New combination approaches to combat methicillin-resistant Staphylococcus aureus (MRSA)

Nanoemulsion of cinnamon oil to combat colistin-resistant Klebsiella pneumoniae and cancer cells

This study aimed to investigate the potential of cinnamon oil nanoemulsion (CONE) as an antibacterial agent against clinical strains of colistin-resistant Klebsiella pneumoniae and its anticancer activity. The prepared and characterized CONE was found to have a spherical shape with an average size of 70.6 ± 28.3 nm under TEM and a PDI value of 0.076 and zeta potential value of 6.9 mV using DLS analysis. The antibacterial activity of CONE against Klebsiella pneumoniae strains was investigated, and it was found to have higher inhibitory activity (18.3 ± 1.2-30.3 ± 0.8 mm) against the tested bacteria compared to bulk cinnamon oil (14.6 ± 0.88-20.6 ± 1.2) with MIC values ranging from 0.077 to 0.31 % v/v which equivalent to 0.2-0.82 ng/ml of CONE. CONE inhibited the growth of bacteria in a dose and time-dependent manner based on the time-kill assay in which Klebsiella pneumoniae B-9 was used as a model among the bacterial strains under investigation. The study also investigated the expression of the mcr-1 gene in the Klebsiella pneumoniae strains and found that all strains were positive for the gene expression and subsequently its presence. The level of mcr-1 gene expression among the B-2, B-4, B-9, and B-11 control strains and that treated with colistin was similar, but it was different in both B-5 and B-2. However, all strains exhibited a significant downregulation in gene expression (ranging from 3.97 to 8.7-fold) after their treatment with CONE. Additionally, the CONE-treated bacterial cells appeared with a great deformation compared with control cells under TEM. Finally, CONE exhibited selective toxicity against different cancer cell lines depending on comparison with the normal cell lines.

Inhibition of pathogenic microbes in oral infectious diseases by natural products: Sources, mechanisms, and challenges

The maintenance of oral health is of utmost importance for an individual's holistic well-being and standard of living. Within the oral cavity, symbiotic microorganisms actively safeguard themselves against potential foreign diseases by upholding a multifaceted equilibrium. Nevertheless, the occurrence of an imbalance can give rise to a range of oral infectious ailments, such as dental caries, periodontitis, and oral candidiasis. Presently, clinical interventions encompass the physical elimination of pathogens and the administration of antibiotics to regulate bacterial and fungal infections. Given the limitations of various antimicrobial drugs frequently employed in dental practice, the rising incidence of oral inflammation, and the escalating bacterial resistance to antibiotics, it is imperative to explore alternative remedies that are dependable, efficacious, and affordable for the prevention and management of oral infectious ailments. There is an increasing interest in the creation of novel antimicrobial agents derived from natural sources, which possess attributes such as safety, cost-effectiveness, and minimal adverse effects. This review provides a comprehensive overview of the impact of natural products on the development and progression of oral infectious diseases. Specifically, these products exert their influences by mitigating dental biofilm formation, impeding the proliferation of oral pathogens, and hindering bacterial adhesion to tooth surfaces. The review also encompasses an examination of the various classes of natural products, their antimicrobial mechanisms, and their potential therapeutic applications and limitations in the context of oral infections. The insights garnered from this review can support the promising application of natural products as viable therapeutic options for managing oral infectious diseases.

In Vitro Synergistic Inhibitory Effects of Plant Extract Combinations on Bacterial Growth of Methicillin-Resistant Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most common pathogens of healthcare-associated infections. Medicinal plants have long been used in the traditional treatment of diseases or syndromes worldwide. Combined use of plant extracts could improve the effectiveness of pharmacological action by obtaining synergism, acting on multiple targets simultaneously, reducing the doses of individual components, and minimizing side effects. We aimed to investigate the synergistic inhibitory effects of selected medicinal plants (Caesalpinia sappan L. (CS), Glycyrrhiza uralensis Fisch. (GU), Sanguisorba officinalis L. (SO), and Uncaria gambir Roxb. (UG)) on the bacterial growth of MRSA and its clinical isolates. SO and UG extracts generated the best synergistic interaction as adjudged by checkerboard synergy assays. MICs of the individual extracts decreased 4-fold from 250 to 62.5 μg/mL, respectively. The SO + UG combination was further evaluated for its effects on bacterial growth inhibition, minimum bactericidal/inhibitory concentration (MBC/MIC) ratio, and time-kill kinetics. The results indicate that the SO + UG combination synergistically inhibited the bacterial growth of MRSA strains with bactericidal effects. SO + UG combination also exhibited more potent effects against clinical isolates. In multistep resistance selection experiments, both standard and isolates of MRSA showed no resistance to the SO + UG combination even after repeated exposure over fourteen passages. Our data suggest that using plant extract combinations could be a potential strategy to treat MRSA infections.

Hierarchical Virtual Screening of Potential New Antibiotics from Polyoxygenated Dibenzofurans against Staphylococcus aureus Strains

Staphylococcus aureus is a microorganism with high morbidity and mortality due to antibiotic-resistant strains, making the search for new therapeutic options urgent. In this context, computational drug design can facilitate the drug discovery process, optimizing time and resources. In this work, computational methods involving ligand- and structure-based virtual screening were employed to identify potential antibacterial agents against the S. aureus MRSA and VRSA strains. To achieve this goal, tetrahydroxybenzofuran, a promising antibacterial agent according to in vitro tests described in the literature, was adopted as the pivotal molecule and derivative molecules were considered to generate a pharmacophore model, which was used to perform virtual screening on the Pharmit platform. Through this result, twenty-four molecules were selected from the MolPort® database. Using the Tanimoto Index on the BindingDB web server, it was possible to select eighteen molecules with greater structural similarity in relation to commercial antibiotics (methicillin and oxacillin). Predictions of toxicological and pharmacokinetic properties (ADME/Tox) using the eighteen most similar molecules, showed that only three exhibited desired properties (LB255, LB320 and LB415). In the molecular docking study, the promising molecules LB255, LB320 and LB415 showed significant values in both molecular targets. LB320 presented better binding affinity to MRSA (-8.18 kcal/mol) and VRSA (-8.01 kcal/mol) targets. Through PASS web server, the three molecules, specially LB320, showed potential for antibacterial activity. Synthetic accessibility (SA) analysis performed on AMBIT and SwissADME web servers showed that LB255 and LB415 can be considered difficult to synthesize and LB320 is considered easy. In conclusion, the results suggest that these ligands, particularly LB320, may bind strongly to the studied targets and may have appropriate ADME/Tox properties in experimental studies.

Chitosan/poly (3-hydroxy butyric acid-co-3-hydroxy valeric acid) electrospun nanofibers with cephradine for superficial incisional skin wound infection management

The belated and compromised incisional skin wound healing caused by the invading of methicillin-resistance staphylococcus aureus is a serious problem in clinic. Designing a new therapeutic strategy to inhibit the growth of invading bacteria at post-surgical site might be helpful in fast healing of post-surgical wounds. In this study, we developed cephradine (Ceph) encapsulated chitosan and poly (3-hydroxy butyric acid-co-3-hydroxy valeric acid, (PHBV)) hybrid nanofibers (Ceph-CHP NFs) employing an electrospinning method to revamp the Ceph bioavailability at the post-surgical wound site to prevent the growth of invading bacteria and trigger the wound healing process. The fabricated nanofibers revealed smooth and uniform surface with a diameter range of 160 ± 25 to 190 ± 55 nm, depending on Ceph concentration. Further, the electrospun hybrid nanofibers exhibited a higher entrapment efficiency (EE) and drug loading capacity (DLC) nearly 72.8 ± 5.2 % and 16.5 ± 3.2 %, respectively. Moreover, the Ceph-CHP NFs showed high swelling rate and biodegradation in presence of lysozyme in contrast to blank CHP NFs. Ceph-CHP NFs exhibited fast drug release in initial few hours followed by slow and controlled drug release drug up to 48 h with a constant rate. In-vitro antimicrobial studies indicated the heightened efficacy of Ceph-CHP NFs against MRSA clinical isolates and exhibited no visible cytotoxicity against keratinocytes, HC11 and L929 cells. Lastly, Ceph-CHP NFs showed the enhanced wound healing and bacterial clearance from post-surgical wound compared to Ceph in C57BL/6 mice skin model. Overall, our results showed that Ceph-CHP NFs might be used as a promising wound dressing material for MRSA-infected post-surgical wounds.

New Weapons to Fight against Staphylococcus aureus Skin Infections

The treatment of Staphylococcus aureus skin and soft tissue infections faces several challenges, such as the increased incidence of antibiotic-resistant strains and the fact that the antibiotics available to treat methicillin-resistant S. aureus present low bioavailability, are not easily metabolized, and cause severe secondary effects. Moreover, besides the susceptibility pattern of the S. aureus isolates detected in vitro, during patient treatment, the antibiotics may never encounter the bacteria because S. aureus hides within biofilms or inside eukaryotic cells. In addition, vascular compromise as well as other comorbidities of the patient may impede proper arrival to the skin when the antibiotic is given parenterally. In this manuscript, we revise some of the more promising strategies to improve antibiotic sensitivity, bioavailability, and delivery, including the combination of antibiotics with bactericidal nanomaterials, chemical inhibitors, antisense oligonucleotides, and lytic enzymes, among others. In addition, alternative non-antibiotic-based experimental therapies, including the delivery of antimicrobial peptides, bioactive glass nanoparticles or nanocrystalline cellulose, phototherapies, and hyperthermia, are also reviewed.

Antibacterial, Antibiofilm and Anti-Inflammatory Activities of Eugenol Clove Essential Oil against Resistant Helicobacter pylori

Eugenol essential oil (EEO) is the major component in aromatic extracts of Syzygium aromaticum (clove) and has several biological properties, such as antibacterial, antioxidant, and anti-inflammatory activities, as well as controlling vomiting, coughing, nausea, flatulence, diarrhea, dyspepsia, stomach distension, and gastrointestinal spasm pain. It also stimulates the nerves. Therefore, the aim of this study was to extract and purify EEO from clove buds and assess its ability to combat resistant Helicobacter pylori. Additionally, EEO's anti-inflammatory activity and its ability to suppress H. pylori biofilm formation, which is responsible for antibiotic resistance, was also investigated. Syzygium aromaticum buds were purchased from a local market, ground, and the EEO was extracted by using hydro-distillation and then purified and chemically characterized using gas chromatography-mass spectrometry (GC-MS). A disk-diffusion assay showed that Helicobacter pylori is sensitive to EEO, with an inhibition zone ranging from 10 ± 06 to 22 ± 04 mm. The minimum inhibition concentration (MIC) of EEO ranged from 23.0 to 51.0 μg/mL against both Helicobacter pylori clinical isolates and standard strains. In addition, EEO showed antibiofilm activity at 25 µg/mL and 50 µg/mL against various Helicobacter pylori strains, with suppression percentages of 49.32% and 73.21%, respectively. The results obtained from the anti-inflammatory assay revealed that EEO possesses strong anti-inflammatory activity, with human erythrocyte hemolysis inhibition percentages of 53.04, 58.74, 61.07, and 63.64% at concentrations of 4, 8, 16, and 32 μg/L, respectively. GC-MS analysis revealed that EEO is a major component of Syzygium aromaticum when extracted with a hydro-distillation technique, which was confirmed by its purification using a chemical separation process. EEO exhibited antibacterial action against resistant Helicobacter pylori strains, as well as antibiofilm and anti-inflammatory activities, and is a promising natural alternative in clinical therapy.

Assessment of Genetic Diversity, Micromorphology and Antimicrobial Activity in Nepeta cataria L

The mosquito repellent Nepetalactone rich Nepeta cataria L. (catmint) plant has a variety of therapeutic and industrial potential. Reports on the genetic diversity of N. cataria germplasm are minimal globally and need attention for adding a new variety into commercial cultivation. The present study, therefore, assessed the genetic diversity among thirteen half-sib genotypes of N. cataria using agro economic and phytochemical traits. The experimental set has shown substantial variation for agro economic traits studied. Among all the studied populations, fresh herb-based essential oil content ranged from 0.1 % to 0.3 %, with a grand mean of 1.67 %. However, the estimated oil yield ranged from 44.4 kg/h to 120.73 kg/h with an average of 71.34 kg/h. Among the eleven phytochemical constituents detected in different concentrations in the essential oil of experimental sets, 4aα,7α,7aα-Nepetalactone (67.9-87.5 %) constituted the significant proportion of essential oil. Altogether, based on mean comparison, the population NC8 was found to be promising for estimated oil yield and 4aα,7α,7aα-Nepetalactone content. The greater heritability estimates (h² bs) and genetic advance as percent of mean (GAM) were observed for important economic parameters, i. e., oil content, herb yield, and oil yield. The cluster analysis revealed the least interactions between various agro economic and phytochemical variables. The microscopic study of trichome showed a positive correlation of abaxial leaf surface with essential oil content. The promising antimicrobial potential of catmint oil was also observed against human health-related pathogens. The results infer from our study provide valuable insight for genetic improvement and product development in the catmint germplasm.

MRSA compendium of epidemiology, transmission, pathophysiology, treatment, and prevention within one health framework

Staphylococcus aureus is recognized as commensal as well as opportunistic pathogen of humans and animals. Methicillin resistant strain of S. aureus (MRSA) has emerged as a major pathogen in hospitals, community and veterinary settings that compromises the public health and livestock production. MRSA basically emerged from MSSA after acquiring SCCmec element through gene transfer containing mecA gene responsible for encoding PBP-2α. This protein renders the MRSA resistant to most of the β-lactam antibiotics. Due to the continuous increasing prevalence and transmission of MRSA in hospitals, community and veterinary settings posing a major threat to public health. Furthermore, high pathogenicity of MRSA due to a number of virulence factors produced by S. aureus along with antibiotic resistance help to breach the immunity of host and responsible for causing severe infections in humans and animals. The clinical manifestations of MRSA consist of skin and soft tissues infection to bacteremia, septicemia, toxic shock, and scalded skin syndrome. Moreover, due to the increasing resistance of MRSA to number of antibiotics, there is need to approach alternatives ways to overcome economic as well as human losses. This review is going to discuss various aspects of MRSA starting from emergence, transmission, epidemiology, pathophysiology, disease patterns in hosts, novel treatment, and control strategies.

Antimicrobial Properties of Ocimum Species: An In Vitro Study

Objective

This study aimed to determine the antimicrobial activity of ethanol-extracts obtained from Ocimum gratissimum L. (clove or African basil, Lamiaceae) and O. santum L. (holy basil) against some microorganisms present in oral cavity related to either medical or dental disease.

Materials and Methods

Antimicrobial properties of both ethanol-extracts of Ocimum species against Streptococcus mutans KPSK2, S. pyogenes ATCC 19615, Staphylococcus aureus ATCC 16794, and Candida albicans ATCC 10231 were primarily determined by agar disk diffusion method. The minimum inhibitory concentration (MIC) and minimum bactericidal or fungicidal concentration (MBC or MFC) of these herbal extracts were further determined by broth micro-dilution method.

Results

Ethanol-extracts of O. sanctum L. and O. gratissimum L. inhibited the growth of all tested microorganisms in various degrees ranging from the strongest antimicrobial activity of O. sanctum against S. pyogenes [MIC at 0.19% (w/v); MBC at 0.78% (w/v)] to the least inhibitory activity of O. gratissimum against C. albicans [MIC at 12.5% (w/v); undetectable MFC]. The ethanol-extract of O. sanctum showed stronger antimicrobial property against the tested bacteria and fungus than O. gratissimum. The ethanol-extracts of both Ocimum species showed stronger antibacterial than antifungal activity. However, the ethanol-extract of O. gratissimum even at a high concentration of 50% (w/v) was unable to eliminate the tested fungus.

Conclusion

Ethanol-extracts of Ocimum species contain effective antibacterial and antifungal properties that may be beneficial for further development of antimicrobial agents in medical and dental fields.

Designing Functionally Substituted Pyridine-Carbohydrazides for Potent Antibacterial and Devouring Antifungal Effect on Multidrug Resistant (MDR) Strains

The emergence of multidrug-resistant (MDR) pathogens and the gradual depletion of available antibiotics have exacerbated the need for novel antimicrobial agents with minimal toxicity. Herein, we report functionally substituted pyridine carbohydrazide with remarkable antimicrobial effect on multi-drug resistant strains. In the series, compound 6 had potent activity against four MDR strains of Candida spp., with minimum inhibitory concentration (MIC) values being in the range of 16-24 µg/mL and percentage inhibition up to 92.57%, which was exceptional when compared to broad-spectrum antifungal drug fluconazole (MIC = 20 µg/mL, 81.88% inhibition). Substitution of the octyl chain in 6 with a shorter butyl chain resulted in a significant anti-bacterial effect of 4 against Pseudomonas aeruginosa (ATCC 27853), the MIC value being 2-fold superior to the standard combination of ampicillin/cloxacillin. Time-kill kinetics assays were used to discern the efficacy and pharmacodynamics of the potent compounds. Further, hemolysis tests confirmed that both compounds had better safety profiles than the standard drugs. Besides, molecular docking simulations were used to further explore their mode of interaction with target proteins. Overall results suggest that these compounds have the potential to become promising antimicrobial drugs against MDR strains.

Extraction, characterization, and anticancer potential of extracellular polymeric substances from marine actinobacteria of Streptomyces species

To check the ability of the anticancer activity, the extracted extracellular polymeric substances (EPS) from marine actinobacteria were done. Potential of the anticancer activity of EPS which was extracted from marine actinobacteria of Streptomyces species through an assay called MTT. Marine actinobacterial isolation, identification and micromorphology of the strain, and biochemical analysis were performed (Shirling and Gottlieb, 1966). The production of EPS from marine actinobacteria was quantified(P. Sivaperumal et al., 2018). Carbohydrate content in the EPS was quantified, and MCF-7 cell proliferation was done using an MTT assay. EPS-producing marine Streptomyces was isolated and identified. The production of EPS and their protein, carbohydrate, lipid, and other parameters were estimated. Further, the EPS showed more than 50% of inhibition after 72 h using the MTT assay in the MCF-7 cancer cell line. The present study exhibited that EPS from marine Streptomyces species has significant anticancer activity.

Antibacterial Activity of Silver Nanoparticles Synthesized by Aspergillus flavus and its Synergistic Effect with Antibiotics

Microbial antibiotic resistance is rapidly increasing as a result of overuse or misuse of antibiotics, as well as a lack of new, effective antibiotics. Alternative antimicrobial treatments, such as nanoparticles, and their potential for stronger synergetic effect when paired with other active chemicals, could be a viable option. This study is prepared to estimate the antibacterial activity of silver nanoparticles (AgNPs) that have been synthesized using the biomass-free filtrate of Aspergillus flavus. The formation of AgNPs was reported by color changed to a dark brownish-black after 72 hours of incubation. The AgNPs surface plasmon resonance peak was indicated in the UV–Vis spectrum at 427 nm. The synthesis of AgNPs with a nanoparticle size of 10 to 35 nm was validated using transmission electron microscopy. The increase in folding area was calculated to detect the synergistic potential of the combined AgNPs with a broad range of conventional antibiotics. AgNPs have broad-spectrum activity against all strains tested. The most sensitive strain was Escherichia coli (11 mm), whereas the most resistant strain was Pseudomonas aeruginosa, as indicated by the lowest inhibition zone (7 mm). The lowest Minimum Inhibitory Concentration indicated was against K. pneumonia and Enterobacter cloacae (0.025 mg/mL, each), followed by Staphylococcus epidermidis (0.05 mg/mL), E. coli and Shigella sp. (0.075 mg/mL, each), and then S. aureus (0.1 mg/mL). Notable synergy was reported between AgNPs and either ampicillin, erythromycin, ceftriaxone, vancomycin, azlocillin, or amoxicillin against S. aureus in the range between 29.3-fold to 8-fold. In addition, synergy was seen between AgNPs and either vancomycin, clindamycin, or erythromycin against P. aeruginosa (31.1-8.0-fold). Also, a maximum increase in IFA when erythromycin and vancomycin were synergized with AgNPs against E. cloacae was reported (IFA of 10.0 and 9.0, respectively). Similarly, AgNPs with either aztreonam or azlocillin against E. coli and amoxicillin, ciprofloxacin, or ceftriaxone against Shigella sp. caused an increase in the fold area of inhibition of between 5.3-3.7-fold. This result may have an advantage in encouraging the use of combined AgNPS with conventional antibiotics in treating infectious diseases caused by antibiotic-resistant bacteria.

Structure-Based Virtual Screening, Docking, ADMET, Molecular Dynamics, and MM-PBSA Calculations for the Discovery of Potential Natural SARS-CoV-2 Helicase Inhibitors from the Traditional Chinese Medicine

Continuing our antecedent work against COVID-19, a set of 5956 compounds of traditional Chinese medicine have been virtually screened for their potential against SARS-CoV-2 helicase (PDB ID: 5RMM). Initially, a fingerprint study with VXG, the ligand of the target enzyme, disclosed the similarity of 187 compounds. Then, a molecular similarity study declared the most similar 40 compounds. Subsequently, molecular docking studies were carried out to examine the binding modes and energies. Then, the most appropriate 26 compounds were subjected to in silico ADMET and toxicity studies to select the most convenient inhibitors to be: (1R,2S)-ephedrine (57), (1R,2S)-norephedrine (59), 2-(4-(pyrrolidin-1-yl)phenyl)acetic acid (84), 1-phenylpropane-1,2-dione (195), 2-methoxycinnamic acid (246), 2-methoxybenzoic acid (364), (R)-2-((R)-5-oxopyrrolidin-3-yl)-2-phenylacetic acid (405), (Z)-6-(3-hydroxy-4-methoxystyryl)-4-methoxy-2H-pyran-2-one (533), 8-chloro-2-(2-phenylethyl)-5,6,7-trihydroxy-5,6,7,8-tetrahydrochromone (637), 3-((1R,2S)-2-(dimethylamino)-1-hydroxypropyl)phenol (818), (R)-2-ethyl-4-(1-hydroxy-2-(methylamino)ethyl)phenol (5159), and (R)-2-((1S,2S,5S)-2-benzyl-5-hydroxy-4-methylcyclohex-3-en-1-yl)propane-1,2-diol (5168). Among the selected 12 compounds, the metabolites, compound 533 showed the best docking scores. Interestingly, the MD simulation studies for compound 533, the one with the highest docking score, over 100 ns showed its correct binding to SARS-CoV-2 helicase with low energy and optimum dynamics. Finally, MM-PBSA studies showed that 533 bonded favorably to SARS-CoV-2 helicase with a free energy value of −83 kJ/mol. Further, the free energy decomposition study determined the essential amino acid residues that contributed favorably to the binding process. The obtained results give a huge hope to find a cure for COVID-19 through further in vitro and in vivo studies for the selected compounds.

A Multistage In Silico Study of Natural Potential Inhibitors Targeting SARS-CoV-2 Main Protease

Among a group of 310 natural antiviral natural metabolites, our team identified three compounds as the most potent natural inhibitors against the SARS-CoV-2 main protease (PDB ID: 5R84), Mpro. The identified compounds are sattazolin and caprolactin A and B. A validated multistage in silico study was conducted using several techniques. First, the molecular structures of the selected metabolites were compared with that of GWS, the co-crystallized ligand of Mpro, in a structural similarity study. The aim of this study was to determine the thirty most similar metabolites (10%) that may bind to the Mpro similar to GWS. Then, molecular docking against Mpro and pharmacophore studies led to the choice of five metabolites that exhibited good binding modes against the Mpro and good fit values against the generated pharmacophore model. Among them, three metabolites were chosen according to ADMET studies. The most promising Mpro inhibitor was determined by toxicity and DFT studies to be caprolactin A (292). Finally, molecular dynamics (MD) simulation studies were performed for caprolactin A to confirm the obtained results and understand the thermodynamic characteristics of the binding. It is hoped that the accomplished results could represent a positive step in the battle against COVID-19 through further in vitro and in vivo studies on the selected compounds.

The Computational Preventive Potential of the Rare Flavonoid, Patuletin, Isolated from Tagetes patula, against SARS-CoV-2

The rare flavonoid, patuletin, was isolated from the flowers of Tagetes patula growing in Egypt. The rarity of the isolated compound inspired us to scrutinize its preventive effect against COVID-19 utilizing a multi-step computational approach. Firstly, a structural similarity study was carried out against nine ligands of nine SARS-CoV-2 proteins. The results showed a large structural similarity between patuletin and F86, the ligand of SARS-CoV-2 RNA-dependent RNA polymerase (RdRp). Then, a 3D-Flexible alignment study of patuletin and F86 verified the proposed similarity. To determine the binding opportunity, patuletin was docked against the RdRp showing a correct binding inside its active pocket with an energy of −20 kcal/mol that was comparable to that of F86 (−23 kcal/mol). Following, several MD simulations as well as MM-PBSA studies authenticated the accurate binding of patuletin in the RdRp via the correct dynamic and energetic behaviors over 100 ns. Additionally, in silico ADMET studies showed the general safety and drug-likeness of patuletin.

Tea Tree Oil Nanoemulsion Potentiates Antibiotics against Multidrug-Resistant Escherichia coli

Extensive efforts are underway to overcome the rising prevalence of antibiotic resistance. Combination therapy may be a potential method to treat multidrug-resistant (MDR) bacterial infections. In this study, tea tree essential oil (TTO) nanoemulsion (nanoTTO) was used in combination with antibiotics to kill microbes. Results showed that nanoTTO enhanced the activities of multiple antibiotics against MDR Escherichia coli (E. coli), and its antimicrobial activity was not changed against bacteria that were cultured in the presence of nanoTTO for 30 passages. Further studies to visualize and quantify intracellular antibiotics concentrations identified that nanoTTO increased the drug accumulation in MDR E. coli by disrupting outer and inner membranes and inhibiting the AcrAB-TolC efflux pump involved in membrane permeability. In addition, nanoTTO was effective in enhancing antibiotic efficacy in the Galleria mellonella infection model and mouse peritonitis model, suggesting a potential strategy against MDR bacterial infections.

Antibacterial activity of essential oils for combating colistin-resistant bacteria

OBJECTIVES

Colistin (polymyxin E) is a bactericidal antibiotic used to treat severe infections caused by multidrug-resistant Gram-negative bacteria. The product of the mcr1 gene generates transferrable plasmid-mediated colistin resistance, which has arisen as a worldwide healthcare problem. This study aimed to isolate, and identify colistin-resistant bacteria, and evaluate the ability of essential oils its fights.

METHODS

: Twenty-seven bacterial isolates were collected from patients who were admitted to National Cancer Institute, Cairo, Egypt, and processed by standard microbiological methods. Essential oils were purchased from AB chem company, Egypt, screened for antibacterial, cytotoxic activity, and (GC-MS) analysis.

RESULTS

A total of 5 bacterial isolates were resistant to colistin with minimum inhibitory concentration (MIC) ranging from 6.25->200µg/ml. Cinnamon oil exhibited the highest activity against colistin-resistant strains followed by thyme and eucalyptus oil. The (MIC) of cinnamon oils against resistant strains ranged from 4.88 to 312.5 µg/ml. Moreover, mcr-1 gene expression was extremely down-regulated after treatment of bacterial strains with cinnamon oil and decreased to 20-35-fold. Examination of treated bacterial cells with sub-inhibitory concentrations under transmission electron microscopy showed various abnormalities occurred in most of these cells.

CONCLUSIONS

cinnamon oil exhibits antibacterial activity against colistin-resistant strains, showing as a promising natural alternative in clinical therapy.

Effect of New 2-Thioxoimidazolidin-4-one Compounds against Staphylococcus aureus Clinical Strains and Immunological Markers’ Combinations

Although the structure-activity relationship indicates that the 4-thioxoimidazolidin ring is essential for antibacterial activities and pharmaceutical applications, there were no enough studies on the derivatives of this compound. Evaluating the new hydantoin compounds C5 (3-((2-bromobenzylidene) amino)-2- thioxoimidazolidin-4-one) and C6 (3-((4- methoxybenzylidene) amino)-2-thioxoimidazolidin-4-one) that were prepared against clinical Staphylococcus aureus isolates for antibacterial, antibiofilm, and antihemagglutination activities is the aim of this study. Therefore, the potential clinical resistance of the strains was evaluated by their ability to form biofilms, antibiotic resistance, and agglutinate erythrocytes macroscopically and microscopically; besides, the bacterial biofilm was screened for any association with the patient's serum immunoglobulin levels and complements. Despite the effective concentration for C5 and C6 compounds, which is ≤ 31.25 μg/ml, the reduction rate is not concentration-dependent; it depends on the molecular docking of the hydantoin compounds. Hence, the effect of the minimal inhibitory concentrations (MICs) is variable. In this study, the results for the compounds (with the concentration of 31.25–62.5 μg/mL for C5 and 62.5–125 μg/mL for C6) significantly manifest the antibacteria, antibiofilm, and antihemagglutination effects against the virulent strains of S. aureus due to the high percentage of biofilm inhibition that was caused by the new hydantoin compounds. Besides, time-kill kinetics studies showed that these compounds pose bactericidal action. Overall, this study revealed that the new hydantoin derivatives have an interesting potential as new antibacterial drugs through the inhibition of bacterial adhesion. The infections of these isolates activate the complement system through the lectin pathway. Nevertheless, these compounds can be improved in order to be used at even lower concentrations.

Multi-Step In Silico Discovery of Natural Drugs against COVID-19 Targeting Main Protease

In continuation of our antecedent work against COVID-19, three natural compounds, namely, Luteoside C (130), Kahalalide E (184), and Streptovaricin B (278) were determined as the most promising SARS-CoV-2 main protease (Mpro) inhibitors among 310 naturally originated antiviral compounds. This was performed via a multi-step in silico method. At first, a molecular structure similarity study was done with PRD_002214, the co-crystallized ligand of Mpro (PDB ID: 6LU7), and favored thirty compounds. Subsequently, the fingerprint study performed with respect to PRD_002214 resulted in the election of sixteen compounds (7, 128, 130, 156, 157, 158, 180, 184, 203, 204, 210, 237, 264, 276, 277, and 278). Then, results of molecular docking versus Mpro PDB ID: 6LU7 favored eight compounds (128, 130, 156, 180, 184, 203, 204, and 278) based on their binding affinities. Then, in silico toxicity studies were performed for the promising compounds and revealed that all of them have good toxicity profiles. Finally, molecular dynamic (MD) simulation experiments were carried out for compounds 130, 184, and 278, which exhibited the best binding modes against Mpro. MD tests revealed that luteoside C (130) has the greatest potential to inhibit SARS-CoV-2 main protease.

Escherichia coli response to subinhibitory concentrations of colistin: insights from a study of membrane dynamics and morphology

Prevalence of widespread bacterial infections brings forth a critical need to understand the molecular mechanisms of the antibiotics as well as the bacterial response to those antibiotics. Improper use of antibiotics, which can be in sub-lethal concentrations is one among the multiple reasons for acquiring antibiotic resistance which makes it vital to understand the bacterial response towards sub-lethal concentrations of antibiotics. In this work, we have used colistin, a well-known membrane active antibiotic used to treat severe bacterial infections and explored the impact of its sub-minimum inhibitory concentration (MIC) on the lipid membrane dynamics and morphological changes of E. coli. Upon investigation of live cell membrane properties such as lipid dynamics using fluorescence correlation spectroscopy, we observed that colistin disrupts the lipid membrane at sub-MIC by altering the lipid diffusivity. Interestingly, filamentation-like cell elongation was observed upon colistin treatment which led to further exploration of surface morphology with the help of atomic force spectroscopy. The changes in the surface roughness upon colistin treatment provides additional insight on the colistin-membrane interaction corroborating with the altered lipid diffusion. Although altered lipid dynamics could be attributed to an outcome of lipid rearrangement due to direct disruption by antibiotic molecules on the membrane or an indirect consequence of disruptions in lipid biosynthetic pathways, we were able to ascertain that altered bacterial membrane dynamics is due to direct disruptions. Our results provide a broad overview on the consequence of the cyclic polypeptide colistin on membrane-specific lipid dynamics and morphology of a live Gram-negative bacterial cell.

Isolation and In Silico SARS-CoV-2 Main Protease Inhibition Potential of Jusan Coumarin, a New Dicoumarin from Artemisia glauca

A new dicoumarin, jusan coumarin, (1), has been isolated from Artemisia glauca aerial parts. The chemical structure of jusan coumarin was estimated, by 1D, 2D NMR as well as HR-Ms spectroscopic methods, to be 7-hydroxy-6-methoxy-3-[(2-oxo-2H-chromen-6-yl)oxy]-2H-chromen-2-one. As the first time to be introduced in nature, its potential against SARS-CoV-2 has been estimated using various in silico methods. Molecular similarity and fingerprints experiments have been utilized for 1 against nine co-crystallized ligands of COVID-19 vital proteins. The results declared a great similarity between Jusan Coumarin and X77, the ligand of COVID-19 main protease (PDB ID: 6W63), Mpro. To authenticate the obtained outputs, a DFT experiment was achieved to confirm the similarity of X77 and 1. Consequently, 1 was docked against Mpro. The results clarified that 1 bonded in a correct way inside Mpro active site, with a binding energy of -18.45 kcal/mol. Furthermore, the ADMET and toxicity profiles of 1 were evaluated and showed the safety of 1 and its likeness to be a drug. Finally, to confirm the binding and understand the thermodynamic characters between 1 and Mpro, several molecular dynamics (MD) simulations studies have been administered. Additionally, the known coumarin derivative, 7-isopentenyloxycoumarin (2), has been isolated as well as β-sitosterol (3).

Jusanin, a New Flavonoid from Artemisia commutata with an In Silico Inhibitory Potential against the SARS-CoV-2 Main Protease

A new flavonoid, Jusanin, (1) has been isolated from the aerial parts of Artemisia commutata. The chemical structure of Jusanin has been elucidated using 1D, 2D NMR, and HR-Ms spectroscopic methods to be 5,2',4'-trihydroxy-6,7,5'-trimethoxyflavone. Being new in nature, the inhibition potential of 1 has been estimated against SARS-CoV-2 using different in silico techniques. Firstly, molecular similarity and fingerprint studies have been conducted for Jusanin against co-crystallized ligands of eight different SARS-CoV-2 essential proteins. The studies indicated the similarity between 1 and X77, the co-crystallized ligand SARS-CoV-2 main protease (PDB ID: 6W63). To confirm the obtained results, a DFT study was carried out and indicated the similarity of (total energy, HOMO, LUMO, gap energy, and dipole moment) between 1 and X77. Accordingly, molecular docking studies of 1 against the target enzyme have been achieved and showed that 1 bonded correctly in the protein's active site with a binding energy of -19.54 Kcal/mol. Additionally, in silico ADMET in addition to the toxicity evaluation of Jusanin against seven models have been preceded and indicated the general safety and the likeness of Jusanin to be a drug. Finally, molecular dynamics simulation studies were applied to investigate the dynamic behavior of the Mpro-Jusanin complex and confirmed the correct binding at 100 ns. In addition to 1, three other metabolites have been isolated and identified to be сapillartemisin A (2), methyl-3-[S-hydroxyprenyl]-cumarate (3), and β-sitosterol (4).

Isolation and In Silico Anti-SARS-CoV-2 Papain-like Protease Potentialities of Two Rare 2-Phenoxychromone Derivatives from Artemisia spp

Two rare 2-phenoxychromone derivatives, 6-demethoxy-4`-O-capillarsine (1) and tenuflorin C (2), were isolated from the areal parts of Artemisia commutata and A. glauca, respectively, for the first time. Being rare in nature, the inhibition potentialities of 1 and 2 against SARS-CoV-2 was investigated using multistage in silico techniques. At first, molecular similarity and fingerprint studies were conducted for 1 and 2 against co-crystallized ligands of eight different COVID-19 enzymes. The carried-out studies indicated the similarity of 1 and 2 with TTT, the co-crystallized ligand of COVID-19 Papain-Like Protease (PLP), (PDB ID: 3E9S). Therefore, molecular docking studies of 1 and 2 against the PLP were carried out and revealed correct binding inside the active site exhibiting binding energies of −18.86 and −18.37 Kcal/mol, respectively. Further, in silico ADMET in addition to toxicity evaluation of 1 and 2 against seven models indicated the general safety and the likeness of 1 and 2 to be drugs. Lastly, to authenticate the binding and to investigate the thermodynamic characters, molecular dynamics (MD) simulation studies were conducted on 1 and PLP.

A bis(pyrazolyl)methane derivative against clinical Staphylococcus aureus strains isolated from otitis externa

OBJECTIVE

The purpose of this study was to evaluate the in vitro antibacterial effects of a p-Cymene-based bis(pyrazolyl)methane derivative (SC-19) to advance in developing alternative therapeutic compounds to fight against bacterial isolates from patients with otitis externa (OE).

METHODS

Eighteen swab specimens were collected from patients aged over 18 years diagnosed with OE within at least 7 days of symptom onset, contaminated by only one bacterium type: Pseudomonas aeruginosa (n = 5); Staphylococcus aureus (n = 8); Klebsiella aerogenes (n = 2); Serratia marcescens (n = 1); Morganella morganii (n = 2). To appraise antibacterial activity, minimal inhibitory concentration (MIC), minimal bactericidal concentration (MBC), minimum biofilm inhibitory concentration (MBIC), and minimum biofilm eradication concentration (MBEC) assays were run at different SC-19 concentrations.

RESULTS

When using SC-19, S. aureus strains showed less bacterial growth, but no bactericidal effect was observed. The MIC and MBC of SC-19 were 62.5 and 2000 μg/ml against S. aureus and were >2000 μg/ml against the other isolates obtained from OE, respectively. In addition, the MBICs and MBECs of SC-19 against S. aureus were 125 and >2000 μg/ml, respectively.

CONCLUSION

Nowadays the acquired antibiotic resistance phenomenon has stimulated research into novel and more efficient therapeutic agents. Hence, we report that, helped by the structural diversity fostered herein by a range of bis(pyrazolyl)methane derivatives, SC-19 can be a promising alternative therapeutic option for treating OE caused by S. aureus given the observed effects on both planktonic state and biofilm.

LEVEL OF EVIDENCE

IV.

Sanguiin H-6 Fractionated from Cloudberry (Rubus chamaemorus) Seeds Can Prevent the Methicillin-Resistant Staphylococcus aureus Biofilm Development during Wound Infection

Staphylococcus aureus is the most common cause of surgical site infections and its treatment is challenging due to the emergence of multi-drug resistant strains such as methicillin-resistant S. aureus (MRSA). Natural berry-derived compounds have shown antimicrobial potential, e.g., ellagitannins such as sanguiin H-6 and lambertianin C, the main phenolic compounds in Rubus seeds, have shown antimicrobial activity. The aim of this study was to evaluate the effect of sanguiin H-6 and lambertianin C fractionated from cloudberry seeds, on the MRSA growth, and as treatment of a MRSA biofilm development in different growth media in vitro and in vivo by using a murine wound infection model where sanguiin H-6 and lambertianin C were used to prevent the MRSA infection. Sanguiin H-6 and lambertianin C inhibited the in vitro biofilm development and growth of MRSA. Furthermore, sanguiin H-6 showed significant anti-MRSA effect in the in vivo wound model. Our study shows the possible use of sanguiin H-6 as a preventive measure in surgical sites to avoid postoperative infections, whilst lambertianin C showed no anti-MRSA activity.

In Silico Screening of Semi-Synthesized Compounds as Potential Inhibitors for SARS-CoV-2 Papain-like Protease: Pharmacophoric Features, Molecular Docking, ADMET, Toxicity and DFT Studies

Papain-like protease is an essential enzyme in the proteolytic processing required for the replication of SARS-CoV-2. Accordingly, such an enzyme is an important target for the development of anti-SARS-CoV-2 agents which may reduce the mortality associated with outbreaks of SARS-CoV-2. A set of 69 semi-synthesized molecules that exhibited the structural features of SARS-CoV-2 papain-like protease inhibitors (PLPI) were docked against the coronavirus papain-like protease (PLpro) enzyme (PDB ID: (4OW0). Docking studies showed that derivatives 34 and 58 were better than the co-crystallized ligand while derivatives 17, 28, 31, 40, 41, 43, 47, 54, and 65 exhibited good binding modes and binding free energies. The pharmacokinetic profiling study was conducted according to the four principles of the Lipinski rules and excluded derivative 31. Furthermore, ADMET and toxicity studies showed that derivatives 28, 34, and 47 have the potential to be drugs and have been demonstrated as safe when assessed via seven toxicity models. Finally, comparing the molecular orbital energies and the molecular electrostatic potential maps of 28, 34, and 47 against the co-crystallized ligand in a DFT study indicated that 28 is the most promising candidate to interact with the target receptor (PLpro).

In Silico Exploration of Potential Natural Inhibitors against SARS-Cov-2 nsp10

In continuation of our previous effort, different in silico selection methods were applied to 310 naturally isolated metabolites that exhibited antiviral potentialities before. The applied selection methods aimed to pick the most relevant inhibitor of SARS-CoV-2 nsp10. At first, a structural similarity study against the co-crystallized ligand, S-Adenosyl Methionine (SAM), of SARS-CoV-2 nonstructural protein (nsp10) (PDB ID: 6W4H) was carried out. The similarity analysis culled 30 candidates. Secondly, a fingerprint study against SAM preferred compounds 44, 48, 85, 102, 105, 182, 220, 221, 282, 284, 285, 301, and 302. The docking studies picked 48, 182, 220, 221, and 284. While the ADMET analysis expected the likeness of the five candidates to be drugs, the toxicity study preferred compounds 48 and 182. Finally, a density-functional theory (DFT) study suggested vidarabine (182) to be the most relevant SARS-Cov-2 nsp10 inhibitor.

Traditional ancient Egyptian medicine: A review

The ancient Egyptians practiced medicine with highly professional methods. They had advanced knowledge of anatomy and surgery. Also, they treated a lot of diseases including dental, gynecological, gastrointestinal, and urinary disorders. They could diagnose diabetes and cancer. The used therapeutics extended from different plants to include several animal products and minerals. Some of these plants are still used in the present day. Fortunately, they documented their life details by carving on stone, clay, or papyri. Although a lot of these records have been lost or destroyed, the surviving documents represent a huge source of knowledge in different scientific aspects including medicine. This review article is an attempt to understand some information about traditional medicine in ancient Egypt, we will look closely at some basics, sources of information of Egyptian medicine in addition to common treated diseases and therapeutics in this great civilization.

Green Synthesized ZnO Nanoparticles Mediated by Streptomyces plicatus: Characterizations, Antimicrobial and Nematicidal Activities and Cytogenetic Effects

Zinc oxide nanoparticles (ZnO-NPs) are regarded as one of the most promising kinds of materials in a variety of fields, including agriculture. Therefore, this study aimed to biosynthesize and characterize ZnO-NPs and evaluate their different biological activities. Seven isolates of actinomycetes were obtained and screened for ZnO-NPs synthesis. The isolate MK-104 was chosen and identified as the Streptomyces plicatus MK-104 strain. The biosynthesized ZnO-NPs exhibited an absorbance peak at 350 nm and were spherical in shape with an average size of 21.72 ± 4.27 nm under TEM. XRD and DLS methods confirmed these results. The biosynthesized ZnO-NPs demonstrated activity against plant pathogenic microbes such as Erwinia amylovora, Aspergillus flavus, Aspergillus niger, Fusarium oxysporum, Fusarium moniliform and Alternaria alternata, with MIC values ranging from 15.6 to 500 µg/mL. Furthermore, ZnO-NPs had a significant effect on Meloidogyne incognita, with death percentages of 88.2, 93.4 and 96.72% after 24, 48 and 72 h of exposure, respectively. Vicia faba seeds were treated with five concentrations of ZnO-NPs (12.5, 25, 50, 100 and 200 µg/mL). Low-moderate ZnO-NP concentrations (12.5-50 µg/mL) were shown to promote seed germination and seedling development, while the mitotic index (MI) decreased as the dosage of ZnO-NPs increased. Micronuclei (MNs) and the chromosomal abnormality index increased as well.

Isolation, Crystal Structure, and In Silico Aromatase Inhibition Activity of Ergosta-5, 22-dien-3β-ol from the Fungus Gyromitra esculenta

Ergosterol derivatives exhibited copious promising biological activities. The fungus Gyromitra esculenta is widely distributed in Europe and North America. In order to examine the chemical properties of Gyromitra esculenta, a phytochemical study has been preceded and resulted in the isolation of the steroid, ergosta-5, 22-dien-3β-ol (brassicasterol), from its methanol extract. The complete identification and absolute configuration of the isolated compound have been established by X-ray structural analysis to be (22E, 24R)-24-methylcholesta-5, 22-dien-3beta-ol. The reported cytotoxicity and the great structural similarity of the isolated compound with the cocrystallized ligand of the aromatase enzyme inspired us to run molecular docking studies against that protein. Ergosta-5, 22-dien-3β-ol occupied the target protein with a binding mode almost the same as the cocrystallized ligand and a binding affinity of −33.55 kcal/mol, which was better than that of the cocrystallized ligand (−22.61 kcal/mol). This promising result encouraged us to conduct in silico ADMET and toxicity studies of ergosta-5, 22-dien-3β-ol against 6 models, and the results expected the likeness of the isolated compound to be a drug. In conclusion, ergosta-5, 22-dien-3β-ol has been isolated from Gyromitra esculenta, identified by X-ray structural analysis, and exhibited promising in silico activities against aromatase enzyme.

Comprehensive In Silico Screening of the Antiviral Potentialities of a New Humulene Glucoside from Asteriscus hierochunticus against SARS-CoV-2

Chromatographic fractionation of the methanolic extract of Asteriscus hierochunticus whole plant led to the identification of a new humulene glucoside (1). The chemical structure of the isolated compound was elucidated by IR, 1D, 2D NMR, and HRESIMS data analysis to be (-)-(2Z,6E,9E)8α-hydroxy-2,6,9-humulatrien-1(12)-olide. In this study, we report the in silico binding affinities of 1 against four different SARS-CoV-2 proteins (COVID-19 main protease (PDB ID: 6lu7), nonstructural protein (PDB ID: 6W4H), RNA-dependent RNA polymerase (PDB ID: 7BV2), and SARS-CoV-2 helicase (PDB ID: 5RMM)). The isolated compound showed excellent binding affinity values (ΔG) of −21.65, −20.05, −28.93, and −21.73 kcal/mol, respectively, against the target proteins compared to the cocrystallized ligands that exhibited ΔG values of −23.75, −17.65, −23.57, and −15.30 kcal/mol, respectively. Further in silico investigations of the isolated compound (1) for its ADMET and toxicity profiles revealed excellent drug likeliness. On the other hand, the results obtained from in vitro antitrypanosomal, antileishmanial, and antimalarial activities of (1) were not promising.

Isolation and In Silico Anti-COVID-19 Main Protease (Mpro) Activities of Flavonoids and a Sesquiterpene Lactone from Artemisia sublessingiana

The emergence of the COVID-19 pandemic declared the huge need of humanity for new and effective antiviral drugs. The reported antimicrobial activities of Artemisia sublessingiana encouraged us to investigate the ethanol extract of its aerial parts which led to the isolation of six flavonoids and a sesquiterpenoid. The structures of the isolated compounds were elucidated by EI-MS, 1D, and 2D NMR spectroscopic methods to be (1) eupatilin, (2) 3′,4′-dimethoxyluteolin, (3) 5,7,3′-trihydroxy-6,4′,5′-trimethoxyflavone, (4) hispidulin, (5) apigenin, (6) velutin, and (7) sesquiterpene lactone 8α,14-dihydroxy-11,13-dihydromelampolide. The isolated compounds were in silico examined against the COVID-19 main protease (Mpro) enzyme. Compounds 1–6 exhibited promising binding modes showing free energies ranging from −6.39 to −6.81 (kcal/mol). The best binding energy was for compound 2. The obtained results give hope of finding a treatment for the COVID-19 pandemic.

Eissa I, Metwaly AM. In Silico Studies of Some Isoflavonoids as Potential Candidates against COVID-19 Targeting Human ACE2 (hACE2) and Viral Main Protease (Mpro)

The Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) caused the "COVID-19" disease that has been declared by WHO as a global emergency. The pandemic, which emerged in China and widespread all over the world, has no specific treatment till now. The reported antiviral activities of isoflavonoids encouraged us to find out its in silico anti-SARS-CoV-2 activity. In this work, molecular docking studies were carried out to investigate the interaction of fifty-nine isoflavonoids against hACE2 and viral Mpro. Several other in silico studies including physicochemical properties, ADMET and toxicity have been preceded. The results revealed that the examined isoflavonoids bound perfectly the hACE-2 with free binding energies ranging from -24.02 to -39.33 kcal mol-1, compared to the co-crystallized ligand (-21.39 kcal mol-1). Furthermore, such compounds bound the Mpro with unique binding modes showing free binding energies ranging from -32.19 to -50.79 kcal mol-1, comparing to the co-crystallized ligand (binding energy = -62.84 kcal mol-1). Compounds 33 and 56 showed the most acceptable affinities against hACE2. Compounds 30 and 53 showed the best docking results against Mpro. In silico ADMET studies suggest that most compounds possess drug-likeness properties.

Synthesis and Molecular Docking of Some Grossgemin Amino Derivatives as Tubulin Inhibitors Targeting Colchicine Binding Site

Six amino derivatives of grossgemin (2–7) were synthesized according to the reported essential pharmacophoric features of colchicine binding site inhibitors (CBSIs). The derivatives 4–6 were obtained for the first time. The pharmacophoric features of 2–7 as CBSIs were studied to be almost identical. Furthermore, the 3D-flexible alignment of compound 5 as a representative example with colchicine showed a very good overlapping. In agreement, compounds 2–7 docked into CBS with binding modes very similar to that of colchicine and exhibited binding free energies of −24.57, −25.05, −32.16, −29.34, −26.38, and −26.86 (kcal/mol), respectively. The binding free energies of 4–7 were better than that of colchicine (−26.13 kcal/mol) with a noticeable superiority to compound 4.

In Vitro and In Silico Cytotoxic and Antibacterial Activities of a Diterpene from Cousinia alata Schrenk

A biologically guided isolation of secondary metabolites from Cousinia alata Schrenk wild plant growing in Akmola region, Kazakhstan, led to the isolation of the bioactive diterpene grindelic acid (1). Six flavonoids were also isolated and identified as retusine (2), pachipodol (3), jaranol (4), penduletin (5), casticin (6), and 5, 7, 3′-trihydroxy-3, 4′-dimethoxyflavone (7). Penduletin (5) showed moderate cytotoxic activity assay. Grindelic acid exhibited promising cytotoxic activity against the Artemia salina nauplii and antibacterial activity against Staphylococcus aureus, Bacillus cereus, and Salmonella enteritidis. The presence of the essential pharmacophoric features of histone deacetylase (HDAC) inhibitors in the structure of grindelic acid encouraged us to run a molecular docking study against the HDAC enzyme to understand its mechanism of action on a molecular level. Grindelic acid showed a binding mode of interaction similar to that of the cocrystallized ligand and exhibited good binding affinity against HDAC with the binding free energy of −18.70 kcal/mol. The structures of isolated compounds were determined by MS, 1D, and 2D NMR spectroscopy methods. Compounds (1–7) were isolated for the first time from Cousinia genus.