exhibited antimalarial activity against Plasmodium falciparum K1 (IC₅₀ 3.1 μg/mL) while it was non-cytotoxic. In contrast, orbiocrellin B (2) showed both antimalarial (IC₅₀ 2.1 μg/mL) and cytotoxic (NCI-H187 cells, IC₅₀ 0.70 μg/mL) activities.     

Cytotoxic eremophilane sesquiterpenoids from the saprobic fungus Berkleasmium nigroapicale BCC 8220

Berkleasmins A-E, five new eremophilane sesquiterpenoids were isolated from the saprobic fungus Berkleasmium nigroapicale BCC 8220. The structures of the new compounds were elucidated by analyses of NMR spectroscopic and mass spectrometry data in combination with chemical means. Berkleasmins A and C exhibited cytotoxic activity against cancer cell-lines (NCI-H187, MCF-7, and KB) as well as nonmalignant Vero cells with IC₅₀ values of 1.1-7.5 μg/mL, and these compounds also showed antimalarial activity with respective IC₅₀ of 3.1 and 2.8 μg/mL.     

Synthesis of Hydrazones from Amino Acids and their Antimicrobial and Cytotoxic Activities

Hydrazones 6a–6n were synthesized from different amino acids with various aldehydes under reflux in methanol/ethanol. The structures of synthesized compounds were ascertained by elemental analysis and spectroscopic techniques. A comparative study of the antimicrobial activity and cytotoxicity was carried out of the N‐protected amino acids, their esters, hydrazides, and the respective hydrazones, providing good results in cytotoxicity studies.     

Antimalarial and antituberculosis substances from Streptomyces sp. BCC26924

Two new carbazomycin dimers (6 and 7) and 3-hydroxy-1,2-dimethyl-2,3-dihydro-1H-carbazol-4-one (9) together with six known compounds, carbazomycins A-D, cyclomarin C, and pimprinine have been isolated from Streptomyces sp. BCC26924. Carbazomycins B, C, and cyclomarin C exhibited antimalarial activity (against Plasmodium falciparum, K1 multi-drug resistant strain) with IC₅₀ in a range of 0.24-2.37 μg/mL. Cyclomarin C exhibited anti-TB activity with a minimum inhibitory concentration value of 0.10 μg/mL, while carbazomycin D, compound 7, and pimprinine displayed MIC values in a range of 12.5-25.0 μg/mL. In addition, compounds 2, 5, 6, and 7 showed weak cytotoxicity against cancerous (MCF-7, KB, NCI-H187) and non-cancerous (Vero) cells.     

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.     

Novel tetranortriterpenoid derivatives from Munronia henryi

Six novel tetranortriterpenoid derivatives were isolated from the methanolic extract of the whole bodies of Munronia henryi, namely, munronins A-F (1-6). In compounds (3-6), the side chains are rare in tetranortriterpenoids. Their structures were established by extensive NMR experiments. Based on the diversity of the side chains, possible biodegradations for the side chains of compounds 1-6 from euphane or tirucallane skeleton are proposed. Munronins A-E exhibited moderate antifeeding activity against Pieris brassicae L, while munronin F showed negative activity.     

Novel polyisoprenylated benzophenone derivatives from Garcinia paucinervis

Four novel polyisoprenylated benzophenone derivatives, paucinones A-D (1-4), were isolated from the leaves of the plant Garcinia paucinervis. Paucinones A-C (1-3) contained an unexpected cyclohexane-spiro-tetrahydrofuran moiety. A 1-methylene-3,3-dimethylcyclohexane group never reported before was found in the structure of paucinone D (4). The structures of these compounds were elucidated with spectroscopic evidences. The relative stereochemistries of 1-4 were determined by NOESY correlations. These compounds showed significant cytotoxicities against HeLa cells.     

Antimicrobial indole alkaloids with adductive C9 aromatic unit from Gelsemium elegans

Gelselegandines A-C (1–3), three unprecedented gelsedines incorporating additional C₉ aromatic unit as side chain, were isolated from Gelsemium elegans. Their structures were elucidated by means of spectroscopic techniques and electronic circular dichroism (ECD) calculation. Additionally, gelselegandines A–C showed moderate antimicrobial activities against four bacterial strains and two fungi.     

New iodotyramine derivatives from Didemnum rubeum

The study of an aqueous extract from the ascidian Didemnum rubeum permitted the isolation of a previously reported derivative diiodo-tyramine derivative together with six new iodo-tyramine derivatives. Their structures were elucidated by NMR and MS analysis.     

Novel cyclopropyl diketones and 14-membered macrolides from the soil fungus Hamigera avellanea BCC 17816

Two novel cyclopropyl diketones, hamavellone A (1) and B (2), and two new 14-membered nonaketide macrolactones, hamigeromycin A (3) and B (4), together with six known compounds, 89-250904-F1 (radicicol analogue A, 5), pseurotin A (6), emodin (7), ω-hydroxyemodin (8), and emodin bianthrones (9 and 10) were isolated from the soil fungus Hamigera avellanea BCC 17816. The structures of the new compounds were defined by analysis of NMR and MS data. The absolute stereochemistry of 3 was addressed by chemical correlation to 5. Hamavellone B (2) exhibited antimalarial activity with an IC₅₀ of 5.2 μg/mL, whereas it also showed comparable cytotoxicity.     

Cytotoxic ent-kauranoid derivatives from Isodon rubescens

An extensive study of the diterpenoids produced by the species of Isodon rubescens, has led to the isolation of 12 new ent-kaurane diterpenoids, hebeirubescensins A-L (1-12), and 19 known analogues. Their structures were determined on the basis of spectroscopic analysis. Selected compounds were assayed for their inhibitory ability against human A549, HT-29, and K562 cells. Among them, hebeirubescensins B and C exhibited significant cytotoxicity with IC₅₀ values of <2.0 μM. The structure-activity relationships were discussed.     

New cytotoxic apigenin derivatives from Selaginella doederleinii

75%aqueous ethanol extract from the whole herbs of Selaginella doederleinii was isolated,and two new apigenin derivatives,doederflavones A(1) and B(2),together with ten known compounds(3-12) were characterized.Their structures were assigned by extensive spectroscopic methods including 1D/2D NMR and HR-ESIMS.Compounds 1-6 bear an aryl substituent at the C-8 or C-6 positions in ring A of apigenin skeleton.Compounds 1 and 2 were evaluated for their in vitro cytotoxicity against four human cancer cell lines A549,MCF-7,SMMC-7721,and LoVo,both of which exhibited significant cytotoxicity against A549 with IC_(50) values of 0.82 μmol/L and 1.32 μmol/L,respectively.     

Takaneones A-C, prenylated butylphloroglucinol derivatives from Hypericum sikokumontanum

Three new prenylated butylphloroglucinol derivatives, takaneones A-C (1-3), were isolated from the MeOH extracts of the aerial parts of Hypericum sikokumontanum together with two new prenylated phloroglucinol derivatives, takaneols A and B (4 and 5). The structures of the isolated compounds were elucidated by exhaustive spectroscopic analysis. The cytotoxicities of the isolated compounds against human cancer cell lines were evaluated. Compounds 2-4 showed cytotoxicities against K562/Adr multi-drug resistant (MDR) cancer cells with IC₅₀ values ranging from 4.7 to 10.0 μg/mL, which were slightly more potent than doxorubicin. Their potency of cytotoxicities against MDR cancer cell lines (KB-C2 and K562/Adr) were similar to those against sensitive cell lines (KB and K562).     

Antimicrobial sesquiterpenes from the Chinese medicinal plant, Chloranthus angustifolius

Two new eudesmane-type sesquiterpenes, 9α-hydroxycurcolonol (1) and 3α-hydroxy-4-deoxy-5-dehydrocurcolonol (2), along with nine known sesquiterpenes (3–11), were isolated from the roots of Chloranthus angustifolius. The antimicrobial activities of compounds 1–11 were evaluated against five bacteria and six fungal strains. Compounds 6–11 showed potent activities against Candida albicans with MIC values ranging from 4 to 8 μg/mL. The structures of the two new compounds 1 and 2 were established by a detailed analysis of their NMR and mass spectroscopic data.     

Acremoxanthones A and B, novel antibiotic polyketides from the fungus Acremonium sp. BCC 31806

Acremoxanthones A and B, novel anthraquinone-xanthone heterodimers with a unique linkage pattern, together with two known compounds, acremonidins A and C, were isolated from the fungus Acremonium sp. BCC 31806. The structures of the acremoxanthones were determined by analysis of 2D NMR and mass spectrometric data. Acremoxanthones and acremonidins exhibited antibacterial, antifungal, antiplasmodial, and cytotoxic activities.     

Formamidobisabolene-based derivatives from a sponge Axinyssa sp.

Chemical examination of a Chinese sponge Axinyssa sp. resulted in the isolation of 12 new formamidobisabolene-based analogues named axinyssines A–L (1–12), along with a new natural product (13) and three known formamidobisabolenes (14–16). Their structures were determined on the basis of extensive NMR and mass spectroscopic analyses in association with ICD data, Mosher reaction and chemical conversion for the assignment of absolute configurations. All compounds were evaluated for antitumor and antimicrobial activities.     

Cage-like monoterpenoid indole alkaloids with antimicrobial activity from Alstonia scholaris

Three new cage-like monoterpenoid indole alkaloids, scholarisines T–V (1–3), together with three known analogues 4–6 were isolated from the leaves of Alstonia scholaris. Among them, 2 represents a unique degraded derivative, whereas 3 shares a rare 5,16-seco lactone scaffold. The structures were mainly established by extensive spectroscopic data analyses, and their plausible biosynthesis pathway from picrinine were proposed. Compared with positive control cefotaxime, alkaloid 2 showed remarkable antibacterial activity against Bacillus subtilis with an MIC value of 3.12?μg/mL, whereas 1–3 exhibited significant antibacterial effects on Escherichia coli with an MIC value of 0.78?μg/mL.     

Novel gallium(III) complexes containing phthaloyl derivatives of neutral aminoacids with apoptotic activity in cancer cells

The reaction of N-phthaloylglycine and N-phthaloyl-dl-alanine with trimethylgallium (1:1) yielded the dinuclear complexes [Me₂Ga(μ-O₂CCH₂N(CO)₂C₆H₄)]₂ (1) and RS-[Me₂Ga(μ-O₂CCHMeN(CO)₂C₆H₄)]₂ (2), respectively. The molecular structure of 2 was determined by X-ray diffraction studies. The cytotoxic activity of the organogallium(III) complexes (1 and 2) was tested against human tumour cell lines 8505C anaplastic thyroid cancer, A253 head and neck tumour, A549 lung carcinoma, A2780 ovarian cancer, DLD-1 colon carcinoma and compared with that of cisplatin.The best response of the synthesized gallium complexes, compared with that of cisplatin, was observed against 8505C anaplastic thyroid cancer and DLD-1 colon carcinoma, while the best IC₅₀ values were found for A253 head and neck carcinoma. While the studied carboxylic acids show no proliferative activity, complexes 1 and 2 present very similar cytotoxic activity against all the studied cancer cell lines (IC₅₀ from ca. 5 to 25 μM). The cytotoxicities of complexes 1 and 2 are in all cases higher than that presented by gallium(III) nitrate. In addition DNA laddering method showed that treatment of the studied cell lines with IC₉₀ doses of 1 and 2 resulted in the induction of apoptotic mode of cell death.