Molecular recognition of a branched peptide with HIV-1 Rev Response Element (RRE) RNA

Interaction of HIV-1 rev response element (RRE) RNA with its cognate protein, Rev, is critical for HIV-1 replication. Understanding the mode of interaction between RRE RNA and ligands at the binding site can facilitate RNA molecular recognition as well as provide a strategy for developing anti-HIV therapeutics. Our approach utilizes branched peptides as a scaffold for multivalent binding to RRE IIB (high affinity rev binding site) with incorporation of unnatural amino acids to increase affinity via non-canonical interactions with the RNA. Previous high throughput screening of a 46,656-member library revealed several hits that bound RRE IIB RNA in the sub-micromolar range. In particular, the lead compound, 4B3, displayed a Kd value of 410 nM and demonstrated selectivity towards RRE. A ribonuclease protection assay revealed that 4B3 binds to the stem-loop structure of RRE IIB RNA, which was confirmed by SHAPE analysis with 234 nt long NL4-3 RRE RNA. Our studies further indicated interaction of 4B3 with both primary and secondary Rev binding sites.

Discovery of a Branched Peptide That Recognizes the Rev Response Element (RRE) RNA and Blocks HIV-1 Replication

We synthesized and screened a unique 46 656-member library composed of unnatural amino acids that revealed several hits against RRE IIB RNA. Among the hit peptides identified, peptide 4A5 was found to be selective against competitor RNAs and inhibited HIV-1 Rev-RRE RNA interaction in cell culture in a p24 ELISA assay. Biophysical characterization in a ribonuclease protection assay suggested that 4A5 bound to the stem-loop region in RRE IIB while SHAPE MaP probing with 234 nt RRE RNA indicated additional interaction with secondary Rev binding sites. Taken together, our investigation suggests that HIV replication is inhibited by 4A5 blocking binding of Rev and subsequent multimerization.

Branched Peptides: Acridine and Boronic Acid Derivatives as Antimicrobial Agents

The emergence of microbial resistance presents a challenge in the development of next generation therapeutics. Herein, we report the discovery of branched peptides decorated with acridine and boronic acid moieties with potent antimicrobial activity. The results revealed minimal inhibitory concentrations (MICs) as low as 1 μg/mL against Staphylococcus aureus, Candida albicans, and Escherichia coli. These peptides were nonhemolytic, and significantly inhibited growth of C. albicans in suspension and biofilm formation. Structure-activity relationship studies suggest the acridine functional group as a driving force for the potent inhibition observed against bacteria.

Effect of intercalator and Lewis acid-base branched peptide complex formation: boosting affinity towards HIV-1 RRE RNA

High throughput screening of a 4096 compound library of boronic acid and acridine containing branched peptides revealed compounds that have dissociation constants in the low nanomolar regime for HIV-1 RRE IIB RNA. We demonstrate that branched peptide boronic acids A5, A6, and A7 inhibit the production of p24, an HIV-1 capsid protein, in a dose-dependent manner.

Characterization and in vitro activity of a branched peptide boronic acid that interacts with HIV-1 RRE RNA

A branched peptide containing multiple boronic acids was found to bind RRE IIB selectively and inhibit HIV-1 p24 capsid production in a dose-dependent manner. Structure-activity relationship studies revealed that branching in the peptide is crucial for the low micromolar binding towards RRE IIB, and the peptide demonstrates selectivity towards RRE IIB in the presence of tRNA. Footprinting studies suggest a binding site on the upper stem and internal loop regions of the RNA, which induces enzymatic cleavage of the internal loops of RRE IIB upon binding.

HIV-1 drug discovery: targeting folded RNA structures with branched peptides

Human immunodeficiency virus type 1 (HIV-1) is an RNA virus that is prone to high rates of mutation. While the disease is managed with current antiretroviral therapies, drugs with a new mode of action are needed. A strategy towards this goal is aimed at targeting the native three-dimensional fold of conserved RNA structures. This perspective highlights medium-sized peptides and peptidomimetics used to target two conserved RNA structures of HIV-1. In particular, branched peptides have the capacity to bind in a multivalent fashion, utilizing a large surface area to achieve the necessary affinity and selectivity toward the target RNA.

Personality and affective forecasting: trait introverts underpredict the hedonic benefits of acting extraverted

People report enjoying momentary extraverted behavior, and this does not seem to depend on trait levels of introversion-extraversion. Assuming that introverts desire enjoyment, this finding raises the question, why do introverts not act extraverted more often? This research explored a novel explanation, that trait introverts make an affective forecasting error, underpredicting the hedonic benefits of extraverted behavior. Study 1 (n = 97) found that trait introverts forecast less activated positive and pleasant affect and more negative and self-conscious affect (compared to extraverts) when asked to imagine acting extraverted, but not introverted, across a variety of hypothetical situations. Studies 2-5 (combined n = 495) found similar results using a between-subjects approach and laboratory situations. We replicated findings that people enjoy acting extraverted and that this does not depend on disposition. Accordingly, the personality differences in affective forecasts represent errors. In these studies, introverts tended to be less accurate, particularly by overestimating the negative affect and self-consciousness associated with their extraverted behavior. This may explain why introverts do not act extraverted more often (i.e., they overestimate hedonic costs that do not actually materialize) and have implications for understanding, and potentially trying to change, introverts' characteristically lower levels of happiness.

Stability of midazolam hydrochloride in a flavored, dye-free oral solution

The stability of injectable midazolam hydrochloride in a solution for oral use was studied at three temperatures over 56 days. A 2.5-mg/mL oral solution was prepared from injectable midazolam hydrochloride and a flavored, dye-free syrup. Samples of solution were stored in amber glass bottles at 7, 20, or 40 degrees C. Duplicate samples were analyzed by high-performance liquid chromatography on days 0, 1, 3, 5, 14, 21, 35, and 56. Samples were also visually inspected on each sampling day. The concentrations of all samples remained greater than 90% of the original concentration and there were no visual signs of microbial growth or changes in color, turbidity, or odor throughout the 56-day period. A 2.5-mg/mL solution of injectable midazolam in syrup was stable for 56 days at 7, 20, or 40 degrees C.

Effects of microsomal enzyme induction on toxicity of p-N, N-bis (2-chloroethyl)aminophenyl alkyl ethers in mice and survival times in L-1210 leukemic mice

Four alkyl ethers of p-N,N-bis(2-chloroethyl)aminophenol were selected to study the effects of microsomal enzyme induction by phenobarbital on the toxicity changes as reflected by LD50 and alteration of survival times in L-1210 leukemic mice. In the phenobarbital pretreated mice the LD50 for the ethyl ether of p-N,N-bis(2-chloroethyl)aminophenol was decreased from 1641 to 1213 microns/kg. This result suggests that O-dealkylation is the major metabolic pathway. The LD50 for the propyl ether of p-N,N-bis(2-chloroethyl)aminophenol was increased by the pretreatment from 605 to 678 microns/kg. The LD50 for the butyl ether was increased from 714 to 910 microns/kg. An additional metabolic pathway, (omega-1)-hydroxylation, is suggested for the propyl and butyl ethers. The hexyl ether appeared to be unaffected by the pretreatment; thus, O-dealkylation was ruled out as a major pathway. In the survival studies, the pretreatment reduced the antitumor effectiveness of the ethyl and the butyl ethers. The survival times were increased for some dose levels for the propyl ether. No significant trend in survival times was observed for the hexyl ether in the pretreated mice.

Synthesis and bioevaluation of a series of fatty acid esters of p-[N,N-bis(2-chloroethyl)amino]phenol

A series of even numbered fatty acid esters (C2-C18) of p-[N,N-bis(2-chloroethyl)amino]phenol were synthesized and evaluated as to acute toxicity as well as effectiveness against L-1210 mouse leukemia. The acetate through the decanoate derivatives demonstrated toxicity between 2 and 3 times that of phenol mustard in HA/ICR mice. The less soluble laurate, myristate, palmitate, and stearate derivatives were less toxic. Significant survival times in the leukemia studies (T/C% greater than or equal to 125) were observed for all compounds except the acetate and hexanoate derivatives. The myristate derivative produced the greatest significant increase in survival time, 162%. The palmitate and stearate derivatives produced significant survival at five and four dosage levels, respectively. The butyrate and laurate derivatives produced significant survival at three dosage levels and the octanoate, decanoate, and myristate at two dosage levels.

Synthesis and bioevaluation of a series of alkyl ethers of p-N,N-bis(2-chloroethyl)aminophenol

A series of even numbered normal alkyl ethers (C2-C14) of p-N,N-bis(2-chloroethyl)aminophenol were synthesized and evaluated as to acute toxicity in mice and effects on survival in L-1210 leukemic mice. All of the ether derivatives demonstrated significantly lower acute toxicity than the parent phenol mustard. Significant survival times (greater than or equal to 125%) were obtained with all compounds except the hexyl derivative. The decyl ether produced the greatest significant increase and the ethyl ether the lowest significant increase in mean survival time. Significant survival times were produced at four dosage levels for the butyl, decyl, and dodecyl derivatives, three dosage levels for the octyl and tetradecyl derivatives, and one dosage level for the ethyl derivative.

Comparison of quantitation methods for L-1210 cell populations and evaluation of selected cytotoxic agents in leukemic mice

A more rapid cell-counting technique using an electronic cell counter was developed as an improvement over the slower hemocytometer method. The electronic counting method produced cell counts that had a smaller standard deviation but were not significantly different from the hemocytometer method. The acetate, hexanoate, and decanoate esters of p-N,N-bis(2-chloroethyl)aminophenol were investigated for acute toxicity in mice, effects on survival times, and effects on L-1210 cell populations in L-1210 leukemic mice. The decanoate ester was the least toxic compound and was most effective in lengthening the lifespan of the mice. The acetate and hexanoate esters were more effective in reducing L-1210 cell populations.