Eight phenolic compounds were successively isolated and identified from the ethanolic extract of the leaves of Faidherbia albida. Five of them were previously isolated from the genus Acacia, such as β- amyrin (L-1), β-sitosterol (L-2), β-sitosterol-3-O-β-D-glucopyranoside.(L-3), Quercetin (L-5) and Gallic acid (L-6), the other three are firstly reported for isolation from the genus Acacia, and named Rhamnocitrin (L-4), Afzelin (L-7) and (6S, 9S)- Roseoside (L-8). The structures were identified and confirmed through different spectroscopic methods including 1H-NMR, 13C-NMR, HMBC and UV spectroscopy, in addition to comparison with authentic samples. Antioxidant activity was determined by the DPPH method revealed that all the tested extracts and fractions exhibited strong antioxidant activity especially ethyl acetate and aqueous fractions of the leaves.

Background: Hypertension represents a widespread cardiovascular condition although usually asymptomatic, is a major risk factor for myocardial ischemia, renal failure and stroke. Amlodipine is considered a powerful dihydropyridine calcium channel blocker used as antihypertensive agent. Its mechanism of action depend on relaxing the smooth muscle of the artery wall and decrease peripheral resistance. Methods: An accurate, sensitive and robust chiral HPLC method was developed for separation and quantitation of S(-)- amlodipine simultaneously in the presence of its R(+)- isomer. Chiral separation was applied using Daicel CROWNPAK CR(+) (5 µm, 4.0x150 mm) column which contains (3,3'-diphenyl-1,1'-binaphthyl)-20-crown-6-ether coated into a 5 µm reversed phase silica support. The mobile phase system was aqueous acidic 70% HClO4 (pH 2.0) and methanol in the proportion of (95:5 v/v), filtered through 0.45 µm membrane and degassed by before use, pumped at a flow rate was 0.8 mL min-1 with UV detector adjusted at 238 nm. Results: The chromatographic HPLC method was validated with respect to ICH guidelines. Linear concentration range was 5-60 µg mL-1 with correlation coefficient (r) about 0.9998, the detection and quantitation limits was found 1.66 and 5.05 µg m-1; respectively. Accuracy was evaluated using standard addition technique with mean recovery about 98.40% while precision was assessed at intraday and interday level. It was found that all %RSD values below 2% Conclusion: A simple, enantioselective, chiral HPLC method was developed and validated for the quantitation of amlodipine [S-(+)- isomer] in racemic tablets using CROWNPAK CR(+) chiral stationary phase. The proposed method is specific, precise, accurate, and robust which can be successfully applied for the routine analysis of S-AML in bulk and pharmaceutical dosage formulations.

Direct-acting antivirals (DAAs) represent a revolution in the treatment of chronic hepatitis C which have emerged at an extremely rapid pace over the past few years. DAAs act directly on the hepatitis C virus at various points in the viral life cycle to inhibit viral production. Among these novel DAAs, are daclatasvir (DCS) and ledipasvir (LDS). Herein, a novel, fast, simple, ultrasensitive and cost-effective spectrofluorimetric method was designed for determination of DCS and LDS in miscellaneous matrices. The method is based on investigation of the native fluorescence of the cited drugs. The relative fluorescence intensity (RFI) was measured at ex/em equal to 315/381 nm for DCS and 332/387 nm for LDS. Under the optimum conditions, the linear ranges of calibration curves were 0.2-30 and 6-120 ng mL-1 for DCS and LDS, respectively with correlation coefficients 0.9998. The detection limits were 0.047 and 1.939 ng mL-1 for DCS and LDS, respectively indicating ultrasensitivity of the proposed method. Consequently, this permits in vitro and in vivo application of the proposed method in spiked and real human plasma with good percentage recovery (96.6–103.6%). The method was validated in compliance with ICH guidelines and US-FDA guidelines. Furthermore, the application was extended to analysis of DCS and LDS in its pharmaceutical formulations (either alone or in presence of other co-formulated drugs) and in synthetic mixture with sofosbuvir or ribavirin.

Direct-acting antivirals (DAAs) represent a revolution in the treatment of chronic hepatitis C which have emerged at an extremely rapid pace over the past few years. DAAs act directly on the hepatitis C virus at various points in the viral life cycle to inhibit viral production. Among these novel DAAs, are daclatasvir (DCS) and ledipasvir (LDS). Herein, a novel, fast, simple, ultrasensitive and cost-effective spectrofluorimetric method was designed for determination of DCS and LDS in miscellaneous matrices. The method is based on investigation of the native fluorescence of the cited drugs. The relative fluorescence intensity (RFI) was measured at ex/em equal to 315/381 nm for DCS and 332/387 nm for LDS. Under the optimum conditions, the linear ranges of calibration curves were 0.2-30 and 6-120 ng mL-1 for DCS and LDS, respectively with correlation coefficients 0.9998. The detection limits were 0.047 and 1.939 ng mL-1 for DCS and LDS, respectively indicating ultrasensitivity of the proposed method. Consequently, this permits in vitro and in vivo application of the proposed method in spiked and real human plasma with good percentage recovery (96.6–103.6%). The method was validated in compliance with ICH guidelines and US-FDA guidelines. Furthermore, the application was extended to analysis of DCS and LDS in its pharmaceutical formulations (either alone or in presence of other co-formulated drugs) and in synthetic mixture with sofosbuvir or ribavirin.

Direct-acting antivirals (DAAs) represent a revolution in the treatment of chronic hepatitis C which have emerged at an extremely rapid pace over the past few years. DAAs act directly on the hepatitis C virus at various points in the viral life cycle to inhibit viral production. Among these novel DAAs, are daclatasvir (DCS) and ledipasvir (LDS). Herein, a novel, fast, simple, ultrasensitive and cost-effective spectrofluorimetric method was designed for determination of DCS and LDS in miscellaneous matrices. The method is based on investigation of the native fluorescence of the cited drugs. The relative fluorescence intensity (RFI) was measured at ex/em equal to 315/381 nm for DCS and 332/387 nm for LDS. Under the optimum conditions, the linear ranges of calibration curves were 0.2-30 and 6-120 ng mL-1 for DCS and LDS, respectively with correlation coefficients 0.9998. The detection limits were 0.047 and 1.939 ng mL-1 for DCS and LDS, respectively indicating ultrasensitivity of the proposed method. Consequently, this permits in vitro and in vivo application of the proposed method in spiked and real human plasma with good percentage recovery (96.6–103.6%). The method was validated in compliance with ICH guidelines and US-FDA guidelines. Furthermore, the application was extended to analysis of DCS and LDS in its pharmaceutical formulations (either alone or in presence of other co-formulated drugs) and in synthetic mixture with sofosbuvir or ribavirin.

Direct-acting antivirals (DAAs) represent a revolution in the treatment of chronic hepatitis C which have emerged at an extremely rapid pace over the past few years. DAAs act directly on the hepatitis C virus at various points in the viral life cycle to inhibit viral production. Among these novel DAAs, are daclatasvir (DCS) and ledipasvir (LDS). Herein, a novel, fast, simple, ultrasensitive and cost-effective spectrofluorimetric method was designed for determination of DCS and LDS in miscellaneous matrices. The method is based on investigation of the native fluorescence of the cited drugs. The relative fluorescence intensity (RFI) was measured at ex/em equal to 315/381 nm for DCS and 332/387 nm for LDS. Under the optimum conditions, the linear ranges of calibration curves were 0.2-30 and 6-120 ng mL-1 for DCS and LDS, respectively with correlation coefficients 0.9998. The detection limits were 0.047 and 1.939 ng mL-1 for DCS and LDS, respectively indicating ultrasensitivity of the proposed method. Consequently, this permits in vitro and in vivo application of the proposed method in spiked and real human plasma with good percentage recovery (96.6–103.6%). The method was validated in compliance with ICH guidelines and US-FDA guidelines. Furthermore, the application was extended to analysis of DCS and LDS in its pharmaceutical formulations (either alone or in presence of other co-formulated drugs) and in synthetic mixture with sofosbuvir or ribavirin.

Felodipine (FLD), a calcium channel antagonist, is commonly prescribed for the treatment of hypertension either with Metoprolol (MET) or Ramipril (RAM) in two different drug combinations. FLD has high plasma protein binding ability affecting its extraction recoveries from plasma samples. Hence, a specific ultrasound assisted dispersive liquid-liquid microextraction (UA-DLLME) method coupled with HPLC using photodiode array detector was developed and validated for the simultaneous determination of FLD, MET and RAM in rat plasma after oral administration of these combinations. The factors affecting UA-DLLME were carefully optimized. In this study, UA-DLLME method could provide simple and efficient plasma extraction procedures with superior recovery results. Under optimum condition, all target drugs were separated within 13 min. The validation procedures was carried out in agreement with US-FDA guidelines and shown to be suitable for anticipated purposes. Linear calibration ranges were obtained in the range 0.05–2.0mgmL−1 for FLD and MET and 0.1–2.0mgmL−1 for RAM with detection limits of 0.013–0.031mgmL−1 for all the studied drug combinations. The%RSD for inter-day and intra-day precisions was in range of 0.63–3.85% and the accuracy results were in the range of 92.13–100.5%. The validated UA-DLLME-HPLC method was successfully applied for the bioavailability studies of FLD, MET and RAM. The pharmacokinetic parameters were calculated for all the investigated drugs in rats after single-dose administrations of two different drug combinations. Although FLD was bioequivalent in the two formulations, a small increase in plasma levels of MET and RAM was found in the presence of FLD.

Felodipine (FLD), a calcium channel antagonist, is commonly prescribed for the treatment of hypertension either with Metoprolol (MET) or Ramipril (RAM) in two different drug combinations. FLD has high plasma protein binding ability affecting its extraction recoveries from plasma samples. Hence, a specific ultrasound assisted dispersive liquid-liquid microextraction (UA-DLLME) method coupled with HPLC using photodiode array detector was developed and validated for the simultaneous determination of FLD, MET and RAM in rat plasma after oral administration of these combinations. The factors affecting UA-DLLME were carefully optimized. In this study, UA-DLLME method could provide simple and efficient plasma extraction procedures with superior recovery results. Under optimum condition, all target drugs were separated within 13 min. The validation procedures was carried out in agreement with US-FDA guidelines and shown to be suitable for anticipated purposes. Linear calibration ranges were obtained in the range 0.05–2.0mgmL−1 for FLD and MET and 0.1–2.0mgmL−1 for RAM with detection limits of 0.013–0.031mgmL−1 for all the studied drug combinations. The%RSD for inter-day and intra-day precisions was in range of 0.63–3.85% and the accuracy results were in the range of 92.13–100.5%. The validated UA-DLLME-HPLC method was successfully applied for the bioavailability studies of FLD, MET and RAM. The pharmacokinetic parameters were calculated for all the investigated drugs in rats after single-dose administrations of two different drug combinations. Although FLD was bioequivalent in the two formulations, a small increase in plasma levels of MET and RAM was found in the presence of FLD.

A simple, sensitive, novel and eco-friendly electrochemical sensor was fabricated using naturally occurring dye and glassy carbon microparticles as an electro-conducting modifier. The modified electrode was characterized by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and scanning electron microscopy (SEM) techniques. This novel electrochemical sensor gave potent electrocatalytic activity and lowest detection limit toward oxidation of dacarbazine (DAC). The proposed method showed good linearity in the range of 7×10−8 to 5×10−6 M with low detection limit of 1.28×10−8 M. Furthermore, different chemical and instrumental variables were studied by factorial design approach and the optimum analytical conditions for determination of DAC were established. The proposed method was successfully applied to study photolytic degradation of DAC in 5% dextrose and 0.9% sodium chloride infusions after exposure to daylight and UV light. The presented work suggested different photo-degradation pathways of DAC indicating its importance for future development of a stable formulation for a long-term infusion therapy.

A simple, sensitive, novel and eco-friendly electrochemical sensor was fabricated using naturally occurring dye and glassy carbon microparticles as an electro-conducting modifier. The modified electrode was characterized by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and scanning electron microscopy (SEM) techniques. This novel electrochemical sensor gave potent electrocatalytic activity and lowest detection limit toward oxidation of dacarbazine (DAC). The proposed method showed good linearity in the range of 7×10−8 to 5×10−6 M with low detection limit of 1.28×10−8 M. Furthermore, different chemical and instrumental variables were studied by factorial design approach and the optimum analytical conditions for determination of DAC were established. The proposed method was successfully applied to study photolytic degradation of DAC in 5% dextrose and 0.9% sodium chloride infusions after exposure to daylight and UV light. The presented work suggested different photo-degradation pathways of DAC indicating its importance for future development of a stable formulation for a long-term infusion therapy.