Schisandrin C Affects Glucose-Stimulated Insulin Secretion in Pancreatic ß-Cells and Glucose Uptake in Skeletal Muscle Cells.

The aim of our study was to investigate the effect of three lignans (schisandrol A, schisandrol B, and schisandrin C) on insulin secretion in rat INS-1 pancreatic ß-cells and glucose uptake in mouse C2C12 skeletal muscle cells. Schisandrol A and schisandrin C enhanced insulin secretion in response to high glucose levels with no toxic effects on INS-1 cells. The effect of schisandrin C was superior to that of gliclazide (positive control), a drug commonly used to treat type 2 diabetes (T2D). In addition, western blot analysis showed that the expression of associated proteins, including peroxisome proliferator-activated receptor γ (PPARγ), pancreatic and duodenal homeobox 1 (PDX-1), phosphatidylinositol 3-kinase (PI3K), Akt, and insulin receptor substrate-2 (IRS-2), was increased in INS-1 cells after treatment with schisandrin C. In addition, insulin secretion effect of schisandrin C were enhanced by the Bay K 8644 (L-type Ca2+ channel agonist) and glibenclamide (K+ channel blocker), were abolished by the nifedipine (L-type Ca2+ channel blocker) and diazoxide (K+ channel activator). Moreover, schisandrin C enhanced glucose uptake with no toxic effects on C2C12 cells. Western blot analysis showed that the expression of associated proteins, including insulin receptor substrate-1 (IRS-1), AMP-activated protein kinase (AMPK), PI3K, Akt, glucose transporter type 4 (GLUT-4), was increased in C2C12 cells after treatment with schisandrin C. Schisandrin C may improve hyperglycemia by enhancing insulin secretion in pancreatic ß-cells and improving glucose uptake into skeletal muscle cells. Our findings may provide evidence that schisandrin C may be beneficial in devising novel anti-T2D strategies.

Antioxidant and Anti-Inflammatory Effects of 3-Dehydroxyceanothetric Acid 2-Methyl Ester Isolated from Ziziphus jujuba Mill. against Cisplatin-Induced Kidney Epithelial Cell Death.

Cisplatin is a platinum-based chemotherapeutic agent for treating solid tumors; however, it presents a risk factor for nephropathy. In the present study, we investigated the antioxidant and anti-inflammatory effects of 3-dehydroxyceanothetric acid 2-methyl ester (3DC2ME) isolated from Ziziphus jujuba Mill. in LLC-PK1 cells following cisplatin-induced cytotoxicity. These cells were exposed to 3DC2ME for 2 h, followed by treatment with cisplatin for 24 h. The treated cells were subjected to cell viability analysis using the Ez-Cytox assay. Reactive oxygen species (ROS) were detected via 2', 7'- dichlorodihydrofluorescein diacetate (DCFH-DA) staining. In addition, western blotting and fluorescent immunostaining were performed to evaluate protein expressions related to oxidative stress and inflammation pathways. Pretreatment with 3DC2ME protected LLC-PK1 cells from cisplatin-induced cytotoxicity and oxidative stress. In addition, pretreatment with 3DC2ME upregulated heme oxygenase 1 (HO-1) via the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway in the cisplatin-treated LLC-PK1 cells. Furthermore, the increase in the expressions of IκB kinase α/ß (IKKα/ß), inhibitor of kappa B alpha (IκBα), nuclear factor kappa B (NF-κB), inducible nitric oxide synthase (iNOS), and cyclooxygenase-2 (COX-2) in these cells was inhibited. These results provide basic scientific evidence for understanding the antioxidant and anti-inflammatory effects of 3DC2ME isolated from Z. jujuba against cisplatin-induced kidney epithelial cell death.

Estrogenic Activity of Mycoestrogen (3ß,5α,22E)-Ergost-22-en-3-ol via Estrogen Receptor α-Dependent Signaling Pathways in MCF-7 Cells.

Armillariella tabescens (Scop.) Sing., a mushroom of the family Tricholomataceae, has been used in traditional oriental medicine to treat cholecystitis, improve bile secretion, and regulate bile-duct pressure. The present study evaluated the estrogen-like effects of A. tabescens using a cell-proliferation assay in an estrogen-receptor-positive breast cancer cell line (MCF-7). We found that the methanol extract of A. tabescens fruiting bodies promoted cell proliferation in MCF-7 cells. Using bioassay-guided fractionation of the methanol extract and chemical investigation, we isolated and identified four steroids and four fatty acids from the active fraction. All eight compounds were evaluated by E-screen assay for their estrogen-like effects in MCF-7 cells. Among the tested isolates, only (3ß,5α,22E)-ergost-22-en-3-ol promoted cell proliferation in MCF-7 cells; this effect was mitigated by the ER antagonist, ICI 182,780. The mechanism underlying the estrogen-like effect of (3ß,5α,22E)-ergost-22-en-3-ol was evaluated using Western blot analysis to detect the expression of extracellular signal-regulated kinase (ERK), phosphatidylinositol 3-kinase (PI3K), Akt, and estrogen receptor α (ERα). We found that (3ß,5α,22E)-ergost-22-en-3-ol induced an increase in phosphorylation of ERK, PI3K, Akt, and ERα. Together, these experimental results suggest that (3ß,5α,22E)-ergost-22-en-3-ol is responsible for the estrogen-like effects of A. tabescens and may potentially aid control of estrogenic activity in menopause.

Inhibition of Intracellular ROS Accumulation by Formononetin Attenuates Cisplatin-Mediated Apoptosis in LLC-PK1 Cells.

Cisplatin is a well-known anticancer drug frequently used for treating solid tumors, including ovarian, testicular, bladder, and cervical tumors. However, usage of cisplatin has been limited because of its adverse effects, particularly nephrotoxicity. Therefore, the present study sought to investigate the protective effect of formononetin against cisplatin-induced cytotoxicity in LLC-PK1 pig kidney epithelial cells as well as the anticancer effect of cisplatin in three different human cervical cancer cell lines, including HeLa, SiHa, and CaSKi cells. We first demonstrated that formononetin strongly prevented cisplatin-induced LLC-PK1 cell death. Although formononetin had no anticancer effect, it did not interrupt the anticancer effect of cisplatin in human cervical carcinoma cell lines. Furthermore, the treatment with formononetin reduced reactive oxygen species (ROS) accumulation and chromatin condensation. The percentage of Annexin V-positive cells also increased following cisplatin treatment. Finally, formononetin-inhibited c-Jun N-terminal kinase (JNK) phosphorylation, cleavage of caspase-8 and caspase-3, and the ratio of Bax to Bcl-2 increased with cisplatin. Taken together, these findings suggest that formononetin may be a possible option to prevent nephrotoxicity induced by cisplatin during treatment for cervical cancer.