Determination of Bergenin in Different Parts of Bergenia ciliata using a Validated RP-HPLC Method

Ejaz Ali,Khalid Hussain,Nadeem Irfan Bukhari,Najma Arshad,Amjad Hussain,Nasir Abbas,Sohail Arshad,Sajida Parveen,Naureen Shehzadi,Shaista Qamar,Abida Qamar 한국생약학회 2021 Natural Product Sciences Vol.27 No.1

Bergenia ciliata (Family: Saxifragaceae) is a folklore remedy for the treatment of various ailments in Asian countries. Bergenin (1) has been isolated as an active constituent in many studies, however, the amount of bergenin has not been determined in all parts of the plant. A simple RP-HPLC method was developed to determine the amount of bergenin in methanol extracts of leaves, rhizomes and roots of the plant. Separation was achieved on an Agilent Eclipse XDB-C18 column maintained at 25 oC using isocratic solvent system (water: methanol: acetic acid; 62.5:37:0.5 v/v/v) adjusted at pH 2 0 at a flow rate of 1.0 mL/min. and detected at 275 nm. Correlation coefficient (0.9952) showed linearity of concentration (5-200 μg/mL) and response. The values of LOD (0.00947 μg/mL) and LOQ (0.02869 μg/mL) indicated that method was sensitive. The recovery of bergenin was 99.99-100% indicating accuracy of method. The methanol extract of rhizomes contained higher amount of bergenin (19.4%) than roots (9.2%) and leaves (6.9%). It is concluded that methanol extract of rhizomes is a better source of bergenin than other parts of the plant. The findings are useful for standardization of bergenin containing extracts and herbal preparations.

Fiscal and Debt Management in a Severely Indebted Low Income Country

(Ejaz Ghani),(Zang Hyoung Soo) 한양대학교 경제연구소 1997 JOURNAL OF ECONOMIC RESEARCH Vol.2 No.1

The individual role of pyrrolic, pyridinic and graphitic nitrogen in the growth kinetics of Pd NPs on N-rGO followed by a comprehensive study on ORR

Ejaz, Ammara,Jeon, Seungwon Elsevier 2018 International journal of hydrogen energy Vol.43 No.11

<P><B>Abstract</B></P> <P>In order to develop and replace the expensive PtC catalyst from the fuel cells, we have attempted to synthesize an efficient catalyst for oxygen reduction reaction (ORR) in an alkaline media. The materials were initially fabricated as follows; (a) synthesizing a nitrogen doped (para-xylylenediamine, nitrogen precursor) graphene oxide (N-rGO); (b) synthesizing palladium nanoparticles on graphene oxide surface (rGO-Pd). The electrochemical analysis showed that the ORR path on the N-rGO catalyst is observed to follow 2-electron mechanism. Conversely, the onset potential, current density and surface area of the rGO-Pd doesn't match with the commercially available PtC catalyst. To overcome these flaws, we have combined the individual effects of each component and fabricated N-rGO-Pd nanocomposite. The covalent interaction between nitrogen part of para-xylylenediamine with oxygenated functionalities of GO, followed by a strong π–π stacking interaction between the aromatic ring of para-xylylenediamine and GO altered the electronic distribution of the carbon support, induced more defects, influenced the size and averted the self agglomeration of the Pd NPs which lead to the astonishing catalytic activity of N-rGO-Pd catalyst. Furthermore, various spectroscopic techniques revealed the individual influence of pyrrolic, pyridinic and graphitic–N on the synthesis, size and extraordinary distribution of Pd NPs.</P> <P><B>Highlights</B></P> <P> <UL> <LI> An ORR catalyst consisting of GO incorporated N and Pd NPs (N-rGO-Pd) is proposed. </LI> <LI> The growth kinetics of Pd NPs are influenced by graphitic, pyrrolic and pyridinic nitrogen. </LI> <LI> The graphitic nitrogen played a significant role in the indirect ORR process. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Fabrication of 1,4-bis(aminomethyl)benzene and cobalt hydroxide @ graphene oxide for selective detection of dopamine in the presence of ascorbic acid and serotonin

Ejaz, A.,Joo, Y.,Jeon, S. Elsevier Sequoia 2017 Sensors and actuators. B Chemical Vol.240 No.-

A simple electrochemical sensor for detecting dopamine was fabricated using 1,4-bis(aminomethyl)benzene (BAMB) and cobalt hydroxide (Co(OH)<SUB>2</SUB>) at graphene oxide (GO) surface using a simple solution-based chemical reduction method. The successful formation of GO-BAMB-Co(OH)<SUB>2</SUB> was confirmed by transmission electron microscopy and X-ray photoelectron spectroscopy, while the electrochemical performance of the material was studied using different techniques, including cyclic voltammetry, differential pulse voltammetry, linear sweep voltammetry, and chronoamperometry in 0.1M PBS at pH 7.4. The GO-BAMB-Co(OH)<SUB>2</SUB>-modified electrode showed an excellent electrochemical response with a broad linear range (3-20 and 25-100μM) and low limit of detection (0.4μM). Furthermore, efficient selective detection of dopamine in the presence of a 10-fold excess concentration of bio-interfering species, such as ascorbic acid and serotonin, was remarkable. The practical feasibility of the sensor was checked using urine samples, which showed appreciable recovery results. The main advantages of this sensor are its simple electrode fabrication procedure, rapid sensing response, remarkable selectivity, repeatability, and stability.

Biologically Inspired Cooperative Spectrum Sensing Scheme for Maritime Cognitive Radio Networks

Ejaz, Waleed,Hasan, Najam ul,Shah, Ghalib A.,Kim, Hyung Seok,Anpalagan, Alagan IEEE 2018 IEEE systems journal Vol.12 No.3

<P>Spectrum sensing is imperative to the success of maritime cognitive radio networks (MCRNs). Spectrum sensing in MCRNs is challenging because of the sea surface movement, the channel interference, and the unstable link quality. Recent research reveals that existing spectrum sensing schemes work well for lower sea states; however, they have failed to perform effectively at higher sea states. There are two disadvantages of performing spectrum sensing at higher sea states: 1) low probability of detection may also cause interference with primary system and 2) energy wastage. In this paper, a biologically inspired cooperative spectrum sensing scheme (BIC3S) is proposed to deal with the reliability and energy consumption challenges associated with the sea environment. It is based on the task allocation model of an insect colony. The proposed BIC3S chooses participating secondary users for cooperative spectrum sensing according to their given sea state. Further, it enables the secondary users to decide whether or not to perform spectrum sensing based on their sea state. Simulation results are presented to demonstrate the performance of the proposed scheme in terms of energy consumption, detection performance, and throughput. It is shown that the proposed BIC3S consumes less energy and, at the same time, achieves higher detection probability and fewer probability of false alarms compared to the existing schemes. Moreover, BIC3S provides better adaptation capabilities for the sea environment.</P>

Synthesis and application of electrochemically reduced N-rGO-Co(OH)₂ nanocomposite for concurrent detection of biomolecules

Ejaz, Ammara,Jeon, Seungwon Pergamon Press 2017 Electrochimica Acta Vol. No.

<P><B>Abstract</B></P> <P>In present work, we prepared nitrogen doped graphene oxide (N-GO) by using 1,3-xylenediamine (XDA) as nitrogen precursor which was further decorated with Co(OH)<SUB>2</SUB> nanoflower. The physiochemical analysis such as X-ray photoelectron spectroscopy and scanning electron microscopy revealed the successful doping of nitrogen on GO and fine dispersion of Co(OH)<SUB>2</SUB> nanoflower on the surface of N-GO. The as prepared N-GO-Co(OH)<SUB>2</SUB> was electrochemically reduced (N-rGO-Co(OH)<SUB>2</SUB>) to precisely adjust its electrochemical properties. The N-rGO-Co(OH)<SUB>2</SUB> was used as a novel electrode modifier for the simultaneous detection of dopamine (DA) and uric acid (UA). From the combined effects of N-doping and excellent electrocatalytic properties of the Co(OH)<SUB>2</SUB> nanoflower, constructed sensor exhibited high electrochemical sensing activity with the wide linear response, limit of detection and limit of quantification of 1.0×10<SUP>−8</SUP> M and 3.0×10<SUP>−8</SUP> M for DA and 1.0×10<SUP>−7</SUP> M and 3.6×10<SUP>−7</SUP> M for UA respectively. The N-rGO-Co(OH)<SUB>2</SUB> nanocomposite showed long-term sensing stability, reproducibility and excellent analytical response in urine for DA and UA detection. Furthermore, N-rGO-Co(OH)<SUB>2</SUB> also revealed remarkable anti-interfering behavior towards other biomolecules including ascorbic acid (AA), serotonin (5-HT) and glucose (Glu). The N-rGO-Co(OH)<SUB>2</SUB> nanocomposite manifests intriguing application potential as the candidate for the application of the electrochemical sensor for simultaneous detection of DA and UA.</P>

I3S: Intelligent spectrum sensing scheme for cognitive radio networks

Ejaz, Waleed,ul Hasan, Najam,Lee, Seok,Kim, Hyung Seok Springer (Biomed Central Ltd.) 2013 EURASIP journal on wireless communications and net Vol.2013 No.-

Improved local spectrum sensing for cognitive radio networks

Ejaz, Waleed,ul Hasan, Najam,Azam, Muhammad Awais,Kim, Hyung Seok Springer (Biomed Central Ltd.) 2012 EURASIP journal on advances in signal processing Vol.2012 No.1

Energy and throughput efficient cooperative spectrum sensing in cognitive radio sensor networks

Ejaz, Waleed,Shah, Ghalib A.,Hasan, Najam ul,Kim, Hyung Seok Wiley Blackwell (John Wiley Sons) 2015 Transactions on emerging telecommunications techno Vol.26 No.7

A highly stable and sensitive GO-XDA-Mn₂O₃ electrochemical sensor for simultaneous electrooxidation of paracetamol and ascorbic acid

Ejaz, Ammara,Jeon, Seungwon Elsevier 2017 ELECTROCHIMICA ACTA Vol.245 No.-

<P><B>Abstract</B></P> <P>Highly stable electrochemical sensor based on strong π- π interactions between GO and XDA was fabricated for simultaneous as well as for individual detection of paracetamol (PCT) and ascorbic acid (AA). The oxidation potential of PCT and AA was greatly resolved with the decoration of Mn<SUB>2</SUB>O<SUB>3</SUB> nanospheres. We believe that, presence of metal oxide on the surface of GO-XDA will offer higher electrochemical performance with its large surface area and fast electron transfer ability. Therefore, a comparative study was executed in the presence and absence of Mn<SUB>2</SUB>O<SUB>3</SUB> nanospheres on the surface of GO-XDA. The GO-XDA-Mn<SUB>2</SUB>O<SUB>3</SUB> modified electrode showed electrocatalytic oxidation of PCT in a very wide linear range of 1×10<SUP>−6</SUP>–1×10<SUP>−3</SUP> M with limit of detection (LOD) and sensitivity of 5.6×10<SUP>−8</SUP> M, 527.04μAmM<SUP>−1</SUP>cm<SUP>−2</SUP> respectively and AA with 1×10<SUP>−5</SUP> –8×10<SUP>−3</SUP> M linear range, LOD and sensitivity of 6.0×10<SUP>−7</SUP> M, 655.74μAmM<SUP>−1</SUP>cm<SUP>−2</SUP> respectively. Furthermore, astonishing stability was found when GO-XDA-Mn<SUB>2</SUB>O<SUB>3</SUB> nanocomposite was stored for over a week. The proposed sensor displayed incredible selectivity, sensitivity and excellent recovery results for real samples with appreciable consistency and precision suggesting practical utility of the GO-XDA-Mn<SUB>2</SUB>O<SUB>3</SUB> as an effective and reliable electrochemical sensor for simultaneous as well as individual determination of PCT and AA.</P> <P><B>Highlights</B></P> <P> <UL> <LI> π–π interaction of graphene oxide (GO) with 1,4-xylenediamine (XDA) was studied. </LI> <LI> The synergistic effect of the Mn<SUB>2</SUB>O<SUB>3</SUB> nanospheres with GO-XDA was electrochemically studied in the detection of Paracetamol (PCT) and ascorbic acid (AA). </LI> <LI> The GO-XDA-Mn<SUB>2</SUB>O<SUB>3</SUB> accurately detected PCT and AA with LOD of 5.6×10<SUP>−8</SUP> M and 6.0×10<SUP>−7</SUP> M respectively. </LI> <LI> The GO-XDA-Mn<SUB>2</SUB>O<SUB>3</SUB> selectively detected PCT and AA simultaneously in the presence of DA, 5-HT and Glu with peak separation of 240mV. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>