High-resolution Electrospray Ionization Mass Spectra Research Articles

Trichodermic acids from an endophytic Trichoderma sp. and their antifungal activity against the phytopathogen Botrytis cinerea

Phytopathogen Botrytis cinerea is a necrotrophic pathogen with a wide host range, which causes considerable economic losses in agriculture. Consequently, it is necessary to find safe and effective antifungal agents against B. cinerea from natural sources. In this study, eight octahydronaphthalene derivatives (1−8) including four new natural products named trichodermic acids E − H (1−4), were isolated from an endophytic fungus Trichoderma sp. Their structures were determined by analysis of their nuclear magnetic resonance (NMR) and high-resolution electrospray ionization mass spectra (HR-ESI-MS) and by electronic circular dichroism (ECD) data. All compounds showed some extent of antifungal activities against B. cinerea with minimum inhibitory concentration (MIC) values ranging from 4 to 64 μg/mL. Notably, compound 8 showed significant inhibition with an MIC of 4 μg/mL, which was visually confirmed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). These findings provide a potential application of trichodermic acids as natural “hit” fungicides in agriculture.

Meldrum-Based-1H-1,2,3-Triazoles as Antidiabetic Agents: Synthesis, In Vitro α-Glucosidase Inhibition Activity, Molecular Docking Studies, and In Silico Approach.

A series of novel alkyl derivatives (2-5a,b) and 1H-1,2,3-triazole analogues (7a-k) of Meldrum's acid were synthesized in a highly effective way by using "click" chemistry and screened for in vitro α-glucosidase inhibitory activity to examine their antidiabetic potential. 1H NMR, 13C-NMR, and high-resolution electrospray ionization mass spectra (HR-ESI-MS) were used to analyze each of the newly synthesized compounds. Interestingly, these compounds demonstrated high to moderate α-glucosidase inhibitory potency having an IC50 range of 4.63-80.21 μM. Among these derivatives, compound 7i showed extraordinary inhibitory activity and was discovered to be several times more potent than the parent compound Meldrum (1) and the standard drug acarbose. Later, molecular docking was performed to understand the binding mode and the binding strength of all the compounds with the target enzyme, which revealed that all compounds are well fitted in the active site of α-glucosidase. To further ascertain the structure of compounds, suitable X-ray single crystals of compounds 5a, 7a, and 7h were developed and studied. The current investigation has shown that combining 1H-1,2,3-triazole with the Meldrum moiety is beneficial. Furthermore, this is the first time that the aforementioned activity of these compounds has been reported.

English

Common bean (Phaseolus vulgaris L.) is a major food crop in Africa and its production is plagued by diseases that reduce the potential yield, thus threatening food security. This study evaluated compounds from Hagenia abyssinica for bioactivity against bean bacterial pathogens Xanthomonus axonopodis pv. phaseoli and Pseudomonus savastanoi pv. phaseolicola. One triterpenoid, 1,3,19-trihydroxy-2-oxo-12-ursen-28-oic acid (1) and two flavans namely, 3,3’,4’,5’-tetrahydroxyflavan (2) and 3,3’,4’,5,7-pentahydroxyflavan (3) were isolated from the bark of H. abyssinica. Structures of the compounds were elucidated based on nuclear magnetic resonance (NMR) and high-resolution electrospray ionization mass spectra (HRESIMS) data analysis. These compounds and the ethyl acetate extract were evaluated against the bean pathogens using agar disc diffusion method. The ethyl acetate crude extract showed activity against the two pathogens with minimum inhibitory concentrations of 1.25 mg/mL. Compound 1 showed good activity against X. axonopodis pv. phaseoli and P. savastanoi pv. phaseolicola with minimum inhibitory concentrations of 5 and 1.25 mg/mL, respectively, whereas compounds 2 and 3 showed modest activity. This study demonstrated that compound 1 and the ethyl acetate crude extract from H. abyssinica have good activity against the two bean pathogens and can be used in the development of biopesticides to control bean diseases.   Key words: Bean pathogens, bioactive compounds, Hagenia abyssinica, Xanthomonus axonopodis pv. phaseoli, Pseudomonus savastanoi pv. phaseolicola.

Natural Antioxidants, Tyrosinase and Acetylcholinesterase Inhibitors from Cercis glabra Leaves.

Cercis glabra is a plant belonging to the legume family, whose flowers and barks are commonly used as food and traditional Chinese medicines. However, its leaves are usually disposed of as wastes. This research comprehensively investigated the bioactive constituents of C. glabra leaves, and two new phenolic, ceroffesters A-B (1-2) and thirteen known compounds (3-15) were isolated. Their structures were elucidated by spectroscopic methods such as nuclear magnetic resonance (1D NMR and 2D NMR), high-resolution electrospray ionization mass spectra (HR-ESI-MS), optical rotatory dispersion (ORD) and electronic circular dichroism (ECD). All of them were assessed for their antioxidant activities through ABTS, DPPH and PTIO methodologies, and evaluated for inhibitory activities against two enzymes (mushroom tyrosinase and acetylcholinesterase). As a result, compounds 3-6, 10 and 13 exhibited evident antioxidant activities. Meanwhile, compounds 5, 10 and 13 showed the most potent tyrosinase inhibitory activities, with IC50 of 0.64, 0.65 and 0.59 mM, and compared with the positive control of 0.63 mM (kojic acid). In the initial concentration of 1 mg/mL, compounds 3, 5 and 6 demonstrated moderate inhibitory activities against acetylcholinesterase with 85.27 ± 0.06%, 83.65 ± 0.48% and 82.21 ± 0.09%, respectively, compared with the positive control of 91.17 ± 0.23% (donepezil). These bioactive components could be promising antioxidants, tyrosinase and acetylcholinesterase inhibitors.

A New 1,3-Benzodioxole Compound from Hypecoum erectum and Its Antioxidant Activity.

The purpose of this study was to identify the chemical components in aerial parts of Hypecoum erectum. A new 1,3-benzodioxole derivative, identified as Hypecoumic acid (1), was isolated, together with the three known compounds: protopine (2), coptisine (3), and cryptopine (4). Their structures were identified based on extensive spectroscopic experiments, including nuclear magnetic resonance (NMR) and high-resolution electrospray ionization mass spectra (HR-ESI-MS), as well as comparison with those reported in the literature. Meanwhile, the in vitro antioxidative activity of all compounds was determined using a DPPH-scavenging assay, and compound 1 (IC50 = 86.3 ± 0.2 μM) was shown to have moderate antioxidative activity.

Terpenoids from the Seeds of Toona sinensis and Their Ability to Attenuate High Glucose-Induced Oxidative Stress and Inflammation in Rat Glomerular Mesangial Cells.

Toona sinensis (A. Juss.) Roem is an edible medicinal plant that belongs to the genus Toona within the Meliaceae family. It has been confirmed to display a wide variety of biological activities. During our continuous search for active constituents from the seeds of T. sinensis, two new acyclic diterpenoids (1–2), together with five known limonoid-type triterpenoids (3–7), five known apotirucallane-type triterpenoids (8–12), and three known cycloartane-type triterpenoids (13–15), were isolated and characterized. Their structures were identified based on extensive spectroscopic experiments, including nuclear magnetic resonance (NMR), high-resolution electrospray ionization mass spectra (HR-ESI-MS), and electronic circular dichroism (ECD), as well as the comparison with those reported in the literature. We compared these findings to those reported in the literature. Compounds 5, 8, and 13–14 were isolated from the genus Toona, and compounds 11 and 15 were obtained from T. sinensis for the first time. The antidiabetic nephropathy effects of isolated compounds against high glucose-induced oxidative stress and inflammation in rat glomerular mesangial cells (GMCs) were assessed in vitro. The results showed that new compounds 1 and 2 could significantly increase the levels of Nrf-2/HO-1 and reduce the levels of NF-κB, TNF-α, and IL-6 at concentrations of 30 μM. These results suggest that compounds 1 and 2 might prevent the occurrence and development of diabetic nephropathy (DN) and facilitate the research and development of new antioxidant and anti-inflammatory drugs suitable for the prevention and treatment of DN.

New acylglycosides from the roots of Rheum palmatum L.

A phytochemical investigation of the EtOH extract of the roots of Rheum palmatum L. was performed, leading to the isolation of 3 new acylglycosides ( 1 – 3 ) and 19 previously reported compounds, including 4 cinnamoyl glucosides ( 4 – 7 ) and 15 anthraquinones ( 8 – 22 ). Their structures were elucidated using nuclear magnetic resonance, infrared, ultraviolet and high-resolution electrospray ionization mass spectra and X-ray diffraction data. The biological activities of compounds 2 , 4 – 9 , and 11 – 13 , including their lymphocyte activation gene 3 (LAG3)/major histocompatibility complex class II (MHC II) and LAG3/fibrinogen-like protein 1 (FGL1) binding inhibition activities, were evaluated. Among the isolates, compound 7 exhibited clear inhibitory activity against the LAG3/FGL1 interaction with an IC 50 of 7.89 μ M, meanwhile compound 6 inhibited the LAG3/MHC II interaction with an IC 50 of 6.00 μ M. • Three undescribed acylglycosides were isolated from roots of Rheum palmatum L. • The absolute configuration of 1 was confirmed by single crystal X-ray diffraction. • This is the first report of the crystal structure of a cinnamoyl glucoside. • Their activities against the interaction of LAG3 with MHC II or FGL1 were evaluated.

Natural tyrosinase inhibitors from Betula platyphylla barks

Abstract During the process of searching for tyrosinase inhibitors from natural medicines, one new monoterpene rhamnoside (1) and 13 known compounds (2–14) were isolated from the ethanolic extract of Betula platyphylla barks by repeated column chromatography. These structures were identified by comprehensive spectroscopic data analysis such as high-resolution electrospray ionization mass spectra (HR-ESI-MS), nuclear magnetic resonance (NMR), optical rotatory dispersion (ORD) and acid hydrolysis. In vitro assay revealed that compounds 6, 7 and 14 showed obvious inhibitory activity against tyrosinase.

Isolation and characterization of antioxidative monoterpenes from Cynanchum atratum roots.

One novel monoterpene rhamnoside (1) and 7 known monoterpenes (2-8) were isolated from the ethanol extract of Cynanchum atratum for the first time. Their structures were identified by comprehensive spectroscopic data analysis such as nuclear magnetic resonance, high-resolution electrospray ionization mass spectra, optical rotatory dispersion, and acid hydrolysis. In the subsequent antioxidant assay, compound 8 exhibited obvious 2,2-diphenyl-2-picrylhydrazyl hydrate radical scavenging activity.

Isolation and characterization of bioactive phenolic compounds from Cinnamomum camphora barks

Abstract Two new phenolic rhamnosides (1–2) and 12 known phenolic compounds (3–14) were isolated from the ethanolic extract of Cinnamomum camphora barks by repeated column chromatography. The structures of all isolated compounds were identified by comprehensive spectroscopic data analysis such as high-resolution electrospray ionization mass spectra, nuclear magnetic resonance, optical rotatory dispersion and chemical method. In vitro assay revealed that compound 8 showed strong inhibitory activity against tyrosinase, and compounds 1, 3–7, 8–9, 13 showed obvious acetylcholinesterase inhibitory activity.

Simultaneous Detection of Ruthenium and Osmium by Photochemical Vapor Generation-Inductively Coupled Plasma-Mass Spectrometry

Efficient simultaneous photochemical vapor generation (PVG) of ruthenium (Ru) and osmium (Os) in the medium of formic acid was demonstrated. A flow-through photoreactor hyphenated to an inductively coupled plasma-mass spectrometer (ICP-MS) was used for the PVG and subsequent detection of the two elements. A similar synergistic enhancement from cobalt and cadmium ions on the PVG efficiency of both Ru and Os was discovered. Following the critical evaluation of the impacts of various transition metal ions, the concentrations of formic acid, cobalt, and cadmium ions, the flow rate of carrier gas, and the UV irradiation time, impressive limits of detection (LODs) of 5 and 0.5 ng L-1 were achieved for Ru and Os, respectively. The accuracy of the proposed PVG-ICP-MS method was validated by the analysis of several water samples with desirable spike recoveries obtained. Furthermore, the volatile compounds of Ru were directed and cryogenically trapped in acetonitrile and generation of carbonyls of Ru was verified by high-resolution electrospray ionization-mass spectra (ESI-MS).

Cytotoxic Polyketide Metabolites from a Marine Mesophotic Zone Chalinidae Sponge-Associated Fungus Pleosporales sp. NBUF144.

Two new polyketide natural products, globosuxanthone F (1), and 2′-hydroxy bisdechlorogeodin (2), were isolated from the fungus Pleosporales sp. NBUF144, which was derived from a 62 m deep Chalinidae family sponge together with four known metabolites, 3,4-dihydroglobosuxanthone A (3), 8-hydroxy-3-methylxanthone-1-carboxylate (4), crosphaeropsone C (5), and 4-megastigmen-3,9-dione (6). The structures of these compounds were elucidated on the basis of extensive spectroscopic analysis, including 1D and 2D NMR and high-resolution electrospray ionization mass spectra (HRESIMS) data. The absolute configuration of 1 was further established by single-crystal X-ray diffraction studies. Compounds 1–5 were evaluated for cytotoxicity towards CCRF-CEM human acute lymphatic leukemia cells, and it was found that 1 had an IC50 value of 0.46 µM.

Cytotoxic Secondary Metabolites Isolated from the Marine Alga-Associated Fungus Penicillium chrysogenum LD-201810.

A new pentaketide derivative, penilactonol A (1), and two new hydroxyphenylacetic acid derivatives, (2’R)-stachyline B (2) and (2’R)-westerdijkin A (3), together with five known metabolites, bisabolane-type sesquiterpenoids 4–6 and meroterpenoids 7 and 8, were isolated from the solid culture of a marine alga-associated fungus Penicillium chrysogenum LD-201810. Their structures were elucidated based on extensive spectroscopic analyses, including 1D/2D NMR and high resolution electrospray ionization mass spectra (HRESIMS). The absolute configurations of the stereogenic carbons in 1 were determined by the (Mo2(OAc)4)-induced circular dichroism (CD) and comparison of the calculated and experimental electronic circular dichroism (ECD) spectra, while the absolute configuration of the stereogenic carbon in 2 was established using single-crystal X-ray diffraction analysis. Compounds 2 and 3 adapt the 2’R-configuration as compared to known hydroxyphenylacetic acid-derived and O-prenylated natural products. The cytotoxicity of 1–8 against human carcinoma cell lines (A549, BT-549, HeLa, HepG2, MCF-7, and THP-1) was evaluated. Compound 3 exhibited cytotoxicity to the HepG2 cell line with an IC50 value of 22.0 μM. Furthermore, 5 showed considerable activities against A549 and THP-1 cell lines with IC50 values of 21.2 and 18.2 μM, respectively.

Two New Apotirucallane-Type Triterpenoids from the Pericarp of Toona sinensis and Their Ability to Reduce Oxidative Stress in Rat Glomerular Mesangial Cells Cultured under High-Glucose Conditions.

Hyperglycemia is a strong risk factor for chronic complications of diabetes. Hyperglycemic conditions foster not only the production of reactive oxygen species (ROS), but also the consumption of antioxidants, leading to oxidative stress and promoting the occurrence and progression of complications. During our continuous search for antioxidant constituents from the pericarp of Toona sinensis (A. Juss.) Roem, we isolated two previously unreported apotirucallane-type triterpenoids, toonasinensin A (1) and toonasinensin B (2), together with five known apotirucallane-type triterpenoids (3–7) and two known cycloartane-type triterpenoids (8–9) from the pericarp. Compounds 8–9 were obtained from T. sinensis for the first time. Their structures were characterized based on interpretation of spectroscopic data (1D, 2D NMR, high-resolution electrospray ionization mass spectra, HR-ESI-MS) and comparison to previous reports. Compounds (2, 4, 6, 7, and 9) were able to inhibit proliferation against rat glomerular mesangial cells (GMCs) cultured under high-glucose conditions within a concentration of 80 μM. Compounds (2, 6, and 7) were tested for antioxidant activity attributable to superoxide dismutase (SOD), malondialdehyde (MDA), and ROS in vitro, and the results showed that compounds (2, 6, and 7) could significantly increase the levels of SOD and reduce the levels of MDA and ROS. The current studies showed that apotirucallane-type triterpenoids (2, 6, and 7) might have the antioxidant effects against diabetic nephropathy.

Lasianosides A-E: New Iridoid Glucosides from the Leaves of Lasianthus verticillatus (Lour.) Merr. and Their Antioxidant Activity.

The genus Lasianthus (Rubiaceae) consists of approximately 180 species, of which the greatest species diversity is found in tropical Asia. Some of the Lasianthus species have been used in folk medicine to treat tinnitus, arthritis, fever, and bleeding. Lasianthus verticillatus (Lour.) Merr. (Syn. Lasianthus trichophlebus auct. non Hemsl.) is a shrub, branchlets terete about 1.5–3 m in height. This paper studies the chemical composition of the leaves of L. verticillatus for the first time, which resulted in the isolation of five undescribed iridoid glucosides, lasianosides A–E (1–5), together with three known compounds (6–8). The undescribed structures of isolated compounds (1–5) were characterized by physical and spectroscopic data analyses, including one-dimensional (1D) and two-dimensional (2D) NMR, IR, UV, and high-resolution electrospray ionization mass spectra (HR-ESI-MS). Furthermore, the electronic circular dichroism data determined the absolute configurations of the new compounds. The free radical scavenging properties of isolated compounds was assessed by 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay, and their cytotoxicity was assessed toward human lung cancer cell line A549 by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method. Among the isolated compounds, 3 and 4 displayed potent radical scavenging activities with IC50 values of 30.2 ± 1.8 and 32.0 ± 1.2 µM, which were comparable to that of Trolox (29.2 ± 0.39 µM), respectively, while 5 possessed moderate activity with an IC50 value of 46.4 ± 2.3 µM. None of the isolated compounds exerted cytotoxicity against human cell line A549. As a result, lasianosides C, D, and E have the potential to be non-toxic safe antioxidant agents.

Lignan glycosides from the stems of Viburnum melanocarpum and their α-glucosidase inhibitory activity

Abstract Two new lignan glycosides (1, 2) and four known lignan glycosides (3–6) have been isolated from the ethanolic extract of the stems of Viburnum melanocarpum through repeated column chromatography. Their structures including absolute configurations were confirmed by spectroscopic data [one-dimensional (1D) and two-dimensional (2D) nuclear magnetic resonance (NMR), high-resolution electrospray ionization mass spectra (HRESIMS), optical rotatory dispersion (ORD) and circular dichroism (CD)] and chemical methods. Additionally, the α-glucosidase inhibitory activity of these compounds was tested in vitro. Compound 1 exhibited the strongest inhibitory activity against α-glucosidase with a half-maximal inhibitory concentration (IC50) value of 10.3 μM.

A Gold Quartet Framework with Reversible Anisotropic Structural Transformation Accompanied by Luminescence Response

Summary Hierarchy and chirality are the fundamental characteristics of biomolecules. Chemistry on hierarchical self-assembly and spontaneous symmetry breaking helps to uncover the mechanism of living activities and the origin of chirality in nature. Herein, we describe a chiral gold quartet framework (GQF) with C4-symmetric structure hierarchically aggregated from an achiral anionic [Au10(dpptrz)4S4]2− (dpptrz-Au10), which was acquired via click-reaction-induced and Au(I)⋅⋅⋅Au(I)-interaction-directed cluster-to-cluster transformation (CCT) from the rationally designed [(dppa)6Au18S8]2+ (dppa-Au18). Inter-cluster hydrogen bonding and alkali ion coordination were observed to assist the hierarchical self-assembly and chiral self-organization of the GQF. Upon exposing the crystal to vacuum, the bottom-up constructed GQF showed an anisotropic structural transformation accompanied by a visual luminescence change in a single-crystal-to-single-crystal (SCSC) manner that became reversible upon removal of vacuum. This research largely advances the potential of polynuclear gold(I)-sulfido clusters in hierarchical self-assembly and luminescent materials.

Setosphaerine A: A New Chlorinated Polyketide Isolated From the Entomogenous Fungus Setosphaeria rostrata

A new chlorinated polyketide setosphaerine A (1), together with 3 known ones penicipyran D (2), 7- O-demethymonocerin (3), and monocerin (4), was isolated from the entomogenous fungus Setosphaeria rostrata. The structure of compound 1 was established on the basis of 1D/2D Nuclear Magnetic Resonance (NMR) spectroscopic and High Resolution Electro Spray Ionization Mass Spectra (HR-ESI-MS) data. Compounds 1 to 4 showed moderate cytotoxicity against 3 human tumor cell lines MCF-7, MGC-803, and Hela with IC50 values ranging from 33 to 243 nM.

Identification of Two New Phenanthrenes from Dendrobii Herba and Their Cytotoxicity towards Human Hypopharynx Squamous Carcinoma Cell (FaDu).

Two new phenanthrenes, (1R,2R)-1,7-hydroxy-2,8-methoxy-2,3-dihydrophenanthrene-4(1H)-one (1) and 2,7-dihydroxy-phenanthrene-1,4-dione (2), were isolated from the ethyl acetate-soluble fraction of Dendrobii Herba, together with seven known phenanthrenes (3–9), two bibenzyls (10–12), and a lignan (13). Structures of 1 and 2 were elucidated by analyzing one-dimensional (1D) and two-dimensional (2D)-NMR and High-resolution electrospray ionization mass spectra (HR-ESI-MS) data. The absolute configuration of compound 1 was confirmed by the circular dichroism (CD) spectroscopic method. In cytotoxicity assay using FaDu human hypopharynx squamous carcinoma cell line, compounds 3–6, 8, 10, and 12 showed activities, with IC50 values that ranged from 2.55 to 17.70 μM.

Gas-phase fragmentation studies of cyclic oligo-β-(1→6)-D-glucosamines by electrospray ionization mass spectrometry using a hybrid high-resolution mass spectrometer

Positive and negative ion high-resolution electrospray ionization mass spectra (MS and MS2) of cyclooligo-β-(1→6)-D-glucosamines and cyclooligo-β-(1→6)-N-acetyl-D-glucosamines were acquired and interpret. It was shown that the cleavages of glycosidic bonds are the main processes in the decay of protonated and metallated molecules. In addition, elimination of the water molecules (and ammonia for cyclooligo-β-(1→6)-D-glucosamines) was observed along with other processes including the unknown skeletal rearrangement. A primary fragmentation of the negatively charged ions (deprotonated molecules) differed from that of the positively charged ones.