Use of Cistus aqueous extracts as botanical fungicides in the control of Citrus sour rot.

In this work, we investigated the in vitro and in vivo antifungal activity of aqueous extracts obtained from eight Cistus plant species against the development of Geotrichum citri-aurantii, the causal agent of citrus sour rot. The results demonstrate the in vitro effectiveness of all tested Cistus species aqueous extracts against G. citri-aurantii, the inhibition of mycelial growth ranged between 80 and 100%. Furthermore, Cistus aqueous extracts totally inhibited germination of G. citri-aurantii arthrospores at a concentration of 5 mg/mL. Among the plant species tested, C. laurifolius, C. salviifolius, C. monspeliensis, C. ladanifer and C. populifolius displayed the best fungistatic activity since the minimum inhibitory concentration (MIC) was <0.625 mg/mL. Under in vivo conditions, incidence of sour rot was lowered to 8.33% when fruits were treated with aqueous extracts of C. populifolius and C. creticus compared to 100% in the control. Disease severity was lowered to 3.74, 4.47 and 5.13% when fruits were treated with C. creticus, C. ladanifer and C. populifolius aqueous extracts, respectively. Using such these biopesticides in a replacement for synthetic fungicides or in combination with other established disease management practices could help control citrus postharvest decay in a more sustainable and eco-friendly way.

Pharmacological studies of a new derivative of amphotericin B, MS-8209, in mouse and hamster scrapie.

Transmissible subacute spongiform encephalopathies (TSSE) are neurodegenerative diseases characterized by the presence of a modified, partially proteinase-resistant host protein, PrPSc, which accumulates in the brains of infected individuals. Recently it has been reported that amphotericin B (AmB) treatment of hamsters infected with scrapie strain 263K prolongs the incubation period of the disease, and dissociates in vivo replication of the scrapie agent from PrPSc accumulation. We report here on data obtained after treatment with AmB and one of its derivatives, MS-8209, in experimental scrapie of mouse and hamster. Treatment was carried out by the intraperitoneal route 6 days per week, at three different dosages initiated at the time of infection. Two regimens were used: during the early time of infection or throughout the experimental infection. Results indicate that MS-8209 was as efficient as AmB in prolonging the incubation time and decreasing PrPSc accumulation in the hamster scrapie model. A dose-dependent response was observed in mice treated early after experimental infection. At a dose of 2.5 mg/kg, MS-8209 significantly prolonged the incubation period (by 11.9%). In long-term treatment of mice, MS-8209 and AmB markedly reduced PrPSc levels in the preclinical stage of the disease. These data demonstrate that the effect of AmB is not restricted to one model (hamster-263K). This regimen leads to an inversion of the PrPSc to proteinase-sensitive protein (PrPSens) ratio, suggesting PrPSens (presumably cellular PrPC) accumulation occurs before its conversion into PrPSc. As it has been shown that AmB does not modify the infectivity titre, we conclude that the drugs could act by inhibiting either the interaction of the scrapie agent with PrPSens during the early times of infection or the conversion of PrPSens into PrPSc.

Transition metal complexes of L-cysteine containing di- and tripeptides.

Nickel(II), cobalt(II), zinc(II), and cadmium(II) complexes of Ala-Cys, Phe-Cys, and Ala-Ala-Cys were studied by potentiometric and spectroscopic methods. Ni(II) induces deprotonation and coordination of the amide nitrogens, and the stable monomeric or oligomeric complexes are formed, depending on the metal to ligand molar ratios. Formation of the stable bis-complexes with [S,O] coordination mode is characteristic for cobalt(II), zinc(II), and cadmium(II) ions.