General Installation of (4H)-Imidazolone cis-Amide Bioisosteres Along the Peptide Backbone.

Imidazolones represent an important class of heterocycles present in a wide range of pharmaceuticals, metabolites, and bioactive natural products and serve as the active chromophore in green fluorescent protein. Recently, imidazolones have received attention for their ability to act as a nonaromatic amide bond bioisotere which improves pharmacological properties. Herein, we present a tandem amidine installation and cyclization with an adjacent ester to yield (4H)-imidazolone products. Using amino acid building blocks, we can access the first examples of α-chiral imidazolones that have been previously inaccessible. Additionally, our method is amenable to on-resin installation which can be seamlessly integrated into existing solid-phase peptide synthesis protocols. Finally, we show that peptide imidazolones are potent cis-amide bond surrogates that preorganize linear peptides for head-to-tail macrocyclization. This work represents the first general approach to the backbone and side-chain insertion of imidazolone bioisosteres at various positions in linear and cyclic peptides.

Design, synthesis, and applications of ring-functionalized histidines in peptide-based medicinal chemistry and drug discovery.

Modified and synthetic α-amino acids are known to show diverse applications. Histidine, which possesses numerous applications when subjected to synthetic modifications, is one such amino acid. The utility of modified histidines varies widely from remarkable biological activities to catalysis, and from nanotechnology to polymer chemistry. This renders histidine residue an important place in scientific research. Histidine is a well-studied scaffold and constitutes the active site of various enzymes catalyzing important reactions in the biological systems. A rational modification in histidine structure with a distinctly developed protocol extensively changes its physical and chemical properties. The utilization of modified histidines in search of potent, target selective and proteostable scaffolds is vital in the development of bioactive peptides with enhanced drug-likeliness. This review is a compilation and analysis of reported side-chain ring modifications at histidine followed by applications of ring-modified histidines in the synthesis of various categories of bioactive peptides and peptidomimetics.

Culturing the unculturables: strategies, challenges, and opportunities for gut microbiome study.

Metagenome sequencing techniques revolutionized the field of gut microbiome study. However, it is equipped with experimental and computational biases, which affect the downstream analysis results. Also, live microbial strains are needed for a better understanding of host-microbial crosstalks and for designing next-generation treatment therapies based on probiotic strains and postbiotic molecules. Conventional culturing methodologies are insufficient to get the dark gut matter on the plate; therefore, there is an urgent need to propose novel culturing methods that can fill the limitations of metagenomics. The current work aims to provide a consolidated evaluation of the available methods for host-microbe interaction with an emphasis on in vitro culturing of gut microbes using organoids, gut on a chip, and gut bioreactor. Further, the knowledge of microbial crosstalk in the gut helps us to identify core microbiota, and key metabolites that will aid in designing culturing media and co-culturing systems for gut microbiome study. After the deeper mining of the current culturing methods, we recommend that 3D-printed intestinal cells in a multistage continuous flow reactor equipped with an extended organoid system might be a good practical choice for gut microbiota-based studies.

Synthetic amino acids-derived peptides target Cryptococcus neoformans by inducing cell membrane disruption.

We investigated synthetic amino acid-based approach to design short peptide-based antibiotics. Tautomerically restricted, amphiphilic 1-aryl-l-histidines along with hydrophobic tryptophan were utilized to synthesize the designed peptides. l-Trp-l-His(1-biphenyl)-NHBzl (12e, IC50 = 1.91 µg/mL; MIC = 3.46 µg/mL) and l-His[1-(4-n-butylphenyl)]-l-Trp-l-His[1-(4-n-butylphenyl)]-NHBzl (16d, IC50 = 1.36 µg/mL; MIC = 2.46 µg/mL) produced potency against Cryptococcus neoformans. Peptides with moderate antibacterial activities (IC50s = 4.40-8.80 µg/mL) were also identified. The mechanism of action and cellular changes revealed that membrane disruption due to interactions of the positively charged peptides with the negatively charged membrane of the cryptococcal cells result in permeabilization, leading to pore formation. The internal localization of the peptides instigated the interactions with DNA causing fragmentation of the genetic material, which together with membrane disruption led to cell death. Flow cytometric analysis points to cells death by apoptotic pathway. Time kill kinetics and synergistic study confirmed the fungicidal nature and synergism with amphotericin B.

Greater COVID-19 Severity and Mortality in Hospitalized Patients in the Delta-phase Compared to the Others: A Single Center Prospective Registry.

BACKGROUND AND OBJECTIVE: To compare clinical and laboratory features, and outcomes in the second COVID-19 phase (delta variant) with the first and third phases in India we performed a registry-based study. METHODS: Patients with confirmed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection were recruited over the study period from March 2020 to July 2022. In the first phase (wild type, March-December 2020) of the 7,476 suspected, 1,395 (18.7%) were positive and 863 (61.8%) were hospitalized, in the second phase (delta, January-July 2021) out of 8,680 suspected, 1,641 (19.4%) tested positive and 388 (23.6%) were hospitalized, and in the third phase (omicron, January-July 2022) out of 5,188 suspected patients, 886 (17.1%) tested positive and 94 (10.6%) were hospitalized. We compared details of admission clinical and laboratory features and in-hospital management and outcomes in the three phases. RESULTS: A total of 2,352 patients were recruited. The majority of the patients were men, aged <45 years were 20% and about 20% of patients had hypertension, diabetes, and cardiovascular diseases. Patients in the second phase had significantly more cough, fever, shortness of breath, and lower oxygen saturation (SpO2) at admission and also had more lymphopenia, C-reactive proteins (CRPs), interleukin-6, ferritin, lactic dehydrogenase, and transaminases than patients in the other two phases. In the second vs the first and third phases, the requirement of supplementary oxygen (47.9 vs 33.1 and 23.4%), proning (89.2 vs 37.1 and 5.3%), high flow nasal oxygen (15.7 vs 8.71 and 5.3%), noninvasive ventilation (14.4 vs 9.1 and 11.7%), invasive ventilation (16.2 vs 9.1 and 9.6%), steroids (94.1 vs 83.4 and 37.2%), remdesivir (91.2 vs 73.8 and 39.4%), and anticoagulants (94.3 vs 83.0 and 61.7%) was significantly more (p < 0.001). The median length of stay in days [interquartile range (IQR)] was longer in the second phase [8 (6-10)] vs the first [7 (5-10)] and the third phase [4 (3-6) days]. The intensive care unit (ICU) stay in the second phase [9 (5-13) days] was also significantly more than the first [6 (2-10)] and third [0 (0-3)] phases (p <0.001). Overall, in-hospital deaths occurred in 176 patients (12.8%). Deaths were significantly higher in the second phase (19.3%), compared to the first (11.0%) and the third (3.3%) phases (p <0.01). We also observed that greater disease severity at presentation was associated with higher mortality in all the phases. CONCLUSION: This study shows that COVID-19 patients that were hospitalized in the second (delta) phase of the epidemic had more severe disease compared to the first and third phases. In the second phase of patients, there was a significantly higher duration of hospitalization, ICU hospitalization, greater oxygen requirement, noninvasive and invasive ventilatory support, and more deaths.

A General Strategy to Install Amidine Functional Groups Along the Peptide Backbone.

Amidines are a structural surrogate for peptide bonds, yet have received considerably little attention in peptides due to limitations in existing methods to access them. The synthetic strategy developed in this study represents the first robust and general procedure for the introduction of amidines into the peptide backbone. We exploit and further develop the utility and efficiency of thioimidate protecting groups as a means to side-step reactivity that ultimately renders existing methods unsuitable for the installation of amidines along the main-chain of peptides. This work is significant because it describes a generally applicable path to access unexplored peptide designs and architectures for new therapeutics made possible by the unique properties of amidines.

Deletion of Specific Conserved Motifs from the N-Terminal Domain of αB-Crystallin Results in the Activation of Chaperone Functions.

Smaller oligomeric chaperones of α-crystallins (αA- and αB-) have received increasing attention due to their improved therapeutic potential in preventing protein aggregating diseases. Our previous study suggested that deleting 54-61 residues from the N-terminal domain (NTD) of αB-crystallin (αBΔ54-61) decreases the oligomer size and increases the chaperone function. Several studies have also suggested that NTD plays a significant role in protein oligomerization and chaperone function. The current study was undertaken to assess the effect of deleting conserved 21-28 residues from the activated αBΔ54-61 (to get αBΔ21-28, Δ54-61) on the structure-function of recombinant αBΔ21-28, Δ54-61. The αBΔ21-28, Δ54-61 mutant shows an 80% reduction in oligomer size and 3- to 25-fold increases in chaperone activity against model substrates when compared to αB-WT. Additionally, the αB∆21-28, ∆54-61 was found to prevent ß-amyloid (Aß1-42) fibril formation in vitro and suppressed Aß1-42-induced cytotoxicity in ARPE-19 cells in a more effective manner than seen with αB-WT or αB∆54-61. Cytotoxicity and reactive oxygen species (ROS) detection studies with sodium iodate (SI) showed that the double mutant protein has higher anti-apoptotic and anti-oxidative activities than the wild-type or αB∆54-61 in oxidatively stressed cells. Our study shows that the residues 21-28 and 54-61 in αB-crystallin contribute to the oligomerization and modulate chaperone function. The deletion of conserved 21-28 residues further potentiates the activated αBΔ54-61. We propose that increased substrate affinity, altered subunit structure, and assembly leading to smaller oligomers could be the causative factors for the increased chaperone activity of αBΔ21-28, Δ54-61.

Effect of Structural Changes Induced by Deletion of 54FLRAPSWF61 Sequence in αB-crystallin on Chaperone Function and Anti-Apoptotic Activity.

Previously, we showed that the removal of the 54-61 residues from αB-crystallin (αBΔ54-61) results in a fifty percent reduction in the oligomeric mass and a ten-fold increase in chaperone-like activity. In this study, we investigated the oligomeric organization changes in the deletion mutant contributing to the increased chaperone activity and evaluated the cytoprotection properties of the mutant protein using ARPE-19 cells. Trypsin digestion studies revealed that additional tryptic cleavage sites become susceptible in the deletion mutant than in the wild-type protein, suggesting a different subunit organization in the oligomer of the mutant protein. Static and dynamic light scattering analyses of chaperone-substrate complexes showed that the deletion mutant has more significant interaction with the substrates than wild-type protein, resulting in increased binding of the unfolding proteins. Cytotoxicity studies carried out with ARPE-19 cells showed an enhancement in anti-apoptotic activity in αBΔ54-61 as compared with the wild-type protein. The improved anti-apoptotic activity of the mutant is also supported by reduced caspase activation and normalization of the apoptotic cascade components level in cells treated with the deletion mutant. Our study suggests that altered oligomeric assembly with increased substrate affinity could be the basis for the enhanced chaperone function of the αBΔ54-61 protein.

Functional Rescue of Cataract-Causing αA-G98R-Crystallin by Targeted Compensatory Suppressor Mutations in Human αA-Crystallin.

The G98R mutation in αA-crystallin is associated with the onset of presenile cataract and is characterized biochemically by an increased oligomeric mass, altered chaperone function, and loss of structural stability over time. Thus, far, it is not known whether the inherent instability caused by gain-of-charge mutation could be rescued by a compensatory loss of charge mutation elsewhere on the protein. To answer this question, we investigated whether αA-G98R-mediated instability could be rescued through suppressor mutations by introducing site-specific "compensatory" mutations in αA-G98R-crystallin, αA-R21Q/G98R, αA-G98R/R116C, and αA-R157Q/G98R. The recombinant proteins were expressed, purified, characterized, and evaluated by circular dichroism (CD), intrinsic fluorescence, and bis-ANS-binding studies. Chaperone-like activities of recombinant proteins were assessed using alcohol dehydrogenase (ADH) and insulin as unfolding substrates. Far-UV CD studies revealed an increased α-helical content in αA-G98R in comparison to αA-WT, αA-R21Q, R157Q, and the double mutants, αA-R21Q/G98R, and αA-R157Q/G98R. Compared to αA-WT, αA-R21Q, and αA-G98R, the double mutants showed an increased intrinsic tryptophan fluorescence, whereas the highest hydrophobicity (bis-ANS-binding) was shown by αA-G98R. Introduction of a second mutation in αA-G98R reduced its bis-ANS-binding activity. Both αA-R21Q/G98R and αA-R157Q/G98R showed greater chaperone-like activity against ADH aggregation than αA-G98R. However, among the three G98R mutants, only αA-R21Q/G98R protected ARPE-19 cells from H2O2-induced cytotoxicity. These results suggest that the lost chaperone-like activity of αA-G98R-crystallin can be rescued by another targeted mutation and that substitution of αA-R21Q-crystallin at the N-terminal region can rescue a deleterious mutation in the conserved α-crystallin domain of the protein.

An investigation on the influence of yogic methods on heart rate variability.

BACKGROUND: The role of underlying mechanisms of yogic strategies which exert beneficiary effects on cardiac autonomic control is poorly understood. We have performed heart rate variability (HRV) analysis on subjects performing yogic methods and control subjects who mimic them through paced breathing and focused attention tasks using external cues. METHODS: Heart rate (HR) time series is generated from electrocardiogram measured from subjects of yogic group (YG); performing yogic practices (n = 15), paced breathing group (PBG); involved in breathing exercises cued at breathing rates (BR) from 3 to 15 cycles per minute (cpm) (n = 23), normal breathing group (NBG) under regular breathing (n = 15), and subjects performing three different cognitive tasks designated as focused attention group (FAG), (n = 24). HRV is analyzed using coherence plots, spectrograms, HRV parameters, and instantaneous frequency recurrence plots (IFRP). RESULTS: HRV is similar among YG and PBG (at BR <12 cpm) and significantly different for YG vs. NBG (p < 0.001) and PBG vs. NBG (p < 0.001). Regularity of breathing oscillations observed in HR is quantified using IFRP and is identical among FAG, PBG, and YG and significantly different for YG vs. NBG (p < 0.01), PBG vs. NBG (p < 0.01), and FAG vs. NBG (p < 0.05). CONCLUSIONS: Low-frequency breathing (BR <12 cpm) plays a primary role in eliciting physiologically significant changes in HRV. By identifying a similarity in breathing oscillations of HR of FAG, YG, and PBG, the results recognize the coexistence of attention and breathing strategies and postulate their joint role in sustaining autonomic benefits, while effects induced by breathing alone on HRV could be attained even intermittently.

The Meta-Position of Phe4 in Leu-Enkephalin Regulates Potency, Selectivity, Functional Activity, and Signaling Bias at the Delta and Mu Opioid Receptors.

As tool compounds to study cardiac ischemia, the endogenous δ-opioid receptors (δOR) agonist Leu5-enkephalin and the more metabolically stable synthetic peptide (d-Ala2, d-Leu5)-enkephalin are frequently employed. However, both peptides have similar pharmacological profiles that restrict detailed investigation of the cellular mechanism of the δOR's protective role during ischemic events. Thus, a need remains for δOR peptides with improved selectivity and unique signaling properties for investigating the specific roles for δOR signaling in cardiac ischemia. To this end, we explored substitution at the Phe4 position of Leu5-enkephalin for its ability to modulate receptor function and selectivity. Peptides were assessed for their affinity to bind to δORs and µ-opioid receptors (µORs) and potency to inhibit cAMP signaling and to recruit ß-arrestin 2. Additionally, peptide stability was measured in rat plasma. Substitution of the meta-position of Phe4 of Leu5-enkephalin provided high-affinity ligands with varying levels of selectivity and bias at both the δOR and µOR and improved peptide stability, while substitution with picoline derivatives produced lower-affinity ligands with G protein biases at both receptors. Overall, these favorable substitutions at the meta-position of Phe4 may be combined with other modifications to Leu5-enkephalin to deliver improved agonists with finely tuned potency, selectivity, bias and drug-like properties.

Resistant Hypertension in Clinical Practice in India: Jaipur Heart Watch.

BACKGROUND: Hypertension is highly prevalent in India but frequency of resistant hypertension has not been well studied. METHODS: We performed a registry-based study at a single center in patients with primary diagnosis of hypertension (n=3073). Details of co-morbidities, medications and blood pressure (BP) control were obtained. Patients with coronary heart disease, cerebrovascular disease and chronic kidney disease were excluded. Resistant hypertension was defined as uncontrolled hypertension (BP ≥140/90) with use of 3 drugs of which one was a diuretic, or any 4 drugs. RESULTS: Mean age of patients was 59±13 years, 47% were women and 26% <50y age. Diabetes was in 31.1%, hypothyroidism in 7.9% and chronic obstructive lung disease in 4.3%. The drugs prescribed were angiotensin converting enzyme inhibitors (ACEi) or angiotensin receptor blockers (ARB) in 61.5%, beta blockers in 49.8%, dihydropyridine calcium channel blockers (CCB) in 46.8%, ARB in 44.4%, diuretics in 32.1% ACEi in 13.4%, other CCBs in 2.6% and mineralocorticoid receptor antagonists (MRA) in 1.1%. One antihypertensive drug was prescribed in 27.4%, two in 41.2%, three in 18.6% and four or more in 5.4%. Prevalence of resistant hypertension using standard definition was 19.4% (95% confidence interval, CI, 18.0-20.8%). It was more in women (23.5%) vs men (15.7%) (p<0.001). Using the alternate definition the prevalence was 6.3% (95% CI 5.3-7.0%) and also more in women (6.9%) vs men (5.4%). Resistant hypertension was more common in patients >60 years (odds ratio 1.36, 95% CI 1.18-1.58) and women (odds ratio 1.64, 95% CI 1.37-1.97). CONCLUSION: Prevalence of resistant hypertension is high in a secondary-care practice in India. It is significantly greater among older patients and women.

Quality of Hypertension Management in Type 2 Diabetes in India: A Multisite Prescription Audit.

BACKGROUND AND OBJECTIVE: Renin-angiotensin system (RAS) blockers (angiotensin converting enzyme inhibitors ACEI, angiotensin receptor blockers, ARB) are preferred drugs to control hypertension among diabetic patients. To determine frequency of RAS blocker use in hypertensive patients with type 2 diabetes, we performed a multisite study in India. METHODS: We evaluated physician prescriptions in consecutive patients with type 2 diabetes at 9 sites in India. Details of socio-demographic characteristics, clinical findings and prescription medicines were obtained. Descriptive statistics are reported. RESULTS: Hypertension treatment details were available in 8056 of 8699 diabetic patients (4829 men, 3227 women). No hypertension was in 3300 (40.9%), hypertension in 3625 (45.0%), and hypertension with vascular disease in 1131 (14.0%). In diabetics with no hypertension, hypertension, and hypertension with vascular disease, respectively, prescriptions of antihypertensive drugs was: RAS blockers in 19.4, 48.2 and 58.1%, beta-blockers in 4.8, 31.6 and 38.8%, calcium channel blockers in 0.4, 27.4 and 14.3% and diuretics in 0.6, 36.4 and 17.1%. ACEIs were prescribed more frequently than ARB's in hypertensive diabetics (60.7 vs 39.2%) as well as in diabetics with vascular disease (58.6 vs 41.4%). In diabetics with hypertension (n=3625) prescription of one, two or three antihypertensive drugs was 49.8%, 33.7% and 3.5% while statins were prescribed in 54.1%. CONCLUSION: Use of RAS blockers (ACEI or ARB) in uncomplicated as well as complicated hypertensive patients with type 2 diabetes is sub-optimal. Most of the patients are on one drug and prescription of ≥3 drugs are rare. Statins are prescribed in only a half.

Structural and functional consequences of chaperone site deletion in αA-crystallin.

The chaperone-like activity of αA-crystallin has an important role in maintaining lens transparency. Previously we identified residues 70-88 as a chaperone site in αA-crystallin. In this study, we deleted the chaperone site residues to generate αAΔ70-76 and αAΔ70-88 mutants and investigated if there are additional substrate-binding sites in αA-crystallin. Both mutant proteins when expressed in E. coli formed inclusion bodies, and on solubilizing and refolding, they exhibited similar structural properties, with a 2- to 3-fold increase in molar mass compared to the molar mass of wild-type protein. The deletion mutants were less stable than the wild-type αA-crystallin. Functionally αAΔ70-88 was completely inactive as a chaperone, while αAΔ70-76 demonstrated a 40-50% reduction in anti-aggregation activity against alcohol dehydrogenase (ADH). Deletion of residues 70-88 abolished the ADH binding sites in αA-crystallin at physiological temperature. At 45°C, cryptic ADH binding site(s) became exposed, which contributed subtly to the chaperone-like activity of αAΔ70-88. Both of the deletion mutants were completely inactive in suppressing aggregation of ßL-crystallin at 53°C. The mutants completely lost the anti-apoptotic property that αA-crystallin exhibits while they protected ARPE-19 (a human retinal pigment epithelial cell line) and primary human primary lens epithelial (HLE) cells from oxidative stress. Our studies demonstrate that residues 70-88 in αA-crystallin act as a primary substrate binding site and account for the bulk of the total chaperone activity. The ß3 and ß4 strands in αA-crystallin comprising 70-88 residues play an important role in maintenance of the structure and in preventing aggregation of denaturing proteins.

Regioselective copper-catalyzed N(1)-(hetero)arylation of protected histidine.

We report regioselective N(1)-arylation of protected histidine using copper(i) iodide as a catalyst, trans-N,N'-dimethylcyclohexane-1,2-diamine as a ligand and readily available aryl iodides as coupling partners under microwave irradiation at 130 °C for 40 min. The reaction provides rapid access to electron-donating, electron-withdrawing and bulky group substituted N-arylated histidines in high yields, including previously inaccessible N-heteroaryl histidines. These N(1)-(hetero)aryl histidines are promising building blocks in peptide-based drug design and discovery.

Room temperature N-arylation of amino acids and peptides using copper(I) and ß-diketone.

A mild and efficient method for the N-arylation of zwitterionic amino acids, amino acid esters and peptides is described. The procedure provides the first room temperature synthesis of N-arylated amino acids and peptides using CuI as a catalyst, diketone as a ligand, and aryl iodides as coupling partners. The method is equally applicable for using relatively inexpensive aryl bromides as coupling partners at 80 °C. Using this procedure, electronically and sterically diverse aryl halides, containing reactive functional groups were efficiently coupled in good to excellent yields.

Analgesic effect of piracetam on peripheral neuropathic pain induced by chronic constriction injury of sciatic nerve in rats.

Despite immense advances in the treatment strategies, management of neuropathic pain remains unsatisfactory. Piracetam is a prototype of nootropic drugs, used to improve cognitive impairment. The present study was designed to investigate the effect of piracetam on peripheral neuropathic pain in rats. Neuropathic pain was induced by the chronic constriction injury of the sciatic nerve. Following this, piracetam was intraperitoneally administered for 2 weeks in doses of 50, 100 and 200 mg/kg, and pain was assessed by employing the behavioural tests for thermal hyperalgesia (hot plate and tail flick tests) and cold allodynia (acetone test). After the induction of neuropathic pain, significant development of thermal hyperalgesia and cold allodynia was observed. The administration of piracetam (50 mg/kg) did not have any significant effect on all the behavioural tests. Further, piracetam (100 mg/kg) also had no effect on the hot plate and tail flick tests; however it significantly decreased the paw withdrawal duration in the acetone test. Piracetam in a dose of 200 mg/kg significantly modulated neuropathic pain as observed from the increased hot plate and tail flick latencies, and decreased paw withdrawal duration (in acetone test). Therefore, the present study suggests the potential use of piracetam in the treatment of neuropathic pain, which merits further clinical investigation.

Protective effect of melatonin on propoxur-induced impairment of memory and oxidative stress in rats.

Propoxur (a carbamate pesticide) has been shown to adversely affect memory and induce oxidative stress on both acute and chronic exposure. This study was designed to explore the modulation of the effects of propoxur over cognitive function by melatonin (MEL). Cognitive function was assessed using step-down latency (SDL) on a passive avoidance apparatus, and transfer latency (TL) on an elevated plus maze. Oxidative stress was assessed by examining brain malondialdehyde (MDA) and reduced glutathione (GSH) levels and catalase (CAT) activity. A significant reduction in SDL and prolongation of TL was observed for the propoxur (10 mg/kg/d; p.o.) treated group at weeks 6 and 7 when compared with control. One week treatment with MEL (50 mg/kg/d; i.p.) antagonized the effect of propoxur on SDL, as well as TL. Propoxur produced a statistically significant increase in the brain MDA levels and decrease in the brain GSH levels and CAT activity. Treatment with MEL attenuated the effect of propoxur on oxidative stress. The results of the present study thus show that MEL has the potential to attenuate cognitive dysfunction and oxidative stress induced by toxicants like propoxur in the brain.

The effect of the essential oil of Eugenia caryophyllata in animal models of depression and locomotor activity.

OBJECTIVE: The essential oil of Eugenia caryophyllata (clove oil; Family: Myrtaceae) is used in dental care as an antiseptic and analgesic. The present study investigates the effect of clove oil on animal models of depression and locomotion. METHODS: Clove oil was administered in doses of 0.025, 0.05, and 0.1 ml/kg/day, intraperitoneally (i.p.) for 3 weeks. The forced swim test (FST) and the tail suspension test (TST) were used to assess depression. To evaluate locomotor activity, the rota rod test and the photoactometer procedure were performed. RESULTS: In the FST, it was observed that the duration of immobility was significantly decreased (P < 0.01) in animals treated with clove oil (0.05 and 0.1 ml/kg); however, the clove oil dose of 0.025 ml/kg showed an insignificant increase in the immobile period. The TST demonstrated that pretreatment with clove oil decreases (P < 0.01) the immobile period significantly at all the three administered doses. Similarly, the photoactometer procedure showed increased locomotor activity at all the three doses, although significant (P < 0.05) only at 0.1 ml/kg. In addition, the rota rod test showed that animals treated with clove oil (0.1 ml/kg) enhanced muscle coordination as demonstrated by a significant increase (P < 0.05) in the latency to fall from the rota rod as compared to the control. However, the lowest administered dose (0.025 ml/kg, i.p.) decreased the latency to fall from the rota rod significantly (P < 0.05) compared to the control. Clove oil (0.05 ml/kg) also showed a decrease in the latency to fall from the rota rod although the result was not statistically significant. DISCUSSION: Thus, it can be concluded that pretreatment with clove oil decreases depression and enhances locomotor activity similar to that exhibited by psychostimulants.

Peptide-based drug discovery: Current status and recent advances.

The progressive development of peptides from reaction vessels to life-saving drugs via rigorous preclinical and clinical assessments is fascinating. Peptide therapeutics have gained momentum with the evolution of techniques in peptide chemistry, such as microwave irradiation in solid- and solution-phase synthesis, ligation chemistry, recombinant synthesis, and amalgamation with synthetic tools, including metal catalysis. Diverse emerging technologies, such as DNA-encoded libraries (DELs) and display techniques, are changing the status quo in the discovery of peptide therapeutics. In this review, we analyzed US Food and Drug Administration (FDA)-approved peptide drugs and those in clinical trials, highlighting recent advances in peptide-based drug discovery.