Addition of tryptophan methyl-ester on [60]fullerene: theoretical investigation of the mechanisms of azomethine ylides and fulleropyrrolidine formation

In this paper, we perform the synthesization of carbon nanoparticles for active principle vectorization, with the suggestion of a reaction mechanism of tryptophan methyl ester addition on [60]fullerene. Firstly, we studied the effect of tryptophan form on its addition reaction on [60]fullerene. So, in order to determine the preferred environment that makes this reaction the most favorable, we considered all tryptophan possible forms in our investigation: the molecular, the zwitterionic, and the dibasic forms. Secondly, we investigate the proposed reaction mechanism of tryptophan methyl ester addition on [60]fullerene using theoretical thermodynamic calculation. Our hypothesis suggests the formation of azomethine ylide molecule in a first step followed by its addition on [60]fullerene in the second step by the photo-addition reaction involving the oxygen in its singlet state. The stability of each reactive intermediate involved in this mechanism is verified thermodynamically. The 12 most stable conformations of azomethine ylide were observed through potential energy surface analysis. They were obtained by a relaxed scan of the four dihedral angles. The calculations were conducted on the optimized geometry of fulleropyrrolidine mono-adduct and the bulk values of its thermodynamic constants were also determined. Infrared spectra observed in 100–4000 cm^?1 region confirmed our hypothesis suggesting the first step of azomethine ylide formation followed by the second step of azomethine ylide addition on [60]fullerene by ν(C_aliphatic-C-N), ν(C_aromatic-C-N) and ^δ(N-H) coupled with ν(C-N) absorption bond.

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Graphical abstract Optimized geometry of the Fulleropyrrolidine monoaduct molecule.

     

Down regulation effect of Rosmarinus officinalis polyphenols on cellular stress proteins in rat pheochromocytoma PC12 cells

Polyphenols are known to exhibit wide spectrum of benefit for brain health and to protect from several neurodegenerative diseases. The present study was sought to determine the neuroprotective effects of Rosmarinus officinalis' polyphenols (luteolin, carnosic acid, and rosmarinic acid) through the investigation of stress-related proteins. We carried out measurement of the expression of heat-shock protein (Hsp) 47 promoter in heat stressed Chinese hamster ovary transfected cells. We performed proteomic analysis and confirmed gene expression by real time PCR in PC12 cells. Results showed that these compounds modulated significant and different effects on the expression of 4 stress-related proteins: heat shock protein 90 α (Hsp90), Transitional endoplasmic reticulum ATPase (VCP/p97), Nucleoside diphosphate kinase (NDK), and Hypoxia up-regulated protein 1 (HYOU1)) at translational and post translational levels in PC12 cells and they downregulated the expression of Hsp47 activity in Chinese hamster transformed cells. These findings suggest that luteolin, carnosic acid, and rosmarinic acid may modulate the neuroprotective defense system against cellular stress insults and increase neuro-thermotolerance.     

Chemical Composition and Behavioral Effects of Five Plant Essential Oils on the Green Pea Aphid Acyrthosiphon pisum (Harris) (Homoptera: Aphididae)

Essential oils (EOs) from Schinus molle, Helichrysum gymnocephalum, Cedrelopsis grevei and Melaleuca viridiflora, four aromatic and medicinal plants, are commonly used in folk medicine. EOs were characterized by gas chromatography/mass spectrometry (GC/MS) and quantified by gas chromatography‐flame ionization detection (GC‐FID); then evaluated for their behavioral effects on adults of the green pea aphid Acyrthosiphon pisum (Harris ) using a Perspex four‐armed olfactometer in order to test the compatibility of their use as phytoinsecticides to control this insect pest. Our results showed that the EOs from the leaves of S. molle, M. viridiflora and C. grevei did not change aphids’ behavior. However, S. molle fruits EO seemed to be attractive while H. gymnocephalum leaves EO exhibited repellency towards aphids at a dose of 10 μl. The major compounds in S. molle fruits EO were 6‐epi‐shyobunol (16.22%) and d ‐limonene (15.35%). While, in H. gymnocephalum leaves EO, 1,8‐cineole was the main compound (47.4%). The difference in aphids’ responses to these two EOs could be attributed to the differences in their compositions. Our findings suggest that these two EOs have potential applications for the integrated pest management of A. pisum (Harris ).