Optimization of sample preparation variables for wedelolactone from Eclipta alba using Box-Behnken experimental design followed by HPLC identification.

INTRODUCTION: Coumestan wedelolactone is an important phytocomponent from Eclipta alba (L.) Hassk. It possesses diverse pharmacological activities, which have prompted the development of various extraction techniques and strategies for its better utilization. The aim of the present study is to develop and optimize supercritical carbon dioxide assisted sample preparation and HPLC identification of wedelolactone from E. alba (L.) Hassk. METHODS: The response surface methodology was employed to study the optimization of sample preparation using supercritical carbon dioxide for wedelolactone from E. alba (L.) Hassk. The optimized sample preparation involves the investigation of quantitative effects of sample preparation parameters viz. operating pressure, temperature, modifier concentration and time on yield of wedelolactone using Box-Behnken design. The wedelolactone content was determined using validated HPLC methodology. The experimental data were fitted to second-order polynomial equation using multiple regression analysis and analyzed using the appropriate statistical method. RESULTS: By solving the regression equation and analyzing 3D plots, the optimum extraction conditions were found to be: extraction pressure, 25 MPa; temperature, 56 °C; modifier concentration, 9.44% and extraction time, 60 min. Optimum extraction conditions demonstrated wedelolactone yield of 15.37 ± 0.63 mg/100 g E. alba (L.) Hassk, which was in good agreement with the predicted values. DISCUSSION AND CONCLUSION: Temperature and modifier concentration showed significant effect on the wedelolactone yield. The supercritical carbon dioxide extraction showed higher selectivity than the conventional Soxhlet assisted extraction method.

Analgesic and anti-inflammatory activities of 18-acetoxy-ent-kaur-16-ene from Annona squamosa L. bark.

The Annona squamosa L. bark was collected from Ahmednagar district, India. 18-Acetoxy-ent-kaur-16-ene was isolated from petroleum ether extract (PE) and studied for its analgesic and anti-inflammatory activities. 18-Acetoxy-ent-kaur-16-ene at the doses of 12.5 and 25 mg/kg, and PE at a dose of 50 mg/kg exhibited significant analgesic along with anti-inflammatory activity.

Development and validation of chiral LC method for the enantiomeric separation of duloxetine on amylose based stationary phase.

A simple, rapid, and robust liquid chromatography method was developed and validated for the enantiomeric separation of duloxetine in bulk drug substance. The enantiomers of duloxetine were resolved on a Chiralpak AD-H (amylose based stationary phase) column using a mobile phase consisting of n-hexane-ethanol-diethyl amine (80:20:0.2, v/v/v) at a flow rate of 1.0 mL/min. The resolution between the enantiomers was found to be not less than 2.8 in optimized method. The presence of diethyl amine in the mobile phase played an important role in enhancing chromatographic efficiency and resolution between the enantiomers. The developed method was extensively validated and proved to be robust. The calibration curve for (R)-enantiomer showed excellent linearity over the concentration range of 750 ng/mL (LOQ) to 7500 ng/mL. The limit of detection and quantitation for (R)-enantiomer were 250 and 750 ng/mL, respectively. The percentage recovery of the (R)-enantiomer ranged between 98.3% to 101.05% in bulk drug samples of duloxetine. The proposed method was found to be suitable and accurate for quantitative determination of (R)-enantiomer in bulk drug substance.

Simultaneous high-performance liquid chromatographic determination of telmisartan and hydrochlorothiazide in pharmaceutical preparation.

A simple, rapid, and precise method was developed for the quantitative simultaneous determination of telmisartan and hydrochlorothiazide in combined pharmaceutical dosage form. Chromatographic separation of two drugs was achieved on an ACE 5 C18 25-cm analytical column using buffer-acetonitrile (60:40, v/v) of pH 5.5, adjusted with acetic acid. The buffer used in mobile phase contains 50mM ammonium acetate in double distilled water. The instrumental settings were: flow rate, 1 mL/min; column temperature, 30 degrees C; and detector wavelength, 260 nm. The internal standard method was used for the quantitation of the ingredients of this combination. Methyl paraben was used as an internal standard. The method was validated for linearity, accuracy, precision, limit of detection, limit of quantification, and robustness. The calibration curve shows excellent linearity over the concentration range for telmisartan and hydrochlorothiazide were 10-150 and 5-75 microg/mL, respectively. The correlation coefficient for telmisartan and hydrochlorothiazide were 0.9999. The relative standard deviation for six replicate measurements in two sets of each drug in tablets are always less than 2%. The proposed method was found to be suitable and accurate for quantitative determination of telmisartan and hydrochlorothiazide in pharmaceutical preparation and it can be used for the quality control of formulation products.

Crystallisation-enhanced bulk hole mobility in phenothiazine-based organic semiconductors.

A series of three novel donor-acceptor systems based on C(3)-malononitrile-substituted phenothiazines was synthesised in good overall yields and their thermal, spectroscopic, and electrochemical properties were characterised. The compounds were prepared through a sequence of Ullmann-coupling, Vilsmeier-Haack formylation and Knoevenagel-condensation, followed by Suzuki-coupling reactions for introduction of aryl substitutents at C(7) position of the phenothiazine. The introduction of a donor unit at the C(7) position exhibited a weak impact on the optical and electrochemical characteristics of the compounds and led to amorphous films with bulk hole mobilities in the typical range reported for phenothiazines, despite the higher charge delocalisation as attested by computational studies. In contrast, highly ordered films were formed when using the C(7)-unsubstituted 3-malononitrile phenothiazine, exhibiting an outstanding mobility of 1 × 10-3 cm2 V-1 s-1, the highest reported for this class of compounds. Computational conformational analysis of the new phenothizanes suggested that free rotation of the substitutents at the C(7) position suppresses the ordering of the system, thereby hampering suitable packing of the new materials needed for high charge carrier mobility.

Major volatile constituents of Annona squamosa L. bark.

The volatile constituents of Annona squamosa L. bark were identified from the essential oil obtained by steam distillation and studied by GC/MS. Six major components were identified as 1H-Cycloprop(e)azulene (3.46%), germacrene D (11.44%), bisabolene (4.48%), caryophyllene oxide (29.38%), bisabolene epoxide (3.64%) and kaur-16-ene (19.13%). The oil was also screened for its antimicrobial activity, which exhibited a significant antimicrobial activity against Bacillus subtilis and Staphylococcus aureus.

Design of selective TACE inhibitors using molecular docking studies: Synthesis and preliminary evaluation of anti-inflammatory and TACE inhibitory activity.

Tumor necrosis factor-α (TNF-α) converting enzyme (TACE) has been considered one of the principal therapeutic targets for the treatment of TNF-dependent pathologies. Several TACE inhibitors have been reported, but none of them has been successfully passed to phase II clinical trials. In the present work, we attempted to design highly selective new non-hydroxamate sulfonamide TACE inhibitors. The docking study was performed on one of the crystal structures of TACE, selected based on its resolution and R value, to tackle the flexibility issue of the active site. The results allowed us to distinguish the analogues with a higher binding affinity toward the active site of TACE and to identify the substituent of analogues needed for binding with the surrounding site of the enzyme. Finally the analogues were docked on crystal structures of six different matrix metalloproteinases (MMPs) for a selectivity study of TACE over MMPs. Some of these analogues were synthesized and subjected to preliminary testing for in vivo anti-inflammatory activity and TACE inhibitory activity.

Liquid chromatographic method for the determination of rosiglitazone in human plasma.

A robust, accurate and sensitive high-performance liquid chromatographic method for the determination of rosiglitazone (I) in human plasma has been developed. Pioglitazone (II) was used as internal standard. Both I and II are extracted from plasma using a liquid-liquid extraction procedure. Isocratic separation of I and II is carried out using a reversed-phase Zorbax SB C(18), 15-cm column with mobile phase consisting of methanol and a mixed phosphate buffer (10 mM monobasic sodium phosphate and dibasic sodium phosphate, pH adjusted to 2.6 with ortho-phosphoric acid) in the ratio 30:70 (v/v) and quantified by UV detection at 245 nm. Linearity was established over the range 5-1250 ng/ml using 1 ml human plasma. The method is specific, the endogenous components in plasma do not interfere with I and II. C.V. (%) of intra-day samples is less than 5.0% at four concentrations tested namely 5, 10, 500 and 1000 ng/ml. Similarly, over the same nominal concentrations, the precision of inter-day (5 days) samples also results in C.V. (%) less than 5.0%. The recoveries of I and II from human plasma were about 79 and 60%, respectively. This method can be used for routine clinical monitoring of I.

Simultaneous determination of metformin in combination with rosiglitazone by reversed-phase liquid chromatography.

A simple, rapid, and precise reversed-phase liquid chromatographic method is developed for the simultaneous determination of metformin in combination with rosiglitazone. This method uses a Zorbax XDB C(18) 15-cm analytical column, a mobile phase of acetonitrile and buffer containing 10mM disodium hydrogen phsosphate, and 5mM sodium dodecyl sulphate in the ratio of 34:66 (v/v), and pH is adjusted to 7.1 with orthophosphoric acid. The instrumental settings are a flow rate of 1 mL/min, column temperature at 40 degrees C, and detector wavelength of 226 nm. The internal standard method is used for the quantitation of metformin and rosiglitazone. Methylparaben is used as an internal standard. The method is validated and shown to be linear. The correlation coefficients for metformin and rosiglitazone are 0.9996 and 0.9997, respectively. The relative standard deviation for six replicate measurements in two sets of each drug in the tablets is always less than 2%.

Simultaneous high-performance liquid chromatographic determination of pioglitazone and metformin in pharmaceutical-dosage form.

A simple, rapid, and precise method is developed for the quantitative simultaneous determination of metformin and pioglitazone in a combined pharmaceutical-dosage form. Separation is achieved with a Zorbax XDB C(18), 15-cm analytical column using buffer-acetonitrile (66:34, v/v) of pH 7.1, adjusted with orthophosphoric acid as the mobile phase. The buffer used in the mobile phase contains 10mM disodium hydrogen phosphate and 5mM sodium dodecyl sulphate in double-distilled water. The instrumental settings are flow rate of 1 mL/min, column temperature at 40 degrees C, and detector wavelength of 226 nm. The internal standard method is used for the quantitation of the ingredients of this combination. Methylparaben is used as an internal standard. The method is validated and shown to be linear for metformin and pioglitazone. The correlation coefficients for metformin and pioglitazone are 0.9991 and 0.9999, respectively. The relative standard deviations for six replicate measurements in two sets of each drug in the tablets are always less than 2%.

Analgesic and anti-inflammatory activity of Caryophyllene oxide from Annona squamosa L. bark.

Caryophyllene oxide was isolated from an unsaponified petroleum ether extract of the bark of Annona squamosa and studied for its analgesic and anti-inflammatory activity. Caryophyllene oxide at the doses of 12.5 and 25mg/kg body wt. and unsaponified petroleum ether extract at a dose of 50mg/kg body wt. showed significant central as well as peripheral analgesic, along with anti-inflammatory, activity. These activities of caryophyllene oxide were comparable with the standard drug used in the respective experiments.

Stability indicating LC method for simultaneous determination of irbesartan and hydrochlorothiazide in pharmaceutical preparations.

A simple and precise stability-indicating liquid chromatography method is developed and validated for the quantitative simultaneous estimation of irbesartan (IRB) and hydrochlorothiazide (HCTZ) in combined pharmaceutical dosage form. A chromatographic separation of the two drugs was achieved with an Ace5 C(18) 25-cm analytical column using buffer-acetonitrile (70:30 v/v). The buffer used in mobile phase contains 50 mM ammonium acetate pH adjusted 5.5 with acetic acid. The instrumental settings are flow rate of 1.5 mL/min, column temperature at 30 degrees C, and detector wavelength of 235 nm using a photodiode array detector. IRB, HCTZ, and their combination drug products were exposed to thermal, photolytic, hydrolytic, and oxidative stress conditions, and the stressed samples were analyzed by the proposed method. Peak homogeneity data of IRB and HCTZ is obtained using photodiode array detector. In the stressed sample chromatograms, it demonstrated the specificity of the assay method for their estimation in presence of degradation products. The described method shows excellent linearity over a range of 10-200 microg/mL for IRB and 5-100 microg/mL for HCTZ. Methylparaben was used as internal standard. The correlation coefficient for IRB and HCTZ are 0.998 and 0.999. The mean recovery values for IRB and HCTZ ranged from 100.45% to 101.25%. The limit of detection for IRB and HCTZ were 0.019 and 0.023 microg/mL, respectively, and the limit of quantification were 0.053 and 0.070 microg/mL, respectively. The proposed method was suitable for quantitative determination and stability study of IRB and HCTZ in pharmaceutical preparations and also can be used in the quality control of bulk manufacturing and pharmaceutical dosage forms.

Stability indicating LC method for the simultaneous determination of amlodipine and olmesartan in dosage form.

A simple, rapid, and precise method is developed for the quantitative simultaneous estimation of amlodipine (AM) and olmesartan (OL) in combined pharmaceutical dosage form. A chromatographic separation of the two drugs was achieved with an ACE 5 C(18) 25-cm analytical column using buffer-acetonitrile (60:40, v/v). The resolution between OL and AM was found to be more than 12. Theoretical plates for OL and AM were 6970 and 11,841, respectively. Tailing factor for OL and AM was 0.90 and 0.98, respectively. OL, AM, and combination drug product were exposed to thermal, photolytic, hydrolytic, and oxidative stress conditions, and the stressed samples were analyzed by the proposed method. Peak homogeneity data of OL and AM is obtained by photodiode array detector in the stressed sample chromatograms, demonstrating the specificity of the method for their estimation in presence of degradation product. The described method shows excellent linearity over a range of 20-400 microg/mL for OL and 5-100 microg/mL for AM. The correlation coefficient for OL and AM are 0.9995 and 0.9998, respectively. The relative standard deviation for six measurements in two sets of each drug in tablets is always less than 2%. The proposed method was found to be suitable and accurate for quantitative determination and stability study of OL and AM in pharmaceutical preparations.