A Comprehensive Review on Journey of Pyrrole Scaffold Against Multiple Therapeutic Targets.

Heterocyclic compounds are that type of substances that are deeply intertwined with biological processes. Heterocycles are found in about 90% of commercially available medicines. In medicinal chemistry, finding new synthetic molecules with drug-like characteristics is a regular problem, which triggered the development of pharmacological molecules, the majority of which are based on N-heterocyclic motifs. Among the heterocycles, the pyrrole scaffold is the most commonly found heterocycle in both natural and synthetic bioactive compounds. Pyrrole has a fivemembered heterocyclic ring with a plethora of pharmacophores, resulting in a library of different lead compounds. Pyrrole derivatives are physiologically active heterocyclic compounds that can be used as scaffolds for antibacterial, antiviral, anticancer, antitubercular, anti-inflammatory, and as enzyme inhibitors. On account of their extensive pharmacological profile, pyrrole and its various synthetic derivatives have drawn much attention from researchers to explore it for the benefit of humankind. This review presents an overview of recent developments in the pyrrole derivatives against multiple therapeutic targets.

Short Antimicrobial Peptides.

BACKGROUND: After the era of serendipitous discovery of penicillin and outburst in the discovery and development of highly efficient antibiotics, a surge in resistance against the target specific drugs was observed, primarily due to a combination of selective pressure of antibiotics use and spontaneous mutations. As per the World Health Organization, antibiotic resistance is one of the greatest threats to the mankind. OBJECTIVE: Short antimicrobial peptides (SAMPs) can be considered as a viable therapeutic alternative to conventional antibiotics in tackling resistant microbes. The ubiquitous nature of SAMPs combined with their ability to act via non-specific modes of action, high activity against a wide spectrum of drug-sensitive and drug-resistant microbes, and relative insusceptibility against the development of resistance adds to their desirability as new generation antibiotics. RESULTS: Due to the natural tendency of peptides to get metabolized by proteolytic enzymes, modification of naturally occurring SAMPs is desirable. The modifications can be done either by incorporating unnatural or modified amino acids into the peptide chain or by protecting C and N termini. The characteristic feature of SAMPs is their hydrophobicity and cationicity, which aid in the effective killing of microbes by selectively binding target and lysing the microbial cells with less deleterious effects on the host cells as compared to AMPs and other conventional antibiotics. CONCLUSION: Herein, we discussed the arsenal of short peptides and peptidomimetics starting from the smallest unit possible - a dipeptide to a decapeptide along with their activity profiles as antimicrobials. Recently, various SAMPs have paved their ways from in vitro studies to clinical trials, as evident from the most recent patent (EP1951194) on oral hygiene. This step by step growth of SAMPs has restored the hope in peptide-based therapeutics, which may prove an essential tool in eradicating antimicrobial resistance and tackling various microbial infections.

Synthesis, stability and mechanistic studies of potent anticryptococcal hexapeptides.

The growing incidents of cryptococcosis in immuno-compromised patients have created a need for novel drug therapies capable of eradicating the disease. The peptide-based drug therapy offers many advantages over the traditional therapeutic agents, which has been exploited in the present study by synthesizing a series of hexapeptides that exhibits promising activity against a panel of Gram-negative and Gram-positive bacteria and various pathogenic fungal strains; the most exemplary activity was observed against Cryptococcus neoformans. The peptides 3, 24, 32 and 36 displayed potent anticryptococcal activity (IC50 = 0.4-0.46 µg/mL, MIC = 0.63-1.25 µg/mL, MFC = 0.63-1.25 µg/mL), and stability under proteolytic conditions. Besides this, several other peptides displayed promising inhibition of pathogenic bacteria. The prominent ones include peptides 18-20, and 26 that exhibited IC50 values ranged between 2.1 and 3.6 µg/mL, MICs of 5-20 µg/mL and MBCs of 10-20 µg/mL against Staphylococcus aureus and methicillin-resistant S. aureus. The detailed mechanistic study on selected peptides demonstrated absolute selectivity towards the bacterial membranes and fungal cells by causing perturbations in the cell membranes, confirmed by the scanning electron microscopy and transmission electron microscopy studies.