Two new cyclic diarylheptanoids from the stems of Ostryopsis nobilis

Two new cyclic diarylheptanoids named ostryopsitrienol(1) and ostryopsitriol(2),together with six known compounds,were isolated from the stems of endemic medicinal plant of Ostryopsis nobilis (Betulaceae).The structures of the new compounds were elucidated by means of HRMS,~1D NMR,~2D NMR and X-ray crystallography analysis.     

Two New Compounds Isolated from<em> Liriope muscari</em>

Two new compounds, (2S,3R)-methyl 7-hydroxy-2-(4-hydroxy-3-methoxy-phenyl)-3-(hydroxymethyl)-2,3-dihydrobenzofuran-5-carboxylate (1) and (4R,5S)-5-(3-hydroxy-2,6-dimethylphenyl)-4-isopropyldihydrofuran-2-one (2), tentatively named norcurlignan and limlactone, respectively, were isolated from Liriope muscari, together with the known compound (-)-pinoresinol (3). The structures of these compounds were elucidated and characterized on the basis of 1D NMR, 2D NMR, CD and MS data. The in vitro antioxidant activities of compounds 1-3 were assessed by the DPPH and ABTS scavenging methods.     

Novel thiosemicarbazone derivatives containing benzimidazole moiety: Green synthesis and anti-malarial activity

A series of (E)-2-[5-chloro-1-(1H-benzo[d]imidazol-2-yl)ethylidene] N-(substituted) hydrazine carbothioamide (7a–7t) and (E)-2-[1-(1H-benzo[d]imidazol-2-yl)ethylidene] N-(substituted) hydrazine carbothioamide (8a–8t) were prepared via the synthesis of 1-(substituted-1H-benzimidazol-2-yl) ethanol (3a–3b) which was synthesized by the condensation of substituted o-phenylenediamine (2a–2b) with dl-lactic acid (1) followed by oxidation with sodium hypochlorite in mild acidic condition to form the corresponding ketones 4a–4b. Final compounds were formed by condensation of 4a–4b with different thiosemicarbazides 6a–6t. A total of 40 compounds were synthesized and characterized by FT-IR, ¹H NMR, ¹³C NMR, Mass spectral technique and elemental analysis, in addition they were evaluated for anti-malarial properties. Among the compounds tested 7o, 7p, 7q, 7r, 7s, 8e and 8h exhibited good antimalarial activity in vitro.     

Structure elucidation and vasodilator activity of methoxy flavonols from Calycotome villosa subsp. intermedia

Two flavonols identified as 3,5,7,4′-tetrahydroxy-3′-methoxyflavone (1) and 3,5,7,4′-tetrahydroxy-8-methoxyflavone (2) were isolated from the seeds of Calycotome villosa subsp. intermedia. The structure elucidation of the isolated compounds was performed by the spectroscopic methods (UV, IR, ¹H NMR, ¹³C NMR and MS) and also by a single crystal X-ray analysis in the case of compound (2). Vasodilator activity of compound (2) was demonstrated in isolated rat aorta contracted with high KCl or with noradrenaline.     

Inducing new secondary metabolites through co-cultivation of the fungus Pestalotiopsis sp. with the bacterium Bacillus subtilis

Two new lactones, pestalotiolactones A (1) and B (2), together with three known compounds (3–5) were isolated from the axenic culture of the endophytic fungus Pestalotiopsis sp., obtained from fruits of Drepanocarpus lunatus (Fabaceae). Co-culture of this fungus with Bacillus subtilis afforded two new sesquiterpenoids pestabacillins A (6) and B (7) as well as eight known compounds (8–15). Their structures were elucidated by extensive analysis of the NMR and MS data as well as by comparison with literature data. All isolated compounds were evaluated for their cytotoxic and antimicrobial activities but proved to be inactive.     

Two xanthones and two rotameric (3⟶8) biflavonoids from the Cameroonian medicinal plant Allanblackia floribunda Oliv. (Guttiferae)

Two xanthones, 2-(3-hydroxy-3,3-dimethyldihydroallyl)-dihydro-6-deoxyisojacareubin (1) and dihydro-6-deoxyjacareubin (2), and two 3 ⟶ 8 rotameric biflavonoids, (2R,3S)-volkensiflavone-7-O-β-acetylglucopyranoside (3) and (2S,3S)-morelloflavone-7-O-β-acetylglucopyranoside (4), together with fifteen known compounds, were isolated from a dichloromethane/methanol (1:1, v/v) extract of the bark of the plant Allanblackia floribunda. The structures of the new compounds were elucidated by NMR spectroscopy and mass spectroscopic techniques and those of the known ones were deduced by comparison with data reported in the literature. The isolated biflavonoids were obtained as mixtures of conformers exhibiting duplicate NMR signals in solution at 25 °C and their respective absolute configurations were assigned using circular dichroism spectroscopy. Selected isolated compounds were assessed for their antibacterial and antioxidant properties.     

New acetylated flavone C-glycosides from Iris lactea

Chemical investigation of the aerial parts of Iris lactea afforded three new flavone C-glycosides including 4?-O-acetyl-embinin (1), 2?,4?-O-diacetyl-embinin (2) and 6″,4?-O-diacetyl-embinin (3) along with the known analogue embinin (4). Their structures were elucidated by 1D and 2D NMR spectroscopic analysis as well as by HRESIMS data. The sugars were characterized following acid hydrolysis of the respective glycosides and TLC analysis compared to known standards. Duplicated signals can be observed in the NMR spectra, indicating the presence of rotamers caused by rotational hindrance around the glycosyl-flavone CC linkage. All isolated compounds were tested for their antimicrobial and cytotoxic activities but found to be inactive.     

Humulene derivatives from Saharian Asteriscus graveolens

Three new sesquiterpene-humulenes, (?)- asteriscunolides I (1), J (2) and (?)-(2Z,6E,9Z)-8-oxo-1α-acetoxy-2,6,9-humulatrien-12-oic acid (3) were isolated from the leaves-flowers of the Saharan medicinal plant Asteriscus graveolens along with six known compounds. The structures of the compounds were determined on the basis of spectroscopic mono and bidimensional NMR, mass spectrometry and by single-crystal X-ray diffraction. Compounds 1–3 were evaluated for cytotoxic assay, no significant activity was detected.     

Synthesis and goat pulmonary vasodilatory activity of some novel 1,3,4-oxadiazoles

A novel series of[(1Z)-1-(2,2-disubstituted-5-pyridin-4-yl-1,3,4-oxadiazol-3(2H)-yl) ethylidene] (PSMB1–PSMB15) were synthesized as title compounds. The synthesis route included the cyclization of carbonyl hydrazone in the presence of excess of acetic anhydride and subsequent condensation with various aromatic amines. All the title compounds were characterized by IR, ¹H NMR, MS and elemental analysis. They were screened for their goat pulmonary vein relaxant activity. Compound PSMB9 was found the most active derivative exhibiting 83.33% relaxation. Isosorbide dinitrate was used as the standard drug for goat pulmonary vein relaxant activity.     

Synthesis,characterization and antimicrobial evaluation of novel halopyrazole derivatives

Two novel halopyrazole derivatives (3, 5) were synthesized from 5-chloro-3-methyl-1-phenylpyrazole-4-carboxaldehyde (1) using appropriate synthetic routes. Newly synthesized compounds were characterized using elemental analysis, spectral data (IR, ¹H NMR, ¹³C NMR and mass spectrometry) and were evaluated for their in vitro antimicrobial activity. The minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and minimum fungicidal concentration (MFC) were determined for the test compounds as well as for reference standards. The investigation of antimicrobial screening revealed that compounds (3, 5) showed good antibacterial and antifungal activities, respectively.     

In vitro antioxidant properties of new thiazole derivatives

A series of novel N2-[2-chloro-4(3,4,5-trimethoxy phenyl azetidin-1-yl]-N4-(substituted aryl)-1,3-thiazole-2,4-diamine (4a–g) were synthesized starting from 3,4,5-trimethoxy benzaldehyde thiosemicarbazone (1). The compound (1) was obtained by condensing 3,4,5-trimethoxy benzaldehyde with thiosemicarbazide in methanol. 3,4,5-Trimethoxy benzaldehyde thiosemicarbazone (1) on treatment with chloracetyl chloride afforded 4-chloro-[2-(3,4,5-trimethoxy benzylidine) hydrazinyl]-1,3-thiazole (2). Compound (2) was reacted with chloracetyl chloride and triethylamine to obtain the corresponding 4-chloro-N-[2-chloro-4(3,4,5-trimethoxy phenyl) azetidin-1-yl]-1,3-thiazole-2-amine (3). Various substitutions on compound 3 with secondary amines yielded series of compounds (4a–g). The newly synthesized compounds were characterized by IR, ¹H NMR, elemental analysis and mass spectral studies. All the compounds were screened for their in vitro antioxidant properties. The IC₅₀ values of compounds 3 and 4a–g revealed that some of the synthesized compounds were showing potent antioxidant activity.     

Microwave assisted selective synthesis of (<Emphasis Type="Italic">E</Emphasis>)-1-(4-Chloro-7-hydroxy-2-aryl-2<Emphasis Type="Italic">H</Emphasis>-chromen-6-yl)-3-arylprop-2-en-1-ones and their antimicrobial activity

A series of new (E)-1-(4-chloro-7-hydroxy-2-aryl-2H-chromen-6-yl)-3-arylprop-2-en-1-ones (2a–2f) have been synthesized by selective mono cyclization of 4,6-dicinnamoyl resorcinols (1a–1f) using Vilsmeier–Haack reagent under conventional heating and microwave irradiation. The structures of the synthesized compounds have been elucidated by elemental analysis, IR, ¹H NMR, ¹³C NMR and Mass spectral data. The synthesized compounds were tested in vitro for antimicrobial activity.     

Two new tricycloalternarenes from Hawaiian endophytic fungus Didymella sp. FT433

Two new compounds, tricycloalterenes M and N (1 and 2) and six known analogs were isolated from the cultured broth of Didymella sp. FT433. The structures of all the compounds were elucidated through the analysis of HRMS and NMR spectroscopic data. The absolute configurations (AC) of the new compounds were determined by CD. All compounds were tested against A2780 and cisplatin resistant A2780 (A2780CisR) cell lines, and pathogenic bacteria Staphylococcus aureus, Escherichia coli, Bacillus subtilis, and Pseudomonas aeruginosa, but none was active.     

Microwave synthesis,characterization and antimicrobial study of new pyrazolyl-oxopropyl-quinazolin-4(3H)-one derivatives

Heterocyclic compounds containing pyrazolyl-oxopropyl-quinazolin-4(3H)-one are reported to possess significant biological activity. Syntheses of 6-bromo-2-(3-chloro-2-oxopropyl)-3-(4-fluorophenyl)quinazolin-4(3H)-one 2 6-bromo-3-(4-fluorophenyl)-2-(3-hydrazinyl-2-oxopropyl)quinazolin-4(3H)-one 3 and 6-bromo-2-(3-(3-(4-(1-(2-chlorophenyl)-3-methyl-1H-pyrazol-5(4H)-ylideneamino)phenyl)-5-(substituted phenyl)-4,5-dihydro-1H-pyrazol-1-yl)-2-oxopropyl)-3-(4-fluorophenyl)quinazolin-4(3H)-one 5a–j using microwave irradiation have been described. These compounds have been characterized on the basis of the UV, IR, ¹H NMR, ¹³C NMR, Mass and elemental analysis. Compounds have been evaluated for their antimicrobial activity.     

Design,synthesis and screening of some novel benzoxazole based 1,3,4-oxadiazoles as potential antimicrobial agents

A series of novel 2-(5-substituted-[1,3,4]oxadiazol-2-yl)-benzoxazoles (7a–h) were synthesized in good yields in two different directions by involving benzoxazole-2-carboxylic acid (1) as raw material and benzoxazole-2-carbonyl chloride (2), benzoxazole-2-carboxylic acid methyl ester (3), benzoxazole-2-carboxylic acid hydrazide (4), benzoxazole-2-carboxylic acid N′-acetyl hydrazide (5a–d) and benzoxazole-2-carboxylic acid-ethylidene-hydrazides (6a–d) as reactive intermediates. The chemical structures of all the synthesized compounds were elucidated by their IR, ¹H NMR and ¹³C NMR and mass spectral data. Further, the target compounds were screened for their antimicrobial activity against various Gram-positive and Gram-negative bacteria.     

Chiral solvating properties of (S)-1-benzyl-6-methylpiperazine-2,5-dione

In CDCl₃ solution, enantiopure (S)-1-benzyl-6-methylpiperazine-2,5-dione (S)-1a formed diastereomeric CO⋯H–N hydrogen-bonded associates with racemic (RS,Z)-1-benzyl-3-[(dimethylamino)methylidene]piperazine-2,5-diones 2a and 2b, (RS)-tert-butyl pyroglutamate (RS)-2c and (RS)-N-benzoylalanine methyl ester (RS)-2d. This resulted in splitting (doubling) of the characteristic signals in the ¹H NMR and ¹³C spectra of racemic compounds 2a–d in the presence of 1 equiv of (S)-1a. The formation of hydrogen-bonded dimers in CDCl₃ solution was studied by ¹H NMR, ¹³C NMR and 2D NMR and confirmed by the intermolecular NOE observed between the hydrogen-bonded amide protons from each of the monomeric units, (S)-1a and 2a–c. On the other hand, a slightly different binding mode was proposed for association of (S)-1a with alaninamide (RS)-2d. Enantiomer compositions of known (weighed) mixtures of both enantiomers of tert-butyl pyroglutamate 2c were re-determined by ¹H NMR in the presence of (S)-1a in CDCl₃. The experimental values were in good agreement with the theoretical values, thus indicating the potential applicability of (S)-1a and related diketopiperazines as chiral solvating agents in NMR spectroscopy.     

Polyketides and nitrogenous metabolites from the endophytic fungus Phomopsis sp. D15a2a

Three new polyketides, phomopones A−C (1–3), one new cyclic tetrapeptide, 18-hydroxydihydrotentoxin (4), and a new amide, 6-hydroxyenamidin (5) together with a known derivative, enamindin (6) were obtained from the endophytic fungus Phomopsis sp. D15a2a isolated from the plant Alternanthera bettzickiana. The structures of the new compounds were elucidated by 1D, 2D NMR and HRMS data. The absolute configurations of the isolated metabolites were determined either by X-ray crystallography, Marfey’s method or by converting the compounds to Mosher esters.     

In vitro microbial studies of new pyrazolyl quinazolin-4(3H) ones

A series of new 2-[2-(2,6-dichlorophenyl)amino]phenyl methyl-3-[(5-substituted phenyl)-1,5-dihydro-1H-pyrazol-3-yl-amino]-6-iodoquinazolin-4(3H) ones (6a–m) have been synthesized by the reaction of 2-[2-(2,6-dichlorophenyl)amino]phenyl methyl-3-substituted phenyl acryl amido-6-iodoquinazolin-4(3H) ones with hydrazine hydrate in the presence of glacial acetic acid. The chalcone (5a–m) have been prepared by the condensation of 2-[2-(2,6-dichlorophenyl)amino]phenyl methyl-3-acetamido-6-iodoquinazolin-4(3H) one with different substituted aromatic aldehyde. The compound 1 on treatment with 5-iodoanthranilic acid in pyridine undergoes cyclisation gave 2-[2-(2,6-dichlorophenyl)amino]phenyl methyl-6-iodo-3,1-benzoxazin-4(3H) one (2). Treatment on benzoxazine with hydrazine hydrate gave 3-amino-2-[2-(2,6-dichlorophenyl)amino]phenyl methyl-6,8-dibromo quinazolin-4(3H) one (3) followed by acetylation synthesized 2-[2-(2,6-dichlorophenyl)amino]phenyl methyl-3-acetamido-6,8-dibromoquinazolin-4(3H)-one (4). The structure of synthesized compounds has been elucidated by IR, ¹H NMR, ¹³C NMR and elemental analysis. The products were screened for antibacterial and antifungal activity. Among the series containing some of the compounds showed promising results against standard drugs.     

Synthesis of 1,3-dithiolane-containing nitromethene compounds and their biological activity as insecticides

1,3-Dithiolane-containing nitromethylene derivatives, as candidates for screening as neonicotinoid insecticides, were synthesized by reaction of compound (4) with 1,2-ethanedithiol. Compounds 7a–g were obtained via Mannich reaction of (E)-1-((1,3-dithiolan-2-yl)methyl)-2-(nitromethylene)imidazolidine (6), primary amines and formaldehyde. The synthesized compounds were identified by ¹H NMR, IR spectroscopy and elemental analysis. Preliminary bioassays indicated that most of the compounds had moderate insecticidal activity against Aphis craccivora. The relationship between molecular structure and biological activity is discussed.     

Two new tetrahydrofuran derivatives from the fungus Mucor spp. SNB-VECD11D isolated from the Chrysomelidae Acalymma bivittula

Two new tetrahydrofuran derivatives, mucorinic acids A (1) and B (2) as well as the three known secondary metabolites dehydroabietic acid (3), Δ8-dihydroabietic acid (4) and 8-pimarenic acid (5) were isolated from a solid culture of the fungus Mucor spp. isolated on insect Acalymma bivittula. The structure of these compounds was elucidated by analysis of NMR and MS spectroscopic data. Compounds were tested in antimicrobial and insecticidal assays. Dehydroabietic acid exhibited moderate larvicidal activity on Aedes aegypti larvae with 65% mortality at 10 ppm. Both new compounds 1 and 2 showed interesting antibacterial activity on Staphylococcus aureus and methicillin resistant S. aureus with MIC values in the 8–16 μg/ml.