A new oxathiolane from Enterobacter cloacae

Enterobacter cloacae is a versatile bacterial species inhabiting a wide variety of niches and is capable of metabolising a wide variety of substances as energy resources. The fermentation culture of this bacterial species has successfully yielded one new compound, Rimboxa (1) and three known compounds, i.e. indole-3-carboxaldehyde (2), indole-3-acetic acid (3) and 3,4-di-t-butylaniline (4). Rimboxa (1) is shown to possess the 1,2-oxathiolane core structure. 3,4-Di-t-butylaniline (4) is isolated for the first time from a natural resource. These compounds were isolated and characterised using extensive chromatographic and spectroscopic methods, and were subjected to cytotoxicity evaluations.     

Antibacterial and antioxidant activity of naphthofuranquinones from the twigs of tropical mangrove Avicennia officinalis

Abstract

Mangrove plants are endowed with various biologically active compounds which have potent antibacterial and antioxidant properties. In present study, a bioactivity-guided fractionation for antibacterial and antioxidant active metabolites from the twigs of Avicennia officinalis collected from Kuala Selangor Nature Park, Selangor, Malaysia gave 13 major fractions. The antibacterial activity of A. officinalis fractions using well-diffusion showed strong selectivity on the Gram-positive bacteria (Staphylococcus epidermidis, S. aureus and Bacillus subtilis) with minimum inhibition concentration (MIC) values of 0.156-5.00?mg/mL. However, no antibacterial activities were observed on the Gram-negative bacteria (Vibrio cholera, Enterobacter cloacae and Escherichia coli). The active antibacterial fractions were further isolated using several chromatographic techniques to give two naphthofuranquinones, namely, avicenol C (1) and stenocarpoquinone B (2). Meanwhile, the antioxidant activity of A. officinalis fractions were evaluated using DPPH radical scavenging assay exhibited low antioxidant activities. Molecular structure of the naphthofuranquinones was elucidated using 1?D and 2?D NMR spectroscopy.     

Synthesis and antimicrobial activities of metal(II) complexes with 2,4-diiodo-6-phenyliminomethyl-phenol

A bidentate ligand, 2,4-diiodo-6-phenyliminomethyl-phenol (HL) has been synthesized from 3,5-diiodosalicylaldehyde and phenylamine in ethanol. Five mononuclear complexes have been synthesized from 2,4-diiodo-6-phenyliminomethyl-phenol reaction with CuCl₂ · 2H₂O, NiCl₂ · 6H₂O, CoCl₂ · 6H₂O, MnCl₂ · 4H₂O, and ZnCl₂ in ethanol or tetrahydrofuran (THF). The complexes were characterized by UV, infrared, ESI-MS, and elemental analyses. Complexes bis(2,4-diiodo-6-phenyliminomethyl-phenol)-copper(II) (1) and bis(2,4-diiodo-6-phenyliminomethyl-phenol)-zinc(II)-THF (5) were characterized by X-ray crystallography. Based on the crystal structure analysis of 1 and 5, coupled to their spectral similarity with other complexes prepared (2, 3, 4), we conclude that 2, 3, and 4 have similar structures to 1. The metal(II) in each complex is four-coordinate by two nitrogens and two oxygens from two ligands. All the complexes were assayed for antibacterial (Bacillus subtilis, Staphylococcus aureus, Streptococcus faecalis, Pseudomonas aeruginosa, Escherichia coli, and Enterobacter cloacae) activities by the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) method. Among the complexes tested, 1 showed the most favorable antimicrobial activity with minimum inhibitory concentrations of 3.125, 6.25, 6.25, 3.125, 3.125, 6.25 µg mL^?1 against B. subtilis, S. aureus, S. faecalis, P. aeruginosa, E. coli, and E. cloacae, respectively.     

Synthesis and antibacterial activities of metal(II) complexes with Schiff bases derived from 3,5-diiodosalicylaldehyde

Two new Schiff bases (2,4-diiodo-6-[(2-morpholin-4-yl-ethylimino)-methyl]-phenol and 2,4-diiodo-6-[(3-morpholin-4-yl-propylimino)-methyl]-phenol), condensed from 3,5-diiodosalicylaldehyde with 2-morpholinoethylamine and 3-morpholinopropylamine, have been designed and synthesized. Reaction of the Schiff bases with Zn(OAc)₂ · 2H₂O, Cu(OAc)₂ · H₂O, Ni(OAc)₂ · 4H₂O, Co(OAc)₂ · 4H₂O, Cd(OAc)₂ · 2H₂O, Mn(OAc)₂ · 4H₂O, Fe(SO4)₂ · 7H₂O, and Hg(OAc)₂ led to the formation of 16 new mononuclear complexes. The complexes were characterized by UV, Infrared, ESI-MS, and elemental analyses, and 3,5-diiodosalicylalidene-2-morpholinoethylaminozinc(II) (1) and 3,5-diiodosalicylalidene-2-morpholinoethylaminocopper(II) (2) were characterized by single crystal X-ray diffraction. Based on crystal structural analysis of 1 and 2, coupled with their spectral similarity with 3–16, it can be concluded that 3–16 have structures similar to 1 and 2. All the complexes were assayed for antibacterial activities against three Gram positive bacterial strains (Bacillus subtilis, Staphylococcus aureus, and Streptococcus faecalis) and three Gram negative bacterial strains (Escherichia coli, Pseudomonas aeruginosa, and Enterobacter cloacae) by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide method. Among the complexes tested, 8 and 16 showed the most favorable antibacterial activity with minimum inhibitory concentration of 0.781, 12.5, 6.25, 3.125, 3.125, 6.25 and 1.562, 6.25, 1.562, 3.125, 3.125, 1.562 µg mL^?1 against B. subtilis, S. aureus, S. faecalis, P. aeruginosa, E. coli, and E. cloacae, respectively.     

Versicorin,a new lovastatin analogue from the fungus Aspergillus versicolor SC0156

A new lovastatin analogue versicorin (1), together with three related compounds, decumbenones A (2) and B (3) and versiol (4), were isolated from mycelial solid cultures of Aspergillus versicolor SC0156. Their structures were elucidated on the basis of MS data and NMR spectroscopic analysis. The new compound versicorin (1) possesses a hexahydro-2H-naphtho[1,8-bc]furan moiety, which is a rare type of the lovastatin-analogous compounds. A hypothetical biosynthetic pathway for compounds 1–4 was proposed.     

Synthesis,characterization, and investigations of antimicrobial activity of benzopyrans,benzofurans and spiro[4.5]decanes

In this study, the radical cyclization reactions of cyclic 1,3-dicarbonyl compounds (1a–c) and α,β-unsaturated alcohols (2a–d) through Mn(OAc)₃ were performed. A series of biologically interesting dihydropyrans (3–5) and dihydrofurans (6–18) were synthesized as a result of these reactions. Spiro compounds (19–20) were obtained from the reactions of 1,3-dicarbonyl compounds and (E)-2,4-diphenyl-but-3-en-2-ol (2e). The unique structure of compound 19 was also confirmed by X-ray crystallography. In addition, the antibacterial activities of synthesized compounds were screened against some bacteria. Their zone diameters showed better results than some known antibiotics.     

Antiangiogenic phenylpropanoid glycosides from Gynura cusimbua

A new phenylpropanoid glycoside, named α-L-rhamnopyranosyl-(1?2)-β-D-[4″-(8E)-7-(3,4-dihydroxyphenyl)-8-propenoate, 1″-O-(7S)-7-(3,4-dihydroxyphenyl)-7-methoxy-ethyl]-glucopyranoside (1), together with nine known compounds (2–10) were isolated from the active fraction (n-Butanol fraction) of Gynura cusimbua for the first time. The known compounds (2–10) were identified as phenylpropanoid glycosides on the basis of extensive spectral data and references. The antiangiogenic activities of compounds (1–10) were evaluated by MTT assay on HUVECs and wild-type zebrafish in vivo model assay. As a result, compounds 1, 6, 7, 8 and 10 exhibited certain antiangiogenic activities.     

Synthesis,characterization, and antimicrobial activities of a dinuclear copper(II) complex with bis(2-[(2-hydroxy-ethylimino)-methyl]-4,6-diiodo-phenol)

A dinuclear copper(II) complex with a newly synthesized tridentate Schiff-base ligand 2-[(2-hydroxy-ethylimino)-methyl]-4,6-diiodo-phenol (HL), of formula [Cu₂L₂Cl₂?·?C₄H₈O] (1), was prepared. Both the ligand and the complex were characterized by X-ray crystallography, confirming that the Schiff base is tridentate and its dinuclear copper(II) complex is five-coordinate from one nitrogen and two oxygens from L and two chlorides. The complex was assayed for antibacterial (Bacillus subtilis, Staphylococcus aureus, Streptococcus faecalis, Pseudomonas aeruginosa, Escherichia coli, and Enterobacter cloacae) activities by the MTT method. Complex 1 exhibited better antimicrobial activity than the ligand.     

Studies on the constituents of the green alga <Emphasis Type="Italic">Ulva lactuca</Emphasis>

Phytochemical investigations on a marine green alga Ulva lactuca led to the isolation of two new compounds (E)-6-heptacosen-5-one (1) and (E)-6-octadecen-5-ol (2), along with four known compounds, (Z)-10-hexacosene (3), docosanoic acid (4), palmitic acid (5), and isofucosterol (6). Compounds 3 and 4 were isolated for the first time from this species. The structures of the compounds were deduced with the help of modern spectroscopic techniques.     

Synthesis,characterization, and investigations of antimicrobial activity of 6,6-dimethyl-3-aryl-3′,4′,6,7-tetrahydro-1′H,3H-spiro[benzofuran-2,2′-naphthalene]-1′,4(5H)-dione

Chalcone-like compounds 3a–l, 2-(benzylidene)-3,4-dihydronaphthalen-1(2H)-one, were synthesized from the addition of different benzaldehyde derivatives (2a–l) to 1,2,3,4-tetrahydro-1-napthalone (1) in basic medium. Mn(OAc)₃-mediated addition of dimedone (4) to chalcone-like compounds gave the spirobenzofuran derivatives (5a-l), 6,6-dimethyl-3-aryl-3′,4′,6,7-tetrahydro-1′H,3H-spiro[benzofuran-2,2′-naphthalene]-1′,4 (5H)-dione, in good yields. The structures of synthesized compounds 5a–l were elucidated on basis of spectral data (NMR, IR) and elemental analysis. In addition, their antibacterial activities were screened against some human pathogenic microorganisms.     

Isolation and identification of two new compounds from the Penicillium sp. SYPF7381

Abstract

Two new compounds, (7R, 2E, 5E)-3,5,7-trimethyl-2,5-octadienedioic-8-methyl ester (1) and neovasipyridone G (3), together with a new natural product compound (7R,2E,5E)-3,5,7-trimethyl-2,5-octadienedioic acid (2), and six known compounds (4–9) were isolated from Penicillium sp. SYPF7381. Their structures were elucidated on the basis of extensive spectroscopic analysis, and the absolute configurations of compounds 1 and 2 were determined by optical rotation. The absolute configuration of compound 3 was determined by means of electronic circular dichroism (ECD) calculation. In addition, the in vitro anti-inflammatory activities of all compounds were assayed in RAW 264.7 cells by assessing LPS-induced NO production. Furthermore, the structure-antiinflammation activity relationships for these isolated compounds were summarized based on the experimental as well as the docking results.     

Anti-β-amyloid aggregation activity of enantiomeric furolactone-type lignans from Archidendron clypearia (Jack) I.C.N.

Abstract

The phytochemical investigation on the twigs and leaves of Archidendron clypearia (Jack) I.C.N. led to the isolation of three pairs of furolactone-type lignans enantiomers, including a pair of new compounds (1R,5S,6S)-Kachiranol (1a) and (1S,5R,6R)-Kachiranol (1b) and four known compounds (2a/2b and 3a/3b). Separation of the furolactone-type lignans enantiomeric mixtures was achieved using chiral HPLC for the first time. Their structures were determined by spectroscopic analysis and comparison between the experimental and calculated electronic circular dichroism (ECD) spectra. All optical pure compounds were evaluated for their inhibitory effects on β-amyloid aggregation by ThT assay. Among them, the inhibitory activity of the compound 1b (71.1%) was higher than the positive control (61.0%) and other compounds. In addition, molecular dynamics and molecular docking were employed to explore the binding relationship between the ligand and the receptor.     

A new aldehyde compound from the fruit of Pandanus tectorius Parkinson ex Du Roi

From the fruit of Pandanus tectorius Parkinson ex Du Roi, one new (1) and six known aldehyde compounds (2–7) were isolated by various chromatography methods. Based on their spectroscopic data, these compounds were identified as (Z)-4-hydroxy-3-(4-hydroxy-3-methylbut-2-en-1-yl) benzaldehyde (1), p-hydroxybenzaldehyde (2), syringaldehyde (3), (E)-ferulaldehyde (4), (E)-sinapinaldehyde (5), vanillin (6) and 5-hydroxymethylfurfual (7). The α-glucosidase inhibitory activity of all compounds was measured. The isolated compounds (1–6) showed better α-glucosidase inhibitory activity (IC₅₀ values ranging from 36.5 to 192.4 μM) than the standard drug acarbose (IC₅₀ = 214.5 μM).     

A simple,fast, solvent-free method for the determination of volatile compounds in <Emphasis Type="Italic">Magnolia grandiflora</Emphasis> linn

Magnolia grandiflora Linn belonging to the Magnoliaceae family has been used to treat hypertension for many years in China. Based on microwave-assisted extraction (MAE) and headspace solid-phase microextraction (HS-SPME) followed by gas chromatography-mass spectrometry (GC-MS), the volatile compounds of Magnolia grandiflora L. were determined. Results indicated that the optimum conditions of the determination of the volatile compounds in Magnolia grandiflora L. were achieved with fiber coating of carboxen/polidimethylsiloxane, microwave power of 700 W and irradiation time of 4 min. Under the optimal conditions, for the first time, 48 volatile compounds were separated and identified from the fresh leaves of Magnolia grandiflora L. The highest content component of 48 compounds was γ-elemene (15.67%). Relative standard deviation (RSD) values less than 11% shows that the present method has good precision. The experimental results demonstrate that MAE-HS-SPME followed by GC-MS is a simple, time-saving solvent-free method, and it is a potential analytic tool for the determination of the volatile compounds in plant materials.     

A new flavone from Malaysia Borneo Marsdenia tinctoria

Marsdenia tinctoria is an indigo producing plant commonly found in Borneo, Malaysia. In this present study, one new flavone kapitone (1) and three known compounds, that is 3,2’-dihydroxyflavone (2), 1-methylcyclobutene (3) and dimethyl isatoate (4) were isolated from the Malaysia Borneo M. tinctoria R. Br. (Apocynaceae). These compounds were isolated and characterised using extensive chromatographic and spectroscopic methods.     

Two new phenolic compounds from the leaves of Alnus sibirica Fisch. ex Turcz.

Two new phenolic compounds, 4-O-glucopyranosyl-5-O-caffeoylshikimic acid (1) and 2,3-digalloyl oregonin (2), were isolated along with eight known phenolic compounds (3–10) from an 80% acetone extract of Alnus sibirica leaves. The chemical structures of these compounds were elucidated using 1D/2D nuclear magnetic resonance and high resolution-MS. The anti-oxidative activities of these compounds were determined by assaying their 1,1-diphenyl-2-picrylhydrazyl radical and nitroblue tetrazolium superoxide anion scavenging activity. All of the isolated phenolic compounds (1–10) exhibited potent anti-oxidative activities. In particular, 2 and 4, which are diarylheptanoids, and 10 which is ellagitannin exhibited excellent anti-oxidative activities with almost the same potency as that of the positive controls L-ascorbic acid and allopurinol.     

New neolignan glycoside and an unusual benzoyl malic acid derivative from Maytenus senegalensis leaves

Further investigation of the methanol leaf extract of Maytenus senegalensis led to the isolation of six compounds, including mayselignoside (1) and an unusual benzoyl malic acid derivative, benzoyl R-(+)-malic acid (2). Two known lignan derivatives (+)-lyoniresinol (3) and ( ? )-isolariciresinol (4), a known neolignan derivative dihydrodehydrodiconiferyl alcohol (5) and the triterpenoid, β-amyrin (6) were also isolated. The structures of these compounds were elucidated by a combination of 1D and 2D NMR and mass spectroscopy. All compounds were tested for cytotoxicity against mouse lymphoma cell line (L5178Y) and for antimicrobial activity against strains of bacteria and fungi. None of the compounds showed promising cytotoxic and/or antimicrobial activities.     

A new flavanone glycoside isolated from Tournefortia sibirica

A new flavanone glycoside, (2S)-dihydrooroxylin A 7-O-[β-D-apiosyl(1→2)]-β-D-glucoside (1), and four known compounds (2–5) were isolated from Tournefortia sibirica L. The chemical structures of these compounds were determined by 1?D and 2?D NMR and HR-ESI-MS spectra, and results were compared with data from the literature. These five compounds (1–5) were isolated from the family Boraginaceae for the first time. Anti-inflammatory effects of compounds (1–5) were evaluated in terms of inhibition of production of NO, TNF-α, and IL-6 in LPS-induced RAW 264.7 cells.     

Two new eremophilenolides from the roots of Ligulariopsis shichuana and their anti-phytopathogenic fungal and antifeedant activities

Two new eremophilenolides, ligushicins A (1) and B (2), and two known compounds including β-sitosterol and ursolic acid were isolated from Ligulariopsis shichuana. The structures of new compounds were established on the basis of 1D and 2D NMR data and HRESIMS data interpretation. The absolute configuration of new compounds was assigned by ECD spectroscopy, and that of ligushicins A (1) was confirmed by X-ray diffraction analysis. The antifungal and antifeedant activities of new compounds were evaluated against four plant pathogenic fungi and third-instar larvae of Plutella xylostella, respectively. Ligushicins A (1) and B (2) exhibited potent antifungal activity against Botrytis cinerea and Fusarium oxysporum with minimum inhibitory concentration (MIC) values ranging from 50 to 100 mg/L, while they also exhibited weak antifeedant activities.     

Microbial carbonylation and hydroxylation of 20(R)-panaxadiol by Aspergillus niger

20(R)-panaxadiol (PD) was metabolised by the fungus Aspergillus niger AS 3.3926 to its C-3 carbonylated metabolite and five other hydroxylated metabolites (1–6). Their structures were elucidated as 3-oxo-20(R)-panaxadiol (1), 3-oxo-7β-hydroxyl- 20(R)-panaxadiol (2), 3-oxo-7β,23α-dihydroxyl-20(R)-panaxadiol (3), 3,12-dioxo- 7β,23β-dihydroxyl-20(R)-panaxadiol (4), 3-oxo-1α,7β-dihydroxyl-20(R)-panaxadiol (5) and 3-oxo-7β,15β-dihydroxyl-20(R)-panaxadiol (6) by spectroscopic analysis. Among them, compounds 2–6 were new compounds. Pharmacological studies revealed that compound 6 exhibited significant anti-hepatic fibrosis activity.