Hamayun Khan

Chemical composition and antioxidant activity of certain Morus species

In the present work, the fruits of four Morus species, namely Morus alba (white mulberry), Morus nigra (black mulberry), Morus laevigata (large white fruit), and Morus laevigata (large black fruit), were analyzed for proximate composition, essential minerals, and antioxidant potentials. For this purpose, the ripe fruits were collected from the northern regions of Pakistan. The major nutritional components (moisture, ash, lipids, proteins, fibres, carbohydrates, and total sugar) were found to be in the suitable range along with good computed energy. Total dry weight, pH, and titratable acidity (percent citric acid) were (17.60±1.94)–(21.97±2.34) mg/100 g, (3.20±0.07)–(4.78±0.15), and (0.84±0.40)%–(2.00±0.08)%, respectively. Low riboflavin (vitamin B2) and niacin (vitamin B3) contents were recorded in all the fruits, while ascorbic acid (vitamin C) was in the range from (15.20±1.25) to (17.03±1.71) mg/100 g fresh weight (FW). The mulberry fruits were rich with regard to the total phenol and alkaloid contents, having values of (880±7.20)–(1650±12.25) mg/100 g FW and (390±3.22)–(660±5.25) mg/100 g FW, respectively. Sufficient quantities of essential macro-(K, Ca, Mg, and Na) and micro-(Fe, Zn, and Ni) elements were found in all the fruits. K was the predominant element with concentration ranging from (1270±9.36) to (1731±11.50) mg/100 g, while Ca, Na, and Mg contents were (440±3.21)–(576±7.37), (260±3.86)–(280±3.50), and (240±3.51)–(360±4.20) mg/100 g, respectivly. The decreasing order of micro-minerals was Fe>Zn>Ni. The radical scavenging activity of methanolic extract of fruits was concentration-dependent and showed a correlation with total phenolic constituents of the respective fruits. Based on the results obtained, mulberry fruits were found to serve as a potential source of food diet and natural antioxidants.

Simpler and highly sensitive enzyme-free sensing of urea via NiO nanostructures modified electrode

In this study, NiO nanostructures were synthesized via a hydrothermal process using ascorbic acid as doping agent in the presence of ammonia. As prepared nanostructures were characterized using Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), Brunauer–Emmett–Teller (BET) specific surface area analysis, and thermogravimetric analysis (TGA). These analyses showed that these nanostructures are in the form of cotton-like porous material and crystalline in nature. Furthermore, the average size of these NiO crystallites was estimated to be 3.8 nm. These nanostructures were investigated for their potential to be a highly sensitive and selective enzyme-free sensor for detection of urea after immobilizing on a glassy carbon electrode (GCE) using 0.1% Nafion as binder. The response of this as developed amperometric sensor was linear in the range of 100–1100 μM urea with a R2 value of 0.990 and limit of detection (LOD) of 10 μM. The sensor responded negligibly to various interfering species including glucose, uric acid, and ascorbic acid. This sensor was applied successfully for determining urea in real water samples such as mineral water, tap water, and river water with acceptable recovery.

Photocatalytic degradation of bromophenol blue in aqueous medium using chitosan conjugated magnetic nanoparticles

Three different chitosan conjugated magnetic nanoparticles (CCMN) of Co, Ni and Fe were prepared using co-precipitation method. The prepared CCMN were characterized by scanning electron microscopy (SEM), Xray diffraction (XRD) and Fourier transform infra-red (FT-IR) spectroscopic techniques. The SEM results showed a smooth surface morphology with almost uniform particle size and irregular shape structure for all CCMN. The XRD study revealed the crystalline structure in case of Co-CCMN and Ni-CCMN, while amorphous nature of Fe-CCMN was observed. The particle size of the prepared CCMN was found to be <95 nm, as confirmed from SEM and XRD analyses. Similarly, FT-IR analysis showed the incorporation and conjugation of Co, Ni and Fe magnetic nanoparticles into the chitosan polymer matrix. The point of zero charge (PZC) was found to be 7.41 for Co-CCMN and Ni-CCMN and 7.70 for Fe-CCMN. The photocatalytic activity of the prepared CCMN was investigated under UV light irradiation (254 nm and 15 W) in the aqueous medium using bromophenol blue (BPB). The photocatalytic process was monitored by UV-visible spectrophotometer for different irradiation times (0 to 10 h). The results showed that all the prepared CCMN displayed good to excellent photocatalytic property where the highest degradation was exhibited by Fe-CCMN (94.5%), followed by Co-CCMN (85.1%) and Ni-CCMN (83.0%). The prepared catalysts were recycled and reused, maintaining good photocatalytic activity for four consecutive batches.

Synthesis, characterization and electrical properties of polypyrrole/V2O5 composites

Polypyrrole (PPy) and its composites with vanadium pentoxide (V2O5) were synthesized in aqueous medium by chemical oxidation polymerization using FeCl3·6H2O as an oxidant. The materials were characterized by Fourier transform infrared (FT-IR) spectroscopy, X-ray diffractometry (XRD), thermogravimetry analyzer (TGA), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), UV/visible spectroscopic techniques and LCR-meter. The FT-IR results confirmed the successful synthesis of PPy and PPy/V2O5 composites. The XRD study showed the amorphous and crystalline nature of PPy and PPy/V2O5 composites, respectively. The TGA analysis showed slight increase in the thermal stability of the composites. The SEM data verified the porous nature of PPy and the composites. The UV/visible spectrometry confirmed the doping of PPy in composites. The electrical properties of the materials displayed their semiconducting nature. The resistance of the samples was found to be dependent on temperature and the contents of V2O5 in the composites.

Spectrophotometric methods for the determination of urea in real samples using silver nanoparticles by standard addition and 2nd order derivative methods

In this work, we have developed simple, sensitive and inexpensive methods for the spectrophotometric determination of urea in urine samples using silver nanoparticles (AgNPs). The standard addition and 2nd order derivative methods were adopted for this purpose. AgNPs were prepared by chemical reduction of AgNO3 with hydrazine using 1,3-di-(1H-imidazol-1-yl)-2-propanol (DIPO) as a stabilizing agent in aqueous medium. The proposed methods were based on the complexation of AgNPs with urea. Using this concept, urea in the urine samples was successfully determined spectrophotometric methods. The results showed high percent recovery with ±RSD. The recoveries of urea in the three urine samples by spectrophotometric standard addition were 99.2%±5.37, 96.3%±4.49, 104.88%±4.99 and that of spectrophotometric 2nd order derivative method were 115.3%±5.2, 103.4%±2.6, 105.93%±0.76. The results show that these methods can open doors for a potential role of AgNPs in the clinical determination of urea in urine, blood, biological, non-biological fluids.

Phytochemical composition, biological potential and enzyme inhibition activity of Scandix pecten-veneris L.

ObjectiveScandix pecten-veneris L. is a less studied wild edible herb and is considered an extinct plant species in many parts of the world. This study was designed to evaluate its phytochemical composition and biological potential of S. pecten-veneris L.MethodsPhytochemicals including alkaloids, flavonoids, polyphenols, and tannins were determined in extracts of S. pecten-veneris. Antioxidant activity was determined using 2,2-diphenyl-1-picrylhydrazyl (DPPH), while reducing power was tested by ferric reducing/antioxidant power (FRAP) assay. Antimicrobial activity against seven bacterial and four fungal strains was evaluated using agar well diffusion assay. Enzymes inhibition study was performed for urease, phosphodiesterase-I, and catalase-II.ResultsS. pecten-veneris showed moderate antiradical activity and reducing potential of hydroxyl radicals to about 20% of the initial value. The antioxidant activity of various extracts of S. pecten-veneris showed a linear correlation with total phenolic contents in the order of water>n-butanol>chloroform>ethyl acetate>methanol extracts. S. pecten-veneris leaves showed the highest inhibitory activity against Staphylococcus aureus while the highest antifungal activity was observed against Candida albicans. The plant extract was most potent against urease enzymes but showed moderate activity against phosphodiestrase-I and carbonic anhydrase-II.ConclusionsOur data demonstrate that in addition to its culinary uses, S. pecten-veneris has good medicinal potential and hence could be used for treating some specific health ailments.概要目的本研究旨在测定Scandix pecten-veneris L.的植物 素和评价其生物学潜力。方法测定S. pecten-veneris 提取物中植物素的含量, 包括生物碱、黄酮、多酚和单宁。使用2,2-二苯 基-1-苦肼基(DPPH)测 定抗氧化活性;同时通 过铁还原/抗氧化能力(FRAP)测定还原能力; 使用琼脂扩散测定法评价对七种细菌和四种真 菌菌株的抗微 生物活性。同时,对脲酶、磷酸二 酯酶-I 和过氧化氢酶-II 进行酶抑制研究。结论沙门氏菌显示出适度的抗自由基活性;羟基自由 基的潜能降至初始值的20%左右。S. pectenveneris 多种提 取物的抗氧化活性与总酚含量呈 线性相关。S. pecten-veneris 叶对金黄色葡萄球菌 表现出最高的抑制活性 ;对白色念珠菌表现出到 最高的抗真菌活性。植物提取物对脲酶的活性最 有效;对磷酸二酯酶-I和 碳酸酐酶-II 显示出中 等活性。结果表明,S. pecten-veneris 具有良好的 药用潜力,可用于治疗一些特定的疾病。

Polypyrrole/MnO 2 composites: synthesis, structural and electrical properties

In the present study, polypyrrole (PPy) and PPy/MnO2 composites were synthesized using a modified chemical oxidation polymerization method. The polymerization was carried out in the aqueous medium using FeCl3·6H2O as an oxidant. The synthesized materials were characterized using XRD, SEM, EDX, TGA, FT-IR, surface area analyzer, UV–visible spectrophotometry and LCR-meter. The results confirmed the successful synthesis of materials with amorphous and crystalline nature of PPy and PPy/MnO2 composites, respectively. PPy/MnO2 composites were found to be thermally more stable with large surface area as compared to PPy. The PPy was found to be porous in nature while PPy/MnO2 composites have compact structure. The elemental analysis confirmed the presence of MnO2 in the composites; however, greater quantity of MnO2 was observed than the added amount with an efficient influence on the doping level of PPy. The synthesized materials showed semiconducting nature and their resistance was found to be dependent on temperature and MnO2 content in the composites.