Collaborative study using common samples to evaluate the performance of anti-drug antibody assays constructed by different companies.

This study was undertaken to evaluate the performance of anti-drug antibody (ADA) assays constructed by each participating company using common samples including ADA, drug and human serum. The ADA assays constructed by each company showed good sensitivity and precision for evaluation of ADA. Cut points for screening and confirmatory assays and assay selectivity were determined by various calculation methods. In evaluations of blind ADA samples, nearly similar results were obtained by the study companies in determinations of whether samples were positive or negative except at the lowest sample concentration (5 ng/mL). In measurement of drug tolerance, for almost samples containing ADA and drugs, more positive results were obtained in assays using acid dissociation compared to those without acid dissociation. Overall, the performance of ADA assays constructed by the 10 companies participating in this study was acceptable in terms of sensitivity and reproducibility for detection and evaluation of immunogenicity in both patients and healthy subjects. On the other hand, based on results for samples containing ADA and drugs, validity of results for ADA assays conducted without acid dissociation was less meaningful and more difficult to evaluate. Thus, acid dissociation was confirmed to be useful for improving drug tolerance.

Adipogenic effects of piperlonguminine in 3T3-L1 cells and plasma concentrations of several amide constituents from Piper chaba extracts after treatment of mice.

In our previous study, piperlonguminine from the fruit of Piper chaba was reported to promote adipogenesis in 3T3-L1 cells like the peroxisome proliferator-activated receptor-γ (PPARγ) agonist, troglitazone. In the present study, the mode of action of piperlonguminine in cells was examined. Piperlonguminine increased mRNA levels of adiponectin, glucose transporter 4, and fatty acid-binding protein (aP2). It also increased mRNA levels of PPARγ2 but, unlike troglitazone, piperlonguminine did not activate PPARγ directly in a nuclear receptor cofactor assay. Analyses of plasma from mice treated with piperlonguminine, piperine, and retrofractamide A, and an extract of the fruit, showed that concentrations of piperlonguminine were higher than those of piperine and retrofractamide A, and that the "area-under-the-curve" of piperine increased following in vivo administration of the extract.

A new amide, piperchabamide F, and two new phenylpropanoid glycosides, piperchabaosides A and B, from the fruit of Piper chaba.

A new amide, piperchabamide F (1), and two new phenylpropanoid glycosides, piperchabaosides A (2) and B (3), were isolated from 80% aqueous acetone extract from fruit of Piper chaba. Their stereostructures were elucidated on the basis of chemical and physicochemical evidence.

Hepatoprotective amide constituents from the fruit of Piper chaba: Structural requirements, mode of action, and new amides.

The 80% aqueous acetone extract from the fruit of Piper chaba (Piperaceae) was found to have hepatoprotective effects on D-galactosamine (D-GalN)/lipopolysaccharide-induced liver injury in mice. From the ethyl acetate-soluble fraction, three new amides, piperchabamides E, G, and H, 33 amides, and four aromatic constituents were isolated. Among the isolates, several amide constituents inhibited D-GalN/tumor necrosis factor-alpha (TNF-alpha)-induced death of hepatocytes, and the following structural requirements were suggested: (i) the amide moiety is essential for potent activity; and (ii) the 1,9-decadiene structure between the benzene ring and the amide moiety tended to enhance the activity. Moreover, a principal constituent, piperine, exhibited strong in vivo hepatoprotective effects at doses of 5 and 10 mg/kg, po and its mode of action was suggested to depend on the reduced sensitivity of hepatocytes to TNF-alpha.

Protective effects of amide constituents from the fruit of Piper chaba on D-galactosamine/TNF-alpha-induced cell death in mouse hepatocytes.

The methanolic extract from the fruit of Piper chaba (Piperaceae) was found to have a hepatoprotective effect on D-galactosamine (D-GalN)/lipopolysaccharide (LPS)-induced liver injury in mice. From the ethyl acetate-soluble fraction, a new amide constituent named piperchabamide E together with twenty known amide constituents (e.g., piperine, piperchabamides A-D, and piperanine) and two aromatic constituents were isolated as the hepatoprotective constituents. With regard to structure-activity relationships, the amide moiety and the 1,9-decadiene structure between the benzene ring and amide moiety were suggested to be important for strong inhibition of D-GalN/tumor necrosis factor-alpha (TNF-alpha)-induced death of hepatocytes. Furthermore, a principal amide constituent, piperine, dose-dependently inhibited increase in serum GPT and GOT levels at doses of 2.5-10 mg/kg (p.o.) in D-GalN/LPS-treated mice, and this inhibitory effect was suggested to depend on the reduced sensitivity of hepatocytes to TNF-alpha.

New amides and gastroprotective constituents from the fruit of Piper chaba.

The 80 % aqueous acetone extract from the fruit of Piper chaba was found to show protective effects on ethanol- and indomethacin-induced gastric lesions in rats. From the aqueous acetone extract, four new amides named piperchabamides A ( 1), B ( 2), C ( 3), and D ( 4) were isolated, and their structures were determined on the basis of chemical and physicochemical evidence. In addition, the gastroprotective effects of the principal constituents, piperine ( 5), piperanine ( 6), pipernonaline ( 7), dehydropipernonaline ( 8), piperlonguminine ( 9), retrofractamide B ( 10), guineensine ( 11), N-isobutyl-(2 E,4 E)-octadecadienamide ( 12), N-isobutyl-(2 E,4 E,14 Z)-eicosatrienamide ( 13), and methyl piperate ( 14), were examined. As a result, compounds 5 - 10 and 12 - 14 significantly inhibited ethanol-induced gastric lesions at a dose of 25 mg/kg, p. o., while 5, 7, 8, 10, 12, and 13 also significantly inhibited indomethacin-induced gastric lesions at the same dose.