Phytochemical composition, antioxidant, and antimicrobial attributes of different solvent extracts from myrica esculenta buch.-ham. ex. d. don leaves

Background: Plant diversity is a basic source of food and medicine for local Himalayan communities. The current study was designed to assess the effect of different solvents (methanol, ethyl acetate, and water) on the phenolic profile, and the corresponding biological activity was studied. Methods: Antioxidant activity was investigated using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2¿-azino-bis(3-ethylbenzothiazoline-6-sulphonic) acid (ABTS) assay, while the antimicrobial activity was evaluated by disk diffusion method using various bacterial and fungal strains. Results: The outcomes demonstrated that methanol acted as the most effective solvent for polyphenols extraction, as strengthened by the liquid chromatography and mass spectroscopy (LC-MS) and fourier transform infrared spectroscopy (FTIR) analysis. M. esculenta methanol extract showed the highest DPPH and ABTS radical scavenger antioxidant activity with IC50 values of 39.29 µg/mL and 52.83 µg/mL, respectively, while the ethyl acetate and aqueous extracts revealed minimum antioxidant potential. Methanol extract also revealed higher phenolic content, 88.94 ± 0.24 mg of equivalent gallic acid (GAE)/g), measured by the Folin–Ciocalteu method, while the minimum content was recorded for aqueous extract (62.38 ± 0.14 GAE/g). The highest flavonoid content was observed for methanol extract, 67.44 ± 0.14 mg quercetin equivalent (QE)/g) measured by an aluminum chloride colorimetric method, while the lowest content was recorded for aqueous extract (35.77 ± 0.14 QE/g). Antimicrobial activity findings also reveal that the methanol extract led to a higher inhibition zone against bacterial and fungal strains. FTIR analysis reveals the presence of various functional groups, viz. alkenes, amines, carboxylic acids, amides, esters, alcohols, phenols, ketones, carboxylic acids, and aromatic compounds. This FTIR analysis could serve as a basis for the authentication of M. esculenta extracts for future industrial applications. Compounds identified by LC-MS analysis were gallic acid, myricanol, myricanone, epigallocatechin 3-O-gallate, ß-sitosterol, quercetin, p-coumaric acid, palmitic acid, n-pentadecanol, n-octadecanol, stigmasterol, oleanolic acid, n-hexadecanol, cis-ß-caryophyllene, lupeol, and myresculoside. Conclusion: This study suggests that the methanolic extract from M. esculenta leaves has strong antioxidant potential and could be a significant source of natural antioxidants and antimicrobials for functional foods formulation.Authors are thankful to A.P. Singh, Dean RIC, I.K. Gujral Punjab Technical University and members of staff in the department of RIC, I.K. Gujral Punjab Technical University for support and encouragement in this work. N. Martins would like to thank the Portuguese Foundation for Science and Technology (FCT-Portugal) for the Strategic project ref. UID/BIM/04293/2013 and “NORTE2020—Northern Regional Operational Program” (NORTE-01-0145-FEDER-000012)

Simultaneous quantitative determination of zidovudine and nevirapine in human plasma using isocratic, reverse phase high performance liquid chromatography

Purpose: To develop a sensitive and rapid reverse phase high performance liquid chromatography (HPLC) method for the measurement of the levels of zidovudine (ZVD) and nevirapine (NVP) in human plasma. Methods: Standard stock solutions for HPLC analysis were prepared by dissolving ZVD and NVP in methanol. In the HPLC measurement, sample detection was carried out at 246 nm using an ultraviolet (UV)-photo diode array (PDA) detector. Plasma sample pretreatment consisted of protein precipitation extraction with methanol. The compounds were separated using a mobile phase consisting of a pH 3.0 solution (obtained by adjusting the pH of water with orthophosphoric acid): acetonitrile (73:27 v/v) on a Phenomenex LUNA C18, column (250×4.6 mm i.d., 5μm) at a flow rate of 0.9 mL min-1. The total run time for the assay was 10.2 min. The method was validated over the range of 300-9600 ng mL-1 and 200-6400 ng mL-1 for ZVD and NVP, respectively. Results: The lowest limits of quantification (LLOQ) and of detection (LOD) were 300 and 63 ng mL-1 for ZVD and 200 and 17 ng mL-1 for NVP, respectively. The method was found to be accurate, with accuracy ranging from -10.92 to +9.57 % and precise, with intra-day, inter-day as well as analyst to analyst precision of 0.68 to 9.38 %. Extraction recoveries of the drugs from plasma were 91.39, 95.01, 89.51 % for ZVD and 90.93, 93.26, 92.13 % for NVP, for LQC (low quality control), MQC (medium quality control) and HQC (high quality control) samples, respectively. Stability data revealed that the drugs were stable in plasma under various test conditions. Conclusion: This assay can be suitably used for the determination of zidovudine (ZVD) and nevirapine (NVP) in human plasma and should be useful in HIV clinical trials and clinical therapeutic drug monitoring (TDM) programs. It would also be potentially useful in the determination of pharmacokinetic profiles and in bioequivalence studies in HIV research.. Keywords: Assay, Zidovudine, Nevirapine, Human plasma, Reverse phase high- performance liquid chromatography.Tropical Journal of Pharmaceutical Research Vol. 8 (1) 2009: pp. 79-8

Arrested States formed on Quenching Spin Chains with Competing Interactions and Conserved Dynamics

We study the effects of rapidly cooling to T = 0 a spin chain with conserved dynamics and competing interactions. Depending on the degree of competition, the system is found to get arrested in different kinds of metastable states. The most interesting of these has an inhomogeneous mixture of interspersed active and quiescent regions. In this state, the steady-state autocorrelation function decays as a stretched exponential $\sim \exp(-{(t/\tau_{o})}^{{1}\over{3}})$, and there is a two-step relaxation to equilibrium when the temperature is raised slightly.Comment: 4 pages, Latex, 3 postscript figures. Phys. Rev. E to appear (1999

Studies in Heterocyclic Compounds -Part VIII

Different azo compounds, 1-(m-nitrophenyl)-3-(p-bromophenyl)-and 1-(m-nitrophenyl) 3-(p-chlorophenyl)-2-(substituted sulphonamidobenzeneazo) propane-1,3-dinoes on condensation with hydrazine hydrate (100%), phenylhydrazine, p-nitrophenyllhydrazine and benzoylhydrazine yield the corresponding 1-simple/substituted-3-(m-nitrophenyl)-5-(p-bromo chlorophenyl)-4-(substituted sulphonamidobenzeneazo) pyrazoles. The homogeneity and purity of these was confirmed by TLC and these on screening in vitro against S. aureus and E. coli were found to exhibit antibacterial activity

Respiratory parameters for the classification of dysfunctional insulin secretion in pancreatic islets

The development of obesity and type 2 diabetes (T2D) has been associated with impaired mitochondrial function. In pancreatic beta (β) cells, mitochondrial energy metabolism plays a central role in triggering and controlling glucose-stimulated insulin secretion (GSIS). Here, we have explored whether mitochondrial bioenergetic parameters assessed with Seahorse extracellular flux technology can quantitatively predict insulin secretion. We metabolically stressed male C57BL/6 mice by high-fat feeding (HFD) and measured the glucose sensitivity of islet respiration and insulin secretion. The diet-induced obese (DIO) mice developed hyperinsulinemia, but no pathological secretory differences were apparent between isolated DIO and chow islets. Real-time extracellular flux analysis, however, revealed a lower respiratory sensitivity to glucose in DIO islets. Correlation of insulin secretion with respiratory parameters uncovers compromised insulin secretion in DIO islets by oxidative power. Normalization to increased insulin contents during DIO improves the quantitative relation between GSIS and respiration, allowing to classify dysfunctional properties of pancreatic insulin secretion, and thereby serving as valuable biomarker for pancreatic islet glucose responsiveness and health

FEM prediction of welding residual stresses in fibre laser welded AA 2024-T3 and comparison with experimental measurement

Welding generates a considerable amount of residual stresses which affect the structural integrity of welded components. It is often assumed that the magnitude of residual stresses around the welded joint is as high as the yield stress of the material. In this investigation, such assumption was found to be overly conservative and failed to accurately represent the distribution of residual stresses in fibre laser-welded aluminium alloy 2024-T3 sheets. Welding simulation based on the finite element method was used to reliably determine the distribution and magnitude of transient residual stress fields and distortions in thin sheets welded using three different sets of welding parameters. The accuracy of the finite element models was checked by calibrating with experimentally measured weld pool geometries and temperature field prior to conducting parametric studies. X-ray and neutron diffraction measurements were performed on the surface and in the bulk of the welded components, respectively, and compared with numerical results. The influence of weld metal softening, welding parameters and restraints on residual stresses and distortion were investigated systematically by numerically simulating ideal conditions which eliminate the practical limitations of conducting experimental studies, for process optimization as well as evaluation of in-service structure integrity and failure modes of the welded sheets

Neutron diffraction analysis of stress and strain partitioning in a two-phase microstructure with parallel-aligned phases

By time-of-flight (TOF) neutron diffraction experiments, the influence of segregation-induced microstructure bands of austenite (γ) and martensite (α′ ) phases on the partitioning of stress and strain between these phases was investigated. Initially, tensile specimens of a Co-added stainless steel were heat treated by quenching and partitioning (Q&P) processing. Tensile specimens were subsequently loaded at 350 °C parallel to the length of the bands within the apparent elastic limit of the phase mixture. Lattice parameters in both axial and transverse directions were simultaneously measured for both phases. The observation of a lattice expansion for the γ phase in the transverse direction indicated a constraint on the free transverse straining of γ arising from the banded microstructure. The lateral contraction of α′ imposed an interphase tensile microstress in the transverse direction of the γ phase. The multiaxial stress state developed in the γ phase resulted in a large deviation from the level of plastic strain expected for uniaxial loading of single phase γ. Since segregation-induced banded microstructures commonly occur in many engineering alloys, the analysis of stress and strain partitioning with the present Q&P steel can be used to interpret the observations made for further engineering alloys with two-phase microstructures

Direct Substrate Delivery into Mitochondrial-Fission Deficient Pancreatic Islets Rescues Insulin Secretion

In pancreatic beta cells, mitochondrial bioenergetics control glucose-stimulated insulin secretion (GSIS). Mitochondrial dynamics are generally associated with quality control, maintaining the functionality of bioenergetics. By acute pharmacological inhibition of mitochondrial fission protein Drp1, we here demonstrate that mitochondrial fission is necessary for GSIS in mouse and human islets. We confirm that genetic silencing of Drp1 increases mitochondrial proton leak in MIN6 cells. However, our comprehensive analysis of pancreatic islet bioenergetics reveals that Drp1 does not control insulin secretion via its effect on proton leak but instead via modulation of glucose-fuelled respiration. Notably, pyruvate fully rescues the impaired insulin secretion of fission-deficient beta cells, demonstrating that defective mitochondrial dynamics solely impact substrate supply upstream of oxidative phosphorylation. The present findings provide novel insights in how mitochondrial dysfunction may cause pancreatic beta cell failure. In addition, the results will stimulate new thinking in the intersecting fields of mitochondrial dynamics and bioenergetics, as treatment of defective dynamics in mitochondrial diseases appears to be possible by improving metabolism upstream of mitochondria