Hydrogen Sulfide Biology and Its Role in Cancer.

Hydrogen sulfide (H2S) is an endogenous biologically active gas produced in mammalian tissues. It plays a very critical role in many pathophysiological processes in the body. It can be endogenously produced through many enzymes analogous to the cysteine family, while the exogenous source may involve inorganic sulfide salts. H2S has recently been well investigated with regard to the onset of various carcinogenic diseases such as lung, breast, ovaries, colon cancer, and neurodegenerative disorders. H2S is considered an oncogenic gas, and a potential therapeutic target for treating and diagnosing cancers, due to its role in mediating the development of tumorigenesis. Here in this review, an in-detail up-to-date explanation of the potential role of H2S in different malignancies has been reported. The study summarizes the synthesis of H2S, its roles, signaling routes, expressions, and H2S release in various malignancies. Considering the critical importance of this active biological molecule, we believe this review in this esteemed journal will highlight the oncogenic role of H2S in the scientific community.

Mass Transfer Modulation and Gas Mapping Based on Covalent Organic Frameworks-Covered Theta Micropipette.

Covalent organic frameworks (COFs) consist nanochannels that are fundamentally important for their application. Up to now, the effect of gas phase on COF nanochannels are hard to explore. Here, TAPB-PDA-COFs (triphenylbenzene-terephthaldehyde-COFs) was synthesized in situ at the tip of a theta micropipette. The COF-covered theta micropipette (CTP) create a stable gas-liquid interface inside the COF nanochannels, through which the humidity-modulated ion mass transfer in the COF nanochannels can be recorded by recording the current across the two channels of the theta micropipette. Results show that the humid air changes the mobility of the ions inside the COF nanochannels, which leads to the change of ionic current. Humid air showed different effects on the ion transfer depending on the solvent polarity index and vapor pressure. Current decreases linearly with the increase of relative humidity (RH) from 11% to 98%. The CTP was also mounted on the scanning electrochemical microscopy as a probe electrode for mapping micrometer-scale humidity distribution.

pH-Dependent Slipping and Exfoliation of Layered Covalent Organic Framework.

Layered/two-dimensional covalent organic frameworks (2D COF) are crystalline porous materials composed of light elements linked by strong covalent bonds. Interlayer force is one of the main factors directing the formation of a stacked layer structure, which plays a vital role in the stability, crystallinity, and porosity of layered COFs. The as-developed new way to modulate the interlayer force of imine-linked 2D TAPB-PDA-COF (TAPB = 1,3,5-tris(4-aminophenyl)benzene, PDA = terephthaldehyde) by only adjusting the pH of the solution. At alkaline and neutral pH, the pore size of the COF decreases from 34 Šdue to the turbostratic effect. Under highly acidic conditions (pH 1), TAPB-PDA-COF shows a faster and stronger turbostratic effect, thus causing the 2D structure to exfoliate. This yields bulk quantities of an exfoliated few/single-layer 2D COF, which was well dispersed and displayed a clear Tyndall effect (TE). Furthermore, nanopipette-based electrochemical testing also confirms the slipping of layers with increase towards acidic pH. A model of pH-dependent layer slipping of TAPB-PDA-COF was proposed. This controllable pH-dependent change in the layer structure may open a new door for potential applications in controlled gas adsorption/desorption and drug loading/releasing.

Nanomedicine-based immunotherapy for central nervous system disorders.

Central nervous system (CNS) disorders represent a broad spectrum of brain ailments with short- and long-term disabilities, and nanomedicine-based approaches provide a new therapeutic approach to treating CNS disorders. A variety of potential drugs have been discovered to treat several neuronal disorders; however, their therapeutic success can be limited by the presence of the blood-brain barrier (BBB). Furthermore, unique immune functions within the CNS provide novel target mechanisms for the amelioration of CNS diseases. Recently, various therapeutic approaches have been applied to fight brain-related disorders, with moderate outcomes. Among the various therapeutic strategies, nanomedicine-based immunotherapeutic systems represent a new era that can deliver useful cargo with promising pharmacokinetics. These approaches exploit the molecular and cellular targeting of CNS disorders for enhanced safety, efficacy, and specificity. In this review, we focus on the efficacy of nanomedicines that utilize immunotherapy to combat CNS disorders. Furthermore, we detailed summarize nanomedicine-based pathways for CNS ailments that aim to deliver drugs across the BBB by mimicking innate immune actions. Overview of how nanomedicines can utilize multiple immunotherapy pathways to combat CNS disorders.

Organic Cyanide Decorated SERS Active Nanopipettes for Quantitative Detection of Hemeproteins and Fe3+ in Single Cells.

It is challenging to develop a robust nanoprobe for real-time operational and accurate detection of heavy metals in single cells. Fe-CN coordination chemistry has been well studied to determine the structural characteristics of hemeproteins by different techniques. However, the frequently used cyanide ligands are inorganic molecules that release cyanide anion under particular conditions and cause cyanide poisoning. In the present study, organic cyanide (4-mercaptobenzonitrile, MBN) was utilized for the first time in developing a facile nanoprobe based on surface-enhanced Raman scattering (SERS) for quantitative detection of hemeproteins (oxy-Hb) and trivalent iron (Fe3+) ions. The nanoprobe prepared by coating the glass capillary tip (100 nm) with a thin gold film, which enables highly localized study in living cell system. The cyanide stretching vibration in MBN was highly sensitive and selective to Fe3+ and oxy-Hb with excellent binding affinity (Kd 0.4 pM and 0.1 nM, respectively). The high sensitivity of the nanoprobe to analyte (Fe3+) was attributed to the two adsorption conformations (-SH and -CN) of MBN to the gold surface. Therefore, MBN showed an exceptional dual-peak (2126 and 2225 cm-1) behavior. Furthermore, the special Raman peaks of cyanide in 2100-2300 cm-1 (silent region of SERS spectra) are distinguishable from other biomolecules characteristic peaks. The selective detection of Fe3+ in both free and protein-bound states in aqueous solution is achieved with 0.1 pM and 0.08 µM levels of detection limits, respectively. Furthermore, practical applicability of fabricated nanoprobe was validated by detection of free Fe3+ in pretreated living HeLa cells by direct insertion of a SERS active nanoprobe. Regarding the appropriate precision, good reproducibility (relative standard deviation, RSD 7.2-7.6%), and recyclability (retain good Raman intensity even after three renewing cycles) of the method, the developed sensing strategy on a nanopipette has potential benefits for label-free, qualitative and quantitative recognition of heavy metal ions within nanoliter volumes.

Molecularly Imprinted Polymer-Based Plasmonic Immunosandwich Assay for Fast and Ultrasensitive Determination of Trace Glycoproteins in Complex Samples.

Glycoproteins play significant roles in many biological processes. Assays of glycoproteins have significant biological importance and clinical values, for which immunoassay has been the workhorse tool. However, immunoassay suffers from some disadvantages, such as poor availability of high-specificity antibodies and limited stability of biological reagents. Herein, we present an antibody-free and enzyme-free approach, called molecularly imprinted polymer (MIP)-based plasmonic immunosandwich assay (PISA), for fast and ultrasensitive detection of trace glycoproteins in complex samples. A gold-based boronate affinity MIP array was used to specifically extract the target glycoprotein from complex samples. After washing away unwanted species, the captured glycoprotein was labeled with boronate affinity silver-based Raman nanotags. Thus, sandwich-like complexes were formed on the array. Upon being shined with a laser beam, the gold-based array generated a surface plasmon wave, which significantly enhanced the surface-enhanced Raman scattering (SERS) signal of the silver-based Raman nanotags. The MIP ensured the specificity of the assay, while the plasmonic detection provided ultrahigh sensitivity. Erythropoietin (EPO), a glycoprotein hormone that controls erythropoiesis or red blood cell production, was employed as a test glycoprotein in this study. Specific detection of EPO in solution down to 2.9 × 10-14 M was achieved. Using a novel strategy to accommodate the method of standard addition to a logarithmic dose-response relationship, EPO in human urine was quantitatively determined by this approach. The analysis time required only 30 min in total. This approach holds promising application prospects in many areas, such as biochemical research, clinical diagnosis, and antidoping analysis.

Humanistic Health Management and Cancer: Associations of Psychology, Nutrition, and Exercise with Cancer Progression and Pathogenesis.

The incidence rate of cancer is increasing year by year due to the aging of the population, unhealthy living, and eating habits. At present, surgery and medication are still the main treatments for cancer, without paying attention to the impact of individual differences in health management on cancer. However, increasing evidence suggests that individual psychological status, dietary habits, and exercise frequency are closely related to the risk and prognosis of cancer. The reminder to humanity is that the medical concept of the unified treatment plan is insufficient in cancer treatment, and a personalized treatment plan may become a breakthrough point. On this basis, the concept of "Humanistic Health Management" (HHM) is proposed. This concept is a healthcare plan that focuses on self-health management, providing an accurate and comprehensive evaluation of individual lifestyle habits, psychology, and health status, and developing personalized and targeted comprehensive cancer prevention and treatment plans. This review will provide a detailed explanation of the relationship between psychological status, dietary, and exercise habits, and the regulatory mechanisms of cancer. Intended to emphasize the importance of HHM concept in cancer prevention and better prognostic efficacy, providing new ideas for the new generation of cancer treatment.

Arsenic Prodrug-Mediated Tumor Microenvironment Modulation Platform for Synergetic Glioblastoma Therapy.

Glioblastoma (GBM) has a distinct internal environment characterized by high levels of glutathione (GSH) and low oxygen partial pressure, which significantly restrict most drugs' effectiveness. Arsenic-based drugs are emerging candidates for treating solid tumors; however, relatively high doses in solo systems and inconsistent complementary systems severely damage the normal tissues. We proposed a novel covalently conjugated strategy for arsenic-based therapy via arsenic-boronic acid complex formation. The boronic acid was modified on silver (AgL) to capture AsV under an alkaline condition named arsenate plasmonic complex (APC) with a distinct Raman response. The APC can precisely release the captured AsV in lysosomal acidic pH that specifically targets TME to initiate a multimodal therapeutic effect such as GSH depletion and reactive oxygen species generation. In addition, GSH activation leads to subconverted AsV into AsIII, which further facilitated glutathione peroxidase (GPx) and superoxide dismutase inhibition, whereas the tumor selective etching of the silver core triggered by endogenous H2O2 that can oxidize to generate highly toxic Ag ions produces and supplies O2 to help the alleviated hypoxia. Both in vitro and in vivo data verify the APC-based chemotherapy paving the way for efficient nanomedicine-enabled boronate affinity-based arsenic chemotherapeutics for on demand site-specific cancer combination treatment of GBM tumors.

Targeted liposomes for combined delivery of artesunate and temozolomide to resistant glioblastoma.

The effective treatment of glioblastoma (GBM) is a great challenge because of the blood-brain barrier (BBB) and the growing resistance to single-agent therapeutics. Targeted combined co-delivery of drugs could circumvent these challenges; however, the absence of more effective combination drug delivery strategies presents a potent barrier. Here, a unique combination ApoE-functionalized liposomal nanoplatform based on artesunate-phosphatidylcholine (ARTPC) encapsulated with temozolomide (ApoE-ARTPC@TMZ) was presented that can successfully co-deliver dual therapeutic agents to TMZ-resistant U251-TR GBM in vivo. Examination in vitro showed ART-mediated inhibition of DNA repair through the Wnt/ß-catenin signaling cascade, which also improved GBM sensitivity to TMZ, resulting in enhanced synergistic DNA damage and induction of apoptosis. In assessing BBB permeation, the targeted liposomes were able to effectively traverse the BBB through low-density lipoprotein family receptors (LDLRs)-mediated transcytosis and achieved deep intracranial tumor penetration. More importantly, the targeted combination liposomes resulted in a significant decrease of U251-TR glioma burden in vivo that, in concert, substantially improved the survival of mice. Additionally, by lowering the effective dosage of TMZ, the combination liposomes reduced systemic TMZ-induced toxicity, highlighting the preclinical potential of this novel integrative strategy to deliver combination therapies to brain tumors.

Biomimetic Dp44mT-nanoparticles selectively induce apoptosis in Cu-loaded glioblastoma resulting in potent growth inhibition.

Selective targeting of elevated copper (Cu) in cancer cells by chelators to induce tumor-toxic reactive oxygen species (ROS) may be a promising approach in the treatment of glioblastoma multiforme (GBM). Previously, the Cu chelator di-2-pyridylketone-4,4-dimethyl-3-thiosemicarbazone (Dp44mT) attracted much interest due to its potent anti-tumor activity mediated by the formation of a highly redox-active Cu-Dp44mT complex. However, its translational potential was limited by the development of toxicity in murine models of cancer reflecting poor selectivity. Here, we overcame the limitations of Dp44mT by incorporating it in new biomimetic nanoparticles (NPs) optimized for GBM therapy. Biomimetic design elements enhancing selectivity included angiopeptide-2 functionalized red blood cell membrane (Ang-M) camouflaging of the NPs carrier. Co-loading Dp44mT with regadenoson (Reg), that transiently opens the blood-brain-barrier (BBB), yielded biomimetic Ang-MNPs@(Dp44mT/Reg) NPs that actively targeted and traversed the BBB delivering Dp44mT specifically to GBM cells. To further improve selectivity, we innovatively pre-loaded GBM tumors with Cu. Oral dosing of U87MG-Luc tumor bearing mice with diacetyl-bis(4-methylthiosemicarbazonato)-copperII (Cu(II)-ATSM), significantly enhanced Cu-level in GBM tumor. Subsequent treatment of mice bearing Cu-enriched orthotopic U87MG-Luc GBM with Ang-MNPs@(Dp44mT/Reg) substantially prevented orthotopic GBM growth and led to maximal increases in median survival time. These results highlighted the importance of both angiopeptide-2 functionalization and tumor Cu-loading required for greater selective cytotoxicity. Targeting Ang-MNPs@(Dp44mT/Reg) NPs also down-regulated antiapoptotic Bcl-2, but up-regulated pro-apoptotic Bax and cleaved-caspase-3, demonstrating the involvement of the apoptotic pathway in GBM suppression. Notably, Ang-MNPs@(Dp44mT/Reg) showed negligible systemic drug toxicity in mice, further indicating therapeutic potential that could be adapted for other central nervous system disorders.

Heme Oxygenase-1 targeting exosomes for temozolomide resistant glioblastoma synergistic therapy.

Glioblastoma (GBM) is a highly fatal and recurrent brain cancer without a complete prevailing remedy. Although the synthetic nanotechnology-based approaches exhibit excellent therapeutic potential, the associated cytotoxic effects and organ clearance failure rest major obstacles from bench to clinics. Here, we explored allogeneic bone marrow mesenchymal stem cells isolated exosomes (BMSCExo) decorated with heme oxygenase-1 (HMOX1) specific short peptide (HSSP) as temozolomide (TMZ) and small interfering RNA (siRNA) nanocarrier for TMZ resistant glioblastoma therapy. The BMSCExo had excellent TMZ and siRNA loading ability and could traverse the blood-brain barrier (BBB) by leveraging its intrinsic brain accumulation property. Notably, with HSSP decoration, the TMZ or siRNA encapsulated BMSCExo exhibited excellent TMZ resistant GBM targeting ability both in vitro and in vivo due to the overexpression of HMOX1 in TMZ resistant GBM cells. Further, the HSSP decorated BMSCExo delivered the STAT3 targeted siRNA to the TMZ resistant glioma and restore the TMZ sensitivity, consequently achieved the synergistically drug resistant GBM treatment with TMZ. Our results showed this biomimetic nanoplatform can serve as a flexible, robust and inert system for GBM treatment, especially emphasizing the drug resistant challenge.

The Role of Hydrogen Sulfide in Respiratory Diseases.

Respiratory diseases are leading causes of death and disability around the globe, with a diverse range of health problems. Treatment of respiratory diseases and infections has been verified to be thought-provoking because of the increasing incidence and mortality rate. Hydrogen sulfide (H2S) is one of the recognized gaseous transmitters involved in an extensive range of cellular functions, and physiological and pathological processes in a variety of diseases, including respiratory diseases. Recently, the therapeutic potential of H2S for respiratory diseases has been widely investigated. H2S plays a vital therapeutic role in obstructive respiratory disease, pulmonary fibrosis, emphysema, pancreatic inflammatory/respiratory lung injury, pulmonary inflammation, bronchial asthma and bronchiectasis. Although the therapeutic role of H2S has been extensively studied in various respiratory diseases, a concrete literature review will have an extraordinary impact on future therapeutics. This review provides a comprehensive overview of the effective role of H2S in respiratory diseases. Besides, we also summarized H2S production in the lung and its metabolism processes in respiratory diseases.

Genome-Wide Analysis of Codon Usage Patterns of SARS-CoV-2 Virus Reveals Global Heterogeneity of COVID-19.

The ongoing outbreak of coronavirus disease COVID-19 is significantly implicated by global heterogeneity in the genome organization of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The causative agents of global heterogeneity in the whole genome of SARS-CoV-2 are not well characterized due to the lack of comparative study of a large enough sample size from around the globe to reduce the standard deviation to the acceptable margin of error. To better understand the SARS-CoV-2 genome architecture, we have performed a comprehensive analysis of codon usage bias of sixty (60) strains to get a snapshot of its global heterogeneity. Our study shows a relatively low codon usage bias in the SARS-CoV-2 viral genome globally, with nearly all the over-preferred codons' A.U. ended. We concluded that the SARS-CoV-2 genome is primarily shaped by mutation pressure; however, marginal selection pressure cannot be overlooked. Within the A/U rich virus genomes of SARS-CoV-2, the standard deviation in G.C. (42.91% ± 5.84%) and the GC3 value (30.14% ± 6.93%) points towards global heterogeneity of the virus. Several SARS-CoV-2 viral strains were originated from different viral lineages at the exact geographic location also supports this fact. Taking all together, these findings suggest that the general root ancestry of the global genomes are different with different genome's level adaptation to host. This research may provide new insights into the codon patterns, host adaptation, and global heterogeneity of SARS-CoV-2.

Correction: SERS-based nanostrategy for rapid anemia diagnosis.

Correction for 'SERS-based nanostrategy for rapid anemia diagnosis' by Pir Muhammad et al., Nanoscale, 2020, 12, 1948-1957, DOI: 10.1039/C9NR09152A.

Assessment of General Populations Knowledge, Attitude, and Perceptions Toward the Coronavirus Disease (COVID-19): A Cross-Sectional Study From Pakistan.

Background: Coronavirus disease 2019 (COVID-19) is a global health threat and caused a universal psychosocial impact on the general population. Therefore, the knowledge, attitude, and perceptions (KAPs) of the general population are critical for the development and effective implementation of standard operating procedures (SOP) to contain the contagion and minimize the losses. Therefore, the current study was conducted to understand and evaluate the KAPs of Pakistani populations toward the COVID-19. Methods: An online cross-sectional study was carried out among participants from 1 May to 30 July 2020 in different areas of Pakistan. The respondents of the study were the general population with age ≥ 18 years. The poll URL was posted on several channels after a call for participation. Other social media platforms such as WeChat, WhatsApp, Facebook, Twitter, Instagram, Messenger, and LinkedIn were engaged to maximize general population engagement. The questionnaire included details about sociodemographic, knowledge about COVID-19, perceptions toward universal safety precautions of COVID-19, and beliefs attitude toward the COVID-19. The obtained data were exported into a Microsoft Excel spreadsheet and SPSS software version 21 for windows. The descriptive statistics values were presented in frequencies and percentages. Binary logistic regression, Chi-square test, and one-way ANOVA were applied to analyze the participants' socio-demographic characteristics and variables related to KAPs. P-value < 0.05 was recorded as significant. Results: A total of 1,000 participants were invited of which 734 participated in this study. The response rate was 73.4% (734/1,000). The gender, marital status, education, and residence showed a significant association with the knowledge score. The majority of the study participants were thinking that COVID-19 may be more dangerous in elderly individuals 94.5% (n = 700), and individuals with chronic diseases or severe complications 96.7% (n = 710) (p = 0.00). More than half of the participants 52.5% (n = 385) showed their concern that either they or their family members might get the infection. More than 98% (n = 703), (P-value = 0.00) of the participants held that COVID-19 would be successfully controlled in Pakistan by following the standard SOPs and government guidelines. Conclusion: This study showed that the general population of Pakistan has good awareness and reasonable attitudes and perceptions toward the full features of the COVID-19. The current study suggests that mass-level effective health education programs are necessary for developing countries to improve and limit the gap between KAP toward COVID-19.

SERS-based nanostrategy for rapid anemia diagnosis.

Iron detection is one of the critical markers to diagnose multiple blood-related disorders that correspond to various biological dysfunctions. The currently available anemia detection approach can be used only for pre-treated blood samples that interfere with the actual iron level in blood. Real-time detection approaches with higher sensitivity and specificity are certainly needed to cope with the commercial level clinical analyses. Herein, we presented a novel strategy to determine the blood iron that can be easily practiced at commercial levels. The blend of well-known iron-cyanide chemistry with nanotechnology is advantageous with ultrahigh sensitivity in whole blood analysis without any pre-treatments. This approach is a combined detection system of the conventional assay (UV-visible spectroscopy) with surface-enhanced Raman scattering (SERS). Organic cyanide modified silver nanoparticles (cAgNPs) can selectively respond to Fe3+ ions and Hb protein with a detection limit of 10 fM and 0.46 µg mL-1, respectively, without being affected by matrix interfering species in the complex biological fluid. We confirmed the clinical potential of our new cAgNPs by assessing iron-status in multiple anemia patients and normal controls. Our SERS-based iron quantitation approach is highly affordable for bulk-samples, cheap, quick, flexible, and useful for real-time clinical assays. Such a method for metal-chelation has extendable features of therapeutics molecular tracking within more complex living systems at cellular levels.

Structural determination of quercusides A and B, new flavonoid glucosides from Quercus incana, by 1D and 2D NMR spectroscopy.

Quercusides A and B, new flavonoid glucosides have been isolated from the chloroform soluble fractions of Quercus incana. Their structures were assigned from (1)H and (13)C nuclear magnetic resonance spectra, distortionless enhancement by polarization transfer (DEPT) and by correlation spectroscopy, heteronuclear multiple quantum correlation (HMQC) and heteronuclear multiple bond correlation (HMBC) experiments. Lupeol, beta-sitosterol and ursolic acid have also been reported from this species.

Controllably prepared molecularly imprinted core-shell plasmonic nanostructure for plasmon-enhanced fluorescence assay.

Plasmon-enhanced fluorescence (PEF) is an emerging technology for sensitive detection. It relies on the plasmonic effect of a noble metal nanostructure to dramatically enhance the fluorescence of target fluorophores around the metal surface. Because there is a compromise between plasmonic enhancement and fluorescence quenching, it is critical to control the distance between the fluorophore and the metal surface to an appropriate range. This makes the fabrication of plasmonic nanostructures for PEF assays a challenging task. Herein, we report a controllably prepared core-shell plasmonic nanostructure coated with molecularly imprinted polymer (MIP) for sensitive and specific PEF assay. Riboflavin (RF) was used as a test compound in this study. RF-imprinted Ag@SiO2 nanoparticles were prepared in a controllable manner, providing an optimal distance between the metal surface and RF molecules. The obtained hybrid nanostructure allowed for sensitive detection and specific recognition towards the target. Based on the plasmonic hybrid nanostructure, a sensitive and specific PEF assay of RF was developed and successfully applied to the determination of RF in human urine. Thus, the study paved the way for controllable preparation of molecularly imprinted plasmonic nanostructures for sensitive and specific PEF assays.

Antibacterial Silver Nanomaterial Synthesis From Mesoflavibacter zeaxanthinifaciens and Targeting Biofilm Formation.

Considering the significance of biological and eco-friendly nanomaterials, in the present study, we have synthesized silver nanoparticles from the exopolysaccharide of recently recovered bacterial strain CEES51 from the Red Sea coastal area of Jeddah, Saudi Arabia. 16S ribosomal RNA gene sequencing was used to characterize the isolated bacteria, and it was identified as Mesoflavibacter zeaxanthinifaciens and assigned an accession number MH707257.1 GenBank. The bacterial strain is an excellent exopolysaccharide producer and survived at hypersaline (30%) and high-temperature (50°C) conditions. The bacterial exopolysaccharides were employed for the fabrication of silver nanoparticles at room temperature. UV-visible spectrophotometer optimized the synthesized nanoparticles, and their size was determined by Nanophox particle size analyzer and dynamic light scattering. Additionally, the X-ray powder diffraction and Fourier-transform infrared spectroscopy studies also approved its crystalline nature and the involvement of organic functional groups in their formation. The synthesized nanomaterials were tested for their antibacterial and antibiofilm properties against pathogenic microorganisms Bacillus subtilis and methicillin-resistant Staphylococcus aureus. The antimicrobial property showed time, and dose-dependent response with a maximum of zone inhibition was observed at around 22 and 18 mm at a dose of 50 µg/well against B. subtilis and S. aureus and a minimum inhibitory concentration of 8 and 10 µg/ml, respectively. Furthermore, the synthesized silver nanoparticles possessed a substantial antibiofilm property and were also found to be biocompatible as depicted by red blood cell lysis assay and their interaction with peripheral blood mononuclear cells and human embryonic kidney 293 cells. Therefore, Mesoflavibacter zeaxanthinifaciens is found to be an excellent source for exopolysaccharide synthesis that assists in the silver nanoparticle production.

Isolation and enzyme-inhibition studies of the chemical constituents from Ajuga bracteosa.

Bractin A (=(2S,3S,4R,5E)-2-{[(2R)-2-hydroxydodecanoyl]amino}triacont-5-ene-1,3,4-triol; 1) and bractin B (=(2S,3S,4R,5E,8E)-2-{[(2R)-2-hydroxyhexacosanoyl]amino}pentadeca-5,8-diene-3,4,15-triol 1-O-beta-D-glucopyranoside; 2), new sphingolipids, and bractic acid (=(5Z,10Z,15Z)-2-decyl-4,7,8,12,13,17,18-heptahydroxy-20,23-dioxopentacosa-5,10,15-trienoic acid; 3), a long-chain polyhydroxy acid, were isolated from the whole plant Ajuga bracteosa along with four known diterpenoids 4-7. Their structures were deduced by spectral studies including 1D- and 2D-NMR spectroscopy. Compounds 1-3 displayed inhibitory potential against enzyme lipoxygenase, while compounds 4-7 inhibited cholinesterase enzymes in a concentration-dependent manner with IC(50) values in the range 10.0-33.0, 14.0-35.2, and 10.0-19.0 microM for lipoxygenase, acetylcholinesterase, and butyrylcholinesterase, respectively. Lineweaver-Burk, and Dixon plots, and their secondary replots indicated that all compounds exhibit non-competitive type of inhibition with K(i) values in the range of 9.5-35.2, 15.2-36.0, and 11.6-20.5 microM, for lipoxygenase, acetylcholinesterase, and butyrylcholinesterase, respectively.