Attributes of Cyazofamid-Resistant Phytophthora litchii Mutants and Its Impact on Quality of Litchi Fruits

In this study, we determined the sensitivity of 148 Phytophthora litchii isolates to cyazofamid, yielding a mean EC50 value of 0.0091 ± 0.0028 μg/mL. Through fungicide adaptation, resistant mutants (RMs) carrying the F220L substitution in PlCyt b were derived from wild-type isolates. Notably, these RMs exhibited a lower fitness compared with the parental isolates. Molecular docking analysis further revealed that the F220L change contributed to a decrease in the binding energy between cyazofamid and PlCyt b. The total phenol and flavonoid contents in the litchi pericarp treated with cyazofamid on day 5 were significantly higher than in other treatments. Overall, the laboratory assessment indicated a moderate risk of cyazofamid resistance in P. litchii, but the emergence of the F220L change could lead to a high level of resistance. Thus, cyazofamid represents a promising agrochemical for controlling postharvest litchi downy blight and extending the shelf life of litchi fruits.

Fragmentation pathways of deprotonated ortho-hydroxybenzyl alcohol

The ortho, meta, and para isomers of hydroxybenzyl alcohol can be unequivocally distinguished by the collision-induced dissociation mass spectra of their anions. The presence of a prominent peak at m/z 121 for an elimination of a dihydrogen molecule renders the ortho-isomer spectrum markedly different from those of its meta and para congeners. Investigations carried out with deuterium-labeled isotopologues of the ortho isomer verified that the labile hydrogen atom on the hydroxyl group and one of the benzylic hydrogen atoms are specifically removed in the formation of the m/z 121 ion. The ortho-isomer spectrum also showed a prominent peak at m/z 93. Experimental data indicated that the m/z 93 product ion originates either from a two-step H2 and CO elimination mechanism or from a direct loss of a HCHO molecule from the precursor anion. The intensity ratio of the m/z 93 and 94 peaks in the spectrum recorded from the m/z 124 ion generated from a sample of o-hydroxybenzyl alcohol dissolved in D2 O supported the notion that the direct HCHO loss is the more dominant pathway for the generation of the phenolate ion under low activation conditions. In contrast, the two-step mechanism becomes the more dominant pathway under high collisional activation conditions. The spectrum also showed a weak peak at m/z 105 for a water loss. Based on computational data, the m/z 105 ion generated in this way appears to be a composite generated from a common ion-neutral complex intermediate in which a hydroxyl anion is positioned equidistantly between one of the benzylic hydrogens and a nearby hydrogen atom of the benzene ring. Upon activation, the complex dissociates to form either a phenide or a quinone methide anion. The reaction forming a carbon dioxide adduct under ion-mobility conditions was used to support the proposed water-loss mechanism.

Anti-tumour Effect and Pharmacokinetics of an Active Ingredient Isolated from Inonotus hispidus

Inonotus hispidus is an anti-tumour drug used in folk medicine. (4S,5S)-4-Hydroxy-3,5-dimethoxycyclohex-2-enone (HDE) is a compound isolated from Inonotus hispidus for the first time. However, the mechanisms underlying its therapeutic effects have not been elucidated. In this study, the in vitro screening, in vivo anti-tumour effects, mechanism of action, pharmacokinetics, and tissue distribution of HDE were investigated. HDE could inhibit the proliferation of HepG2 cells. Additionally, its half-maximal inhibitory concentration was 7.9 µg/mL. Increasing HDE concentrations significantly increased apoptosis rate in a dose-dependent manner. Furthermore, HDE was rapidly absorbed into mouse plasma, reaching a maximum concentration at 30 min. The area under the plasma HDE concentration-time curves for the studied organs were as follows: spleen > liver > lung > kidney > muscle > thymus > heart > brain. HDE also inhibited tumour growth up to 69%. The weights of organs harvested from HDE-treated mice were not significantly different from those harvested from control mice. Furthermore, HDE upregulated Fas expression and downregulated FasL expression in HepG2 cells. HDE significantly increased caspase-3 and caspase-8 activity. The anti-tumour effect of HDE might be realized by activating the Fas-mediated apoptotic pathway. We also found that HDE undergoes enterohepatic circulation or is quickly absorbed by the body, and the drug is released back into systemic circulation. In conclusion, HDE significantly inhibited H22 hepatocarcinoma cells (H22)tumour growth in mice without damaging organs; therefore, it may be suitable for treating liver cancer.

Two New Amides from Streptomyces michiganensis

A new amide glycoside, 3-α-glucopyranosyloxy- N-methyl-3-phenylpropanamide (1), and a new cyclodipeptide, (3 S,6 S)-3,6-bis(4-acetamidobutyl)piperazine-2,5-dione (2), were isolated from the solid culture of Streptomycetes michiganensis strain SC0642. Their structures were elucidated by spectroscopic methods.