Quantitative structure activity relationship (QSAR) of piperine analogsfor bacterial NorA efflux pump inhibitors

Quantitative structure activity relationship (QSAR) analysis of piperine analogs as inhibitors of efflux pump NorA from Staphylococcus aureus has been performed in order to obtain a highly accurate model enabling prediction of inhibition of S. aureus NorA of new chemical entities from natural sources as well as synthetic ones. Algorithm based on genetic function approximation method of variable selection in Cerius2 was used to generate the model. Among several types of descriptors viz., topological, spatial, thermodynamic, information content and E-state indices that were considered in generating the QSAR model, three descriptors such as partial negative surface area of the compounds, area of the molecular shadow in the XZ plane and heat of formation of the molecules resulted in a statistically significant model with r

Isolation, cytotoxicity evaluation and HPLC-quantification of the chemical constituents from Prangos pabularia.

Phytochemical analysis of the dichloromethane:methanol (1:1) extract of root parts of Prangos pabularia led to the isolation of twelve cytotoxic constituents, viz., 6-hydroxycoumarin (1), 7-hydroxycoumarin (2), heraclenol-glycoside (3), xanthotoxol (4), heraclenol (5), oxypeucedanin hydrate (6), 8-((3,3-dimethyloxiran-2-yl)methyl)-7-methoxy-2H-chromen-2-one (7), oxypeucedanin hydrate monoacetate (8), xanthotoxin (9), 4-((2-hydroxy-3-methylbut-3-en-1-yl)oxy)-7H-furo[3,2-g]chromen-7-one (10), imperatorin (11) and osthol (12). The isolates were identified using spectral techniques in the light of literature. 3-(4,5-dimethyl thiazol-2yl)-2,5-diphenyltetrazolium bromide (MTT) cytotoxicity screening of the isolated constituents was carried out against six human cancer cell lines including lung (A549 and NCI-H322), epidermoid carcinoma (A431), melanoma (A375), prostate (PC-3) and Colon (HCT-116) cell lines. Osthol (12) exhibited the highest cytotoxicity with IC50 values of 3.2, 6.2, 10.9, 14.5, 24.8, and 30.2 µM against epidermoid carcinoma (A431), melanoma (A375), lung (NCI-H322), lung (A549), prostate (PC-3) and colon (HCT-116) cell lines respectively. Epidermoid carcinoma cell line A431 was sensitive to most of the compounds followed by lung (A549) cancer cell line. Finally a simple and reliable HPLC method was developed (RP-HPLC-DAD) and validated for the simultaneous quantification of these cytotoxic constituents in Prangos pabularia. The extract was analyzed using a reversed-phase Agilent ZORBAX eclipse plus column C18 (4.6×250 mm, 5 µm) at 250 nm wavelength using a gradient water-methanol solvent system at a flow rate of 0.8 ml/min. The RP-HPLC method is validated in terms of recovery, linearity, accuracy and precision (intra and inter-day validation). This method, because of shorter analysis time, makes it valuable for the commercial quality control of Prangos pabularia extracts and its future pharmaceutical preparations

Limits of detection (LOD) and quantification (LOQ) of marker compounds <b>1–12</b>.

<p>a) The calibration curves were constructed by plotting the peak areas versus the concentration of each analyte.</p><p>b) LOD refers to the limit of detection.</p><p>c) LOQ refers to the limit of quantification.</p><p>Limits of detection (LOD) and quantification (LOQ) of marker compounds <b>1–12</b>.</p

Chemical structure of marker compounds isolated from plant Prangos pabularia.

<p>(<b>1</b>), 6-hydroxo-coumarin (<b>2</b>), Umbelliferone (<b>3</b>), Heraclenol glycoside (<b>4</b>), Xanthotoxol (<b>5</b>), Heraclenol (<b>6</b>), Oxypeucedanin hydrate (<b>7</b>), 8-((3,3-dimethyloxiran-2-yl)methyl)-7-methoxy-2H-chromen-2-one (Merangin) (<b>8</b>), Oxypeucedanin hydrate monoacetate (<b>9</b>), Xanthotoxin (<b>10</b>), 4-((2-hydroxy-3-methylbut-3-en-1-yl)oxy)-7H-furo[3,2-g]chromen-7-one (<b>11</b>), Imperatorin (<b>12</b>), Osthol.</p

Intra and inter-day precisions area of HPLC method of marker compounds <b>1–12</b>.

<p>Intra and inter-day precisions area of HPLC method of marker compounds <b>1–12</b>.</p

Recovery percentage of marker compounds <b>1–12</b>.

<p>Recovery percentage of marker compounds <b>1–12</b>.</p