Samina Afzal

Development of highly potent melanogenesis inhibitor by in vitro, in vivo and computational studies

The present work describes the synthesis of few hydroxylated amide derivatives as melanogenesis inhibitors. In vitro, in vivo and computational studies proved that compound 6d is a highly potent melanogenesis inhibitor compared to standard kojic acid. The title amides 4a–e and 6a–e were synthesized following simple reaction routes with excellent yields. Most of the synthesized compounds exhibited good mushroom tyrosinase inhibitory activity, but compound 6d showed excellent activity (IC50 0.15 µM) compared to standard kojic acid (IC50 16.69 µM). Lineweaver–Burk plots were used for the determination of kinetic mechanism, and it was found that compounds 4c and 6d showed non-competitive inhibition while 6a and 6b showed mixed-type inhibition. The kinetic mechanism further revealed that compound 6d formed irreversible complex with the target enzyme tyrosinase. The Ki values determined for compounds 4c, 6a, 6b and 6d are 0.188, 0.84, 2.20 and 0.217 µM respectively. Results of human tyrosinase inhibitory activity in A375 human melanoma cells showed that compound 6d exhibited 91.9% inhibi-tory activity at a concentration of 50 µg/mL. In vivo cytotoxicity evaluation of compound 6d in zebrafish embryos showed that it is non-toxic to zebrafish. Melanin depigmentation assay performed in zebrafish indicated that compound 6d possessed greater potential in decreasing melanin contents compared to kojic acid at the same concentration. Computational studies also supported the wet lab findings as compound 6d showed a highest binding affinity with the target protein (PDBID: 2Y9X) with a binding energy value of −7.90 kcal/mol. Molecular dynamic simulation studies also proved that amide 6d formed the most stable complex with tyrosinase. Based upon our in vitro, in vivo and computational studies, we propose that compound 6d is a promising candidate for the development of safe cosmetic agent.

Synthesis, Bioevaluation and Molecular Dynamic Simulation Studies of Dexibuprofen–Antioxidant Mutual Prodrugs

Dexibuprofen–antioxidant conjugates were synthesized with the aim to reduce its gastrointestinal effects. The esters analogs of dexibuprofen 5a–c were obtained by reacting its –COOH group with chloroacetyl derivatives 3a–c. The in vitro hydrolysis data confirmed that synthesized prodrugs 5a–c were stable in stomach while undergo significant hydrolysis in 80% human plasma and thus release free dexibuprofen. The minimum reversion was observed at pH 1.2 suggesting that prodrugs are less irritating to stomach than dexibuprofen. The anti-inflammatory activity of 5c (p < 0.001) is more significant than the parent dexibuprofen. The prodrug 5c produced maximum inhibition (42.06%) of paw-edema against egg-albumin induced inflammation in mice. Anti-pyretic effects in mice indicated that prodrugs 5a and 5b showed significant inhibition of pyrexia (p < 0.001). The analgesic activity of 5a is more pronounced compared to other synthesized prodrugs. The mean percent inhibition indicated that the prodrug 5a was more active in decreasing the number of writhes induced by acetic acid than standard dexibuprofen. The ulcerogenic activity results assured that synthesized prodrugs produce less gastrointestinal adverse effects than dexibuprofen. The ex vivo antiplatelet aggregation activity results also confirmed that synthesized prodrugs are less irritant to gastrointestinal mucosa than the parent dexibuprofen. Molecular docking analysis showed that the prodrugs 5a–c interacts with the residues present in active binding sites of target protein. The stability of drug–target complexes is verified by molecular dynamic simulation study. It exhibited that synthesized prodrugs formed stable complexes with the COX-2 protein thus support our wet lab results. It is therefore concluded that the synthesized prodrugs have promising pharmacological activities with reduced gastrointestinal adverse effects than the parent drug.

Carvacrol derivatives as mushroom tyrosinase inhibitors; synthesis, kinetics mechanism and molecular docking studies

The present work describesthe development of highly potent mushroom tyrosinase inhibitor better than the standard kojic acid. Carvacrol derivatives 4a-f and 6a-d having substituted benzoic acid and cinnamic acidresidues were synthesized with the aim to possess potent tyrosinase inhibitory activity.The structures of the synthesized compounds were ascertained by their spectroscopic data (FTIR, 1HNMR, 13CNMR and Mass Spectroscopy).Mushroom tyrosinase inhibitory activity of synthesized compounds was determined and it was found that one of the derivative 6c possess higher activity (IC50 0.0167μM) than standard kojic acid (IC50 16.69μM). The derivatives 4c and 6b also showed good tyrosinase inhibitory activity with (IC50 16.69μM) and (IC50 16.69μM) respectively.Lineweaver—Burk and Dixon plots were used for the determination of kinetic mechanism of the compounds 4c and 6b and 6c. The kinetic analysis revealed that compounds 4c and 6b showed mixed-type inhibition while 6c is a non-competitive inhibitor having Ki values19 μM, 10 μM, and 0.05 μMrespectively. The enzyme inhibitory kinetics further showed thatcompounds 6b and 6c formed irreversible enzyme inhibitor complex while 4c bind reversibly with mushroom tyrosinase.The docking studies showed that compound 6c have maximum binding affinity against mushroom tyrosinase (PDBID: 2Y9X) with binding energy value (-7.90 kcal/mol) as compared to others.The 2-hydroxy group in compound 6c interacts with amino acid HIS85 which is present in active binding site. The wet lab results are in good agreement with the dry lab findings.Based upon our investigation we may propose that the compound 6c is promising candidate for the development of safe cosmetic agent.

Isolation of squarrosal and squarrosol compounds from methanol root extract of Ruellia squarrosa (Acanthaceae)

Purpose : To identify, characterize and structurally elucidate bioactive compounds from root of Ruellia squarrosa. Methods : One kilogram of crude Ruellia squarrosa root was shade dried for 14 days, ground to a fine powder and subjected to a methanol extraction. The resultant extract underwent column chromatography for further purification. The isolated compounds were subjected to ultraviolet spectroscopy (UV), infra-red (IR), proton nuclear magnetic resonance ( 1 H-NMR), 13 C–NMR and high resolution electron ionization mass spectrometry (HR-EI-MS) for the identification, characterization and structural elucidation of bioactive compounds. The most active compounds were tested for anticancer activities against human prostate cancer cell. Results : Two active compounds, squarrosol and squarrosal, were obtained with half-maximal inhibitory concentration (IC 50 ) of 15.6 and 26.6 μg/mL, respectively, against human prostate cancer cell lines. Squarrasol showed a significantly (p < 0.05) greater inhibition of cell proliferation than the same dose of squarrasal. Conclusion : These findings suggest that extracts of Ruellia squarrosa containing the bioactive compounds, squarrosol and squarrosal, can potentially be developed for the treatment of human prostate cancer. Keywords : Ruellia squarrosa, Prostate cancer, Squarrosol, Squarrosal, Anit-proliferative

Immunomodulatory, antiglycation and anti-ulcerative properties of Ruellia squarrosa Fenzl Acanthaceae

Purpose: To evaluate the immunomodulatory, antiglycation and anti-ulcerative properties of Ruellia squarrosa Fenzl. Acanthaceae. Methods: Aerial parts and roots of Ruellia squarrosa were collected and extracted by maceration using dichloromethane and methanol as solvents. Luminol-enhanced chemiluminescence assay was used to evaluate immunomodulatory activity while antiglycation assay was performed by fluorescence method with rutin as standard. Anti-ulcerative activity was evaluated by enzymatic methods, namely, urease inhibition and carbonic anhydrase inhibition assays. Results: Dichloromethane extract showed immunomodulatory activity with half-maximal inhibitory concentration (IC 50 ) of 39.48 ± 8.06 % using ibuprofen as standard and antiglycation effect (IC 50 = 382.21 ± 3.43) using rutin as standard. The methanol extract of the aerial parts of the plant showed urease inhibition activity (IC 50 = 130.2 ± 0.57) using thiourea as standard. The methanol extract of the aerial parts of the plant also showed carbonic anhydrase inhibition activity (IC 50 = 1656.7 ± 0.08) using acetazolamide as standard. Conclusion: It was concluded from the present study that aerial and root extracts of the Ruellia squarrosa have significant immunomodulatory, antiglycation and anti-ulcerative properties. Keywords: Ruellia squarrosa , Immunomodulatory, Antiglycation, Anti-ulcerative activity, Carbonic anhydrase inhibition, Urease

Antioxidant, acetylcholinesterase, butyrylcholinesterase, and α-glucosidase inhibitory activities of Corchorus depressus

Background: Corchorus depressus (Cd) commonly known as Boa-phalee belonging to the family Tiliaceae having 50 genera and 450 species. Cd is not among the studied medicinal agent despite its potential in ethnopharmacology. Objectives: The present study investigated antioxidant, acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and α-glucosidase inhibitory activities of Cd. The dichloromethane and methanolic extracts of the Cd were evaluated for biological activities such as antioxidant and enzyme inhibitory activities of AChE, BChE, and α-glucosidase. Materials and Methods: Antioxidant activity was evaluated by measuring free radical scavenging potential of Cd using 1,1-diphenyl-2-picrylhydrazyl. Enzyme inhibition activities were done by measuring optical density. Results: The methanol extract of roots of Cd showed potential free radical scavenging activity 99% at concentration 16.1 μg/ml. AChE was inhibited by aerial part of dichloromethane fraction by 46.07% ± 0.45% while dichloromethane extracts of roots of Cd possessed significant activity against BChE with 86% inhibition compared with standard drug Eserine at concentration 0.5 mg/ml. The dichloromethane extract of roots of Cd showed 79% inhibition against α-glucosidase enzyme activity with IC50 62.8 ± 1.5 μg/ml. Conclusion: These findings suggest Cd as useful therapeutic option as antioxidant and inhibition of AChE, BChE, and α-glucosidase activities. Abbreviations used: DPPH: 1,1-diphenyl-2-picrylhydrazyl, Cd: Corchorus depressus, AChE: Acetylcholinesterase, BChE: Butyrylcholinesterase, AD: Alzheimers disease.

Immunomodulatory, cytotoxicity, and antioxidant activities of roots of Ziziphus mauritiana

Aims: The study is conducted to evaluate the immunomodulatory, cytotoxicity, and antioxidant potential of Ziziphus mauritiana (Rhamnaceae). Phytochemical analysis of Z. mauritiana revealed the presence of alkaloids, anthraquinone glycoside, cardiac glycoside, saponin, tannin, and flavonoids. Methodology: The cytotoxicity of the plant Z. mauritiana was evaluated by brine shrimp lethality test. Antioxidant parameters such as superoxide dismutase (SOD), total antioxidant capacity (T-AOC), and malondialdehyde (MDA) levels were calculated in the plasma of rats after chronic administration of 400 mg/kg of Z. mauritiana for 6 weeks. Results: The dichloromethane extract of the plant exhibited significant immunomodulatory activity, with inhibitory concentration 50% of 55.43 ± 7.9. The dichloromethane extracts of the plant showed 70% mortality at concentration 1000 μg/ml. SOD and T-AOC levels were increased while MDA level in the plasma was reduced in the plasma of rats treated with dichloromethane Z. mauritiana. Conclusion: This can be deduced that the root of Z. mauritiana has immunomodulatory, cytotoxic, and antioxidant potential. Abbreviations used: SOD: Superoxide dismutase; T-AOC: Total antioxidant capacity; MDA: Malondialdehyde; ZMRD: Z. mauritiana root extract of dichloromethane fraction; LD50: Z. mauritiana root extract of methanol fraction ZMRM, lethal dose 50.

Sustained release biodegradable solid lipid microparticles: Formulation, evaluation and statistical optimization by response surface methodology

Abstract For preparing nebivolol loaded solid lipid microparticles (SLMs) by the solvent evaporation microencapsulation process from carnauba wax and glyceryl monostearate, central composite design was used to study the impact of independent variables on yield (Y1), entrapment efficiency (Y2) and drug release (Y3). SLMs having a 10-40 μm size range, with good rheological behavior and spherical smooth surfaces, were produced. Fourier transform infrared spectroscopy, differential scanning calorimetry and X-ray diffractometry pointed to compatibility between formulation components and the zeta-potential study confirmed better stability due to the presence of negative charge (-20 to -40 mV). The obtained outcomes for Y1 (29-86 %), Y2 (45-83 %) and Y3 (49-86 %) were analyzed by polynomial equations and the suggested quadratic model were validated. Nebivolol release from SLMs at pH 1.2 and 6.8 was significantly (p < 0.05) affected by lipid concentration. The release mechanism followed Higuchi and zero order models, while n > 0.85 value (Korsmeyer- Peppas) suggested slow erosion along with diffusion. The optimized SLMs have the potential to improve nebivolol oral bioavailability.