Total Synthesis and Structure Revision of Palmarumycin B6.

Palmarumycin B6 and its regioisomer were synthesized via 7- and 13-step routes using 2-chlorophenol and 4-chlorophenyl methyl ether as the starting materials in overall yields of 2.7% and 12%, respectively. Their structures were characterized by 1H and 13C NMR, HRESIMS, and X-ray diffraction data. The structure of palmarumycin B6 was revised as 6-chloropalmarumycin CP17. The bioassay results showed that the larvicidal activity of palmarumycin B6 with an LC50 value of 32.7 µM was significantly higher than that of its 8-chloro isomer, with an LC50 value of 227.3 µM.

Molecular mechanism of activation of human musk receptors OR5AN1 and OR1A1 by (R)-muscone and diverse other musk-smelling compounds.

Understanding olfaction at the molecular level is challenging due to the lack of crystallographic models of odorant receptors (ORs). To better understand the molecular mechanism of OR activation, we focused on chiral (R)-muscone and other musk-smelling odorants due to their great importance and widespread use in perfumery and traditional medicine, as well as environmental concerns associated with bioaccumulation of musks with estrogenic/antiestrogenic properties. We experimentally and computationally examined the activation of human receptors OR5AN1 and OR1A1, recently identified as specifically responding to musk compounds. OR5AN1 responds at nanomolar concentrations to musk ketone and robustly to macrocyclic sulfoxides and fluorine-substituted macrocyclic ketones; OR1A1 responds only to nitromusks. Structural models of OR5AN1 and OR1A1 based on quantum mechanics/molecular mechanics (QM/MM) hybrid methods were validated through direct comparisons with activation profiles from site-directed mutagenesis experiments and analysis of binding energies for 35 musk-related odorants. The experimentally found chiral selectivity of OR5AN1 to (R)- over (S)-muscone was also computationally confirmed for muscone and fluorinated (R)-muscone analogs. Structural models show that OR5AN1, highly responsive to nitromusks over macrocyclic musks, stabilizes odorants by hydrogen bonding to Tyr260 of transmembrane α-helix 6 and hydrophobic interactions with surrounding aromatic residues Phe105, Phe194, and Phe207. The binding of OR1A1 to nitromusks is stabilized by hydrogen bonding to Tyr258 along with hydrophobic interactions with surrounding aromatic residues Tyr251 and Phe206. Hydrophobic/nonpolar and hydrogen bonding interactions contribute, respectively, 77% and 13% to the odorant binding affinities, as shown by an atom-based quantitative structure-activity relationship model.

Design, Synthesis, and Structure-Activity Relationship of New Pyrimidinamine Derivatives Containing an Aryloxy Pyridine Moiety.

The pyrimidinamine diflumetorim is an ideal template for the discovery of agrochemical lead compounds due to its unique mode of action, novel chemical structure, and lack of reported resistance. To develop a new pyrimidinamine fungicide effective against cucumber downy mildew (CDM), a series of new pyrimidinamine derivatives containing an aryloxy pyridine moiety were designed and synthesized by employing the recently reported intermediate derivatization method (IDM). The structures of all compounds were identified by 1H NMR, elemental analyses, HRMS, and X-ray diffraction. Bioassays demonstrated that some of the title compounds exhibited excellent fungicidal activities against CDM. Compound 9 gave the best activity (EC50 = 0.19 mg/L), which is significantly better than the commercial fungicides diflumetorim, flumorph, and cyazofamid. The relationship between structure and fungicidal activity of the synthesized pyrimidinamines was explored. The study showed that compound 9 is a promising fungicide candidate for further development.

Bioactive spirobisnaphthalenes from the endophytic fungus Berkleasmium sp.

Nine new spirobisnaphthalenes, palmarumycins B1-B9 (1-9), along with 13 known compounds (10-22), were isolated from cultures of the fungus Berkleasmium sp., an endophyte isolated from the medicinal plant Dioscorea zingiberensis C. H. Wright. The structures of the new compounds were elucidated by analysis of the 1D and 2D NMR and HRESIMS spectra and by comparison with known compounds. Compounds 7-9 contain an uncommon 2,3-dihydro-1H-inden-1-one unit. All isolated compounds were evaluated for their antibacterial activities against Bacillus subtilis, Staphylococcus hemolyticus, Agrobacterium tumefaciens, Pseudomonas lachrymans, Ralstonia solanacearum, and Xanthomonas vesicatoria and for their antifungal effects against the spore germination of Magnaporthe oryzae. Palmarumycin C8 (22) exhibited the best antibacterial and antifungal effects. In addition, diepoxin δ (11) and palmarumycin C8 (22) showed pronounced cytotoxic activities against five human cancer cell lines (HCT-8, Bel-7402, BGC-823, A 549, A 2780) with IC50 values of 1.28-5.83 µM.

Preparative separation of spirobisnaphthalenes from endophytic fungus Berkleasmium sp. Dzf12 by high-speed counter-current chromatography.

High-speed counter-current chromatography (HSCCC) was applied for the first time for the preparative separation of spirobisnaphthalenes from a crude extract of the endophytic fungus Berkleasmium sp. Dzf12, associated with the medicinal plant Dioscorea zingiberensis. Six spirobisnaphthalenes were successfully separated by HSCCC with a two-phase solvent system composed of n-hexane-chloroform-methanol-water (1.5:3.0:2.5:2.0, v/v). About 18.0 mg of diepoxin κ (1), 245.7 mg of palmarumycin C13 (2), 42.4 mg of palmarumycin C16 (3), 42.2 mg of palmarumycin C15 (4), 32.6 mg of diepoxin δ (5), and 22.3 mg of diepoxin γ (6) with purities of 56.82, 71.39, 76.57, 75.86, 91.01 and 82.48%, respectively, as determined by high-performance liquid chromatography (HPLC), were obtained from 500 mg of the crude extract in a one-step elution within 7 h of separation procedure by HSCCC. The purified spirobisnaphthalenes were further structurally characterized by means of physicochemical and spectrometric analysis.

Phenolic compounds from Halimodendron halodendron (Pall.) voss and their antimicrobial and antioxidant activities.

Halimodendron halodendron has been used as forage in northwestern China for a long time. Its young leaves and flowers are edible and favored by indigenous people. In this study, eleven phenolic compounds were bioassay-guided and isolated from the aerial parts of H. halodendron for the first time. They were identified by means of physicochemical and spectrometric analysis as quercetin (1), 3,5,7,8,4'-pentahydroxy-3'-methoxy flavone (2), 3-O-methylquercetin (3), 3,3'-di-O-methylquercetin (4), 3,3'-di-O-methylquercetin-7-O-ß-d-glucopyranoside (5), isorhamentin-3-O-ß-d-rutinoside (6), 8-O-methylretusin (7), 8-O-methylretusin-7-O-ß-d-glucopyranoside (8), salicylic acid (9), p-hydroxybenzoic acid (ferulic acid) (10), and 4-hydroxy-3-methoxy cinnamic acid (11). They were sorted as flavonols (1-6), soflavones (7 and 8), and phenolic acids (9-11). Among the compounds, flanools 1-4 revealed a strong antibacterial activity with minimum inhibitory concentration (MIC) values of 50-150 µg/mL, and median inhibitory concentration (IC(50)) values of 26.8-125.1 µg/mL. The two isoflavones (7 and 8) showed moderate inhibitory activity on the test bacteria. Three phenolic acids (9, 10 and 11) showed strong antibacterial activity with IC(50) values of 28.1-149.7 µg/mL. Antifungal activities of the compounds were similar to their antibacterial activities. All these phenolic compounds showed significant antimicrobial activity with a broad spectrum as well as antioxidant activity based on 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging and ß-carotene-linoleic acid bleaching assays. In general, the flavonol aglycones with relatively low polarity exhibited stronger activities than the glycosides. The results suggest the potential of this plant as a source of functional food ingredients and provide support data for its utilization as forage as well.

Antimicrobial flavonoids from the twigs of Populus nigra x Populus deltoides.

A bioassay-guided fractionation of the ethyl acetate extract from the twigs of the hybrid poplar 'Neva', Populus nigra L. × Populus deltoides Marsh, led to the isolation of three flavonoids, which were identified by means of spectrometric and physicochemical analysis as 5-hydroxy-7-methoxy-flavone (1), 5,7-dihydoxy-flavone (2) and 5,7-dihydroxy-flavonol (3). These compounds were further screened for their antimicrobial activity against plant pathogens, including three bacteria (Pseudomonas lachrymans, Ralstonia solanacearum and Xanthomonas vesicatoria) and one fungus (Magnaporthe oryzae). Compounds 2 and 3 showed significant antibacterial activity, with minimum inhibitory concentrations (MICs) ranging from 15 to 25 µg mL(-1), and median inhibitory concentrations (IC(50) values) from 4 to 18 µg mL(-1). The results obtained provide promising baseline information for the potential use of the extract and flavonoids from this plant as antimicrobial agents to help control plant diseases.

Antimicrobial metabolites from the endophytic fungus Pichia guilliermondii isolated from Paris polyphylla var. yunnanensis.

Three steroids and one nordammarane triterpenoid were isolated for the first time from the endophytic fungus Pichia guilliermondii Ppf9 derived from the medicinal plant Paris polyphylla var. yunnanensis. By means of physicochemical and spectrometric analysis, they were identified as ergosta-5,7,22-trienol (1), 5α,8α-epidioxyergosta-6,22-dien-3ß-ol (2), ergosta-7,22-dien-3ß,5α,6ß-triol (3), and helvolic acid (4). Both micro-dilution-colorimetric and spore germination assays were employed to evaluate their antimicrobial activity. Among them, helvolic acid (4) exhibited the strongest antibacterial activity against all test bacteria, with MIC values ranging from 1.56 µg/mL to 50 µg/mL, and IC(50) values from 0.98 µg/mL to 33.19 µg/mL. It also showed strong inhibitory activity on the spore germination of Magnaporthe oryzae with an IC(50) value of 7.20 µg/mL. Among the three steroids, 5α,8α-epidioxyergosta-6,22-dien-3ß-ol (2) exhibited relatively strong antimicrobial activity. The results suggest that the endophytic fungus Pichia guillermondii Ppf9 could be a candidate for producing helvolic acid, and the metabolites from this fungus could be potentially developed as antimicrobial agents in the future.

The fungicidal terpenoids and essential oil from Litsea cubeba in Tibet.

A new C9 monoterpenoid acid (litseacubebic acid, 1) and a known monoterpene lactone (6R)-3,7-dimethyl-7-hydroxy-2-octen-6-olide (2), along with three known compounds--vanillic acid (3), trans-3,4,5-trimethoxylcinnamyl alcohol (4), and oxonantenine (5)--were isolated with bioassay-guided purification from the fruit extract of Litsea cubeba collected in Tibet. The structure of 1 was elucidated by MS, ¹H-NMR, ¹³C-NMR, COSY, HSQC, HMBC, NOE spectral data as 2,6-dimethyl-6-hydroxy-2E,4E-hepta-2,4-diene acid. Additionally 33 compounds were identified from the essential oil of L. cubeba. The preliminary bioassay results showed that 1 and 2 have good fungicidal activities against Sclerotinia sclerotiorum, Thanatephorus cucumeris, Pseudocer-cospora musae and Colletotrichum gloeosporioides at the concentration of 588 and 272 µM, and the essential oil has good fungicidal activities against T. cucumeris and S. sclerotiorum, with IC50 values of 115.58 and 151.25 µg/mL, repectively.

Antimicrobial compounds from the endophytic fungus Fusarium sp. Ppf4 isolated from the medicinal plant Paris polyphylla var. yunnanensis.

Two sterols and one fatty acid were obtained by bioassay-guided fractionation from the light petroleum extract of the fungus Fusarium sp. Ppf4 isolated from the rhizomes of Paris polyphylla var. yunnanensis Hand.-Mazz., a medicinal species distributed in the southwest of China. The compounds were elucidated as 5alpha, 8alpha-epidioxyergosta-6, 22-dien-3beta-ol (1), ergosta-8(9), 22-dien-3beta, 5alpha, 6beta, 7alpha-tetraol (2), and butanedioic acid (3), respectively, by means of physical and spectrometric analysis. Both fungal spore germination and micro-dilution-MTT assays were employed to evaluate their antimicrobial activity. Compound 1 was found to be the most bioactive, and compound 3 less active against the test pathogens. This is the first report of the antimicrobial activity of the compounds isolated from the endophytic Fusarium sp. Ppf4 associated with P. polyphylla var. yunnanensis. The results provide promising baseline information for the potential use of the compounds of this endophytic fungus as an antimicrobial agent to control plant and animal diseases.

Spirobisnaphthalenes from the endophytic fungus Dzf12 of Dioscorea zingiberensis and their antimicrobial activities.

Five spirobisnaphthalenes, namely palmarumycin CP17 (1), diepoxin kappa (2), diepoxin eta (3), diepoxin xi (4), and diepoxin gamma (5), were isolated from the endophytic fungus Dzf12 associated with the medicinal plant Dioscorea zingiberensis C. H. Wright. Their structures were identified by physicochemical and spectrometric analysis. Among these spirobisnaphthalenes, 2 was found to have antibacterial activity, and the mixture of 3 and 4 was detected to have both antibacterial and antifungal activities.

Chemical composition and in vitro antimicrobial activity of the volatile oils from Gliomastix murorum and Pichia guilliermondii, two endophytic fungi in Paris polyphylla var. yunnanensis.

Volatile oils were obtained by hydro-distillation from Gliomastix murorum and Pichia guilliermondii, two endophytic fungi isolated from the traditional Chinese medicinal herb Paris polyphylla var. yunnanensis. The oils were analyzed for their chemical composition by gas chromatography-mass spectrometry (GC-MS). Palmitic acid (15.5%), (E)-9-octadecenoic acid (11.6%), 6-pentyl-5,6-dihydropyran-2-one (9.7%), and (7Z,10Z)-7,10- hexadecadienoic acid (8.3%) were the major compounds of the 40 identified components in G. murorum volatile oil. 1,1,3a,7-Tetramethyl-1a,2,3,3a,4,5,6,7b-octahydro-1H-cyclopropa[a]- naphthalene (25.9%), palmitic acid (15.5%), 1-methyl-2,4-di- (prop-1-en-2-yl)-1- vinylcyclohexane (7.9%), (E)-9-octadecenoic acid (7.3%), and (9E,12E)-ethyl-9,12-octadecadienoate (5.2%) were the major compounds of the 27 identified components in P. guilliermondii volatile oil. The in vitro antimicrobial activity of the volatile oils was also investigated to evaluate their efficacy against six bacteria and one phytopathogenic fungus. The minimum inhibitory concentration (MIC) values of the volatile oils against the test bacteria ranged from 0.20 mg/mL to 1.50 mg/mL. One of the most sensitive bacteria was Xanthomonas vesicatoria with an MIC of 0.20 mg/mL and 0.40 mg/mL for G. murorum and P. guilliermondii, respectively. The mean inhibitory concentration (IC50) of the volatile oils against spore germination of Magnaporthe oryzae was 0.84 mg/mL for G. murorum and 1.56 mg/mL for P. guilliermondii. These results indicated that the volatile oils from the endophytic fungi have strong antimicrobial activity and could be a potential source of antimicrobial ingredients.

Three novel sesquiterpene esters from Celastrus angulatus.

Three new sesquiterpene polyol esters with a beta-dihydroagarofuran skeleton, NW12 (1), NW27 (2), and NW31 (4), together with a known compound, NW30 (3), were isolated from the root bark of Celastrus angulatus. Their chemical structures were elucidated by analyses of MS and NMR spectral data. Preliminary insecticidal and antitumor activities of these compounds were evaluated. Compounds 1-4 showed moderate stomach toxicity against Mythimna separata, and their KD50 values were 673.6, 1121.3, 1720.0 and 548.6 microg/g, respectively. Only 1 and 3 exhibited slight antitumor activity against human breast cancer cell line (Bcap-37), and their IC50 values were all above 50 microM.

Structure of asteroid bodies in the vitreous of galactose-fed dogs.

PURPOSE: Asteroid hyalosis is a condition in which white spherical particles (asteroid bodies) are suspended in the vitreous, usually in the dependent part of the vitreous. These particles seldom cause serious visual symptoms; however, their presence can be a source of irritation. It has been suggested, but not confirmed, that asteroid hyalosis may be associated with systemic diseases such as diabetes, hyperlipidemia, or hypertension. Studies indicate that these particles are composed of lipid material and calcium; however, the specific composition and structure of asteroid bodies remains unknown. We have observed that asteroid hyalosis occurs in galactose-fed dogs, and this represents the first animal model which consistently forms this vitreal condition. The purpose of this study was to identify the main structural component of the asteroid bodies present in the vitreous of these dogs. METHODS: Vitreous humor containing asteroid bodies was collected and frozen from long-term galactose-fed beagles and from age-matched normal controls where asteroid bodies were absent. A portion of the frozen vitreous was sent out for elemental analysis. Thawed vitreous samples were sonicated with HPLC grade water and the aqueous layer was extracted three times with chloroform and then three times with n-butanol. The three organic layers from each extraction were combined and the solvents removed in vacuo. The residue from each extraction was re-dissolved in methanol and analyzed by electrospray ionization mass spectrometry (ESI-MS). RESULTS: Vitreous-containing asteroid bodies had significantly higher levels of calcium and phosphorus. Negative mode ESI-MS analysis of the n-butanol extracts from vitreous samples with and without asteroid bodies were similar with both containing a predominant peak with a mass to charge ratio (m/z) of 538.4. However, similar analyses of the chloroform extracts indicated that three peaks with m/z values of 547.1, 690.5, and 1430.6 were present only in vitreous samples containing asteroid bodies. Subtraction analysis indicated that the m/z of 690.5 peak corresponded to the main component present. This peak was identified and confirmed to be the quasimolecular ion of 1,2-dipalmitoyl-glycero-3-phosphoethanolamine (DPPE). CONCLUSIONS: Based on the current belief that asteroid bodies are composed of lipid-calcium complexes, we propose that the main component of asteroid hyalosis in the galactose-fed dog is a quasimolecular ion of DPPE in which two molecules of DPPE are complexed through their phosphates groups with calcium.