HIV-1 protease inhibitors containing a novel C2 symmetrical hydroxyalkylgem-diamino core structure

Two series of peptidomimetics containing a novel C₂ symmetrical hydroxyalkylgem-diamino core structure were prepared, from amino acid starting materials, and evaluated as inhibitors of HIV-1 protease (HIV-1 Pr). 1, 1-Diamino-3-hydroxypropane (gHse) derivatives showed weak inhibitory potency (IC₅₀> 10 μM). In the 1, 1-diamino-2-hydroxyethane (gSer) series, a compound containing P1/P1’benzyl and P2/P2’Fmoc substitueras, displayed a significant HIV-1 Pr inhibition (IC₅₀= 440 nM). © Munksgaard 1997.     

Substrate-based inhibitors of HIV-1 protease

Summary Peptide substrates of HIV-1 protease can be divided into two categories based on the nature of the scissile dipeptide and amino acid preference at the S2 and S2' subsites. Inhibitors based on substrate peptide sequences seem to fall into two similar categories as well. There has been tremendous progress in the design of inhibitors for the HIV protease since the first peptide-based inhibitors were described in 1989. Using a variety of different dipeptide isosteres, it has been possible to obtain highly potent, highly selective inhibitors of HIV protease which have K_i values in the subnanomolar range and which exhibit anti-infective activity in vitro in the nanomolar range. Protease inhibitors developed by Roche, Abbott, Searle and Dupont-Merck are currently undergoing clinical trials. The rapid progress in this field, the diversity of inhibitor types and the increasing use of structural information in designing nonpeptide inhibitors augurs well for future success of protease inhibitor-based therapy.     

Assessment of the pharmacology and tolerability of PF-04457845, an irreversible inhibitor of fatty acid amide hydrolase-1, in healthy subjects

AIMS

To evaluate the pharmacology and tolerability of PF-04457845, an orally available fatty acid amide hydrolase-1 (FAAH1) inhibitor, in healthy subjects.

METHODS

Double-blind, randomized, placebo-controlled single and multiple rising dose studies and an open-label, randomized, food effect study were conducted. Plasma and urine PF-04457845 concentrations, plasma fatty acid amide concentrations and FAAH1 activity in human leucocytes were measured. Tolerability, including effects on cognitive function, were assessed.

RESULTS

PF-04457845 was rapidly absorbed (median t_max 0.5–1.2 h). Exposure increased supraproportionally to dose from 0.1 to 10 mg and proportionally between 10 and 40 mg single doses. The pharmacokinetics appeared dose proportional following 14 days once daily dosing between 0.5 and 8 mg. Steady-state was achieved by day 7. Less than 0.1% of the dose was excreted in urine. Food had no effect on PF-04457845 pharmacokinetics. FAAH1 activity was almost completely inhibited (>97%) following doses of at least 0.3 mg (single dose) and 0.5 mg once daily (multiple dose) PF-04457845. Mean fatty acid amide concentrations increased (3.5- to 10-fold) to a plateau and then were maintained following PF-04457845. FAAH1 activity and fatty acid amide concentrations returned to baseline within 2 weeks following cessation of dosing at doses up to 4 mg. There was no evidence of effects of PF-04457845 on cognitive function. PF-04457845, at doses up to 40 mg single dose and 8 mg once daily for 14 days, was well tolerated.

CONCLUSIONS

PF-04457845 was well tolerated at doses exceeding those required for maximal inhibition of FAAH1 activity and elevation of fatty acid amides.     

Synthesis and anti-HIV activity of new C2 symmetric derivatives designed as HIV-1 protease inhibitors

The synthesis of several new anti-HIV-1 compounds is described. The new compounds contain a C(2) symmetry axis and a dihidroxyethylene moiety based on the D-tartaric acid back bone. The synthesis of these compounds was achieved in 36-69% overall yields from D-tartaric acid. The protocol included: acetylation of hydroxyl groups, followed by diamide formation and deacetylation or reduction with LiAlH(4). The anti-HIV 1 activities of these substances were evaluated in PM-1 cells, using Indinavir as standard (IC(50) = 0.2 microM). Two amino alcohol derivatives showed good inhibitory activity against the virus, with IC(50) = 2.0 and 4 microM.     

Chromone and chromanone derivatives as strand transfer inhibitors of HIV-1 integrase

HIV-1 integrase catalyzes terminal cleavage at the 3′ end of the proviral DNA, removing a pair of bases and causing strand transfer by joining the 3′ end to 5′-phosphates in the target DNA. Several aryl 1,3-diketo acids that can inhibit the strand transfer reaction of HIV-1 IN have been identified. Here we synthesized a new series of compounds with a chromone or chromanone ring as conformationally constrained scaffolds of 1,3-diketo acids, and then tested their ability to inhibit HIV-1 IN-mediated strand transfer. All compounds moderately inhibited HIV-1 IN activity, indicating that the conformational restriction of one keto group into a chromone or chromanone ring decreases inhibition of the HIV-1 IN strand transfer.     

3D-QSAR studies on chromone derivatives as HIV-1 protease inhibitors: application of molecular field analysis

Three-dimensional quantitative structure-activity relationship (3D-QSAR) models were developed for chromone derivatives against HIV-1 protease using molecular field analysis (MFA) with genetic partial least square algorithms (G/PLS). Three different alignment methods: field fit, pharmacophore-based, and receptor-based were used to derive three MFA models. All models produced good predictive ability with high cross-validated r(2) (r(2) (cv)), conventional r(2), and predictive r(2)(r(2)(pred)) values. The receptor-based MFA showed the best statistical results with r(2) (cv) = 0.789, r(2)= 0.886, and r(2)(pred) = 0.995. The result obtained from the receptor-based model was compared with the docking simulation of the most active compound 21 in this chromone series to the binding pocket of HIV-1 protease (PDB entry 1AJX). It was shown that the MFA model related well with the binding structure of the complex and can provide guidelines to design more potent HIV-1 protease inhibitors.     

HEPT类HIV-1逆转录酶抑制剂的研究进展

逆转录酶是设计抗艾滋病药物研究的选择性靶酶,从作用机制、构效关系等方面综述HEPT及其类似物作为HIV-1逆转录酶抑制剂的研究进展.     

Pharmacokinetic study of a tripeptide HIV-1 protease inhibitor,KNI-174, in rats after intravenous and intraduodenal administrations

Recently, as a new type of anti-AIDS drug, an HIV-1 protease inhibitor, KNI-174, has been synthesized; it shows a potent and selective HIV-1 protease inhibitory activity in vitro. In this study, we developed an HPLC assay system for KNI-174 in rat plasma and examined the pharmacokinetics of KNI-174 in rats using this assay method after both intravenous (i.v.) and intraduodenal (i.d.) administrations to obtain the disposition characteristics and bioavailability of this new anti-AIDS drug. This HPLC assay method is specific to KNI-174 and the standard curve was linear from 0.02 to 30 μg ml^?1 plasma. After i.v. administration, 10.0 mg kg^?1, KNI-174 disappeared from the rats' plasma in a three-exponential decay. The mean terminal elimination half-life, t_1/2ÀZ, was 3.97 ± 0.19 (S.E.)h, the total body clearance, CL_tot, was 9.53 ± 1.08 ml min^?1 and the distribution volume at steady state, V_{d, ss}′ was 7070 ± 960 ml kg^?1. In the case of the i.d. administration, 10.0 mg kg^?1, the mean peak plasma concentration, C_max, and the peak time, t_max, were 0.196 ± 0.076 μg ml^?1 and 0.444 ± 0.193 h, respectively. The bioavailability of KNI-174 till infinity, BA^(0-infinity), was 5.37 per cent. Because the IC₅₀ of KNI-174 against HIV-1 in PHA-PBM was 138 ng ml^?1, the time needed for maintaining the concentrations above IC₅₀ after a single i.d. administration of KNI-174 is estimated to be 0.350 ± 0.184 h.     

Multidrug resistance reversal properties and cytotoxic evaluation of representatives of a novel class of HIV-1 protease inhibitors

Objectives P‐Glycoprotein (P‐gp) plays a central role in the development of resistance against cytostatics in anticancer therapy and against human immunodeficiency virus (HIV) therapeutics of the HIV‐1 protease inhibitor type. An approach to reverse the so‐called multidrug resistance (MDR) phenomenon by the use of P‐gp inhibiting agents is a challenge in the therapy of cancer and AIDS. Effective in‐vitro inhibitors have P‐gp substrate properties so that the expected in‐vivo effects have been disappointing so far. Consequent higher dosages cause toxic effects. Methods Novel HIV‐1 protease inhibitors (H17, JW41, JW33 and JW46) have been evaluated in comparison with ritonavir as P‐gp inhibiting agents, in the exclusively P‐gp overexpressing model cell line mouse T lymphoma using flow cytometry. The cytotoxic properties against various cell lines were characterized in the MTT (3‐[4,5‐dimethylthiazol‐2‐yl]‐2,5‐diphenyltetrazolium bromide) assay to estimate potential toxic effects in therapeutically relevant concentrations in metabolically active HepG2 cells, drug‐sensitive Jurkat cells and in gastric carcinoma cells. Key findings Concentration‐dependent effective reversal properties have been discussed in context and proved to be mainly influenced by the number of potential hydrogen bond acceptor functions. The compounds showed no cytotoxic properties in P‐gp inhibiting concentration ranges. Ritonavir, a known P‐gp substrate, proved to be less toxic in the P‐gp expressing cell line than in the nonexpressing cell line at the cell‐exposed concentrations and thus showed P‐gp substrate properties. Two compounds, H17 and JW41, showed no P‐gp substrate properties, with higher toxicity in the P‐gp expressing cell line compared with the nonexpressing cell line. Conclusions The novel compounds have been shown to be prospective AIDS therapeutics, acting as effective and nontoxic P‐gp inhibitors compared with ritonavir, which is a known P‐gp inhibitor with unfavourable toxic and P‐gp substrate properties.     

Absorption of new HIV-1 protease inhibitor,KNI-272, after intraduodenal and intragastric administrations to rats: Effect of solvent

KNI-272 is a tripeptide drug that has a strong pharmacological potential for treating human immunodeficiency virus type 1 (HIV-1). We have already reported the pharmacokinetic characteristics of KNI-272 after intravenous and intraduodenal (ID) administrations to rats. In this study, KNI-272 was administered to rats as a solution and the effect of four kinds of solvent on the bioavailability (BA) of KNI-272 was determined using rats. The mixtures included propylene glycol (PG) and water (70% PG), a solution of PG (100% PG), a solution of Tween 80 (Tween 80), and a mixture of PG and HCO60, a polyoxyethylated, 60μmol, castor oil derivative (PG:HCO60=7:3). After ID administration to rats at a dose of 50.0 mg kg^?1, the mean peak plasma concentrations, C_max, were 2.58±0.53 (SE) (70% PG), 3.28±0.51 (100% PG), 3.15±0.51 (Tween 80), and 4.66±0.68 μg mL^?1 (PG:HCO60). The highest BA, 44.6%, was obtained after ID administration of KNI-272 dissolved in PG:HCO60. On the other hand, after intragastric (IG) administration of KNI-272 solution in which the drug was dissolved with PG:HCO60, the T_max, the C_max, and the BA were 1.25±0.60h, 2.33±0.65 μg mL^?1, and 24.2%, respectively. The C_max and BA values were equal to half of the values obtained after ID administration of KNI-272 dissolved in the same solution. In this study, as the PG concentration in the solution increased and the other additives (Tween 80 and HCO60) were coadministered, the BA of KNI-272 after ID administration increased. These results suggest that, for the development of an oral dosage form of KNI-272, a non-ionic surfactant that dissolves in the duodenum or small intestine and that enhances the absorption of this drug from the gastrointestinal tract into the enterocytes is needed.     

Conformational versatility of the Nα-acylated tripeptide amide tail of oxytocin

The synthesis, physical and analytical characterization, and crystal-state structural analysis by X-ray diffraction of three analogues of the N^α-acylated tripeptide amide tail of oxytocin, each containing a cyclic C^{α, α-} disubstituted glycine at position 2, have been performed. The peptides arc Boc-L-Pro-Ac₃c-Gly-NH₂, Z-L-Pro-Ac₅c-Gly-NH₂ and Z-L-Pro-Ac₅c-Gly-NH₂. While the former is folded in a type-II β-turn conformation at the -L-Pro-Ac₃c- sequence, the two latter tripeptides form two consecutive (type-II, type-I′) β-turns. The Ac₅c- and Ac₆c-tripeptides are the first examples of such a highly folded structural combination in a position-2 analogue of the N^α-acylated -L-Pro-L-Leu-GIy-NH² sequence.     

Conformational studies on host-guest peptides containing chiral α-methyl-α-amino acids

The conformational behaviour of host-guest peptides of the type Ac-Ala-Xxx-Ala-Ala-Xxx-Ala-Ala-Xxx-Ala-Ala-NH-PEGM (Xxx =α-aminoisobutyric acid (Aib), (S)-2-ethylalanine ((S)-Iva). (S)-2-methyiserine ((S)-α-MeSer)) has been studied by CD spectroscopy in CF₃CH₂OH. CH₃OH. and water and by i.r. spectroscopy in CHCl₃ and in the solid state. In this way the relative helix-inducing potential of the two chiral α-methyl-α-amino acids (S)-Iva and (S)-α-MeSer could be established in comparison to the strong helix-former Aib. The results show that (S)-Iva exerts a comparable helix-inducing effect as Aib, making this amino acid a valuable complementary tool for the stabilization or induction of helices. No significant helix-promoting effect was observed for (S)-α-MeSer in polar solvents; however, the i.r.-spectroscopic data in CHCl₃ and in the solid state point to a helical conformation under these conditions. Possible reasons for the different behaviour of (S)-Iva and (S)-α-MeSer are briefly discussed.     

N‐hydroxy‐substituted 2‐aryl acetamide analogs: A novel class of HIV‐1 integrase inhibitors

An in silico method has been used to discover N‐hydroxy‐substituted 2‐aryl acetamide analogs as a new class of HIV‐1 integrase inhibitors. Based on the molecular requirements of the binding pocket of catalytic active site, two molecules (compounds 2 and 4b ) were designed as fragments. These were further synthesized and biologically evaluated. In vitro potency along with docking studies highlighted compound 4b as an active fragment which was further used to synthesize new leads as HIV‐1 integrase inhibitors. Finally, six promising compounds (compounds 5b , 5c , 5e, 6–2c, 6–3b, and 6–5b ) were identified by integrase inhibition assay (>50% inhibition). Based on in vitro anti‐HIV‐1 activity in a reporter gene‐based cell assay system, compounds 5d , 6s , and 6k were found as novel HIV‐1 integrase inhibitors due to its better selectivity index. Additionally, docking study revealed the importance of H‐bond as well as hydrophobic interactions with Asn155, Lys156, and Lys159 which were required for their anti‐HIV‐1 activity.     

New active HIV-1 protease inhibitors derived from 3-hexanol: conformation study of the free inhibitors in crystalline state and in complex with the enzyme

Four novel linear non‐peptidic HIV‐1 protease inhibitors derived from 2,5‐diamino‐1,6‐diphenyl‐3‐hexanol were synthesized and characterized. All of them exhibit tight binding to HIV‐1 protease, with inhibition constants K_i in the range 20 pm –5 nm . The investigated inhibitors were crystallized, and their crystal structures were determined by X‐ray diffraction. In all cases, the conformations found in the crystalline state differ significantly from the conformations obtained by computational docking of the inhibitor in the binding cleft of native HIV‐1 protease. Owing to the prevalence of hydrophobic substituents in all these inhibitors, the conformational mobility in water solution is restricted to their compact forms. The spectrum of low‐energy conformations in solution dramatically changes during the formation of inhibitor crystals (phenyl ring stacking as a leading motif) or during the formation of a complex with HIV‐1 protease (elongated conformation suitable to fit the enzyme pockets as a factor responsible for tight binding). High conformational flexibility and low conformational stress in the molecules of these inhibitors most likely increase their biological activity in comparison with more rigid compounds.     

Plasma pharmacokinetics and urinary and biliary excretion of a new potent tripeptide HIV-1 protease inhibitor,KNI-272, in rats after intravenous administration

The pharmacokinetic (PK) characteristics of KNI-272, a potent and selective HIV-1 protease inhibitor, were evaluated in rats after intravenous (IV) administration. The effect of dose on KNI-272 plasma kinetics, and the urinary and biliary elimination kinetics of KNI-272, were examined. After IV administration of 10.0 mg kg^?1 KNI-272, the mean terminal elimination half-life, t_1/2λz, was 3.49 ± 0.19 (SE) h, the total plasma clearance, CL_tot, was 15.1 ± 1.2 mL min^?1 and the distribution volume at steady state, V_d,ss, was 3790±280 mL kg^?1. On the other hand, after 1.0mg kg^?1 IV administration, t_d,ss, was 3.04±0.11 h, CL_tot was 15.9±0.2mL min^?1, and V_d,ss was 6950±600 mL kg^?1. The PK parameters of KNI-272 after IV administration showed that the disposition of KNI-272 in the rat plasma is linear within the dose range from 1.0 to 10.0mg kg^?1. Using an equilibrium dialysis method, the plasma binding of KNI-272 was measured in vitro. The free fractions were 17.7 ± 0.6%, 12.1±1.5%, and 13.8 ± 1.4% at the total concentration ranges of 9.898 ± 0.097 μg mL^?1, 0.888 ± 0.008 μg mL^?1, and 0.470±0.55 μg mL^?1, respectively. The percentages of the dose excreted into the urine and bile as the unchanged form were 1.20 ± 1.06% and 1.61 ± 0.32% at 1.0mg kg^?1 dose, and 0.164 ± 0.083% and 1.42 ± 0.26% at 10.0 mg kg^?1 dose, respectively. The renal clearance (CL_R) and the biliary clearance (CL_B) were calculated to be 0.191 and 0.256mL min^?1 for 1.0mg kg^?1, and 0.0248 and 0.215 mL min^?1 for 10.0 mg kg^?1, respectively. When comparing these values with the CL_tot values, the urinary and biliary excretion of KNI-272 are minor disposition routes.     

Comparison of a new orally potent tripeptide HIV-1 protease inhibitor (anti-aids drug) based on pharmacokinetic characteristics in rats after intravenous and intraduodenal administrations

Recently, a series of KNI compounds such as KNI-227 and KNI-272 has been synthesized and shows potent and selective HIV-1 protease inhibitory activity in vitro. In this study, we developed an HPLC assay system for KNI-227 and KNI-272 in rat plasma and examined the pharmacokinetic characteristics in rats after both intravenous (i.v.) and intraduodenal (i.d.) administrations to obtain the disposition characteristics and bioavailabilities of these new anti-AIDS drugs. After i.v. administration of KNI-227, 10.0mg kg^?1, the mean terminal elimination half-life, t_1/2λz, was 0.808±0.161(SE)h, the total body clearance, CL_tot, was 11.7±3.3 ml min^?1 and the distribution volume at steady state (V_d,ss) was 1410.460 ml kg^?1. On the other hand, after i.v. administration of KNI-272, 10.0mg kg^?1, t_1/2λz was 2.86±0.78 h, CL_tot was 15.3±1.4 ml min^?1 and V_d,ss was 3440.670 ml kg^?1. In the case of the i.d. administration of drugs, the mean peak plasma concentrations, C_max, of KNI-227 and KNI-272 were 0.374±0.110μg ml^?1 and 0.900±0.093 μg ml^?1, respectively. The bioavailabilities (BA) of KNI-227 and KNI-272 to infinity, BA^(0-∞), were 5.90% and 42.3%, respectively. As compared with the lead compound, KNI-174, the BA of KNI-272 was improved about 10 times. Although the anti-AIDS virus activity of these two drugs has not been investigated in vivo, KNI-272 is expected to be a better candidate for oral anti-AIDS therapies.     

Synthesis,in vitro evaluation and molecular docking studies of novel coumarin‐isatin derivatives as α‐glucosidase inhibitors

This study synthesized a series of novel coumarin‐isatin derivatives and evaluated them for α‐glucosidase inhibitory activity. The majority of the screened compounds exhibited excellent inhibition activities with IC₅₀ values of 2.56 ± 0.08–268.79 ± 3.04 μm , when compared to acarbose. Among the newly derivatives, compound 5p was found to be the most active compound in the library of coumarin‐isatin derivatives. Furthermore, enzyme kinetic studies showed that compound 5p is a non‐competitive inhibitor with a K_i of 2.14 μm . Molecular docking analysis revealed the existence of hydrophobic and hydrogen interactions between compound 5p and the active site of α‐glucosidase. Our results indicate that coumarin‐isatin derivatives as a new class of α‐glucosidase inhibitors.