Displaying publications 4281 - 4300 of 10390 in total

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  1. Ibogan, Aspidosperman, Vincamine, and Bisindole Alkaloids from a Malayan Tabernaemontana corymbosa: Iboga Alkaloids with C-20α Substitution
    Nge CE, Chong KW, Thomas NF, Lim SH, Low YY, Kam TS
    J Nat Prod, 2016 05 27;79(5):1388-99.
    PMID: 27077800 DOI: 10.1021/acs.jnatprod.6b00129
    Ten new indole alkaloids (1-10) comprising five ibogan, two aspidosperman, one vincamine, and two bisindole alkaloids, in addition to 32 known alkaloids, were isolated from the stem-bark extract of a Malayan Tabernaemontana corymbosa. The structures of these alkaloids were determined based on analysis of the NMR and MS data and, in five instances (1, 3, 5, 6, 8), confirmed by X-ray diffraction analysis. Two of the iboga alkaloids, conodusines B (2) and C (3), and the iboga-containing bisindole tabernamidine B (10) are notable for the presence of an α-substituted acetyl group at C-20 of the iboga carbon skeleton. The iboga alkaloid (+)-conodusine E (5) had MS and NMR data that were identical to those of (-)-ervatamine I, recently isolated from Ervatamia hainanensis. Establishment of the absolute configuration of (+)-conodusine E (5) was based on analysis of the ECD data, correlation with (-)-heyneanine, and X-ray analysis, which showed that (+)-5 belongs to the same enantiomeric series as exemplified by (-)-coronaridine. The configuration at C-20' of the previously reported Tabernaemontana bisindole alkaloid 19'-oxotabernamine (renamed tabernamidine B) required revision based on the present results. Several of the bisindoles showed pronounced in vitro growth inhibitory activity against drug-sensitive and vincristine-resistant KB cells.
    Matched MeSH terms: Antineoplastic Agents, Phytogenic/chemistry; Vincamine/chemistry; Plant Leaves/chemistry; Plant Bark/chemistry; Indole Alkaloids/chemistry*; Tabernaemontana/chemistry
  2. Fulltext Synthetic B-Cell Epitopes Eliciting Cross-Neutralizing Antibodies: Strategies for Future Dengue Vaccine
    Ramanathan B, Poh CL, Kirk K, McBride WJ, Aaskov J, Grollo L
    PLoS One, 2016;11(5):e0155900.
    PMID: 27223692 DOI: 10.1371/journal.pone.0155900
    Dengue virus (DENV) is a major public health threat worldwide. A key element in protection from dengue fever is the neutralising antibody response. Anti-dengue IgG purified from DENV-2 infected human sera showed reactivity against several peptides when evaluated by ELISA and epitope extraction techniques. A multi-step computational approach predicted six antigenic regions within the E protein of DENV-2 that concur with the 6 epitopes identified by the combined ELISA and epitope extraction approach. The selected peptides representing B-cell epitopes were attached to a known dengue T-helper epitope and evaluated for their vaccine potency. Immunization of mice revealed two novel synthetic vaccine constructs that elicited good humoral immune responses and produced cross-reactive neutralising antibodies against DENV-1, 2 and 3. The findings indicate new directions for epitope mapping and contribute towards the future development of multi-epitope based synthetic peptide vaccine.
    Matched MeSH terms: Dengue Virus/chemistry; Vaccines, Synthetic/chemistry; Viral Envelope Proteins/chemistry; Epitopes, T-Lymphocyte/chemistry; Epitopes, B-Lymphocyte/chemistry; Dengue Vaccines/chemistry
  3. γ-Fe2O3 nanoparticles filled polyvinyl alcohol as potential biomaterial for tissue engineering scaffold
    Ngadiman NH, Idris A, Irfan M, Kurniawan D, Yusof NM, Nasiri R
    J Mech Behav Biomed Mater, 2015 Sep;49:90-104.
    PMID: 26002419 DOI: 10.1016/j.jmbbm.2015.04.029
    Maghemite (γ-Fe2O3) nanoparticle with its unique magnetic properties is recently known to enhance the cell growth rate. In this study, γ-Fe2O3 is mixed into polyvinyl alcohol (PVA) matrix and then electrospun to form nanofibers. Design of experiments was used to determine the optimum parameter settings for the electrospinning process so as to produce elctrospun mats with the preferred characteristics such as good morphology, Young's modulus and porosity. The input factors of the electrospinnning process were nanoparticles content (1-5%), voltage (25-35 kV), and flow rate (1-3 ml/h) while the responses considered were Young's modulus and porosity. Empirical models for both responses as a function of the input factors were developed and the optimum input factors setting were determined, and found to be at 5% nanoparticle content, 35 kV voltage, and 1 ml/h volume flow rate. The characteristics and performance of the optimum PVA/γ-Fe2O3 nanofiber mats were compared with those of neat PVA nanofiber mats in terms of morphology, thermal properties, and hydrophilicity. The PVA/γ-Fe2O3 nanofiber mats exhibited higher fiber diameter and surface roughness yet similar thermal properties and hydrophilicity compared to neat PVA PVA/γ-Fe2O3 nanofiber mats. Biocompatibility test by exposing the nanofiber mats with human blood cells was performed. In terms of clotting time, the PVA/γ-Fe2O3 nanofibers exhibited similar behavior with neat PVA. The PVA/γ-Fe2O3 nanofibers also showed higher cells proliferation rate when MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay was done using human skin fibroblast cells. Thus, the PVA/γ-Fe2O3 electrospun nanofibers can be a promising biomaterial for tissue engineering scaffolds.
    Matched MeSH terms: Biocompatible Materials/chemistry*; Ferric Compounds/chemistry*; Polyvinyl Alcohol/chemistry*; Nanoparticles/chemistry*; Tissue Scaffolds/chemistry*; Nanofibers/chemistry
  4. Fulltext Gamma scintigraphic study of the hydrodynamically balanced matrix tablets of Metformin HCl in rabbits
    Razavi M, Karimian H, Yeong CH, Sarji SA, Chung LY, Nyamathulla S, et al.
    Drug Des Devel Ther, 2015;9:3125-39.
    PMID: 26124637 DOI: 10.2147/DDDT.S82935
    The purpose of this study is to evaluate the in vitro and in vivo performance of gastro-retentive matrix tablets having Metformin HCl as model drug and combination of natural polymers. A total of 16 formulations were prepared by a wet granulation method using xanthan, tamarind seed powder, tamarind kernel powder and salep as the gel-forming agents and sodium bicarbonate as a gas-forming agent. All the formulations were evaluated for compendial and non-compendial tests and in vitro study was carried out on a USP-II dissolution apparatus at a paddle speed of 50 rpm. MOX2 formulation, composed of salep and xanthan in the ratio of 4:1 with 96.9% release, was considered as the optimum formulation with more than 90% release in 12 hours and short floating lag time. In vivo study was carried out using gamma scintigraphy in New Zealand White rabbits, optimized formulation was incorporated with 10 mg of (153)Sm for labeling MOX2 formulation. The radioactive samarium oxide was used as the marker to trace transit of the tablets in the gastrointestinal tract. The in vivo data also supported retention of MOX2 formulation in the gastric region for 12 hours and were different from the control formulation without a gas and gel forming agent. It was concluded that the prepared floating gastro-retentive matrix tablets had a sustained-release effect in vitro and in vivo, gamma scintigraphy played an important role in locating the oral transit and the drug-release pattern.
    Matched MeSH terms: Chemistry, Pharmaceutical; Excipients/chemistry*; Hypoglycemic Agents/chemistry; Metformin/chemistry; Polymers/chemistry*; Polysaccharides, Bacterial/chemistry
  5. Comparative Cytotoxicity of Glycyrrhiza glabra Roots from Different Geographical Origins Against Immortal Human Keratinocyte (HaCaT), Lung Adenocarcinoma (A549) and Liver Carcinoma (HepG2) Cells
    Basar N, Oridupa OA, Ritchie KJ, Nahar L, Osman NM, Stafford A, et al.
    Phytother Res, 2015 Jun;29(6):944-8.
    PMID: 25779384 DOI: 10.1002/ptr.5329
    Glycyrrhiza glabra L. (Fabaceae), commonly known as 'liquorice', is a well-known medicinal plant. Roots of this plant have long been used as a sweetening and flavouring agent in food and pharmaceutical products, and also as a traditional remedy for cough, upper and lower respiratory ailments, kidney stones, hepatitis C, skin disorder, cardiovascular diseases, diabetes, gastrointestinal ulcers and stomach ache. Previous pharmacological and clinical studies have revealed its antitussive, antiinflammatory, antiviral, antimicrobial, antioxidant, immunomodulatory, hepatoprotective and cardioprotective properties. While glycyrrhizin, a sweet-tasting triterpene saponin, is the principal bioactive compound, several bioactive flavonoids and isoflavonoids are also present in the roots of this plant. In the present study, the cytotoxicity of the methanol extracts of nine samples of the roots of G. glabra, collected from various geographical origins, was assessed against immortal human keratinocyte (HaCaT), lung adenocarcinoma (A549) and liver carcinoma (HepG2) cell lines using the in vitro 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazoliumbromide cell toxicity/viability assay. Considerable variations in levels of cytotoxicity were observed among various samples of G. glabra.
    Matched MeSH terms: Flavonoids/chemistry; Glycyrrhiza/chemistry*; Plant Extracts/chemistry; Saponins/chemistry; Triterpenes/chemistry; Plant Roots/chemistry
  6. Purification and characterisation of an F16L mutant of a thermostable lipase
    Ali MS, Yun CC, Chor AL, Rahman RN, Basri M, Salleh AB
    Protein J, 2012 Mar;31(3):229-37.
    PMID: 22350313 DOI: 10.1007/s10930-012-9395-8
    A mutant of the lipase from Geobacillus sp. strain T1 with a phenylalanine to leucine substitution at position 16 was overexpressed in Escherichia coli strain BL21(De3)pLysS. The crude enzyme was purified by two-step affinity chromatography with a final recovery and specific activity of 47.4 and 6,315.8 U/mg, respectively. The molecular weight of the purified F16L lipase was approximately 43 kDa by 12% SDS-PAGE analysis. The F16L lipase was demonstrated to be a thermophilic enzyme due its optimum temperature at 70 °C and showed stability over a temperature range of 40-60 °C. The enzyme exhibited an optimum pH 7 in phosphate buffer and was relatively stable at an alkaline pH 8-9. Metal ions such as Ca(2+), Mn(2+), Na(+), and K(+) enhanced the lipase activity, but Mg(2+), Zn(2+), and Fe(2+) inhibited the lipase. All surfactants tested, including Tween 20, 40, 60, 80, Triton X-100, and SDS, significantly inhibited the lipolytic action of the lipase. A high hydrolytic rate was observed on long-chain natural oils and triglycerides, with a notable preference for olive oil (C18:1; natural oil) and triolein (C18:1; triglyceride). The F16L lipase was deduced to be a metalloenzyme because it was strongly inhibited by 5 mM EDTA. Moderate inhibition was observed in the presence of PMSF at a similar concentration, indicating that serine residues are involved in its catalytic action. Further, the activity was not impaired by water-miscible solvents, including methanol, ethanol, and acetone.
    Matched MeSH terms: Lipase/chemistry; Metals/chemistry; Organic Chemicals/chemistry; Recombinant Proteins/chemistry; Surface-Active Agents/chemistry; Geobacillus/chemistry
  7. Fulltext Extraction, Purification, and Characterization of Polysaccharides of Araucaria heterophylla L and Prosopischilensis L and Utilization of Polysaccharides in Nanocarrier Synthesis
    Samrot AV, Kudaiyappan T, Bisyarah U, Mirarmandi A, Faradjeva E, Abubakar A, et al.
    Int J Nanomedicine, 2020;15:7097-7115.
    PMID: 33061370 DOI: 10.2147/IJN.S259653
    Background: Plant gums consist of polysaccharides which can be used in the preparation of nanocarriers and provide a wide application in pharmaceutical applications including as drug delivery agents and the matrices for drug release. The objectives of the study were to collect plant gums from Araucaria heterophylla L and Prosopis chilensis L and to extract and characterize their polysaccharides. Then to utilize these plant gum-derived polysaccharides for the formulation of nanocarriers to use for drug loading and to examine their purpose in drug delivery in vitro.

    Methods: Plant gum was collected, polysaccharide was extracted, purified, characterized using UV-Vis, FTIR, TGA and GCMS and subjected to various bioactive studies. The purified polysaccharide was used for making curcumin-loaded nanocarriers using STMP (sodium trimetaphosphate). Bioactivities were performed on the crude, purified and drug-loaded nanocarriers. These polysaccharide-based nanocarriers were characterized using UV-Vis spectrophotometer, FTIR, SEM, and AFM. Drug release kinetics were performed for the drug-loaded nanocarriers.

    Results: The presence of glucose, xylose and sucrose was studied from the UV-Vis and GCMS analysis. Purified polysaccharides of both the plants showed antioxidant activity and also antibacterial activity against Bacillus sp. Purified polysaccharides were used for nanocarrier synthesis, where the size and shape of the nanocarriers were studied using SEM analysis and AFM analysis. The size of the drug-loaded nanocarriers was found to be around 200 nm. The curcumin-loaded nanocarriers were releasing curcumin slow and steady.

    Conclusion: The extracted pure polysaccharide of A. heterophylla and P. chilensis acted as good antioxidants and showed antibacterial activity against Bacillus sp. These polysaccharides were fabricated into curcumin-loaded nanocarriers whose size was below 200 nm. Both the drug-loaded nanocarriers synthesized using A. heterophylla and P. chilensis showed antibacterial activity with a steady drug release profile. Hence, these natural exudates can serve as biodegradable nanocarriers in drug delivery.

    Matched MeSH terms: Anti-Bacterial Agents/chemistry; Antioxidants/chemistry; Drug Carriers/chemistry*; Prosopis/chemistry*; Nanostructures/chemistry*; Plant Gums/chemistry
  8. Characterization of a type I pullulanase from Anoxybacillus sp. SK3-4 reveals an unusual substrate hydrolysis
    Kahar UM, Ng CL, Chan KG, Goh KM
    Appl Microbiol Biotechnol, 2016 Jul;100(14):6291-307.
    PMID: 27000839 DOI: 10.1007/s00253-016-7451-6
    Type I pullulanases are enzymes that specifically hydrolyse α-1,6 linkages in polysaccharides. This study reports the analyses of a novel type I pullulanase (PulASK) from Anoxybacillus sp. SK3-4. Purified PulASK (molecular mass of 80 kDa) was stable at pH 5.0-6.0 and was most active at pH 6.0. The optimum temperature for PulASK was 60 °C, and the enzyme was reasonably stable at this temperature. Pullulan was the preferred substrate for PulASK, with 89.90 % adsorbance efficiency (various other starches, 56.26-72.93 % efficiency). Similar to other type I pullulanases, maltotriose was formed on digestion of pullulan by PulASK. PulASK also reacted with β-limit dextrin, a sugar rich in short branches, and formed maltotriose, maltotetraose and maltopentaose. Nevertheless, PulASK was found to preferably debranch long branches at α-1,6 glycosidic bonds of starch, producing amylose, linear or branched oligosaccharides, but was nonreactive against short branches; thus, no reducing sugars were detected. This is surprising as all currently known type I pullulanases produce reducing sugars (predominantly maltotriose) on digesting starch. The closest homologue of PulASK (95 % identity) is a type I pullulanase from Anoxybacillus sp. LM14-2 (Pul-LM14-2), which is capable of forming reducing sugars from starch. With rational design, amino acids 362-370 of PulASK were replaced with the corresponding sequence of Pul-LM14-2. The mutant enzyme formed reducing sugars on digesting starch. Thus, we identified a novel motif involved in substrate specificity in type I pullulanases. Our characterization may pave the way for the industrial application of this unique enzyme.
    Matched MeSH terms: Culture Media/chemistry*; Glucans/chemistry; Maltose/chemistry; Oligosaccharides/chemistry; Starch/chemistry; Trisaccharides/chemistry
  9. An Electrochemical Sandwich Immunosensor for the Detection of HER2 using Antibody-Conjugated PbS Quantum Dot as a label
    Lah ZMANH, Ahmad SAA, Zaini MS, Kamarudin MA
    J Pharm Biomed Anal, 2019 Sep 10;174:608-617.
    PMID: 31265987 DOI: 10.1016/j.jpba.2019.06.024
    A facile electrochemical sandwich immunosensor for the detection of a breast cancer biomarker, the human epidermal growth factor receptor 2 (HER2), was designed, using lead sulfide quantum dots-conjugated secondary HER2 antibody (Ab2-PbS QDs) as a label. Using Ab2-PbS QDs in the development of electrochemical immunoassays leads to many advantages such as straightforward synthesis and well-defined stripping signal of Pb(II) through acid dissolution, which in turn yields better sensing performance for the sandwiched immunosensor. In the bioconjugation of PbS QDs, the available amine and hydroxyl groups from secondary anti-HER2 and capped PbS QDs were bound covalently together via carbonyldiimidazole (CDI) acting as a linker. In order to quantify the biomarker, SWV signal was obtained, where the Pb2+ ions after acid dissolution in HCl was detected. The plated mercury film SPCE was also detected in situ. Under optimal conditions, HER2 was detected in a linear range from 1-100 ng/mL with a limit of detection of 0.28 ng/mL. The measures of satisfactory recoveries were 91.3% to 104.3% for the spiked samples, displaying high selectivity. Therefore, this method can be applied to determine HER2 in human serum.
    Matched MeSH terms: Antibodies/chemistry*; Carbon/chemistry; Imidazoles/chemistry; Lead/chemistry*; Sulfides/chemistry*; Receptor, ErbB-2/chemistry*
  10. Date pits activated carbon for divalent lead ions removal
    Krishnamoorthy R, Govindan B, Banat F, Sagadevan V, Purushothaman M, Show PL
    J Biosci Bioeng, 2019 Jul;128(1):88-97.
    PMID: 30679113 DOI: 10.1016/j.jbiosc.2018.12.011
    Phosphoric acid impregnated activated carbon from date pits (DPAC) was prepared through single step activation. Prepared DPAC was studied for its structural, elemental, chemical, surface and crystal nature. Adsorption ability of the DPAC was assessed through divalent lead ions separation studies. Effect of adsorbent dosage, contact time, pH, operating temperature and initial feed concentration on lead removal by DPAC was studied. Maximum Pb(II) adsorption capacity of 101.35 mg/g was attained for a contact time of 30 min and pH of 6 at 30°C. Increase in initial feed concentration enhanced the adsorption ability of DPAC and the rise in adsorbent dosage resulted in improved Pb(II) removal efficiency. Thermodynamic studies revealed that the lead adsorption on DPAC was exothermic and instantaneous in nature. Kinetic and equilibrium studies confirmed the suitability of pseudo-second order and Langmuir isotherm for divalent lead ions binding on DPAC. Reusability studies showed that HCl was the effective regeneration medium and the DPAC could be reused for a maximum of 4 times with slight reduction in Pb(II) removal efficiency (<10%). Results indicated the promising use of date pits biomass as a low cost and efficient starting material to prepare activated carbon for divalent lead ions removal.
    Matched MeSH terms: Carbon/chemistry*; Charcoal/chemistry*; Phosphoric Acids/chemistry; Powders/chemistry; Seeds/chemistry*; Phoeniceae/chemistry*
  11. Photodynamic characterization of amino acid conjugated 15(1)-hydroxypurpurin-7-lactone for cancer treatment
    Lim SH, Yam ML, Lam ML, Kamarulzaman FA, Samat N, Kiew LV, et al.
    Mol Pharm, 2014 Sep 2;11(9):3164-73.
    PMID: 25077598 DOI: 10.1021/mp500351s
    This study aims to improve the photodynamic properties and biological effectiveness of 15(1)-hydroxypurpurin-7-lactone dimethyl ester (G2), a semisynthetic photosensitizer, for the PDT treatment of cancer. The strategy we undertook was by conjugating G2 with aspartic acid and lysine amino acid moieties. The photophysical properties, singlet oxygen generation, distribution coefficiency (Log D in octanol/PBS pH 7.4), and photostability of these analogues and their in vitro bioactivities such as cellular uptake, intracellular localization, and photoinduced cytotoxicity were evaluated. In addition, selected analogues were also investigated for their PDT-induced vasculature occlusion in the chick chorioallantoic membrane model and for their antitumor efficacies in Balb/C mice bearing 4T1 mouse mammary tumor. From the study, conjugation with aspartic acid improved the aqueous solubility of G2 without affecting its photophysical characteristics. G2-Asp showed similar in vitro and in vivo antitumor efficacies compared to the parent compound. Given the hydrophilic nature of G2-Asp, the photosensitizer is a pharmaceutically advantageous candidate as it can be formulated easily for systemic administration and has reduced risk of aggregation in vascular system.
    Matched MeSH terms: Amino Acids/chemistry*; Antineoplastic Agents/chemistry; Lactones/chemistry*; Porphyrins/chemistry*; Photosensitizing Agents/chemistry; Singlet Oxygen/chemistry
  12. Nanoglue: an alternative way to display cell-internalizing peptide at the spikes of hepatitis B virus core nanoparticles for cell-targeting delivery
    Lee KW, Tey BT, Ho KL, Tejo BA, Tan WS
    Mol Pharm, 2012 Sep 4;9(9):2415-23.
    PMID: 22775561 DOI: 10.1021/mp200389t
    Cell-internalizing peptides (CIPs) can be used to mediate specific delivery of nanoparticles across cellular membrane. The objective of this study was to develop a display technique using hepatitis B virus (HBV) capsid-binding peptide as a "nanoglue" to present CIPs on HBV nanoparticles for cell-targeting delivery. A CIP was selected from a phage display library and cross-linked specifically at the tips of the spikes of the HBV capsid nanoparticle via the "nanoglue" by using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) and N-hydroxysulfosuccinimide (sulfo-NHS). Fluorescent oligonucleotides packaged in the nanoparticles and the fluorescein molecules conjugated on the nanoparticles were delivered to cells by using this display technique. This study demonstrated a proof of principle for cell-targeting delivery via "nanoglue" bioconjugation.
    Matched MeSH terms: Ethyldimethylaminopropyl Carbodiimide/chemistry; Peptides/chemistry; Succinimides/chemistry; Viral Proteins/chemistry; Capsid Proteins/chemistry; Nanoparticles/chemistry*
  13. Green synthesis of gold nanoparticles from Scutellaria barbata and its anticancer activity in pancreatic cancer cell (PANC-1)
    Wang L, Xu J, Yan Y, Liu H, Karunakaran T, Li F
    Artif Cells Nanomed Biotechnol, 2019 Dec;47(1):1617-1627.
    PMID: 31014134 DOI: 10.1080/21691401.2019.1594862
    Nanotechnology has been materialized as a proficient technology for the development of anticancer nanoparticles all the way through an environment-friendly approach. Conventionally, nanoparticles have been assembled by dissimilar methods, but regrettably rely on the negative impact on the natural environment. Amalgamation of nanoparticles by means of plant extract is alternate conservative methods. Scutellaria barbata species was used majorly as food or as medicines against various diseases, and extensive research was conducted for their therapeutic properties. The present research was mainly focused on the synthesis of gold nanoparticles from the Scutellaria barbata by green route method and evaluation of its anticancer activity against pancreatic cancer cell lines (PANC-1). The gold nanoparticles have been characterized by UV-visible spectroscopy, TEM, SAED, AFM, and FTIR analysis. The synthesized gold nanoparticles (AuNPs) possessed effective anticancer activity against pancreatic cancer cell lines (PANC-1). Hence, further research on this plant may lead to the development of novel anticancer drugs which can be used to combat pancreatic cancer.
    Matched MeSH terms: Antineoplastic Agents/chemistry; Gold/chemistry*; Plant Extracts/chemistry*; Scutellaria/chemistry*; Green Chemistry Technology; Chemistry Techniques, Synthetic
  14. Oppositinines A and B: new vasorelaxant beta-carboline alkaloids from Neisosperma oppositifolia
    Ahmad K, Thomas NF, Hadi AH, Mukhtar MR, Mohamad K, Nafiah MA, et al.
    Chem Pharm Bull (Tokyo), 2010 Aug;58(8):1085-7.
    PMID: 20686264
    A phytochemical study on the bark of Neisosperma oppositifolia (Apocynaceae) yielded two new beta-carboline indole alkaloids, oppositinines A (1) and B (2), together with five known alkaloids, isoreserpiline, isocarapanaubine, vobasine, 10-methoxydihydrocorynantheol-N-oxide, and ochropposinine oxindole. Structural elucidation of 1 and 2 was performed using 2D NMR methods. Oppositinines A (1) and B (2) showed potent vasorelaxant effects on the rat aorta.
    Matched MeSH terms: Carbolines/chemistry; Plant Extracts/chemistry; Plants, Medicinal/chemistry; Vasodilator Agents/chemistry; Plant Stems/chemistry*; Apocynaceae/chemistry*
  15. Structural and functional studies of a 50 kDa antigenic protein from Salmonella enterica serovar Typhi
    Choong YS, Lim TS, Chew AL, Aziah I, Ismail A
    J Mol Graph Model, 2011 Apr;29(6):834-42.
    PMID: 21371926 DOI: 10.1016/j.jmgm.2011.01.008
    The high typhoid incidence rate in developing and under-developed countries emphasizes the need for a rapid, affordable and accessible diagnostic test for effective therapy and disease management. TYPHIDOT®, a rapid dot enzyme immunoassay test for typhoid, was developed from the discovery of a ∼50 kDa protein specific for Salmonella enterica serovar Typhi. However, the structure of this antigen remains unknown till today. Studies on the structure of this antigen are important to elucidate its function, which will in turn increase the efficiency of the development and improvement of the typhoid detection test. This paper described the predictive structure and function of the antigenically specific protein. The homology modeling approach was employed to construct the three-dimensional structure of the antigen. The built structure possesses the features of TolC-like outer membrane protein. Molecular docking simulation was also performed to further probe the functionality of the antigen. Docking results showed that hexamminecobalt, Co(NH(3))(6)(3+), as an inhibitor of TolC protein, formed favorable hydrogen bonds with D368 and D371 of the antigen. The single point (D368A, D371A) and double point (D368A and D371A) mutations of the antigen showed a decrease (single point mutation) and loss (double point mutations) of binding affinity towards hexamminecobalt. The architecture features of the built model and the docking simulation reinforced and supported that this antigen is indeed the variant of outer membrane protein, TolC. As channel proteins are important for the virulence and survival of bacteria, therefore this ∼50 kDa channel protein is a good specific target for typhoid detection test.
    Matched MeSH terms: Antigens, Bacterial/chemistry*; Bacterial Proteins/chemistry*; Chlorides/chemistry; Cobalt/chemistry; Membrane Proteins/chemistry; Salmonella enterica/chemistry*
  16. Platelet-activating factor (PAF) receptor binding antagonist activity of the methanol extracts and isolated flavonoids from Chromolaena odorata (L.) King and Robinson
    Ling SK, Pisar MM, Man S
    Biol Pharm Bull, 2007 Jun;30(6):1150-2.
    PMID: 17541171
    The leaf, stem and root extracts of Chromolaena odorata were evaluated for their effect on platelet-activating factor (PAF) receptor binding on rabbit platelets using 3H-PAF as a ligand. The leaf extract demonstrated high PAF receptor binding inhibitory activity of 79.2+/-2.1% at 18.2 microg/ml. A total of eleven flavonoids were subsequently isolated from the active leaf extract and evaluated for their effects on PAF receptor binding. Eight of the flavonoids exhibited >50% inhibition on the binding activity at 18.2 microg/ml. These flavonoids were identified as eriodictyol 7,4'-dimethyl ether, quercetin 7,4'-methyl ether, naringenin 4'-methyl ether, kaempferol 4'-methyl ether, kaempferol 3-O-rutinoside, taxifolin 4'-methyl ether, taxifolin 7-methyl ether and quercetin 4'-methyl ether. Their IC50 values ranged from 19.5 to 62.1 microM.
    Matched MeSH terms: Flavonoids/chemistry; Plant Extracts/chemistry; Plant Leaves/chemistry; Plant Roots/chemistry; Plant Stems/chemistry; Chromolaena/chemistry*
  17. Fulltext Preparation, characterization and therapeutic properties of gum arabic-stabilized gallic acid nanoparticles
    Hassani A, Azarian MMS, Ibrahim WN, Hussain SA
    Sci Rep, 2020 10 20;10(1):17808.
    PMID: 33082415 DOI: 10.1038/s41598-020-71175-8
    Gallic acid (GA) is a natural phenolic compound with therapeutic effects that are often challenged by its rapid metabolism and clearance. Therefore,  GA was encapsulated using gum arabic into nanoparticles to increase its bioavailability. The formulated nanoparticles (GANPs) were characterized for physicochemical properties and size and were then evaluated for antioxidant and antihypertensive effects using various established in vitro assays, including 1,1-diphenyl-2-picrylhydrazyl (DPPH), nitric oxide scavenging (NO), β-carotene bleaching and angiotensin-converting enzyme (ACE) inhibitory assays. The GANPs were further evaluated for the in vitro cytotoxicity, cell uptake and cell migration in four types of human cancer cell lines including (MCF-7, MDA-MB231) breast adenocarcinoma, HepG2 hepatocellular cancer, HT-29 colorectal adenocarcinoma, and MCF-10A breast epithelial cell lines. The GANPs demonstrated potent antioxidant effects and have shown promising anti-cancer properties in a dose-dependent manner with a predilection toward HepG2 and MCF7 cancer cells. The uptake of GANPs was successful in the majority of cancer cells with a propensity to accumulate in the nuclear region of the cells. The HepG2 and MCF7 cancer cells also had a significantly higher percentage of apoptosis and were more sensitive to gallic acid nanoparticle treatment in the cell migration assay. This study is the first to confirm the synergistic effects of gum arabic in the encapsulation of gallic acid by increasing the selectivity towards cancer cells and enhancing  the antioxidant properties. The formulated nanoparticles also had remarkably low toxicity in normal cells. Based on these findings, GANPs may have promising therapeutic applications towards the development of more effective treatments with a probable targeting precision in cancer cells.
    Matched MeSH terms: Angiotensin-Converting Enzyme Inhibitors/chemistry; Antineoplastic Agents/chemistry; Antioxidants/chemistry; Gallic Acid/chemistry; Gum Arabic/chemistry; Nanoparticles/chemistry
  18. Fulltext Characterization and Evaluation of Bone-Derived Nanoparticles as a Novel pH-Responsive Carrier for Delivery of Doxorubicin into Breast Cancer Cells
    Haque ST, Islam RA, Gan SH, Chowdhury EH
    Int J Mol Sci, 2020 Sep 14;21(18).
    PMID: 32937817 DOI: 10.3390/ijms21186721
    Background: The limitations of conventional treatment modalities in cancer, especially in breast cancer, facilitated the necessity for developing a safer drug delivery system (DDS). Inorganic nano-carriers based on calcium phosphates such as hydroxyapatite (HA) and carbonate apatite (CA) have gained attention due to their biocompatibility, reduced toxicity, and improved therapeutic efficacy. Methods: In this study, the potential of goose bone ash (GBA), a natural derivative of HA or CA, was exploited as a pH-responsive carrier to successfully deliver doxorubicin (DOX), an anthracycline drug into breast cancer cells (e.g., MCF-7 and MDA-MB-231 cells). GBA in either pristine form or in suspension was characterized in terms of size, morphology, functional groups, cellular internalization, cytotoxicity, pH-responsive drug (DOX) release, and protein corona analysis. Results: The pH-responsive drug release study demonstrated the prompt release of DOX from GBA through its disintegration in acidic pH (5.5-6.5), which mimics the pH of the endosomal and lysosomal compartments as well as the stability of GBA in physiological pH (pH 7.5). The result of DOX binding with GBA indicated an increment in binding affinity with increasing concentrations of DOX. Cell viability and cytotoxicity analysis showed no innate toxicity of GBA particles. Both qualitative and quantitative cellular uptake analysis in both cell lines displayed an enhanced cellular internalization of DOX-loaded GBA compared to free DOX molecules. The protein corona spontaneously formed on the surface of GBA particles exhibited its affinity toward transport proteins, structural proteins, and a few other selective proteins. The adsorption of transport proteins could extend the circulation half-life in biological environment and increase the accumulation of the drug-loaded NPs through the enhanced permeability and retention (EPR) effect at the tumor site. Conclusion: These findings highlight the potential of GBA as a DDS to successfully deliver therapeutics into breast cancer cells.
    Matched MeSH terms: Biocompatible Materials/chemistry; Bone and Bones/chemistry*; Calcium Phosphates/chemistry; Doxorubicin/chemistry*; Drug Carriers/chemistry*; Nanoparticles/chemistry*
  19. Screening and identification of five peptides from pinto bean with inhibitory activities against α-amylase using phage display technique
    Ngoh YY, Lim TS, Gan CY
    Enzyme Microb Technol, 2016 Jul;89:76-84.
    PMID: 27233130 DOI: 10.1016/j.enzmictec.2016.04.001
    The objective of this study was to screen and identify α-amylase inhibitor peptides from Pinto bean. Five Pinto bean bioactive peptides were successfully identified: PPHMLP (P1), PLPWGAGF (P3), PPHMGGP (P6), PLPLHMLP (P7) and LSSLEMGSLGALFVCM (P9). Based on ELISA results, their promising optical density values were 1.27; 3.71, 1.67, 3.20 and 1.03, respectively, which indicated the binding interaction between the peptide and α-amylase occurred. The highest inhibitory activity (66.72%) of the chemically synthesized peptide was shown in SyP9 followed by SyP1 (48.86%), SyP3 (31.17%), SyP7 (27.88%) and SyP6 (23.96%). The IC50 values were 1.97, 8.96, 14.63, 18.45 and 20.56mgml(-1), respectively. Structure activity relationship study revealed that α-amylase was inhibited due to its residues of Ala230, Asp229, Asp326, Tyr54, Met195, Leu194 and His233 were bound. On the other hand, the residues of PBBP (i.e. histidine, proline and methionine) were found to have the highest potency in the binding interaction.
    Matched MeSH terms: Enzyme Inhibitors/chemistry; Oligopeptides/chemistry; Peptides/chemistry*; Plant Proteins/chemistry*; Phaseolus/chemistry*; Plant Lectins/chemistry
  20. Immunomodulatory Properties of Water-Soluble Polysaccharides Extracted from the Fruiting Body of Chinese Caterpillar Mushroom, Ophiocordyceps sinensis Cultivar OCS02® (Ascomycetes)
    Yap ACS, Li X, Yap YHY, Razif MFM, Jamil AHA, Ng ST, et al.
    Int J Med Mushrooms, 2020;22(10):967-977.
    PMID: 33426826 DOI: 10.1615/IntJMedMushrooms.2020036351
    Ophiocordyceps sinensis (=Cordyceps sinensis) has been known for its various medicinal properties, in particular immunomodulatory activities associated with its polysaccharides. In this study, the fruiting body of O. sinensis cultivar OCS02® was investigated for its chemical composition and monosaccharide profile. Cold water extract (CWE) obtained from this fruiting body was fractionated by molecular weight (MW) into high (HMW), medium (MMW), and low (LMW) fractions. Polysaccharides in the extract and fractions were identified as heteroglycans containing mostly glucose and mannose with small amounts of galactose, fucose, arabinose, and xylose. The immunomodulatory potential of these heteroglycans was evaluated by induction of cytokine/chemokine secretion using murine macrophage RAW 264.7. All treatments showed significant modulation of IL-6, IL-9, MIP-2, and TIMP-1, especially for CWE, HMW, and MMW, which might be due to their high ratios of glucose and the presence of protein. Further investigation on the structure-function relationship of these fruiting body polysaccharide fractions is needed to delineate the underlying mechanism of their immunomodulatory effect both in vitro and in vivo.
    Matched MeSH terms: Agaricales/chemistry*; Hypocreales/chemistry*; Immunologic Factors/chemistry; Plant Extracts/chemistry; Polysaccharides/chemistry; Fruiting Bodies, Fungal/chemistry*
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