High-resolution Electrospray Ionization Research Articles

Furanonaphthoquinones, Diterpenes, and Flavonoids from Sweet Marjoram and Investigation of Antimicrobial, Bacterial Efflux, and Biofilm Formation Inhibitory Activities.

The chloroform extract of Origanum majorana exhibited high antibacterial and antifungal activities against 12 bacterial and 4 fungal strains; therefore, it was subjected to bioassay-guided isolation to afford six compounds (1-6). The structures were determined via one- and two-dimensional nuclear magnetic spectroscopy and high-resolution electrospray ionization mass spectrometry experiments. The compounds were identified as furanonaphthoquinones [majoranaquinone (1), 2,3-dimethylnaphtho[2,3-b]furan-4,9-dione (2)], diterpenes [19-hydroxyabieta-8,11,13-trien-7-one (3), 13,14-seco-13-oxo-19-hydroxyabieta-8-en-14-al (4)], and flavonoids [sterubin (5) and majoranin (6)]. Compounds 1 and 2 were first obtained from a natural source and compounds 3 and 4 were previously undescribed. Majoranaquinone (1) exhibited a high antibacterial effect against 4 Staphylococcus, 1 Moraxella, and 1 Enterococcus strains (MIC values between 7.8 μM and 1 mM). In the efflux pump inhibition assay, majoranaquinone (1) showed substantial activity in Escherichia coli ATCC 25922 strain. Furthermore, 1 was found to be an effective biofilm formation inhibitor on E. coli ATCC 25922 and E. coli K-12 AG100 bacteria. Our findings proved that bioactivities of majoranaquinone (1) significantly exceed those of the essential oil constituents; therefore, it should also be considered when assessing the antimicrobial effects of O. majorana.

Polyporenic Acids from the Mushroom Buglossoporus quercinus Possess Chemosensitizing and Efflux Pump Inhibitory Activities on Colo 320 Adenocarcinoma Cells.

Polyporenic acids N-R (1-5), five novel 24-methylene lanostane triterpenes along with seven known polyporenic acids (6-12), were identified from the fruiting bodies of Buglossoporus quercinus. The isolation of compounds 1-12 was performed by a combination of multistep flash chromatography and reversed-phase high-performance liquid chromatography (HPLC). The structure determination was carried out by extensive spectroscopic analysis, including 1D and 2D nuclear magnetic resonance (NMR) and high-resolution electrospray ionization mass spectrometry (HR-ESI-MS) experiments. The isolated fungal metabolites were investigated for their antiproliferative activity in vitro by 3-(4,5-dimethylthiazol2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay on the resistant Colo 320 human colon adenocarcinoma cell line expressing P-glycoprotein (ABCB1). The lanostane triterpenes exerted moderate antiproliferative activity with IC50 values in the range of 20.7-106.2 μM. A P-glycoprotein efflux pump modulatory test on resistant Colo 320 cells highlighted that fungal metabolites 3, 5, 8, and 10-12 have the ability to inhibit the efflux pump activity of cancer cells. Moreover, the drug interactions of triterpenes with doxorubicin were studied by the checkerboard method. Compounds 3-4, and 7-12 interacted in a synergistic manner, while an outstanding potency was detected for compound 9, which was defined as strong synergism (CI = 0.276). The current study reveals that B. quercinus is a remarkable source of fungal steroids with considerable chemosensitizing activity on cancer cells.

Six New Phenolic Glycosides from the Seeds of Moringa oleifera Lam. and Their α-Glucosidase Inhibitory Activity.

Plant-derived phytochemicals have recently drawn interest in the prevention and treatment of diabetes mellitus (DM). The seeds of Moringa oleifera Lam. are widely used in food and herbal medicine for their health-promoting properties against various diseases, including DM, but many of their effective constituents are still unknown. In this study, 6 new phenolic glycosides, moringaside B-G (1-6), together with 10 known phenolic glycosides (7-16) were isolated from M. oleifera seeds. The structures were elucidated by 1D and 2D NMR spectroscopy and high-resolution electrospray ionization mass spectrometry (HR-ESI-MS) data analysis. The absolute configurations of compounds 2 and 3 were determined by electronic circular dichroism (ECD) calculations. Compounds 2 and 3 especially are combined with a 1,3-dioxocyclopentane moiety at the rhamnose group, which are rarely reported in phenolic glycoside backbones. A biosynthetic pathway of 2 and 3 was assumed. Moreover, all the isolated compounds were evaluated for their inhibitory activities against α-glucosidase. Compounds 4 and 16 exhibited marked activities with IC50 values of 382.8 ± 1.42 and 301.4 ± 6.22 μM, and the acarbose was the positive control with an IC50 value of 324.1 ± 4.99 μM. Compound 16 revealed better activity than acarbose.

Dryoptkirbioside, A New Fructofuranoside glycerol, and Other Constituents from Dryopteris kirbi Hook et Grav Rhizomes.

A new fructofuranoside glycerol, dryoptkirbioside (1), along with fourteen known compounds (2-15), was isolated from the MeOH extract of Dryopteris kirbi rhizomes by silica gel column chromatography, Sephadex LH-20 column chromatography, and semipreparative HPLC. The structure of the new compound was determined by analyses of its spectroscopic data including nuclear magnetic resonance (NMR), and high-resolution electrospray ionisation mass spectrometry (HRESI-MS) and chemical conversions. The n-hexane-soluble portion and the EAFA fraction showed strong activities against lung (A549), breast (MCF-7), and cervical (HeLa) human cancer cell lines (IC50 values ranging from 4.0 to 8.8 µg/mL). Aspidinol P (5) and aspidinol B (6) exhibited moderate to low cytotoxicity on the three cell lines (IC50 values ranging from 20.4 to 58.7 µM). The MeOH extract and n-hexane-soluble portion had excellent activities against Staphylococcus aureus and Bacillus subtilis (MICs 11.7 and 23.4 µg/mL), whereas the EtOAc- and n-BuOH-soluble portions were significantly active on S. aureus (MICs 46.9 and 93.8 µg/mL). The main fractions EAFB, EAFC and nBFB displayed excellent activity against S. aureus (MICs 11.7 and 23.4 µg/mL). Aspidinol B (6) had significant activity, while aspidinol P (5) was moderately active against S. aureus and B. subtilis (MICs 42.0 and 89.5 µM).

Sarcodonol A–D from fruiting bodies of Sarcodon imbricatus inhibits HCoV-OC43 induced apoptosis in MRC-5 cells

Four new 26-carboxylated ergostane-type sterols (Sarcodonol A–D) were isolated from 70% ethanol extracts of dried fruiting bodies of Sarcodon imbricatus. Their chemical structures were elucidated using 1D- and 2D-nuclear magnetic resonance and high-resolution electrospray ionization mass spectrometry, and confirmed by comparison with previously reported data. As far as we know, this is the first instance of isolating a 26-carboxylated ergostane-type sterol from nature. The determined antiviral efficacy of sarcodonol A–D (1–4) against HCoV-OC43 in MRC-5 cells confirmed that sarcodonol D (4) had significant antiviral activity. Notably, sarcodonol D (4) potently blocked virus infection at low-micromolar concentration and showed high SI (IC50 = 2.26 μM; CC50 > 100 μM; SI > 44.2). In addition, this research shows that the antiviral effect of sarcodonol D (4) via reduced apoptosis increased by viral infection is through mitochondrial stress regulation. This suggests that sarcodonol D (4) is a potential candidate for use as an antiviral treatment.

Identification of compounds using HPLC-QTOF-MS online antioxidant activity mapping from aerial parts of Ligularia stenocephala

Inflammation, diabetes, and even malignancies are pharmacological effects connected by antioxidant capacity and free radicals. Many antioxidants scavenge free radicals originating from dietary sources such as fruits, vegetables, and teas. To identify the bioactive components of Ligularia stenocephala, an effective method combining HPLC-QTOF-MS and bioactivity evaluation was investigated for the first time. Antioxidant agents were isolated from L. stenocephala, a folk medicine used for edema and scrofula in Korea, Japan, and China. The phytochemical investigation of the aerial parts of L. stenocephala resulted in the separation and determination of six compounds (1–6). In particular, the chemical structures were identified as hyperoside (1), 3,5-dicaffeoylquinic acid (2), 3,5-dicaffeoylquinic acid methyl ester (3), trifolin (4), rutin (5), and 3,4-dicaffeoylquinic acid (6). Their structures were identified using 1D and 2D NMR spectroscopy and high-resolution electrospray ionization mass spectrometry (HR-ESI-MS) data analysis. The results showed that phenolic components were responsible for the antioxidant inhibitory activity of L. stenocephala. Additionally, to understand the mechanisms of the antioxidant inhibitory activity of L. stenocephala, a docking simulation study was performed to support the in vitro results. Taken together, this new method is rapid, inexpensive, and can be applied to identify the active components of medicinal herbs without separation.

Two New Compounds from Allii Macrostemonis Bulbus and Their In Vitro Antioxidant Activities.

Two new compounds named 4,4'-bis(β-D-glucopyranosyloxy)biphenyl (1) and spirostane-25(27)-en-2α,3β-diol-3-O-β-D-xylopyranosyl(1→3)-β-D-glucopyranosyl(1→4)-β-D-galactopyranoside (2) were isolated from n-butanol extraction part of 80% ethanol extract of Allii Macrostemonis Bulbus. Alongside these, ten known compounds (3-12) were also identified, including a flavonoid glycoside (3), seven steroids (4-10), a nucleoside (11), and a phenylpropanoid glycoside (12) were found. Notably, compounds 3-6 were isolated from this plant for the first time. The structures of all compounds were confirmed using high-resolution electrospray ionization mass spectrometry (HR-ESI-MS), 1D, and 2D NMR spectroscopy. Some of these compounds showed strong antioxidant activity, and compound 1 demonstrated the most potent reduction of ferric ions (Fe3+) with an IC50 value of 0.59 ± 0.18 mg/mL. Compounds 2 and 3 exhibited the highest scavenging activity against superoxide anion radicals (O2-·) with an IC50 value of 0.02 ± 0.01 mg/mL. Additionally, compound 3 displayed substantial scavenging activity against 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) with IC50 values of 0.21 ± 0.17 mg/mL and 0.02 ± 0.01 mg/mL, respectively. The discovery of these two new compounds is a reference for identifying Allii Macrostemonis Bulbus quality markers. Moreover, their exceptional antioxidant activity offers a promising avenue for uncovering novel natural antioxidants.

Identification of glycine betaine as a host-derived molecule required for the vegetative proliferation of the protozoan parasite Perkinsus olseni.

Perkinsus olseni is an industrially significant protozoan parasite of Manila clam, Ruditapes philippinarum. So far, various media, based on Dulbecco's Modified Eagle Medium and Ham's F-12 nutrient mixture with supplementation of fetal bovine serum (FBS), have been developed to proliferate the parasitizing trophozoite stage of P. olseni. The present study showed that P. olseni did not proliferate in FBS-deficient Perkinsus broth medium (PBMΔF), but proliferated well in PBMΔF supplemented with tissue extract of host Manila clams, indicating that FBS and Manila clam tissue contained molecule(s) required for P. olseni proliferation. Preliminary characterization suggested that the host-derived molecule(s) was a heat-stable molecule(s) with a molecular weight of less than 3 kDa, and finally a single molecule required for the proliferation was purified by high-performance liquid chromatography processes. High-resolution electrospray ionization mass spectrometry and nuclear magnetic resonance analyses identified this molecule as glycine betaine (=trimethylglycine), and the requirement of this molecule for P. olsseni proliferation was confirmed by an assay using chemically synthesized, standard glycine betaine. Although glycine betaine was required for the proliferation of all examined Perkinsus species, supplementation of glycine betaine precursors, such as choline and betaine aldehyde, enhanced the proliferation of 4 Perkinsus species (P. marinus, P. chesapeaki, P. mediterraneus and P. honshuensis), but not of 2 others (P. olseni and P. beihaiensis). Thus, it was concluded that the ability to biosynthesise glycine betaine from its precursors varied among Perkinsus species, and that P. olseni and P. beihaiensis lack the ability required to biosynthesize glycine betaine for proliferation.

New Sesterterpenoid from the Marine Fungus Penicillium oxalicum M893

Objectives The aim of the project was the isolation, structural elucidation, and antimicrobial and antifungal activities of compounds from the culture broth of the marine fungus Penicillium oxalicum M893 (isolated from the marine brown alga Spatoglossum sp.). Methods Combined chromatographic techniques were used to isolate antibacterial and antifungal compounds from the MeOH extract Penicillium oxalicum M893. The structures were elucidated by analyses of high-resolution electrospray ionization mass spectral and nuclear magnetic resonance data. The antimicrobial and antifungal effects of compounds were evaluated using the dilution turbidimetric broth method. Results One new sesterterpenoid, oxaliterpenoid (1), and six known compounds, aspergillusidone C (2), nidulin (3), emeguisin B (4), aspergillusether A (5), aspergillusether J (6), and guisinol (7) were isolated from the methanol extract of the culture broth of Penicillium oxalicum M893. All compounds showed potent antibacterial activities against Gram-(+) bacteria, E. faecalis (ATCC299212), S. aureus (ATCC25923), and B. cereus (ATCC14579), and the yeast Candida albicans (ATCC10231), with MIC values ranging from 2 to 128 µg/mL.

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.

Antimalarial and neuroprotective ent-abietane diterpenoids from the aerial parts of Phlogacanthus curviflorus.

Six new ent-abietane diterpenoids, abientaphlogatones A-F (1-6), along with two undescribed ent-abietane diterpenoid glucosides, abientaphlogasides A-B (7-8) and four known analogs were isolated from the aerial parts ofPhlogacanthus curviflorus (P. curviflorus). The structures of these compounds were determined using high-resolution electrospray ionization mass spectrometry (HR-ESI-MS), one-dimensional and two-dimensional nuclear magnetic resonance (NMR) spectroscopy, electronic circular dichroism (ECD) spectra, and quantum chemical calculations. Notably, compounds 5 and 6 represented the first reported instances of ent-norabietane diterpenoids from the genus Phlogacanthus. In the β-hematin formation inhibition assay, compounds 2, 4, 7-10, and 12 displayed antimalarial activity, with IC50 values of 12.97-65.01 μmol·L-1. Furthermore, compounds 4, 5, 8, and 10 demonstrated neuroprotective activity in PC12 cell injury models induced by H2O2 and MPP+.

Unprecedented Antimicrobial and Cytotoxic Polyketides from Cultures of Diaporthe africana sp. nov.

Four unprecedented polyketides named isoprenylisobenzofuran B (2), isoprenylisobenzofuran C1/C2 (3), diaporisoindole F1/F2 (4), and isochromophilonol A1/A2 (7) were isolated from ethyl acetate extracts of the newly described endophytic fungus Diaporthe africana. Additionally, the previously reported cyclic depsipeptide eucalactam B (1) was also identified, along with the known compounds diaporisoindole A/B (5), tenellone B (6) and beauvericin (8). The taxonomic identification of the fungus was accomplished using a polyphasic approach combining multi-gene phylogenetic analysis and microscopic morphological characters. The structures 1-8 were determined by a detailed analysis of their spectral data, namely high-resolution electrospray ionization mass spectrometry (HR-ESIMS), 1D/2D nuclear magnetic resonance (NMR) spectroscopy, as well as electronic circular dichroism (ECD) spectra. In addition, chemical methods such as Marfey's analysis were also employed to determine the stereochemistry in compound 1. All the compounds obtained were evaluated for antimicrobial and in vitro cytotoxic properties. Compounds 3-8 were active against certain fungi and Gram-positive bacteria with MIC values of 8.3 to 66.6 µg/mL. In addition, 3-5 displayed cytotoxic effects (22.0 ≤ IC50 ≤ 59.2 µM) against KB3.1 and L929 cell lines, whereas compounds 6-8 inhibited the growth of seven mammalian cancer cell lines with IC50 ranging from 17.7 to 49.5 µM (6), 0.9 to 12.9 µM (7) and 1.9 to 4.3 µM (8).

Seasonal Monitoring of Volatiles and Antioxidant Activity of Brown Alga Cladostephus spongiosus.

Cladostephus spongiosus was harvested once a month during its growing season (from May to August) from the Adriatic Sea. Algal volatile organic compounds (VOCs) were obtained by headspace solid-phase microextraction (HS-SPME) and hydrodistillation (HD) and analysed by gas chromatography and mass spectrometry (GC-MS). The effects of air drying and growing season on VOCs were determined. Two different extraction methods (ultrasound-assisted extraction (UAE) and microwave-assisted extraction (MAE)) were used to obtain ethanolic extracts of C. spongiosus. In addition, the seasonal antioxidant potential of the extracts was determined, and non-volatile compounds were identified from the most potent antioxidant extract. Aliphatic compounds (e.g., pentadecane) were predominantly found by HS-SPME/GC-MS. Hydrocarbons were more than twice as abundant in the dry samples (except in May). Aliphatic alcohols (e.g., hexan-1-ol, octan-1-ol, and oct-1-en-3-ol) were present in high percentages and were more abundant in the fresh samples. Hexanal, heptanal, nonanal, and tridecanal were also found. Aliphatic ketones (octan-3-one, 6-methylhept-5-en-2-one, and (E,Z)-octa-3,5-dien-2-one) were more abundant in the fresh samples. Benzene derivatives (e.g., benzyl alcohol and benzaldehyde) were dominant in the fresh samples from May and August. (E)-Verbenol and p-cymen-8-ol were the most abundant in dry samples in May. HD revealed aliphatic compounds (e.g., heptadecane, pentadecanal, (E)-heptadec-8-ene, (Z)-heptadec-3-ene), sesquiterpenes (germacrene D, epi-bicyclosesquiphellandrene, gleenol), diterpenes (phytol, pachydictyol A, (E)-geranyl geraniol, cembra-4,7,11,15-tetraen-3-ol), and others. Among them, terpenes were the most abundant (except for July). Seasonal variations in the antioxidant activity of the ethanolic extracts were evaluated via different assays. MAE extracts showed higher peroxyl radical inhibition activity from 55.1 to 74.2 µM TE (Trolox equivalents). The highest reducing activity (293.8 µM TE) was observed for the May sample. Therefore, the May MAE extract was analysed via high-performance liquid chromatography with high-resolution mass spectrometry and electrospray ionisation (UHPLC-ESI-HRMS). In total, 17 fatty acid derivatives, 9 pigments and derivatives, and 2 steroid derivatives were found. The highest content of pheophorbide a and fucoxanthin, as well as the presence of other pigment derivatives, could be related to the observed antioxidant activity.

Cycloartane Saponins from Astragalus glycyphyllos and Their In Vitro Neuroprotective, Antioxidant, and hMAO-B-Inhibiting Effects.

Astragalus glycyphyllos (Fabaceae) is used in the traditional medicine of many countries against hepatic and cardiac disorders. The plant contains mainly flavonoids and saponins. From a defatted methanol extract from its overground parts, a new triterpenoid saponin, 3-O-[α-L-rhamnopyranosyl-(1→2)]-β-D-xylopyranosyl]-24-O-α-L-arabinopyranosyl-3β,6α,16β,24(R),25-pentahydroxy-20R-cycloartane, together with the rare saponin astrachrysoside A, were isolated using various chromatography methods. The compounds were identified via extensive high resolution electrospray ionisation mass spectrometry (HRESIMS) and NMR analyses. Both saponins were examined for their possible antioxidant and neuroprotective activity in three different in vitro models. Rat brain synaptosomes, mitochondria, and microsomes were isolated via centrifugation using Percoll gradient. They were treated with the compounds in three different concentrations alone, and in combination with 6-hydroxydopamine or tert-butyl hydroperoxide as toxic agents. It was found that the compounds had statistically significant dose-dependent in vitro protective activity on the sub-cellular fractions. The compounds exhibited a weak inhibitory effect on the enzyme activity of human recombinant monoamine oxidase type B (hMAO-B), compared to selegiline.

Identification of bolegrevilol B and C as novel antioxidant compounds in Suillus grevillei mushroom.

Suillus grevillei is a popular species of mushroom available worldwide. In this study, we isolated compounds, bolegrevilol B and bolegrevilol C, from the mushroom and observed their potent lipid peroxidation-inhibiting activity. The structures of bolegrevilol B and bolegrevilol C were elucidated as 3-geranylgeranyl-1,2,4-trihydroxybenzene and 3-geranylgeranyl-1,2-dihydroxy-4-methoxybenzene, respectively, through high-resolution electrospray ionization mass spectrometry (-) and 1D and 2D nuclear magnetic resonance analyses. Bolegrevilol B and C inhibited lipid peroxidation and exhibited IC50 values of 2.0±0.29 µm and 1.0±0.13 µm, respectively. Furthermore, bolegrevilol B and C demonstrated potent neuroprotective activities in neuronal hybridoma N18-RE-105 cells against L-glutamate toxicity (EC50 of 1.8±1.7n m and 7.2±6.9n m, respectively). Bolegrevilol B was found in nature for the first time, and, to the best of our knowledge, this is the first study to report the antioxidant activities of bolegrevilol B and C.

C21 steroids from the roots of Marsdenia tenacissima

A phytochemical investigation of the dichloromethane soluble fraction of the ethanolic extract obtained from the roots of Marsdenia tenacissima led to the discovery of the sixteen undescribed pregnane C21 steroids (1–16) and isolation of eleven known C21 steroidal analogues (17–27). Their chemical structures were elucidated by one- and two-dimensional nuclear magnetic resonance spectroscopy and, high resolution–electrospray ionization mass spectrometry and their absolute configurations were determined using electronic circular dichroism or single-crystal X-ray diffraction. The in vitro anti-proliferative effects of 1–16 were evaluated against HepG2 (human hepatocellular cancer), A549 (lung cancer), and MCF-7 (human breast cancer) cell lines. Even though some of them showed moderate cytotoxic activities, marsectohexol derivative 12 exhibited significant cytotoxicity against A549 cells with an IC50 value of 5.2 μM.

Panapophenanthrin, a Rare Oligocyclic Diterpene from Panus strigellus.

During the course of our search for biologically active secondary metabolites from fungal cultures, a new oligocyclic diterpenoidal derivative, panapophenanthrin (1), was isolated from Panus strigellus. In addition, two known metabolites, panepophenanthrin (2) and dihydrohypnophilin (3), were also obtained. The chemical structures of the isolated compounds were elucidated based on extensive 1D and 2D NMR spectral analyses together with high-resolution electrospray ionization mass spectrometry (HR-ESI-MS). The absolute configuration was determined through TDDFT-ECD calculations. All of the compounds were assessed for their antimicrobial and cytotoxic activities. Compounds 1 and 3 showed moderate to weak activities in the performed antimicrobial assays, while compound 1 exhibited potent cytotoxic activity against the mammalian cell lines mouse fibroblast (L929) and human endocervical adenocarcinoma (KB3.1).

Two Decarestrictine Analogs from the Soil-Derived Fungus Penicillium sp. YUD18003 Associated with Gastrodia elata.

Two new decarestrictine analogs decarestrictine P and penicitone, together with eight known homologous compounds were isolated from the soil fungus from the rhizosphere of Penicillium sp. YUD18003 related to Gastrodia elata. Their different structures include a decanolides decartestridine P and a long-chain polyhydroxyketone penicitone. The structures of new compounds were determined by nuclear magnetic resonance (NMR) spectroscopic analysis and high resolution electrospray ionization mass spectrometry (HR-ESI-MS), while their absolute configurations were determined by spectroscopic methods, DP4+ probability analysis, modified Snatzke's method and electron circular dichroism (ECD) calculations. All compounds were evaluated for antimicrobial activities.

Asperphenalenones Isolated from the Biocontrol Agent Clonostachys rosea and Their Antimicrobial Activities.

Clonostachys rosea is a fungus widely distributed on Earth and has a high capacity to adapt to complex environments in soil, plants, or sea. It is an endophyte that can be used as a potential biocontrol agent to protect plants from pathogenic fungi, nematodes, and insects. However, the spectrum of secondary metabolites produced by C. rosea has only scarcely been studied. In the present study, eight new phenalenones, asperphenalenones F-M (1-8), together with two known derivatives, asperphenalenones E and B (9 and 10), were isolated from the axenic rice culture of this fungus. The structures of the new compounds were elucidated by nuclear magnetic resonance, high-resolution electrospray ionization mass spectrometry, electronic circular dichroism, and gas chromatography-mass spectrometry analyses. Asperphenalenones J-M (5-8) are unusual phenalenone adducts that are conjugated to diterpenoid glycosides. Asperphenalenones F and H showed moderate antibacterial activity against methicillin-resistant Staphylococcus aureus, with minimal inhibitory concentrations of 12.5 and 25 μM, respectively. Asperphenalenone B exhibited low antiviral activity against the human immunodeficiency virus replication. Furthermore, asperphenalenones F and H exhibited low cytotoxicity against Jurkat cells, while all other compounds were devoid of cytotoxicity.

1H NMR-guided isolation of hasubanan alkaloids from the alkaloidal extract of Stephania longa

1H NMR-guided fractionation led to the isolation of 16 alkaloids from the alkaloidal extract of Stephania longa, including 11 new hasubanan alkaloids (1–11) and five known alkaloids (12–16). Interestingly, compounds 2 and 11 are typically considered protonated tertiary amine compounds, whereas compounds 1 and 10 are regarded as oxidized versions of the corresponding compounds. Their gross structures were determined through an extensive analysis of spectroscopic data (NMR (nuclear magnetic resonance) and HRESIMS (high resolution electrospray ionization mass spectroscopy)), and their absolute configurations were established by comparing their experimental and calculated electronic circular dichroism (ECD) spectra. The new (3) and a known (12) compounds in all isolates displayed stronger antineuroinflammatory effects (IC50 values of 1.8 and 11.1 μM, respectively) than minocycline (IC50 value of 15.5 μM) against NO production on LPS-activated BV2 cells.