Bipul Kumar

Multifunctional self-assembled cationic peptide nanostructures efficiently carry plasmid DNA in vitro and exhibit antimicrobial activity with minimal toxicity

In this study, a modified dehydropeptide, Boc-FΔF-εAhx-OH, was conjugated with an aminoglycoside antibiotic, neomycin, to construct a multifunctional conjugate, Pep-Neo. The amphiphilic conjugate (Pep-Neo) was able to self-assemble into cationic nanostructures in an aqueous solution at low concentrations. Nanostructure formation was evidenced by TEM and dynamic light scattering analyses. The average hydrodynamic diameter of the self-assembled Pep-Neo nanostructures was found to be ∼279 nm with a zeta potential of +28 mV. The formation of nanostructures with a hydrophobic core and cationic hydrophilic shell resulted in an increased local concentration of cationic charge (ca. in 50% aqueous methanol, i.e. disassembled structure, zeta potential decreased to +17.6 mV), leading to efficient interactions with negatively charged plasmid DNA (pDNA). The size and zeta potential of the resulting Pep-Neo/pDNA complex were found to be ∼154 nm and +19.4 mV, respectively. Having been characterized by physicochemical techniques, the complex was evaluated for its toxicity and ability to deliver nucleic acid therapeutics. The flow cytometry results on MCF-7 cells revealed that Pep-Neo/pDNA complex transfected ∼27% cells at a w/w ratio of 66.6 while the standard transfection reagent, Lipofectamine, could transfect only ∼15% cells. MTT and hemolysis assays showed the non-toxic nature of the projected conjugate at various concentrations. Further, these nanostructures were shown to encapsulate hydrophobic drugs in the core. Finally, Pep-Neo nanostructures showed efficient antibacterial activity against different strains of Gram-positive and -negative bacteria. Interestingly, unlike neomycin, which is highly effective against Gram-negative bacteria, these nanostructures showed considerably high efficiency against Gram-positive strains, highlighting the promising potential of these nanostructures for various biomedical applications.

A cross-sectional pilot study of antibiotic resistance in Propionibacterium acnes strains in Indian acne patients using 16s-RNA polymerase chain reaction: A comparison among treatment modalities including antibiotics, benzoyl peroxide, and isotretinoin

Background: Antibiotic resistance is a worldwide problem in acne patients due to regional prescription practices, patient compliance, and genomic variability in Propionibacterium acnes, though the effect of treatment on the resistance has not been comprehensively analyzed. Aims: Our primary objective was to assess the level of antibiotic resistance in the Indian patients and to assess whether there was a difference in the resistance across common treatment groups. Subjects and Methods: A cross-sectional, institutional based study was undertaken and three groups of patients were analyzed, treatment naïve, those on antibiotics and patients on benzoyl peroxide (BPO) and/isotretinoin. The follicular content was sampled and the culture was verified with 16S rRNA polymerase chain reaction, genomic sequencing, and pulsed-field gel electrophoresis. Minimum inhibitory concentration (MIC) assessment was done for erythromycin (ERY), azithromycin (AZI), clindamycin (CL), tetracycline (TET), doxycycline (DOX), minocycline (MINO), and levofloxacin (LEVO). The four groups of patients were compared for any difference in the resistant strains. Results: Of the 52 P. acnes strains isolated (80 patients), high resistance was observed to AZI (100%), ERY (98%), CL (90.4%), DOX (44.2%), and TETs (30.8%). Low resistance was observed to MINO (1.9%) and LEVO (9.6%). Statistical difference was seen in the resistance between CL and TETs; DOX/LEVO and DOX/MINO (P < 0.001). High MIC90 (≥256 μg/ml) was seen with CL, macrolides, and TETs; moreover, low MIC90 was observed to DOX (16 μg/ml), MINO (8 μg/ml), and LEVO (4 μg/ml). Though the treatment group with isotretinoin/BPO had the least number of resistant strains there was no statistical difference in the antibiotic resistance among the various groups of patients. Conclusions: High resistance was seen among the P. acnes strains to macrolides-lincosamides (AZI and CL) while MINO and LEVO resistance was low.

Synthesis and antibacterial activity screening of quaternary ammonium derivatives of triazolyl pyranochromenones

AbstractA series of quaternary ammonium derivatives of triazolyl pyranochromen-2-ones have been synthesized and characterized; their antibacterial potential were investigated against two gram negative (Pseudomonas aeruginosa and Escherichia coli) and two gram positive bacterial strains (Bacillus cereus and Staphylococcus aureus). In order to develop structure-activity relationship (SAR), the effect of varying the substituent (R) at the C-10 position of pyranochromen-2-one as well as the length of the spacer (n) between the triazolyl pyranochromen-2-ones and quaternary ammonium group, on the antibacterial activity of compounds has been evaluated. Some of the screened compounds exhibited antibacterial potential against the studied strains in the microgram range. Graphical AbstractA series of quaternary ammonium derivatives of triazolyl pyranochromen-2-ones have been synthesized, characterized AND their antibacterial potential investigated. In order to develop structure-activity relationship (SAR), the effect of varying the substituent (R) at the C-10 position of pyranochromen-2-one as well as the length of the spacer (n) between the triazolyl pyranochromen-2-ones and quaternary ammonium group, on the antibacterial activity of compounds has been evaluated.

Evaluation of antimicrobial efficacy of quaternized poly[bis(2-chloroethyl)ether-alt-1,3-bis[3-(dimethylamino)propyl]urea] against targeted pathogenic and multi-drug-resistant bacteria

Here, we have investigated in vitro antimicrobial efficacy of a quaternized cationic polymer, poly[bis(2-chloroethyl)ether-alt-1,3-bis[3-(dimethylamino)propyl]urea] (polyquaternium-2), against gram-positive as well as gram-negative bacteria along with several multi-drug-resistant bacterial strains. The antimicrobial efficacy of this polymer was first tested against some clinical pathogens followed by microorganisms isolated from acne lesions. Interestingly, polyquaternium-2 exhibited significant antimicrobial activity against methicillin-resistant Staphylococcus aureus, for which very limited drugs are available. Most importantly, the polymer displayed low haemolytic activity and non-toxic behaviour against mammalian cells. The results showed the promising potential of the projected polymer to be utilized as an antibacterial agent for various biomedical applications.

Acetamide Derivatives of Chromen‐2‐ones as Potent Cholinesterase Inhibitors

Alzheimers disease (AD), a neurodegenerative disorder, is a serious medical issue worldwide with drastic social consequences. Inhibition of cholinesterase is one of the rational and effective approaches to retard the symptoms of AD and, hence, consistent efforts are being made to develop efficient anti‐cholinesterase agents. In pursuit of this, a series of 19 acetamide derivatives of chromen‐2‐ones were synthesized and evaluated for their acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory potential. All the synthesized compounds exhibited significant anti‐AChE and anti‐BChE activity, with IC50 values in the range of 0.24–10.19 μM and 0.64–30.08 μM, respectively, using donepezil hydrochloride as the standard. Out of 19 compounds screened, 3 compounds, viz. 22, 40, and 43, caused 50% inhibition of AChE at 0.24, 0.25, and 0.25 μM, respectively. A kinetic study revealed them to be mixed‐type inhibitors, binding with both the CAS and PAS sites of AChE. The above‐selected compounds were found to be effective inhibitors of AChE‐induced and self‐mediated Aβ1–42 aggregation. ADMET predictions demonstrated that these compounds may possess suitable blood–brain barrier (BBB) permeability. Hemolytic assay results revealed that these compounds did not lyse human RBCs up to a thousand times of their IC50 value. MTT assays performed for the shortlisted compounds showed them to be negligibly toxic after 24 h of treatment with the SH‐SY5Y neuroblastoma cells. These results provide insights for further optimization of the scaffolds for designing the next generation of compounds as lead cholinesterase inhibitors.

Multifunctional biosynthesized silver nanoparticles exhibiting excellent antimicrobial potential against multi-drug resistant microbes along with remarkable anticancerous properties

This study demonstrates the therapeutic potential of silver nanoparticles (AgNPs), which were biosynthesized using the extracts of Citrus maxima plant. Characterization through UV-Vis spectrophotometry, Dynamic Light Scattering (DLS), Fourier Transform Infrared spectroscopy (FTIR), X-ray Diffraction (XRD) and Transmission Electron Microscopy (TEM) confirmed the formation of AgNps in nano-size range. These nanoparticles exhibited enhanced antioxidative activity and showed commendable antimicrobial activity against wide range of microbes including multi-drug resistant bacteria that were later confirmed by TEM. These particles exhibited minimal toxicity when cytotoxicity study was performed on normal human lung fibroblast cell line as well as human red blood cells. It was quite noteworthy that these particles showed remarkable cytotoxicity on human fibrosarcoma and mouse melanoma cell line (B16-F10). Additionally, the apoptotic topographies of B16-F10 cells treated with AgNps were confirmed by using acridine orange and ethidium bromide dual dye staining, caspase-3 assay, DNA fragmentation assay followed by cell cycle analysis using fluorescence-activated cell sorting. Taken together, these results advocate promising potential of the biosynthesized AgNps for their use in therapeutic applications.

Letter to the Editor submitted in response to “The Extinction of Topical Erythromycin Therapy for Acne Vulgaris and Concern for the Future of Topical Clindamycin.”

We read with great interest a recent report in your journal “The Extinction of Topical Erythromycin Therapy for Acne Vulgaris and Concern for the Future of Topical Clindamycin”. The increasing prevalence of antibiotic resistance in acne vulgaris is a global phenomenon. The resistance has been found against almost all commonly used antibiotics, but the resistance against erythromycin and clindamycin is rampant and is a worldwide menace (1–15). We would like to quote various studies from different corners of the globe, with special focus on few distinctive ones (Table 1). High resistance against erythromycin and clindamycin was reported by Coates et al. (1) as early as in 2002 with 94.4 and 90.3% resistance reported respectively from UK verifying that antibiotic resistance in acne is not a novel trend. Ross et al. (2) also demonstrated 90% resistance against both the antibiotics in 2003 from Spain. In Asia, high resistance was reported from Singapore with 69.2 and 50% resistance reported respectively against erythromycin and clindamycin (8). Various other authors have also confirmed resistance against erythromycin and clindamycin. In our recently published study from North India, high resistance was found against erythromycin and clindamycin: 98 and 90.4%, respectively (16). The major reasons cited were indiscriminate usage of these two antibiotics in the previous decades with monotherapy also being used. This study also recommended to avoid using antibiotics alone in the light of the high resistance values noted and to combine with retinoids and/or benzoyl peroxide wherever possible. Thus, the point that this report of yours intends to bring forth has already been established all over the world. Prescription of topical erythromycin had already been a thing of the past and so is the scenario of topical clindamycin monotherapy. The prescription of topical clindamycin monotherapy has already declined and it would not require 20 more years for its extinction as the physicians and dermatologists worldwide are already well-versed with the current antibiotic resistance in acne patients, this being observed way back in 2002. The current acne treatment guidelines have already incorporated these findings and thus the recommendation to avoid antibiotic monotherapy (17).

Bifunctionally engineered polyethylenimines as efficient DNA carriers and antibacterials against resistant pathogens

In this study, we have designed and developed two series of bifunctional conjugates by tethering polyethylenimine with streptomycin. By varying the amount of streptomycin, conjugates, polyethylenimine-streptomycin, have been synthesized and characterized spectroscopically. Gel electrophoresis assay revealed a slight decrease in the cationic charge density on the conjugates as these retarded the mobility of pDNA at higher w/w ratios. Further, transfection studies showed that both the series of conjugates transfected the mammalian cells efficiently with low-molecular weight polyethylenimine-streptomycin conjugates were more competent (∼9-fold enhancement with respect to native bPEI) exhibiting high cell viability too. Besides, both the series of conjugates displayed excellent antibacterial activity on pathogenic bacteria, even better than native streptomycin on resistant strains. Altogether, these results ensure the promising potential of the projected bifunctional conjugates as safe and efficient gene delivery vectors as well as antibacterials for future biomedical applications.

An Indian Desert Shrub ‘Hiran Chabba’, Farsetia Hamiltonii Royle, Exhibits Potent Antioxidant and Hepatoprotective Effect Against Iron-Overload Induced Liver Toxicity in Swiss Albino Mice

BACKGROUND Farsetia hamiltonii Royle, also known as Hiran Chabba grows in desert regions. It is widely used as folk medicine to treat joint pains, diarrhea and diabetes. However, its antioxidant and iron chelation abilities both in vitro and in vivo have not yet been investigated. METHODS The 70% methanolic extract of F.hamiltonii (FHME) was investigated for its free radical scavenging and iron chelation potential, in vitro. An iron-overload situation was established by intraperitoneal injection of iron-dextran in Swiss albino mice, followed by oral administration of FHME. Liver damage and serum parameters due to iron-overload were measured biochemically and histopathologically to test iron-overload remediation and hepatoprotective potential of FHME. Phytochemical analyses were performed to determine its probable bioactive components. RESULTS FHME showed promising antioxidant activity, scavenged various reactive oxygen and nitrogen species and chelated iron in vitro. FHME reduced liver iron, serum ferritin, normalized serum parameters, reduced oxidative stress in liver, serum and improved liver antioxidant status in iron-overloaded mice. It also alleviated liver damage and fibrosis as evident from biochemical parameters and morphological analysis of liver sections. The phytochemical analyses of FHME reflected the presence of alkaloids, phenols, flavonoids and tannins. HPLC analysis indicated presence of tannic acid, quercetin, methyl gallate, catechin, reserpine, ascorbic acid and gallic acid. CONCLUSIONS Based on the experimental outcome, FHME, an ethnologically important plant can be envisaged as excellent antioxidant and iron chelator drug capable of remediating iron-overload induced hepatotoxicity and the bioactive compounds present in FHME might be responsible for its efficacy.