Effect of osthole on advanced glycation end products-induced renal tubular hypertrophy and role of klotho in its mechanism of action.

BACKGROUND: Osthole has been widely reported to have pharmacological activities such as anti-cancer, anti-inflammation and anti-hyperlipidemic effects. Klotho was identified as an anti-senescence protein in a variety of tissues. Loss of klotho has been associated with chronic kidney disease. However, potential roles and molecular events for osthole and klotho in diabetic nephropathy remain unclear. PURPOSE: In the current study, we undertook to study the effect of osthole on klotho expression in advanced glycation end products (AGE)-cultured human renal proximal tubular cells, and to investigate the molecular mechanisms of osthole and exogenous klotho against AGE-induced renal tubular hypertrophy. METHODS: Cell viability was elucidated by MTT assay. Protein expression was measured by Western blotting. mRNA level was analyzed by real-time PCR. Cellular hypertrophy growth was evaluated by hypertrophy index. Relative cell size was detected by flow cytometry. RESULTS: We found that raising the ambient AGE concentration causes a dose-dependent decrease in klotho synthesis. Osthole significantly increased AGE-inhibited klotho mRNA and protein expression. Osthole and exogenous klotho treatments significantly attenuated AGE-induced Janus kinase 2 (JAK2)-signal transducers and activators of transcription 1 (STAT1) and STAT3 activation. Moreover, protein levels of suppressor of cytokine signaling 1 (SOCS1) and SOCS3 were augmented by osthole and exogenous klotho. The abilities of osthole and exogenous klotho to reverse AGE-induced cellular hypertrophy were verified by the observation that osthole and exogenous klotho inhibited p21Waf1/Cip1/collagen IV/RAGE expression, total protein content, and cell size. CONCLUSION: Consequently, we found that osthole attenuated AGE-induced renal tubular hypertrophy via induction of klotho expression and suppression of the JAK2-STAT1/STAT3 signaling. These results also showed that klotho might be used as a unique molecular target for the treatment of diabetic nephropathy.

Antimutagenic and antiproliferative effects of roasted and defatted peanut dregs on human leukemic U937 and HL-60 cells.

The antimutagenic effects on Salmonella typhimurium TA98 and TA100 strains and antiproliferative effects on leukemia cell lines (U937 and HL-60) of peanut protein isolate (PPI), peanut protein isolate enzyme hydrolysate (PPIEH), roasted and defatted peanut dregs (RDPD), and roasted and defatted peanut dregs enzyme hydrolysate (RDPDEH) were investigated. The antimutagenic effects on B(a)P and 4-NQO toward the TA98 and TA100 strains were found to follow a diminishing order: RDPD > RDPDEH >> PPI = PPIEH with dose-dependency. Antiproliferative effects on leukemia cells U937 and HL-60 were also detected. RDPD was found to be the most effective of all the peanut preparations. At 100 microg/mL concentration, RDPD inhibited the proliferation of U937 and HL-60 cells by 56% and 52%, respectively. We propose to consider RDPD and RDPDEH in the development of natural chemotherapeutic or chemopreventive dietary supplements against leukemia and to upgrade the utilization of these by-products in peanut oil production.

Transacylation and de-esterification reactions of pectin as catalyzed by pectinesterases from tomato and citrus.

The optimal conditions for the de-esterification reaction of tomato pectinesterase (PE) and citrus PE was 0.1-0.2 M NaCl and at pH 7.5-8.5, 65 degrees C, almost identical to those for the transacylation reaction as observed by turbidity (absorbance at 400 nm) change. Among the PEs tested, pea pod PE presented the most remarkable catalysis on the transacylation reaction, and 1.5% pectin solution was determined to be suitable for this reaction. Low methoxy pectin with a DE (degree of esterification) of 31% displayed a slow turbidity increase, revealing that the extent of DE was influential on the transacylation. Besides citrus pectin, apple pectin was also proved to progress transacylation reaction by PEs from tomato and citrus sources as apparently observed by turbidity method.