Nanoparticle-Shielded dsRNA Delivery for Enhancing RNAi Efficiency in Cotton Spotted Bollworm Earias vittella (Lepidoptera: Nolidae).

The spotted bollworm Earias vittella (Lepidoptera: Nolidae) is a polyphagous pest with enormous economic significance, primarily affecting cotton and okra. However, the lack of gene sequence information on this pest has a significant constraint on molecular investigations and the formulation of superior pest management strategies. An RNA-seq-based transcriptome study was conducted to alleviate such limitations, and de novo assembly was performed to obtain transcript sequences of this pest. Reference gene identification across E. vittella developmental stages and RNAi treatments were conducted using its sequence information, which resulted in identifying transcription elongation factor (TEF), V-type proton ATPase (V-ATPase), and Glyceraldehyde -3-phosphate dehydrogenase (GAPDH) as the most suitable reference genes for normalization in RT-qPCR-based gene expression studies. The present study also identified important developmental, RNAi pathway, and RNAi target genes and performed life-stage developmental expression analysis using RT-qPCR to select the optimal targets for RNAi. We found that naked dsRNA degradation in the E. vittella hemolymph is the primary reason for poor RNAi. A total of six genes including Juvenile hormone methyl transferase (JHAMT), Chitin synthase (CHS), Aminopeptidase (AMN), Cadherin (CAD), Alpha-amylase (AMY), and V-type proton ATPase (V-ATPase) were selected and knocked down significantly with three different nanoparticles encapsulated dsRNA conjugates, i.e., Chitosan-dsRNA, carbon quantum dots-dsRNA (CQD-dsRNA), and Lipofectamine-dsRNA conjugate. These results demonstrate that feeding nanoparticle-shielded dsRNA silences target genes and suggests that nanoparticle-based RNAi can efficiently manage this pest.

Design, Synthesis and Evaluation of Benzimidazole Hybrids to Inhibit Acetylcholinesterase and COX for Treatment of Alzheimer's Disease.

BACKGROUND: A simultaneous administration of an acetylcholinesterase (AChE) inhibitor and a NSAID as a drug cocktail has been documented to exhibit significantly protective effects in AD patients. But it suffers from poor patent compliance, pharmacodynamics and pharmacokinetic issues. OBJECTIVE: The present study is aimed to design and synthesize a hybrid molecule capable of exhibiting both AChE inhibition and anti-inflammatory activities for de-accelerating the progression of AD. The synthesized molecules will be evaluated for in vitro and in vivo models. METHODS: The present study involves the coupling of ibuprofen or naproxen to varied disubstituted amines (AChE inhibitor pharmacophore) through benzimidazole to develop two series of compounds i.e. IB01-IB05 and NP01-NP05. The synthesized compounds were characterized using FTIR, 1H-NMR, 13C-NMR and MS. All compounds were evaluated for in vitro AChE inhibitory and COX inhibitory activities. The most active compound was taken for in vivo evaluation. RESULTS: Compounds of series IB01-IB05 are found more potent as compared to NP01-NP05. The maximally potent compound IB04 in in vitro evaluation is selected for in vivo evaluation of memory restoration activity using scopolamine-induced amnesia model in mice. It significantly reverses the scopolamine-induced changes (i.e., escape latency time, mean time spent in target quadrant, brain AChE activity and oxidative stress) in a dose-dependent manner. IB04 at 8 mg/kg is significantly effective in lowering AD manifestation in comparison to donepezil. CONCLUSION: The findings indicate that Benzimidazole hybrids utilizing ibuprofen and pyrrolidine moiety may prove a useful template for the development of new chemical moieties against AD with multiple potencies.

Prevalence of reproductive drugs usage in humans and animals: A pilot study in Patiala city of India.

Reproductive drugs that include contraceptive and fertility drugs are used to manage reproductive health in both humans and animals. Contraceptive drugs are mainly used by humans for reversible contraception whereas fertility drugs are mainly used in animals to increase milk production, poultry products and meat production. Usage of these drugs has increased manifold in the last decade. These drugs are excreted through body fluids (mainly urine and milk) that lead to contamination of surface water, milk and animal produce. Consumption of such contaminated products or water results in reproductive disorders and different types of cancers in humans. This questionnaire-based study was designed and conducted involving gynecologists, pharmacies, medical stores and veterinarians in Patiala city and its adjoining areas in India to evaluate the quantitative and qualitative aspects of use of these drugs. A total of 150 survey points were identified with random sampling method. Data was analyzed using appropriate statistical tools. The results showed that contraceptive drugs constitute 86% of reproductive drugs usage in humans. Further, steroidal contraceptives constitute a huge 94.7% share of contraceptive drugs, and of these combined oral contraceptives have 79.79% share among which a combination is ethinylestradiol and levonorgestrel is the most popular (20.92%). The consumption of COCs is higher than that of progestin only pills (Z = 3.39) as well as estrogen only pills (Z = 4.30). In contrast, usage of non-hormonal fertility drugs (89%) dominates over the hormonal class (11%) in humans. The most widely used non-hormonal fertility drug is clomiphene citrate (73.87%). In animals, the prescription rate of hormonal fertility drugs is higher (83%) than the non-hormonal one, where in the most widely prescribed drug is buserelin acetate. These findings are in consonance with the similar studies carried out in US, Europe and Canada which suggest that reproductive drugs usage pattern is more or less similar across the globe. A careful control to discourage indiscriminate use of such drugs is the need of hour to prevent damage of environment and ultimately to the health of living beings.

Assessment of shelf-life of Gymnema sylvestre extract through WHO recommended stability study involving chromatographic and biological activity analyses.

Stability study on Gymnema sylvestre extract under WHO recommended accelerated and long-term conditions for 6 and 30 months, respectively was carried out by taking gymnemagenin as a marker and by evaluating antidiabetic activity through different models. Gymnemagenin was not detected in any stability sample indicating that gymnemic acids (GAs) remain stable in the extract under the test conditions. The extract and its GA rich fraction exhibited mild α-glucosidase inhibitory activity (18-27%) that remained same during the study. Neither hypoglycemic nor anti-hyperglycemic effect was induced by the extract in normal rats in oral glucose tolerance test. The extract and GA rich fraction showed significant antidiabetic activity in alloxan-induced diabetic rats that remained same in all stability samples. Based on these findings, a shelf-life of at least 30 months is suggested for G. sylvestre extract under long-term conditions, and gymnemagenin as a marker for shelf-life assessment of products derived from the plant.

A panoramic review of IL-6: Structure, pathophysiological roles and inhibitors.

Interleukin-6 (IL-6) is a pleiotropic pro-inflammatory cytokine. Its deregulation is associated with chronic inflammation, and multifactorial auto-immune disorders. It mediates its biological roles through a hexameric complex composed of IL-6 itself, its receptor IL-6R, and glycoprotein 130 (IL-6/IL-6R/gp130). This complex, in turn, activates different signaling mechanisms (classical and trans-signaling) to execute various biochemical functions. The trans-signaling mechanism activates various pathological routes, like JAK/STAT3, Ras/MAPK, PI3K-PKB/Akt, and regulation of CD4+ T cells and VEGF levels, which cause cancer, multiple sclerosis, rheumatoid arthritis, anemia, inflammatory bowel disease, Crohn's disease, and Alzheimer's disease. Involvement of IL-6 in pathophysiology of these complex diseases makes it an important target for the treatment of these diseases. Though some anti-IL-6 monoclonal antibodies are being used clinically, but their high cost, only parenteral administration, and possibility of immunogenicity have limited their use, and warranted the development of novel small non-peptide molecules as IL-6 inhibitors. In the present report, all molecules reported in literature as IL-6 inhibitors have been classified as IL-6 production, IL-6R, and IL-6 signaling inhibitors. Reports available till date are critically studied to identify important and salient structural features common in these molecules. These analyses would assist medicinal chemists to design novel and potent IL-6 production and signaling inhibitors, through knowledge- and/or computer-based approaches, for the treatment of complex multifactorial diseases.

Novel Coupled Molecules from Active Structural Motifs of Synthetic and Natural Origin as Immunosuppressants.

INTRODUCTION: Nitric oxide (NO) is an important mediator in the pathogenesis and control of immune system-related disorders and its levels are modulated by inducible NO synthase (iNOS). Oxidative stress is another pathological indication in majority of autoimmune disorders. The present study aims at the development of coupled molecules via selection of pharmacophores for both immunomodulatory and antioxidant activities through iNOS inhibition. METHODS: Variedly substituted coumarin moieties are coupled with naturally occurring phenols through an amide linkage and were predicted for activities using computer-based program PASS. The compounds predicted to have dual activities were synthesized. Docking studies were carried out against iNOS (PDB 1R35) and compounds having good docking score were evaluated for immunomodulatory and antioxidant activities. RESULTS: The synthesized compounds were found to be pure and were obtained in good yields. Compounds with maximum docking score (YR1a, YR2e, YR2c and YR4e) were selected for evaluation by in vitro models. Compounds YR2e and YR2c markedly inhibited the reduction of NBT dye and showed maximum % iNOS inhibition. In DPPH assay, compound YR4e was observed as the most potent antioxidant (EC50 0.33 µM/mL). Based on these studies, compounds YR2e and YR2c were selected for haemagglutination test. Compound YR2e was observed as the most active immunosuppressant with maximal inhibitory ability of iNOS and NBT reduction and lower HAT value of 3.5. CONCLUSION: Compound YR2e can be utilized as a pharmacological agent in the prevention or treatment of immunomodulatory diseases such as tumors, rheumatoid arthritis, ulcerative colitis, organ transplant and other autoimmune disorders.

WHO prescribed shelf life assessment of Syzygium cumini extract through chromatographic and biological activity analyses.

BACKGROUND: Regulatory guidelines recommend shelf life of herbal products to be established through systematic stability studies. OBJECTIVE: The study was designed to establish shelf life of Syzygium cumini extract through accelerated and long-term stability testing as per WHO guidelines. MATERIAL AND METHODS: The extract was stored under accelerated (40°C/75 %RH) and long-term (25°C/60 %RH) stability conditions for 6 and 30 months, respectively. Samples were withdrawn at periodic intervals and analysed through two validated HPLC-UV methods (I and II) for fingerprint and quantitative analysis of markers. Antidiabetic activity of control and stability samples was evaluated by α-glucosidase inhibitory model. RESULTS: Method I generated a well resolved fingerprint of the control sample that was found to contain gallic acid (GA, 1.45 % w/w) and ellagic acid (EA, 3.97 % w/w). The content of GA did not change under both the stability conditions, but that of EA varied insignificantly (3.97-4.77 % w/w) under long-term conditions up to 24 months and subsequently decrease to 3.15 % w/w after 30 months. There was no visible change in LC-UV fingerprint of any stability sample with respect to control. α-Glucosidase inhibitory activity of all stability samples also remained unaltered as compared to control sample (IC50 1.48 mg/mL). GA and EA did not elicit any activity at the concentrations present in the extract. CONCLUSION: Phytochemical composition and antidiabetic efficacy of S. cumini extract remain unchanged during its storage under both accelerated and long-term stability conditions, which suggest its shelf life to be 30 months. Also, GA and EA are not appropriate anti-diabetic markers.

Inducible nitric oxide synthase inhibitors: A comprehensive update.

Inducible nitric oxide synthase (iNOS), which is expressed in response to bacterial/proinflammatory stimuli, generates nitric oxide (NO) that provides cytoprotection. Overexpression of iNOS increases the levels of NO, and this increased NO level is implicated in pathophysiology of complex multifactorial diseases like Parkinson's disease, Alzheimer's disease, multiple sclerosis, rheumatoid arthritis, and inflammatory bowel disease. Selective inhibition of iNOS is an effective approach in treatment of such complex diseases. l-Arginine, being a substrate for iNOS, is the natural lead to develop iNOS inhibitors. More than 200 research reports on development of nitric oxide synthase inhibitors by different research groups across the globe have appeared in literature so far. The first review on iNOS, in 2002, discussed the iNOS inhibitors under two classes that is, amino acid and non-amino acid derivatives. Other review articles discussing specific chemical classes of iNOS inhibitors also appeared during last decade. In the present review, all reports on both natural and synthetic iNOS inhibitors, published 2002 onwards, are studied, classified, and discussed to provide comprehensive information on iNOS inhibitors. The synthetic inhibitors are broadly classified into two categories that is, arginine and non-arginine analogs. The latter are further classified into amidines, five- or six-membered heterocyclics, fused cyclics, steroidal type, and chalcones analogs. Structures of the most/significantly potent compounds from each report are provided to know the functional groups important for incurring iNOS inhibitory activity and selectivity. This review is aimed to provide a comprehensive view to the medicinal chemists for rational designing of novel and potent iNOS inhibitors.

Antimicrobial Potential of Benzimidazole Derived Molecules.

Structural resemblance of benzimidazole nucleus with purine nucleus in nucleotides makes benzimidazole derivatives attractive ligands to interact with biopolymers of a living system. The most prominent benzimidazole compound in nature is N-ribosyldimethylbenzimidazole, which serves as an axial ligand for cobalt in vitamin B12. This structural similarity prompted medicinal chemists across the globe to synthesize a variety of benzimidazole derivatives and to screen those for various biological activities, such as anticancer, hormone antagonist, antiviral, anti-HIV, anthelmintic, antiprotozoal, antimicrobial, antihypertensive, anti-inflammatory, analgesic, anxiolytic, antiallergic, coagulant, anticoagulant, antioxidant and antidiabetic activities. Hence, benzimidazole nucleus is considered as a privileged structure in drug discovery, and it is exploited by many research groups to develop numerous compounds that are purported to be antimicrobial. Despite a large volume of research in this area, no novel benzimidazole derived compound has emerged as clinically effective antimicrobial drug. In the present review, we have compiled various reports on benzimidazole derived antimicrobials, classified as monosubstituted, disubstituted, trisubstituted and tetrasubstituted benzimidazoles, bisbenzimidazoles, fused-benzimidazoles, and benzimidazole derivative-metal complexes. The purpose is to collate these research reports, and to generate a generalised outlay of benzimidazole derived molecules that can assist the medicinal chemists in selecting appropriate combination of substituents around the nucleus for designing potent antimicrobials.

Reproductive drugs and environmental contamination: quantum, impact assessment and control strategies.

Industrial and municipal solid wastes, noise, pesticides, fertilizers and vehicular emission are visible pollutants responsible for environmental contamination and ill-effects on health of all living systems. But, environmental contamination due to drugs or medicines used for different purposes in humans and animals goes unseen largely and can affect the health of living system severely. During the last few decades, the usage of drugs has increased drastically, resulting in increased drug load in soil and water. Contraceptive and fertility drugs are extensively and effectively used in humans as well as animals for different purposes. Usage of these reproductive drugs in humans is increased manifold to manage reproductive problems and/or for birth control with changing lifestyles. These drugs are excreted in urine and faeces as metabolite or conjugated forms, leading to contamination of water, milk and animal produce, which are consumed directly by humans as well as animals. These drugs are not eliminated even by water treatment plant. Consumption of such contaminated water, milk, meat and poultry products results in reproductive disorders such as fertility loss in men and increase risk of different types of cancers in humans. Therefore, assessment of impact of environmental contamination by these drugs on living system is of paramount importance. The purpose of this review article is to provide a comprehensive analysis of various research and review reports on different contraceptive and fertility drugs used in human and animals, their occurrence in the environment and their ill-effects on living systems. The approaches to control this invisible menace have also been proposed.

Bioanalytical Method Validation for Dronedarone and Duloxetine in Blood Serum.

The present work relates to the development and validation of reversed-phase HPLC-UV-photodiode array methods for the estimation of two drugs in blood serum: dronedarone hydrochloride (DDN), a class III antiarrhythmic drug, and duloxetine hydrochloride (DLX), an antidepressant. Chromatographic analysis of DLX was carried out on a Nucleodur C18 column (250 × 4.6 mm, 5 µm) using ammonium acetate buffer (32 mM, pH 5.5) and acetonitrile (40 + 60, v/v; flow rate of 1.0 mL/min; detection wavelength of 290 nm) as the mobile phase. A Waters XTerra C18 column (250 × 4.6 mm, 5 µm) was used for the chromatographic analysis of DDN using an acetonitrile-ammonium formate buffer (20 mM, pH 3.0, with formic acid; 45 + 55, v/v; flow rate 1.0 mL/min) as the mobile phase. Pentazocine and bupropion HCl were used as the internal reference standards for DLX and DDN, respectively. Excellent linearity was observed for DLX (r2 = 0.9996; concentration range 0.2-10.0 µg/mL) and DDN (r2 = 0.9997; concn. range 2.0-50.0 µg/mL). The LODs for DLX and DDN were 0.022 and 0.78 µg/mL, respectively, and the LOQs 0.066 and 2.4 µg/mL, respectively.

Accelerated Stability Studies on Dried Extracts of Centella asiatica Through Chemical, HPLC, HPTLC, and Biological Activity Analyses.

Regulatory guidelines recommend systematic stability studies on a herbal product to establish its shelf life. In the present study, commercial extracts (Types I and II) and freshly prepared extract (Type III) of Centella asiatica were subjected to accelerated stability testing for 6 months. Control and stability samples were evaluated for organoleptics, pH, moisture, total phenolic content (TPC), asiatic acid, kaempherol, and high-performance thin layer chromatography fingerprints, and for antioxidant and acetylcholinesterase inhibitory activities. Markers and TPC and both the activities of each extract decreased in stability samples with respect to control. These losses were maximum in Type I extract and minimum in Type III extract. Higher stability of Type III extract than others might be attributed to the additional phytoconstituents and/or preservatives in it. Pearson correlation analysis of the results suggested that TPC, asiatic acid, and kaempferol can be taken as chemical markers to assess chemical and therapeutic shelf lives of herbal products containing Centella asiatica.

Stability Testing of Herbal Drugs: Challenges, Regulatory Compliance and Perspectives.

Stability testing is an important component of herbal drugs and products (HDPs) development process. Drugs regulatory agencies across the globe have recommended guidelines for the conduct of stability studies on HDPs, which require that stability data should be included in the product registration dossier. From the scientific viewpoint, numerous chemical constituents in an herbal drug are liable to varied chemical reactions under the influence of different conditions during its shelf life. These reactions can lead to altered chemical composition of HDP and consequently altered therapeutic profile. Many reports on stability testing of HDPs have appeared in literature since the last 10 years. A review of these reports reveals that there is wide variability in temperature (-80 to 100 °C), humidity (0-100%) and duration (a few hours-36 months) for stability assessment of HDPs. Of these, only 1% studies are conducted in compliance with the regulatory guidelines for stability testing. The present review is aimed at compiling all stability testing reports, understanding key challenges in stability testing of HDPs and suggesting possible solutions for these. The key challenges are classified as chemical complexity and biochemical composition variability in raw material, selection of marker(s) and influences of enzymes. Copyright © 2016 John Wiley & Sons, Ltd.

Forced degradation, LC-UV, MS(n) and LC-MS-TOF studies on azilsartan: Identification of a known and three new degradation impurities.

In the present study, Azilsartan (AZL) was subjected to ICH recommended forced degradation conditions of hydrolysis, oxidation, dry heat and photolysis. The drug degraded to four degradation products (I-IV) under acidic, alkaline and water hydrolysis and photolysis. All the four degradation products were resolved in a single run on a C-18 column (250mm×4.6mm; 5µ) with isocratic elution using mobile phase composed of ammonium formate (20mM, pH 3.0), methanol and acetonitrile (40:5:40% v/v), at a flow rate of 0.8mlmin(-1) at ambient temperature. The products were characterized through +ESI-MS(n) spectra of AZL and LC-MS-TOF studies as 2-ethoxy-3H-benzo-imidazole-4-carboxylic acid (I), 2-hydroxy-3-[2'-(5-oxo-4,5-dihydro-[1,2,4]oxadiazol-4-ylmethyl]-3H-benzoimidazole-4-carboxylic acid (II, deethylated AZL), 3-[2'-(1H-diazirin-3-yl)-biphenyl]-4-ylmethyl]-2-ethoxy-3H-benzoimidazole-4-carboxylic acid (III), and 3-[4'-(2-ethoxy-benzo-imidazol-1-ylmethyl)-biphenyl-2-yl]-4H-[1,2,4]oxadiazol-5-one (IV, decarboxylated AZL). Product I was found to be a known process related impurity whereas the products II-IV were identified as new degradation impurities. The most probable mechanisms for formation of these degradation products were proposed.

Characterization of stress degradation products of duloxetine hydrochloride employing LC-UV/PDA and LC-MS/TOF studies.

Duloxetine HCl was subjected to forced degradation under conditions of hydrolysis (neutral, acidic and alkaline), oxidation, photolysis and thermal stress, as suggested in the ICH guideline Q1A(R2). The drug showed significant degradation under acidic, alkaline and aqueous hydrolytic as well as photolytic conditions. The drug remained stable under thermal and oxidative stress conditions. In total, seventeen degradation products (I-XVII) were formed under varied conditions, which could be separated by chromatography of respective degraded solutions on C18 (250 mm×4.6 mm; 5 µ, Nulceodur) column using isocratic elution method. Detection wavelength was selected as 290 nm. MS/TOF accurate mass studies were carried out to establish the complete fragmentation pathway of the drug and degradation products, which, in turn, was utilized in characterization of the products. The degradation pathway of the drug leading to generation of fifteen products I-X, XII-XIII, XV-XVII was postulated and this has not been reported so far.

Identification and characterization of stress degradation products of dronedarone hydrochloride employing LC-UV/PDA, LC-MS/TOF and MS(n) studies.

Dronedarone HCl was subjected to forced decomposition conditions of hydrolysis (neutral, acidic and alkaline), oxidation, photolysis and thermal stress, as suggested in the ICH guideline Q1A(R2). The drug showed significant degradation under alkaline hydrolytic and alkaline photolytic conditions while it remained stable in neutral, acidic, thermal and oxidative conditions. In total, six degradation products (I-VI) were formed, which could be separated by chromatography on C18 (250 mm × 4.6 mm; 5 µ, Xterra) column using isocratic elution method. Detection wavelength was selected as 288 nm. Multi-stage (MS(n)) and MS/TOF accurate mass studies were carried out to establish the complete fragmentation pathway of the drug which in turn was utilized in characterization of the products. The degradation pathway of the drug leading to generation of products I-VI was postulated and this has not been reported so far.

Identification of four new degradation products of epirubicin through forced degradation, LC-UV, MSn and LC-MS-TOF studies.

Epirubicin (EPI) was subjected to International Conference on Harmonization recommended forced degradation under the conditions of hydrolysis, oxidation, dry heat and photolysis to characterize its possible impurities and/or degradation products. The drug was found highly unstable to alkaline hydrolysis even at room temperature, unstable to acid hydrolysis at 80°C and to oxidation at room temperature. The hydrolytic and oxidative degradation products were resolved on an Agilent RP8 (150 mm × 4.6 mm; 5 µm) column with isocratic elution using mobile phase composed of ammonium formate (10 mM, pH 3.0), acetonitrile and methanol. The drug degraded to four oxidative products (O-I, O-II, O-III and O-IV) and to one acid hydrolyzed product (A-I). Purity of each peak in liquid chromatography-ultraviolet (LC-UV) chromatogram was ascertained through photodiode array (LC-PDA) analysis. The products were characterized through electrospray ionization-mass spectrometry (+ESI-MS(n)) studies on EPI and liquid chromatography-time of flight mass spectrometry (LC-MS-TOF) studies on degraded drug solutions. The products, O-I-O-IV, were characterized as 2-hydroxy-8-desacetylepirubicin-8-hydroperoxide, 4-hydroxy-8-desacetylepirubicin-8-hydroperoxide, 8-desacetylepirubicin-8-hydroperoxide and 8-desacetylepirubicin, respectively, and product A-I was characterized as deglucosaminylepirubicin. While A-I was found to be a pharmacopoeial impurity, all oxidative products were found to be new degradation impurities. The mechanisms and pathways of degradation of EPI were discussed and outlined.

Coumarin: a promising scaffold for anticancer agents.

Coumarin enjoys an important place in drug discovery process due to its presence in diversity of biologically active compounds. Many compounds of plant origin are derivatives of coumarin. Taking these natural products as lead, research groups across the globe have designed and synthesized numerous coumarin analogues for treatment of varied diseases. Cancer is one of the dreadful chronic diseases, and many drugs are available for its treatment. However, due to heterogeneity of cancer, the search is still on to develop drugs for specific types of cancers. The present review is an attempt to study various coumarin derivatives of natural as well as synthetic origins, which are identified or developed for the treatment of different types of cancers. Herein, we have classified various anticancer coumarin derivatives on the basis of their origin as well as substitution around it. These are discussed under the headings of natural, semi-synthetic and synthetic coumarin derivatives. The synthetic coumarin derivatives are further classified as mono-, di- and poly-substituted and fused coumarin derivatives. Of the six positions available for substituents on coumarin nucleus, only three positions (C-3, C-4 and C-7) are exploited for the selection of functional groups appropriate for anticancer activity. The other positions (C-5, C-6 and C-8) are either unexplored or very less exploited. The present review is expected to provide the medicinal chemists a guide to choose new functional groups for substitution at different positions of coumarin nucleus for development of novel compounds for the treatment of a specific type of cancer.

Isolation and characterization of a degradation product in leflunomide and a validated selective stability-indicating HPLC-UV method for their quantification.

Leflunomide (LLM) is subjected to forced degradation under conditions of hydrolysis, oxidation, dry heat, and photolysis as recommended by International Conference on Harmonization guideline Q1A(R2). In total, four degradation products (I-IV) were formed under different conditions. Products I, II and IV were formed in alkaline hydrolytic, acidic hydrolytic and alkaline photolytic conditions. LLM and all degradation products were optimally resolved by gradient elution over a C18 column. The major degradation product (IV) formed in hydrolytic alkaline conditions was isolated through column chromatography. Based on its 1H NMR, IR and mass spectral data, it was characterized as a British Pharmacopoeial impurity B. The HPLC method was found to be linear, accurate, precise, sensitive, specific, rugged and robust for quantification of LLM as well as product IV. Finally, the method was applied to stability testing of the commercially available LLM tablets.