Evaluating Phenyl Propanoids Isolated from Citrus medica as Potential Inhibitors for Mitotic kinesin Eg5

Background:

Human mitotic kinesins play an essential role in mitotic cell division. Targeting the spindle separation phase of mitosis has gained much attention in cancer chemotherapy. Spindle segregation is carried out mainly by the kinesin, Eg5. Many Eg5 inhibitors are in different phases of clinical trials as cancer drugs. This enzyme has two allosteric binding sites to which the inhibitors can bind. The first site is formed by loop L5, helix α2 and helix α3 and all the current drug candidates bind un-competitively to this site with ATP/ADP. The second site, formed by helix α4 and helix α6, which has gained attention recently, has not been explored well. Some inhibitors that bind to this site are competitive, while others are uncompetitive to ATP/ADP. Phenylpropanoids are pharmacologically active secondary metabolites.

Methods:

In this study, we have evaluated fourteen phenyl propanoids extracted from Citrus medica for inhibitory activity against human mitotic kinesin Eg5 in vitro steady-state ATPase assay. Ther interactions and stability using molecular docking and molecular dynamics simulations.

Results and Discussions:

Of the fourteen compounds tested, naringin and quercetin showed good activity with IC50 values in the micromolar range. Molecular docking studies of these complexes showed that both the molecules interact with the key residues of the active site predominantly thorough hydrophobic & aromatic π–π interactions consistent with the known inhibitors. Besides, these molecules also form hydrogen bonding interactions stabilizing the complexes. Molecular dynamics simulations of these complexes confirm the stability of these interactions.

Conclusion:

These results can be used as a strong basis for further modification of these compounds to design new inhibitors with higher potency using structure-based drug design.

Biogenic phytochemicals (cassinopin and isoquercetin) capped copper nanoparticles (ISQ/CAS@CuNPs) inhibits MRSA biofilms

Purified glycosides, Isoquercetin and Cassinopin from Crotalaria candicans were selected for the synthesis of biogenic copper nanoparticles (CuNPs).The designed biogenic CuNPs was characterized and when evaluated against panel of gram negative and positive bacteria, the biogenic CuNPs were found to be more effective against methicillin resistant Staphylococcus aureus (MRSA). Antibacterial, anti-biofilm effects and time kill studies confirmed the ability of biogenic CuNPs to curtail MRSA. Scanning electron microscopy, Crystal violet staining and fluorescent live-dead imaging showed that treatment with sub lethal levels of glycoside capped CuNPs resulted in greater than 50% decline in biofilm formation by MRSA, which implies that anti-biofilm effect of biogenic CuNPs is not dependent on antibacterial effect. Alizarin red assay implied that prolonged treatment of biogenic CuNPs in presence of MRSA, releases Cu(II) ions and hence antibiofilm effect is primarily mediated by NP and is not due to released Cu(II) ion. The NPs caused altered membrane permeability and reduced surface hydrophobicity, thus accounting for its antibiofilm effect.

Zero valent silver nanoparticles capped with capsaicinoids containing Capsicum annuum extract, exert potent anti-biofilm effect on food borne pathogen Staphylococcus aureus and curtail planktonic growth on a zebrafish infection model

Food plants Hungarian wax pepper (HWP) and Green Bell pepper (GBP), belonging to Capsicum annuum were utilized for biogenic fabrication of zero valent, nano-silver (AgNPs) through a photo-mediation procedure. In the bacterial strains evaluated, HWP/GBP AgNPs demonstrated effective bacteriostatic and bactericidal effect against Staphylococcus aureus. Time kill results portrayed that HWP/GBP nano-silver exhibited comparable bactericidal potency on S. aureus. Anti-biofilm potential of HWP/GBP AgNPs displayed significant effects at sub MIC levels, by triggering 50% biofilm reduction of the food spoilage microbe S. aureus, inferring that the anti-biofilm outcome is not dependent on antibacterial result, and this was confirmed by SEM and fluorescence studies. Histopathological analyses of S. aureus infected zebrafish liver did not display any abnormality changes such as extensive cell death and degeneration, upon treatment with HWP/GBP AgNPs and the zero-valent silver nanoparticles were comparatively less toxic and more operative in restraining the bioburden in S. aureus infected zebrafish model by a >1.7 log fold. Ability of light reduced HWP/GBP AgNPs to alleviate the in vitro and in vivo planktonic mode of growth and curb the biofilm formation of S. aureus is also demonstrated.

Ferulic acid derivative inhibits NorA efflux and in combination with ciprofloxacin curtails growth of MRSA in vitro and in vivo

A series of ferulic acid (FA) derivatives were synthesized and evaluated for its ability to inhibit NorA efflux in methicillin resistant Staphylococcus aureus (MRSA), by in silico docking analysis. Based on prediction from glide scores and ability to reduce EtBr MIC, two of the ten derivatives S3- [4-((E)-2-(diethylcarbamoyl)vinyl)-2-methoxyphenyl acetate] and S6- [(E)-methyl 3-(4-((p-tolylcarbamoyl)methoxy)-3-methoxyphenyl)acrylate] were chosen as putative efflux pump inhibitors (EPI's). Time dependent accumulation studies revealed that S6 caused enhanced EtBr accumulation relative to standard NorA efflux inhibitor reserpine, in clinical isolate of MRSA (CIMRSA) and in NorA overexpressed strain of S. aureus (SA1199B). S6 also exhibited synergy with Ciprofloxacin (CPX) against NorA overexpressed strain (SA1199B) of S. aureus but not in NorA knock out strain (K1758). MIC reversal studies showed that S3 in CIMRSA and S6 in NorA overexpressed strain of S. aureus (SA1199B), caused a 4 fold reduction in CPX MIC. In vitro time kill studies revealed that both S3 and S6 with sub MIC of CPX caused a significant 4 log CFU decline in CIMRSA. A decline of >3 log fold CFU by time kill assay implies synergy between FA derivatives and CPX. When tested in vivo in infected muscle tissue of zebrafish both S3 and S6 with CPX caused >3.2 log decline in CIMRSA cell counts relative to CPX treatment alone. Of the two potent derivatives, S6 probably acts through NorA whereas S3 might exert its effect through pump other than NorA. Greater in vitro and in vivo efficiency of FA derivatives implies its potential to be used as an adjuvant along with CPX to curtail MRSA infection in higher animal models.

Secured Hash Based Burst Header Authentication Design for Optical Burst Switched Networks

The optical burst switching (OBS) is a promising technology that could meet the fast growing network demand. They are featured with the ability to meet the bandwidth requirement of applications that demand intensive bandwidth. OBS proves to be a satisfactory technology to tackle the huge bandwidth constraints, but suffers from security vulnerabilities. The objective of this proposed work is to design a faster and efficient burst header authentication algorithm for core nodes. There are two important key features in this work, viz., header encryption and authentication. Since the burst header is an important in optical burst switched network, it has to be encrypted; otherwise it is be prone to attack. The proposed MD5&RC4-4S based burst header authentication algorithm runs 20.75 ns faster than the conventional algorithms. The modification suggested in the proposed RC4-4S algorithm gives a better security and solves the correlation problems between the publicly known outputs during key generation phase. The modified MD5 recommended in this work provides 7.81 % better avalanche effect than the conventional algorithm. The device utilization result also shows the suitability of the proposed algorithm for header authentication in real time applications.

Jacalin-capped silver nanoparticles minimize the dosage use of the anticancer drug, shikonin derivatives, against human chronic myeloid leukemia

Silver nanoparticles enhance the anticancer efficacy of shikonin derivatives.

Design, synthesis and “in vitro” anti-leukemic evaluation of ferulic acid analogues as BCR-Abl inhibitors

A series of ferulic acid derivatives was synthesized and evaluated for anti-proliferative activity against K562, U937 and Hep G2 cells. The compounds were further tested for BCR-Abl kinase inhibition.

Acetyl shikonin induces IL-12, nitric oxide and ROS to kill intracellular parasite Leishmania donovani in infected hosts

Acetyl shikonin (AS), a naphthoquinone isolated from Arnebia nobilis, was tested against visceral leishmaniasis in this study, revealing that AS provides a chemo-immunotherapeutic strategy against visceral leishmaniasis.

Development and extraction optimization of baicalein and pinostrobin from Scutellaria violacea through response surface methodology

Objective:

To develop a process that involves optimization of the amount of baicalein and pinostrobin from the hydro-methanolic extract of the leaves of Scutellaria violacea by response surface methodology (RSM).

Materials and Methods:

The combinatorial influence of various extraction parameters on the extraction yield was investigated by adopting Box–Behnken experimental design. Preliminary experiments carried out based on the traditional one variable at a time optimization revealed four such operational parameters to play a crucial role by influencing the yield. These four process parameters at three levels were considered to obtain the Box–Behnken experimental design.

Results:

RSM based model fitted to the resulting experimental data suggested that 52.3% methanol/water, 12.46:1 solvent-solid ratio, 285 rpm agitation and 6.07 h of extraction time are the optimal conditions which yielded a maximized amount of baicalein and pinostrobin of 2.9 and 4.05 mg/g DM. Analysis of variance revealed a high correlation coefficient (R² = 0.999 for baicalein and 0.994 for pinostrobin), signifying a good fit between the regression model (second order) and the experimental observations.

Conclusion:

The present study signifies that both the metabolites have been extracted from S. violacea for the first time. Further, this study developed an optimized extraction procedure to obtain maximum yield of the metabolites, which is unique and better than conventional extraction methodology. The operational parameters under optimized conditions accounts for the lowest cost in extraction process thus, providing an efficient, rapid and cost-effective method for isolation and scale up of these commercially vital flavonoids.

Dual role of pinostrobin-a flavonoid nutraceutical as an efflux pump inhibitor and antibiofilm agent to mitigate food borne pathogens

Drastic 128 fold MIC reversal in MRSA stain via EPI effect. Remarkable anti-biofilm effect against gram negative bacteria. Efflux pump other than NorA is involved.

An unique solvent assisted ‘green’ hydrotropic precipitation and response surface optimization for isolation of the dietary micronutrient β-sitosterol-d-glucopyranoside from Desmostachya bipinnata

Novel Box–Behnken optimized isolation of the dietary micronutrient β-sitosterol-d-glucopyranoside by solvent assisted ‘green’ hydrotropic precipitation from Desmostachya bipinnata.

Box–Behnken designed adsorption based elution – unique separation process for commercially important acetyl shikonin from Arnebia nobilis

Box–Behnken optimized, adsorption based robust separation technique for acetyl shikonin (AS), a commercially important compound from industrial crop Arnebia nobilis.

Dual role of select plant based nutraceuticals as antimicrobial agents to mitigate food borne pathogens and as food preservatives

Dual role of commercially important nutraceuticals from plants that potentiate the therapeutic effect of commercial antibiotics to combat food pathogens.

Preparation of gold nanoparticles using Salicornia brachiata plant extract and evaluation of catalytic and antibacterial activity

The current study deals with the synthesis of gold nanoparticles (AuNPs) using Salicornia brachiata (Sb) and evaluation of their antibacterial and catalytic activity. The SbAuNPs showed purple color with a characteristic surface plasmon resonance peak at 532 nm. Scanning electron microscopy and transmission electron microscopy revealed polydispersed AuNPs with the size range from 22 to 35 nm. Energy dispersive X-ray and thin layer X-ray diffraction analysis clearly shows that SbAuNPs was pure and crystalline in nature. As prepared gold nanoparticles was used as a catalyst for the sodium borohydride reduction of 4-nitro phenol to 4-amino phenol and methylene blue to leucomethylene blue. The green synthesized nanoparticles exhibited potent antibacterial activity against the pathogenic bacteria, as evidenced by their zone of inhibition. In addition, we showed that the SbAuNPs in combination with the regular antibiotic, ofloxacin, exhibit superior antibacterial activity than the individual.

Spectroscopy investigation on chemo-catalytic, free radical scavenging and bactericidal properties of biogenic silver nanoparticles synthesized using Salicornia brachiata aqueous extract

Nanosized silver have been widely used in many applications, such as catalysis, photonics, sensors, medicine etc. Thus, there is an increasing need to develop high-yield, low cost, non-toxic and eco-friendly procedures for the synthesis of nanoparticles. Herein, we report an efficient, green synthesis of silver nanoparticles utilizing the aqueous extract of Salicornia brachiata, a tropical plant of the Chenopodiaceae family. Silver nanoparticles have been characterized by ultraviolet-visible spectroscopy, scanning electron microscopy and transmission electron microscopy. The morphology of the particles formed consists of highly diversified shapes like spherical, rod-like, prism, triangular, pentagonal and hexagonal pattern. However, addition of sodium hydroxide to the extract produces mostly spherical particles. The stable nanoparticles obtained using this green method show remarkable catalytic activity in the reduction of 4-nitro phenol to 4-amino phenol. The reduction catalyzed by silver nanoparticles followed the first-order kinetics, with a rate constant of, 0.6×10(-2) s(-1). The bactericidal activity of the synthesized silver nanoparticles against the pathogenic bacteria, Staphylococcus aureus, Staphylococcus aureus E, Bacillus subtilis and Escherichia coli, was also explored using REMA. The obtained results showed that the minimum inhibitory concentration required to induce bactericidal effect is lower than the control antibiotic, ciprofloxacin. In addition to these, the biogenic synthesized nanoparticles also exhibited excellent free radical scavenging activity.

β-Sitosterol-d-glucopyranoside isolated from Desmostachya bipinnata mediates photoinduced rapid green synthesis of silver nanoparticles

A sunlight-induced synthesis of silver nanoparticles using β-sitosterol-d-glucopyranoside, a bio-surfactant isolated from the Indian sacred grass Desmostachya bipinnata.

Synergistic antimicrobial profiling of violacein with commercial antibiotics against pathogenic micro-organisms

CONTEXT

Chromobacterium violaceum Bergonzini (Neisseriaceae), a Gram-negative bacterium, secretes a spectacular pigment called violacein. Violacein is a quorum-sensing metabolite and is also an active antimicrobial, anticancer agent. However, its efficiency as a potential drug, alone or in synergy with other active principles, has not being completely exploited. With the advent of different multi-drug resistant strains, it becomes essential to find a new natural product(s) that could be effectively used as a therapeutic agent.

OBJECTIVE

This work focused on the extraction of violacein from an isolated strain of C. violaceum and determined the combinatory effect of violacein with commercial antibiotics against various pathogens.

MATERIALS AND METHODS

Violacein production was optimized and was later extracted using ethanol and characterized by liquid chromatography-mass spectrometry and infrared spectroscopy. Then, individual minimum inhibitory concentration (MIC) values for each of the antibiotics were determined followed by violacein-commercial antibiotics (1:1) combinations, tested at different concentrations starting from 500 to 1 µg/ml against major pathogens.

RESULTS AND DISCUSSION

The individual MIC data for violacein was found to be 5.7 µg/ml (Staphylococcus aureus), 15.6 µg/ml (Klebsiella pneumoniae), 18.5 µg/ml (Pseudomonas aeruginosa), 20.0 µg/ml (Vibrio cholerae) and 5.7 µg/ml (Salmonella typhi). Violacein-gentamicin and violacein-cefadroxil combinations had MIC of 1.0 µg/ml against S. aureus. Most violacein-macrolide and violacein--aminoglycoside class combinations revealed fractional inhibitory concentration indices (FICI) of <0.5, thus exhibiting synergism. Furthermore, violacein-azithromycin and violacein-kanamycin combination, exhibited significant synergy (FICI-0.3) against S. typhi.

CONCLUSION

Violacein works synergistically with most commercial antibiotics and could be used as drug in combination with other antimicrobial agents.

A new antifeedant clerodane diterpenoid from Tinospora cordifolia

Phytochemical investigation of the chloroform extract of Tinospora cordifolia yielded a new clerodane diterpenoid tincordin along with tinosporide, 8-hydroxytinosporide, columbin, 8-hydroxycolumbin and 10-hydroxycolumbin. The structure of the new compound was elucidated comprehensively using 1D and 2D NMR methods. All major clerodane diterpenoids isolated were tested for their efficacy as insect antifeedants against Earias vitella, Plutella xylostella and Spodoptera litura.

NMR analysis of a series of substituted pyrazolo[3,4-d] pyrimidines-4-amines

A series of 21 substituted pyrazolo[3,4-d]pyrimidines-4-amines were studied by (1)H and (13)C NMR. The application of two-dimensional techniques, HMQC and HMBC, allowed the complete assignment of the spectra for all the compounds.

6-Fluoropyridoxal polymer conjugates: novel 19F pH indicators for magnetic resonance spectroscopy

Fluorinated macromolecular probes (6-fluoropyridoxal-polymer conjugates) have been synthesized and characterized as potential pH indicators for magnetic resonance spectroscopy and imaging applications. The 19F pH sensor 2-fluoro-5-hydroxy-3-(hydroxymethyl)-6-methyl-4-pyridinecarboxal-+ ++dehyde (6-fluoropyridoxal; 2) has been conjugated to carrier molecules (polyamino dextran, polylysine, and albumin) by reductive alkylation for enhanced vascular retention and tissue targeting. The pH indicator polymer conjugates were purified by exhaustive dialysis and isolated in good yields (66-84%). The 6-fluoropyridoxal-polymer conjugates exhibit excellent 19F pH sensitivity and pKa suitable for in vivo studies. The potential application of these polymeric indicators has been demonstrated in whole blood. These novel macromolecular pH probes offer a new approach for studying tissue physiology.