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Abdul Hameed and Naveed Akhtar

Abstract

In the present study, berries of two different species of Solanaceae family, Withania somnifera (WS) and Solanum nigrum (SN), were extracted in methanol and then fractionated with solvents, ranging from non-polar to polar, for their phytochemical profiling and investigation of antioxidant and tyrosinase enzyme inhibition capacity. The methanolic extract and n-hexane, ethyl acetate (WSEA, SNEA) and aqueous fractions were chemically analyzed and evaluated for biological activity. Total flavonoids and total phenolics were quantified in WSEA (96.91 ± 1.56 μg QE mg-1 sample and 178.45 ± 2.78 μg GAE mg-1 s ample, r esp.) and S NEA (89.58 ± 0.98 μg QE mg-1 sample and 120.15 ± 2.33 μg GAE mg-1 sample, resp.). HPLC-DAD analysis of ethyl acetate fractions of WS and SN measured 13.74 and 5.34 μg GAE mg-1 dry fraction and 3.72 and 3.41 μg QE mg-1 dry fraction, resp. WSEA and SNEA fractions showed the highest 2,2-diphenyl-2-picryl hydrazyl (DPPH) radical scavenging, total antioxidant capacity and iron reducing power activity. The highest inhibition of tyrosinase enzyme was also exhibited by WSEA and SNEA (59.6 and 58.7 %) resp. This investigation justifies the medicinal value of W. somnifera and S. nigrum berry extracts as potential and readily available sources of natural antioxidants. Marked tyrosinase enzyme inhibition activity and antioxidant activity of both plant extracts might be due to polyphenols and flavonoids.

Open access

K. Abdul Hameed and S. Palani

Abstract

In this paper, a novel bacterial foraging algorithm (BFA) based approach for robust and optimal design of PID controller connected to power system stabilizer (PSS) is proposed for damping low frequency power oscillations of a single machine infinite bus bar (SMIB) power system. This paper attempts to optimize three parameters (Kp, Ki, Kd) of PID-PSS based on foraging behaviour of Escherichia coli bacteria in human intestine. The problem of robustly selecting the parameters of the power system stabilizer is converted to an optimization problem which is solved by a bacterial foraging algorithm with a carefully selected objective function. The eigenvalue analysis and the simulation results obtained for internal and external disturbances for a wide range of operating conditions show the effectiveness and robustness of the proposed BFAPSS. Further, the time domain simulation results when compared with those obtained using conventional PSS and Genetic Algorithm (GA) based PSS show the superiority of the proposed design.

Open access

Mahmood Ahmed, Muhammad Abdul Qadir, Muhammad Imtiaz Shafiq, Muhammad Muddassar, Abdul Hameed, Muhammad Nadeem Arshad and Abdullah M. Asiri

Abstract

Curcumin is a natural product with enormous biological potential. In this study, curcumin synthesis was revisited using different reaction solvents, a catalyst (n-butylamine) and a water scavenger [(n-BuO)3B], to develop the optimal procedure for its rapid acquisition. During synthesis, solvent choice was found to be an important parameter for better curcumin yield and high purity. In a typical reaction, acetyl acetone was treated with boron trioxide, followed by condensation with vanillin in the presence of tri-n-butyl borate as water scavenger and n-butylamine as catalyst at 80 °C in ethyl acetate to afford curcumin. Moreover, curcumin was also extracted from turmeric powder and spectroscopic properties such as IR, MS, 1H NMR and 13C NMR with synthetic curcumin were established to identify any impurity. The purity of synthetic and extracted curcumin was also checked by TLC and HPLC-DAD. To computationally assess its therapeutic potential against cyclin dependent kinases (CDKs), curcumin was docked in different isoforms of CDKs. It was observed that it did not dock at the active sites of CDK2 and CDK6. However, it could enter into weak interactions with CDK4 protein.

Open access

Othman A. Al Hanbali, Haji Muhammad Shoaib Khan, Muhammad Sarfraz, Mosab Arafat, Shakeel Ijaz and Abdul Hameed

Abstract

Use of transdermal patches can evade many issues associated with oral drug delivery, such as first-pass hepatic metabolism, enzymatic digestion attack, drug hydrolysis and degradation in acidic media, drug fluctuations, and gastrointestinal irritation. This article reviews various transdermal patches available in the market, types, structural components, polymer role, and the required assessment tools. Although transdermal patches have medical applications for smoking cessation, pain relief, osteoporosis, contraception, motion sickness, angina pectoris, and cardiac disorders, advances in formulation development are ongoing to make transdermal patches capable of delivering more challenging drugs. Transdermal patches can be tailored and developed according to the physicochemical properties of active and inactive components, and applicability for long-term use. Therefore, a number of chemical approaches and physical techniques for transdermal patch development are under investigation.