Ipomoea batatas has long been used in folk medicine for the treatment of hyperglycemia or as a food additive for the prevention of type 2 diabetes. However, neither the plant extract nor its active components have been evaluated systematically. In this work four crude extracts, including n-hexane-(IBH), 95% MeOH-(IBM), n-BuOH-(IBB), and H 2 O-soluble (IBW) fractions, were prepared by fractionation of a methanolic extract of purple I. batatas leaves. Twenty-four pure compounds 1-24 were then isolated by various chromatographic techniques and their structures identified from NMR and MS data. Glucose uptake assays in differentiated 3T3-L1 adipocytes and rat primary hepatocytes, as well as western blot analysis, were carried out to evaluate the antidiabetic activity of this species. The IBH crude fraction, with methyl decanoate (22) as a major and active compound, showed the greatest effect on glucose uptake, most likely via activation of Glut4 and regulation of the PI3K/AKT pathway. Quercetin 3-O-β-D-sophoroside (1), quercetin (3), benzyl β-d-glucoside (10), 4-hydroxy-3-methoxybenzaldehyde (12), and methyl decanoate (22) could be important components contributing to the antidiabetic effects. We conclude that purple I. batatas leaves have potential as an antidiabetic plant source and the active constituents 1, 3, 10, 12, and 22 are promising lead candidates for future investigation.
The overexpression of EGFR and/or ErbB2 occurs frequently in ovarian cancers and is associated with poor prognosis. The purpose of this study was to examine the anticancer effects and molecular mechanisms of berberine on human ovarian cancer cells with different levels of EGFR and/or ErbB2. We found that berberine reduced the motility and invasiveness of ovarian cancer cells. Berberine depleted both EGFR and ErbB2 in ovarian cancer cells. Furthermore, berberine suppressed the activation of the EGFR and ErbB2 downstream targets cyclin D1, MMPs, and VEGF by down‐regulating the EGFR‐ErbB2/PI3K/Akt signaling pathway. The berberine‐mediated inhibition of MMP‐2 and MMP‐9 activity could be rescued by co‐treatment with EGF. Finally, we demonstrated that berberine induced ErbB2 depletion through ubiquitin‐mediated proteasome degradation. In conclusion, the suppressive effects of berberine on the ovarian cancer cells that differ in the expression of EGFR and ErbB2 may be mediated by the dual depletion of EGFR and/or ErbB2.
Background. Purple sweet potato leaves (PSPL) are widely grown and are considered a healthy vegetable in Taiwan. PSPL contain a high content of flavonoids, and the boiling water-extracted PSPL (PSPLE) is believed to prevent metabolic syndrome. However, its efficacy has not yet been verified. Therefore, we investigated the effect of PSPLE on adipocytes. Methods. The differentiated 3T3-L1 cells used in this study were derived from preadipocytes that were differentiated into adipocytes using an adipogenic agent (insulin, dexamethasone, and 3-isobutyl-1-methylxanthine); approximately 90% of the cells were differentiated using this method. Results. Treating the differentiated 3T3-L1 cells with PSPLE caused a dose-dependent decrease in the number of adipocytes rather than preadipocytes. In addition, treatment with PSPLE resulted in apoptosis of the differentiated 3T3-L1 cells as determined by DAPI analysis and flow cytometry. PSPLE also increased the expression of cleaved caspase-3 and poly ADP-ribose polymerase (PARP). Furthermore, PSPLE induced downregulation of interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) gene expression in the differentiated 3T3-L1 cells. Conclusions. These results suggest that PSPLE not only induced apoptosis but also downregulated inflammation-associated genes in the differentiated 3T3-L1 cells.
Purple sweet potato leaves (PSPLs) are healthy vegetable that is rich in anti-oxidants. A solution of boiling water extract of PSPL (PSPLE) is believed to be able to prevent obesity and metabolic syndrome in the countryside of Taiwan, but its efficacy has not yet been verified. The purpose of this study was to investigate the possible anti-adipogenesis effect of PSPLE in vitro. PSPLE was used to treat the 3T3-L1 cells, and the effects on cell proliferation and adipogenesis were investigated. The results showed that PSPLE caused a dose-dependent decrease in the cell proliferation of 3T3-L1 preadipocytes, but did not alter the cell viability. In addition, PSPLE induced ERK inactivation in the 3T3-L1 preadipocytes. Furthermore, pre-treatment of confluent 3T3-L1 cells with PSPLE led to reduced lipid accumulation in differentiated 3T3-L1 cells. The inhibition of lipogenesis could result from the PSPLE-induced down-regulation of the expression of the C/EBPα and SREBP-1 transcription factors during 3T3-L1 adipocyte differentiation. These results suggest that PSPLE not only inhibits cell proliferation at an early stage but also inhibits adipogenesis at a later stage of the differentiation program.
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