Ultrasonic-Assisted Extraction of Dictyophora rubrovolvata Volva Proteins: Process Optimization, Structural Characterization, Intermolecular Forces, and Functional Properties.

Dictyophora rubrovolvata volva, an agricultural by-product, is often directly discarded resulting in environmental pollution and waste of the proteins' resources. In this study, D. rubrovolvata volva proteins (DRVPs) were recovered using the ultrasound-assisted extraction (UAE) method. Based on one-way tests, orthogonal tests were conducted to identify the effects of the material-liquid ratio, pH, extraction time, and ultrasonic power on the extraction rate of DRVPs. Moreover, the impact of UAE on the physicochemical properties, structure characteristics, intermolecular forces, and functional attributes of DRVPs were also examined. The maximum protein extraction rate was achieved at 43.34% under the best extraction conditions of UAE (1:20 g/mL, pH 11, 25 min, and 550 W). UAE significantly altered proteins' morphology and molecular size compared to the conventional alkaline method. Furthermore, while UAE did not affect the primary structure, it dramatically changed the secondary and tertiary structure of DRVPs. Approximately 13.42% of the compact secondary structures (α-helices and ß-sheets) underwent a transition to looser structures (ß-turns and random coils), resulting in the exposure of hydrophobic groups previously concealed within the molecule's core. In addition, the driving forces maintaining and stabilizing the sonicated protein aggregates mainly involved hydrophobic forces, disulfide bonding, and hydrogen bonding interactions. Under specific pH and temperature conditions, the water holding capacity, oil holding capacity, foaming capacity and stability, emulsion activity, and stability of UAE increased significantly from 2.01 g/g to 2.52 g/g, 3.90 g/g to 5.53 g/g, 92.56% to 111.90%, 58.97% to 89.36%, 13.85% to 15.37%, and 100.22% to 136.53%, respectively, compared to conventional alkali extraction. The findings contributed to a new approach for the high-value utilization of agricultural waste from D. rubrovolvata.

Process Optimization, Structural Characterization, and Calcium Release Rate Evaluation of Mung Bean Peptides-Calcium Chelate.

To reduce grievous ecological environment pollution and protein resource waste during mung bean starch production, mung bean peptides-calcium chelate (MBP-Ca) was synthesized as a novel and efficient calcium supplement. Under the optimal conditions (pH = 6, temperature = 45 °C, mass ratio of mung bean peptides (MBP)/CaCl2 = 4:1, MBP concentration = 20 mg/mL, time = 60 min), the obtained MBP-Ca achieved a calcium chelating rate of 86.26%. MBP-Ca, different from MBP, was a new compound rich in glutamic acid (32.74%) and aspartic acid (15.10%). Calcium ions could bind to MBP mainly through carboxyl oxygen, carbonyl oxygen, and amino nitrogen atoms to form MBP-Ca. Calcium ions-induced intra- and intermolecular interactions caused the folding and aggregation of MBP. After the chelation reaction between calcium ions and MBP, the percentage of ß-sheet in the secondary structure of MBP increased by 1.90%, the size of the peptides increased by 124.42 nm, and the dense and smooth surface structure of MBP was transformed into fragmented and coarse blocks. Under different temperatures, pH, and gastrointestinal simulated digestion conditions, MBP-Ca exhibited an increased calcium release rate compared with the conventional calcium supplement CaCl2. Overall, MBP-Ca showed promise as an alternative dietary calcium supplement with good calcium absorption and bioavailability.

Non-targeted analysis of vulgarisins by using collisional dissociation mass spectrometry for the discovery of analogues from Prunella vulgaris.

Vulgarisins are members of diterpenoids with rare 5/6/4/5 ring skeleton from Prunella vulgaris Linn. (P. vulgaris). Their molecular scaffolds comprise different hydroxylation and degree of esterification. Vulgarisins have attracted many attentions in the fields of food and medicine for their potent bioactivities. Firstly, four reference compounds were analyzed by higher-energy collisional dissociation mass spectrometry (HCD MS/MS) and the fragmentation patterns for molecular scaffold were summarized. And then, a high-performance liquid chromatography/electrospray ionization/high-resolution mass spectrometry (HPLC-ESI-HR-MS) method was adopted to investigate the P. vulgaris extracts. Finally, the proposed analysis results were successfully applied to facilitate the discovery of the vulgarisins analogues from P. vulgaris. For the four reference compounds, the sodium adduct was the predominate ion in full scan. A specific fragmentation pathway of [M+Na]+ ions leads to produce diagnostic ions of vulgarisins at m/z 325 under HCD, which was formed through consecutive-side chains lost. Twenty-three diterpenoids, including 18 vulgarisins analogues, were identified or tentatively characterized in the botanical extracts of P. vulgaris based on their elemental constituents and characteristic fragment ion profiles. Two new vulgarisins analogues in the plant were isolated and their structures were illustrated based on extensive spectroscopic analysis using 1D and 2D nuclear magnetic resonance (NMR) spectroscopy. The HCD MS/MS method, including the profiles of the diagnostic ions induced by characteristic fragmentation, is an effective technique for the discovery of vulgarisins analogues in P. vulgaris. The expected fragmentation pattern knowledge will also facilitate the analysis of other natural products.

Synthesis and Bioactivities Study of Novel Pyridylpyrazol Amide Derivatives Containing Pyrimidine Motifs.

In this study, thirteen new pyridylpyrazolamide derivatives containing pyrimidine motifs were synthesized via six-step reactions. Bioassay results showed that some of the synthesized compounds revealed good antifungal properties against Sclerotinia sclerotiorum, Phytophthora infestans, Thanatephorus cucumeris, Gibberella zeae, Fusarium oxysporum, Cytospora mandshurica, Botryosphaeria dothidea, and Phompsis sp. at 50 µg/mL, which were similar to those of Kresoxim-methyl or Pyrimethanil. Meanwhile, bioassay results indicated that the synthesized compounds showed a certain insecticidal activity against Spodoptera litura, Mythimna separata, Pyrausta nubilalis, Tetranychus urticae, Rhopalosiphum maidis, and Nilaparvata lugens at 200 µg/mL, which was lower than that of Chlorantraniliprole. To the best of our knowledge, this study is the first report on the antifungal and insecticidal activities of pyridylpyrazol amide derivatives containing a pyrimidine moiety.

Gold nanostars-enhanced Raman fingerprint strip for rapid detection of trace tetracycline in water samples.

Rapid and accurate detection of antibiotics at trace levels in food represents a great challenge. Tetracycline (TC), as a sort of broad-spectrum antibiotic, has been extensively used in animal infection therapy and animal husbandry as growth promoters. Large amounts of TC residues in animal-derived foods affect food quality and safety, and cause undesirable side effects such as allergic reactions and bacterial antibiotic resistance. Here, a Raman fingerprint strip sensor was reported based on surface-enhanced Raman scattering technology and demonstrated for ultrasensitive detection of TC. In this approach, 4-aminothiophenol (4-ATP) modified gold nanostars (GNSs) were used as a strong Raman reporter, which was coated with anti-TC monoclonal antibody serving as a biorecognition to acquire both visual and Raman signals on the test line. To demonstrate the performance of this strip, TC standard solutions with concentrations ranging from 0.5 to 50 ng/mL was detected, the limit of the detection (LOD) for the Raman signal was 0.04 ng/mL, which was 100 times more sensitive than those of color intensity quantifications. The other analogues, oxytetracycline, and chlortetracycline were detected using this method, making them suitable for the samples with TC analogues screening.

[Correlation between endogenous harmful components in mainstream cigarette smoke and chemical constituents in tobacco leaves].

Correlation analysis between main chemical constituents of tobacco leaves and endogenous harmful components in mainstream cigarette smoke was conducted. Leaf stalk positions exhibited a high relation with endogenous harmful components and hazard index (H). Upper stalk position leaves had greater release of 1-butanone,4-(methylnitrosoamino)-1-(3-pyridinyl)-(NNK), B[a]P, HCN, NH3 and phenol in mainstream cigarette smoke, and a higher hazard index than middle position leaves except for crotonaldehyde, which had greater release from middle position leaves. Different endogenous harmful components in mainstream cigarette smoke presented complicated correlation with main chemical constituents in tobacco. The same type of leaf chemical constituents presented different correlations with various endogenous harmful components in mainstream cigarette smoke. Cigarette hazard index showed significantly positive correlations with contents of nicotine, protein, total nitrogen, major polyphenols and organic acids, while significantly negative correlation with potassium and carbonaceous substances, such as total sugars, reducing sugars and starch. The results suggested that properly increasing potassium content and decreasing nitrogenous constituents in cured tobacco leaf may reduce the cigarette hazard index.

The limonoids and their antitobacco mosaic virus (TMV) activities from Munronia unifoliolata Oliv.

Five new limonoids, named munronoids K-O (1-5), together with three known limonoids were isolated from Munronia unifoliola Oliv. These limonoids were involved in the skeletons of evodulone, gedunin, and peieurianin types of limonoids, and their structures were established on the basis of spectroscopic data. Compound 5 featuring a γ-lactone ring instead of the ß-substituted furan ring was found in the peieurianin type for the first time. The antitobacco mosaic virus (anti-TMV) activities of compounds 1-8 were also evaluated with half-leaf, enzyme-linked immunosorbent assay, and Western blot methods, and limonoids 1, 5, and 8 showed stronger anti-TMV treatment activities than the positive control ningnanmycin. Six compounds (1-5 and 8) exhibited infection inhibition activities against TMV.

[Studies on the chemical constituents from Euphorbia chrysocoma].

OBJECTIVE: To study the chemical constituents from the aerial part of Euphorbia chrysocoma. METHODS: All compounds were isolated and purified by many methods, including siliga gel and reversed phase RP-18 column chromatographies, preparative thin layer chromatography, Sephadex LH-20, and recrystallization. Their structures were mainly elucidated by ESI-MS and NMR spectra and their physical characters. RESULTS: Six compounds were isolated from the petroleum ether section from 75% ethanol extraction of the material. Their structures were identified as taraxerol (1), epitaraxerol (2), beta-sistosterol (3), beta-sitostenone (4), jolkinolide E (5), and sesamin (6). CONCLUSION: Compounds 1, 2, 4, 5, and 6 are isolated from this plant for the first time.

[Diterpenoid alkaloids from roots of Aconitum recemulosum and their inhibitory effects on PAF-induced platelet aggregation].

OBJECTIVE: To study diterpenoid alkaloids from the roots of Aconitum recemulosum, and their inhibitory effects on PAF-induced platelet aggregation. METHOD: The root of A. recemulosum was extracted with 95% EtOH. The total alkaloids extracted were isolated and purified by several kinds of column chromatography over silica gel, RP-18, and Sephadex LH-20, and identified based on spectral analysis. And the inhibitory effects of isolated compounds on PAF-induced platelet aggregation were detected. RESULT: Five alkaloids were isolated and identified as sachaconitine (1), 14-acetylsachaconitine (2), hemsleyanine C (3), circinasine A (4), and talatisamine (5). The results showed compounds 1 and 2 have moderate inhibition effect on PAF. CONCLUSION: Compounds 1-5 were firstly isolated from this plant. Furthermore, compounds 1 and 2 possessed moderate inhibitory effects on PAF-induced platelet aggregation.

Unusual transposition of allenic framework in intramolecular cyclization of acetal-tethered (allenylmethyl)silanes.

Treatment of acetal-tethered (allenylmethyl)silanes, which were obtained from the corresponding 3-bromo-5-silyl-1,3-pentadienes by a Pd-catalyzed reaction with an acetal-tethered malonate, with TiCl(4) gave not only vinylcyclohexene derivatives via a standard S(E)2' pathway but also unusual allenylcyclopentane species via cyclization at the delta-position. Deuterium-labeling experiments revealed participation of a 1,2-hydride shift in a carbocation intermediate for the formation of the latter products.

Palladium-catalyzed preparation of vinylallenes from 2-bromo-1,3,5-trienes via an alkylidene-pi-allylpalladium-mediated formal SN2" pathway.

[Structure: see text] A novel Pd-catalyzed reaction to prepare conjugated vinylallenes from 2-bromo-1,3,5-triene and a soft nucleophile via a formal SN2" pathway was developed. The reaction proceeds via alkylidene-pi-allylpalladium and allenyl-pi-allylpalladium intermediates, and a dynamic process involving the two palladium intermediates played important roles in determining the selectivity of the Pd-catalyzed reaction. The reaction was extended to an asymmetric counterpart, and an axially chiral vinylallene was obtained with up to 81% ee.

Vinyl ketones to allenes: preparation of 1,3-dien-2-yl triflates and their application in Pd-catalyzed reactions with soft nucleophiles.

[chemical reaction: see text]. A general route of converting alkenyl ketones to functionalized allenes was developed. Substituted 1,3-dien-2-yl triflates, which were prepared from the alkenyl ketones via silyl dienol ethers, were excellent substrates for the palladium-catalyzed reaction with soft nucleophiles giving the multisubstituted allenes in high yields. Comparison between the dienyl triflates and analogous bromodienes in the Pd-catalyzed reaction was studied as well.

Preparation of multisubstituted allenes from allylsilanes.

[reaction: see text] A three-step route of converting allylsilanes to functionalized allenes was developed. Thermal decomposition of 1,1-dibromo-2-(silylmethyl)cyclopropanes, which were quantitatively prepared by treatment of allylsilane derivatives with CHBr3/KO(t)Bu, afforded substituted 2-bromo-1,3-butadienes with elimination of bromosilanes. The Pd-catalyzed reaction of the bromodienes with soft nucleophiles gave the allene derivatives. Previously inaccessible tri- and tetrasubstituted allenes can be prepared by this method as well.