Natural polyprenylated benzophenones inhibiting cysteine and serine proteases.

We have investigated the in vitro inhibition of papain, trypsin, and cathepsins B and G by five benzophenone-type compounds, three natural ones isolated from Garcinia brasiliensis and two synthetic derivatives. The activities of pentaprenylated trihydroxy-substituted benzophenone guttiferone A (1) on all assayed enzymes were approximately 2-69 folds higher than that manifested by mono-hydroxylated tetraprenylated and triprenylated compounds epiclusianone (2) and garciniaphenone (3), respectively, the other natural benzophenones that also inhibited significantly the four enzymes. Differently, the synthetic derivatives 2,2',4-trihydroxybenzophenone (4) and diphenylmethanone (5) have inhibited weakly the studied proteases. Furthermore, compound 1 has bonded preferentially to cathepsin G, once its IC(50) value (2.7+/-0.1 microM) on such peptidase is quite similar to that of the classical inhibitor of serine proteases, chymostatin (2.1+/-0.1 microM). Interesting structure-activity relationships (SARs) were confirmed by flexible docking simulations, likewise the potential usefulness of natural compound 1 as antitumoral drug is strengthened by our results concerning the antiproteolytic activity.

Efeitos agudos da aplicação endovenosa do cogumelo-do-sol (Agaricus blazei Murill) sobre a pressão arterial média e a freqüência cardíaca de ratos anestesiados / Acute effects of the endovenous application of the royal mushroom (Agaricus blazei Murill) on mean arterial pressure and heart rate of anesthetized rats

Este trabalho objetivou verificar os efeitos agudos da aplicação endovenosa do extrato aquoso do Agaricus blazei Murill sobre a pressão arterial média (PAM) e a freqüência cardíaca (FC) de ratos anestesiados. Foram usados Rattus novergicus albinus, n = 6, anestesiados com tiopental sódico, traqueostomizados e canulados através da veia jugular e da artéria carótida. Foram injetadas as concentrações de 1,25 mg/kg, 2,50 mg/kg e 5,00 mg/kg do extrato aquoso em volume de 0,2 mL. A PAM foi registrada com um sistema Biopac, modelo MP100, e a FC com um eletrocardiógrafo ECG-4 Funbec. Os resultados foram obtidos no controle e nos tempos 15, 30, 45, 60 e 120s após a aplicação dos extratos. Os valores foram expressos em média ± EPM e analisados estatisticamente pelos testes "t" de Student-Newman-Keuls e Tukey (p<0,05). O extrato aquoso de A. blazei reduziu a PAM de maneira concentração dependente, sendo que a concentração de 1,25 mg/kg não provocou modificações significativas na PAM nem na FC; a de 2,50 mg/kg provocou diminuição da PAM aos 15s (p<0,01) e da FC aos 30s (p<0,001) e a de 5,00 mg/kg diminuiu a PAM aos 15s (p<0,001) e a FC aos 15 e 30s (p<0,001).

The aim of this paper was to verify the acute effects of the endovenous application of the aqueous extract of Agaricus blazei Murill on mean arterial pressure and heart rate of the anesthetized rats. The injected concentrations were: 1.25 mg/kg, 2.50 mg/kg and 5.00 mg/kg, in volume of 0.2 mL. The rats were anesthetized with sodium thiopental and, after tracheotomy, both jugular vein and carotid artery were cannulated. The MAP was recorded with a Biopac System, model MP100. The HR was obtained with an electrocardiograph model ECG-4 (Funbec). The records were made in the control and 15, 30, 45, 60 and 120s after the application of the different concentrations of the extracts. The values were expressed by mean ± SEM and by paired "t"-Student-Newman-Keuls and Tukey tests (p<0.05). The aqueous extract of the A. blazei decreased the MAP of dependent manner. The concentration of 1.25 mg/kg did not provoke effects; 2.50 mg/kg provoked decrease of the PAM at 15s (p<0.01) and of the HR at 30s (p<0.001) and 5.00 mg/kg provoked decrease of the PAM at 15s (p<0.001) and of the HR at 15 and 30s (p<0.001).

Solid-phase library synthesis, screening, and selection of tight-binding reduced peptide bond inhibitors of a recombinant Leishmania mexicana cysteine protease B.

A one-bead-two-compound inhibitor library was synthesized by the split-mix method for the identification of inhibitors of a recombinant cysteine protease from Leishmania mexicana, CPB2.8DeltaCTE. The inhibitor library was composed of octapeptides with a centrally located reduced bond introduced by reductive amination of the resin-bound amines with Fmoc amino aldehydes. The library was screened on solid phase, and less than 1% of the library contained active compounds. The inhibitors displayed great specificity in the subsites flanking the enzyme catalytic triad with Cha and Ile/Leu preferred in P(2), Phe in P(1), Cha and Ile/Leu in P(1)', and Ile/Leu in P(2)'. Some of the inhibitors were resynthesized, and the kinetics of inhibition were determined in solution-phase assays. Most of the inhibitors had micromolar K(i) values, and a few inhibited the enzyme at nanomolar concentrations. One inhibitor, DKHF(CH(2)NH)LLVK (K(i) = 1 microm), was tested for antiparasite efficacy and shown to affect parasite survival with an IC(50) of approximately 50 microm.