Rabia Hamid

Development of Dual Inhibitors against Alzheimer’s Disease Using Fragment-Based QSAR and Molecular Docking

Alzheimers (AD) is the leading cause of dementia among elderly people. Considering the complex heterogeneous etiology of AD, there is an urgent need to develop multitargeted drugs for its suppression. β-amyloid cleavage enzyme (BACE-1) and acetylcholinesterase (AChE), being important for AD progression, have been considered as promising drug targets. In this study, a robust and highly predictive group-based QSAR (GQSAR) model has been developed based on the descriptors calculated for the fragments of 20 1,4-dihydropyridine (DHP) derivatives. A large combinatorial library of DHP analogues was created, the activity of each compound was predicted, and the top compounds were analyzed using refined molecular docking. A detailed interaction analysis was carried out for the top two compounds (EDC and FDC) which showed significant binding affinity for BACE-1 and AChE. This study paves way for consideration of these lead molecules as prospective drugs for the effective dual inhibition of BACE-1 and AChE. The GQSAR model provides site-specific clues about the molecules where certain modifications can result in increased biological activity. This information could be of high value for design and development of multifunctional drugs for combating AD.

Mechanistic insights into mode of action of potent natural antagonists of BACE-1 for checking Alzheimer's plaque pathology.

Alzheimers is a neurodegenerative disorder resulting in memory loss and decline in cognitive abilities. Accumulation of extracellular beta amyloidal plaques is one of the major pathology associated with this disease. β-Secretase or BACE-1 performs the initial and rate limiting step of amyloidic pathway in which 37-43 amino acid long peptides are generated which aggregate to form plaques. Inhibition of this enzyme offers a viable prospect to check the growth of these plaques. Numerous efforts have been made in recent years for the generation of BACE-1 inhibitors but many of them failed during the preclinical or clinical trials due to drug related or drug induced toxicity. In the present work, we have used computational methods to screen a large dataset of natural compounds to search for small molecules having BACE-1 inhibitory activity with low toxicity to normal cells. Molecular dynamics simulations were performed to analyze molecular interactions between the screened compounds and the active residues of the enzyme. Herein, we report two natural compounds of inhibitory nature active against β-secretase enzyme of amyloidic pathway and are potent lead molecules against Alzheimers disease.

In Vitro Antioxidant and Cytotoxic Activities of Arnebia benthamii (Wall ex. G. Don): A Critically Endangered Medicinal Plant of Kashmir Valley

Arnebia benthamii is a major ingredient of the commercial drug available under the name Gaozaban, which has antibacterial, antifungal, anti-inflammatory, and wound-healing properties. In the present study, in vitro antioxidant and anticancer activity of different extracts of Arnebia benthamii were investigated. Antioxidant potential of plant extracts was evaluated by means of total phenolics, DPPH, reducing power, microsomal lipid peroxidation, and hydroxyl radical scavenging activity. The highest phenolic content (TPC) of 780 mg GAE/g was observed in ethyl acetate, while the lowest TPC of 462 mg GAE/g was achieved in aqueous extract. At concentration of 700 µg/mL, DPPH radical scavenging activity was found to be highest in ethyl acetate extract (87.99%) and lowest in aqueous extract (73%). The reducing power of extracts increased in a concentration dependent manner. We also observed its inhibition on Fe2+/ascorbic acid-induced lipid peroxidation (LPO) on rat liver microsomes in vitro. In addition, Arnebia benthamii extracts exhibited antioxidant effects on Calf thymus DNA damage induced by Fenton reaction. Cytotoxicity of the extracts (10–100 µg/mL) was tested on five human cancer cell lines (lung, prostate, leukemia, colon, and pancreatic cell lines) using the Sulphorhodamine B assay.

Isolation and antiproliferative activity of Lotus corniculatus lectin towards human tumour cell lines.

The objective of the study was to investigate the anti cancer activity of a lectin isolated from Lotus corniculatus seeds. A tetrameric 70kDa galactose specific lectin was purified using two step simple purification protocol which involved affinity chromatography on AF-BlueHC650M and gel filtration on Sephadex G-100. The lectin was adsorbed on AF-BlueHC650M and desorbed using 1M NaCl in the starting buffer. Gel filtration on Sephadex G-100 yielded a major peak absorbance that gave two bands of 15kDa and 20kDa in SDS PAGE. Hemagglutination activity was completely preserved, when the temperature was in the range of 20-60°C. However, drastic reduction in activity occurred at temperatures above 60°C. Full hemagglutination activity was retained at ambient pH 4-12. Thereafter no activity was observed above pH 13. Hemaglutination of the lectin was inhibited by d-galactose. The lectin showed a strong antiproliferative activity towards human leukemic (THP-1) cancer cells followed by lung cancer (HOP62) cells and HCT116 with an IC50 of 39μg/ml and 50μg/ml and 60μg/ml respectively. Flow cytometry analysis showed an increase in the percentage of cells in sub G0G1 phase confirming that Lotus corniculatus lectin induced apoptosis. Morphological observations showed that Lotus corniculatus lectin (LCL) treated THP-1 cells displayed apparent apoptosis characteristics such as nuclear fragmentation, appearance of membrane enclosed apoptotic bodies and DNA fragmentation. Lotus corniculatus lectin (LCL) effectively inhibits the cell migration in a dose dependent manner as indicated by the wound healing assay.

Radical scavenging and antibacterial activity of Arnebia benthamii methanol extract

OBJECTIVE To evaluate in vitro antioxidant and antibacterial activity of methanolic extract of Arnebia benthamii (A. benthamii) whole plant. METHODS Plasmid damage was analyzed by agarose gell electrophoresis. Calf thymus DNA was monitored by TBARS formation. DPPH, reducing power and lipid peroxidation was evaluated by using standard procedures. Antibacterial assay was monitored by disc diffusion method. RESULTS DPPH radical scavenging and hydroxyl radical scavenging potential of the plant revealed that the extract to be active radical scavenger. Reducing (Fe(3+)-Fe(2+)) power and lipid peroxidation inhibition efficiency (TBARS assay) of the extract was also evaluated and the extract showed promising activity in preventing lipid peroxidation and might prevent oxidative damages to biomolecules. The extract offered a significant protection against plasmid and calf thymus DNA damage induced by hydroxyl radicals. The extract was also evaluated on different bacterial strains and the maximum antibacterial activity was exhibited against Escherichia coli (E. coli) when compared with standard drug. CONCLUSIONS These findings demonstrate that the methanol extract of A. benthamii has excellent anti-oxidant activities and could be considered as a potential source of lead molecules for pharmaceutical industries.

Phytochemical screening, physicochemical properties, acute toxicity testing and screening of hypoglycaemic activity of extracts of Eremurus himalaicus baker in normoglycaemic Wistar strain albino rats.

In the present study EtOAc, MeOH, and aqueous extracts of Eremurus himalaicus were evaluated for hypoglycaemic effect in normal rats using both oral glucose tolerance test and 14-day oral administration study. Phytochemical and physicochemical screening was also done. In oral glucose tolerance test the aqueous and MeOH extracts of Eremurus himalaicus at a dose level of 500 mg/kg body weight prior to glucose load resulted in a significant fall in blood glucose level within 150 min. of glucose administration. The aqueous extract at a dose level of 250 mg/kg body weight and 500 mg/kg body weight also showed good hypoglycaemic response (P < 0.001); this was followed by MeOH extract at a dose level of 500 mg/kg body weight (P < 0.05), while MeOH extract at dose level of 250 mg/kg body weight and ethyl acetate extract at dose level of 250 mg/kg body weight and 500 mg/kg body weight exhibited insignificant effect. Phytochemical screening of extracts revealed the presence of alkaloids, terpenoids, phenolics, tannins, saponins, cardiac glycosides, and flavonoids. The results indicate that aqueous extract possess significant hypoglycaemic activity in normoglycaemic rats which may be attributed to the above-mentioned chemical constituents.

Polymorphism of the XRCC3 gene and risk of gastric cancer in a Kashmiri population: a case-control study.

DNA repair plays a critical role in protecting the genome of the cell from the insults of cancer-causing agents. Genetic polymorphisms in DNA repair genes may influence individual variation in DNA repair capacity, which may be associated with the risk of developing cancer. Inherited polymorphisms of DNA repair genes may contribute to variations in DNA repair capacity and genetic susceptibility to different cancers. The X-ray repair complementing defective repair in Chinese hamster cells 3 (XRCC3) gene is a member of the RAD51 gene family. It encodes an important protein that functions in the homologous recombination repair of a DNA double-strand break. For gastric cancer, the importance of mutations in mismatch repair genes has been well documented, but less is known about other DNA repair pathways in gastric carcinogenesis. In this study, we have focused on the XRCC3 gene, involved in homologous recombinational repair. The Kashmir valley has an increased incidence of gastric cancer and its etiology has not been understood fully as yet. As the Kashmiri population is ethnically and demographically different from that in other parts of the world, the aim of this study was to determine whether a single nucleotide polymorphism of the XRCC3 gene (Thr241Met) of exon 7 can influence the risk of gastric cancer in the population. As many as 80 histopathologically confirmed gastric cancer cases and 70 healthy controls, age, sex, and ethnicity matched for known genotypes of XRCC3 exon 7 were studied. We genotyped for this variant using PCR-restriction fragment length polymorphisms. The XRCC3 genotype and allele frequencies were not significantly different between cases and controls (P=0.92 for the genotype; P=0.72 for the allele). The XRCC3 241Met allele frequency (6.6%) was significantly lower in healthy Kashmiri controls than reported previously in healthy US White controls (38.9%). Compared with the XRCC3 241Thr/Thr genotype, the variant XRCC3 241Thr/Met and Met/Met genotypes were not associated with an increased risk of gastric cancer (adjusted odds ratio=1.19; 95% confidence interval=0.44–3.18). These findings suggest that polymorphisms of XRCC3 Thr241Met may not play a role in the etiology of gastric cancer. Further studies with a larger number of participants and simultaneous measurement of different polymorphisms in DNA repair genes in the same pathway are needed.

Free Radical Scavenging Activity of Elsholtzia densa

Medicinal plants have been used traditionally to cure a variety of diseases since ancient times. Elsholtzia densa, a rare annual herb of the Kashmir valley, was assessed for its antioxidant efficacy. Antioxidant activity of the crude extracts was evaluated using 1, 1- diphenyl-2-picryl hydrazyl free radical (DPPH), DNA sugar damage, lipid peroxidation, ferric thiocyanate (FTC) and hydrogen peroxide scavenging assays. The maximum percentage decrease of 1,1-diphenyl-2-picryl hydrazyl radical (DPPH) standard solution was recorded for the 50% ethanolic extract (90.48%). The extracts were further evaluated using the thiobarbituric acid reactive substances assay. The methanolic extract showed the highest activity (32.02%) in reducing oxidative damage to DNA. The antioxidant activity of the extracts was also determined using the linoleic acid system and the highest antioxidant activity (49.64%) was found in the 50% ethanolic extract. In the case of the FTC assay, the 50% ethanolic extract showed the highest activity (70.14%) which was comparable to that of α-tocopherol. Moreover, total phenolics concentration was found to be 62.5mg% and 77.5mg% in the cases of absolute ethanolic and 50% ethanolic extracts, respectively. These findings indicate promising antioxidant activity of crude extracts of the plant and the need for further exploration of their effective use in both modern and traditional systems of medicine.

Podophyllum hexandrum aqueous extract as a potential free radical scavenger

Abstract The present study was undertaken to evaluate the effect of the aqueous extract of Podophyllum hexandrum against free radical-mediated damage and also explore its anticancer activity. The extract exhibited significant activity in scavenging 1, 1-diphenyl-2-picryl-hydrazyl radicals, •OH radical-mediated DNA damage, and lipid peroxide production in rat liver microsomes. The extract was also tested for its reducing abilities. The activity of liver marker enzymes and antioxidant defense enzymes in rat liver homogenate was assessed in control and carbon tetrachloride (CCl4)-treated animals. It was observed that CCl4-induced changes viz., increases in the activities of aspartate aminotransferase, alanine aminotransferase, and lactate dehydrogenase, a decrease in reduced glutathione as well as decreases in the activities of superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, and glutathione-S-transferase. All these parameters showed reversal when pretreated with aqueous extract of P. hexandrum. Podophylotoxin and etoposide are the two known anticancer agents derived from P. hexandrum and interestingly the aqueous extract of P. hexandrum showed a typical DNA ladder formation in HL-60 cells confirming its role as an inducer of apoptosis. The results obtained suggest that the plant extract exhibits inhibition of and free radical production and lipid peroxidation, increase in antioxidant enzyme activities, revealing its antioxidant properties, and is also able to show potent anticancer activity as depicted by its ability to cause fragmentation of DNA.

Recent Trends in the Fabrication of Starch Nanofibers: Electrospinning and Non-electrospinning Routes and Their Applications in Biotechnology

Electrospinning a versatile and the most preferred technique for the fabrication of nanofibers has revolutionized by opening unlimited avenues in biomedical fields. Presently, the simultaneous functionalization and/or post-modification of as-spun nanofibers with biomolecules has been explored, to serve the distinct goals in the aforementioned field. Starch is one of the most abundant biopolymers on the earth. Besides, being biocompatible and biodegradable in nature, it has unprecedented properties of gelatinization and retrogradation. Therefore, starch has been used in numerous ways for wide range of applications. Keeping these properties in consideration, the present article summarizes the recent expansion in the fabrication of the pristine/modified starch-based composite scaffolds by electrospinning along with their possible applications. Apart from electrospinning technique, this review will also provide the comprehensive information on various other techniques employed in the fabrication of the starch-based nanofibers. Furthermore, we conclude with the challenges to be overcome in the fabrication of nanofibers by the electrospinning technique and future prospects of starch-based fabricated scaffolds for exploration of its applications.