A new 3,4-seco-isopimarane and three new isopimarane diterpenoids from Kaempferia champasakensis collected from Vietnam and their cytotoxic activities.

A phytochemical investigation of Kaempferia champasakensis rhizomes led to the isolation of a new 3,4-seco-isopimarane diterpene, kaempferiol A (1), and three new isopimarane diterpenes, kaempferiols B-D (2-4), together with six known isopimarane diterpenes (5-10). The structures of 1-4 were elucidated by extensive spectroscopic analyses, including HR-ESI-MS, UV, IR, and 1D and 2D NMR. The absolute configurations of 1, 3, and 4 were determined by ECD calculations, while that of 2 was established using the modified Mosher method. All isolated compounds were tested for cytotoxicity against three human cancer cell lines, lung cancer (A549), cervical cancer (HeLa), and breast cancer (MCF-7). Among them, 6 and 7 showed moderate cytotoxic activities against the three tested cell lines, with IC50 values ranging from 38.04 to 27.77 µM, respectively.

Phenolic Derivatives with Anti-Acetylcholinesterase Inhibitory Activities from Galeola nudifolia in Vietnam.

A new phenolic derivative, galeomalate A (1), together with five known structurally related compounds (2-6), was isolated from the ethyl acetate extract of Galeola nudifolia collected in Vietnam. The structures were elucidated by various spectroscopic methods, including 1D and 2D NMR, HR-ESI-TOF-MS, and CD data, and chemical conversion of the sugar moiety. All isolated compounds possessed acetylcholinesterase (AChE) inhibitory activities in a dose-dependent manner. Among them, compounds 2 and 3 exhibited the first and second highest inhibitory activity on AChE with IC50 values of 122.13 and 125.49 µM, respectively. Compounds 1 and 4-6 inhibited the AChE activity by mixed modes of action comprising competitive and non-competitive modes, whereas 2 and 3 exerted their inhibitory activities in a competitive manner. Molecular docking analyses suggested that the phenyl-ß-D-glucopyranoside unit of 2 and 3 bound to the active site of AChE for the competitive inhibitory activities, while the mixed inhibitory activity of 4 was due to the two binding patterns in the active-site and the active-site entrance of AChE. Furthermore, the docking studies indicated that 1, 5, and 6 would inhibit AChE in a mixed inhibitory manner by adopting three distinct binding patterns of the additional phenyl-ß-D-glucopyranoside unit at the active-site entrance.

Regulatory mechanisms of glucose absorption in the mouse proximal small intestine during fasting and feeding.

Fasting is known to alter the function of various organs and the mechanisms of glucose metabolism, which affect health outcomes and slow aging. However, it remains unclear how fasting and feeding affects glucose absorption function in the small intestine. We studied the effects of the fasting and feeding on glucose-induced short-circuit current (Isc) in vitro using an Ussing chamber technique. Glucose-induced Isc by SGLT1 was observed in the ileum, but little or no Isc was observed in the jejunum in ad libitum-fed mice. However, in mice fasted for 24-48 h, in addition to the ileum, robust glucose-induced Isc was observed over time in the jejunum. The expression of SGLT1 in the brush border membranes was significantly decreased in the jejunum under fed conditions compared to 48 h fasting, as analyzed by western blotting. Additionally, when mice were fed a 60% high glucose diet for 3 days, the increase in glucose-induced Isc was observed only in the ileum, and totally suppressed in the jejunum. An increase in Na+ permeability between epithelial cells was concomitantly observed in the jejunum of fasted mice. Transepithelial glucose flux was assessed using a non-metabolizable glucose analog, 14C-methyl α-D-glucopyranoside glucose (MGP). Regardless of whether fed or fasted, no glucose diffusion mechanism was observed. Fasting increased the SGLT1-mediated MGP flux in the jejunum. In conclusion, segment-dependent up- and down-regulation mechanisms during fasting and feeding are important for efficient glucose absorption once the fast is broken. Additionally, these mechanisms may play a crucial role in the small intestine's ability to autoregulate glucose absorption, preventing acute hyperglycemia when large amounts of glucose are ingested.

Arginase inhibitory activities of guaiane sesquiterpenoids from Curcuma comosa rhizomes.

Arginases are bimanganese enzymes involved in many human illnesses, and thus are targets for disease treatments. The screening of traditional medicinal plants demonstrated that an ethanol extract of Curcuma comosa rhizomes showed significant human arginase I and II inhibitory activity, and further fractionation led to the isolation of three known guaiane sesquiterpenoids, alismoxide (1), 7α,10α-epoxyguaiane-4α,11-diol (2) and guaidiol (3). Tests of their inhibitory activities on human arginases I and II revealed that 1 exhibited selective and potent competitive inhibition for human arginase I (IC50 = 30.2 µM), whereas the other compounds lacked inhibitory activities against human arginases. To the best of our knowledge, this is the first demonstration of human arginase I inhibitory activity by a sesquiterpenoid. Thus, 1 is a primary and specific inhibitory molecule against human arginase I.

Inverse regulation of claudin-2 and -7 expression by p53 and hepatocyte nuclear factor 4α in colonic MCE301 cells.

Colonic epithelial cells move up along the crypt villus axis and are differentiated into absorptive or secretory cells. Claudin-7 (CLDN7), a tight junctional protein, is mainly located at the surface of crypt, whereas CLDN2 is located at the bottom. However, the expression mechanism and function of these CLDNs are not fully understood. The expression levels of CLDN2 and CLDN7 were altered depending on the culture days in MCE301 cells derived from mouse colon. The nuclear levels of transcriptional factors p53 and hepatocyte nuclear factor 4α (HNF4α) at day 21 were higher than those at day 7. Tenovin-1 (TEN), a p53 activator, increased the nuclear levels of p53 and HNF4α. The mRNA level and promoter activity of CLDN7 were increased by TEN, whereas those of CLDN2 were decreased. The changes of CLDNs expression were inhibited by p53 and HNF4α siRNAs. The association between p53 and HNF4α was elevated by TEN. In addition, the binding of p53 and HNF4α to the promoter region of CLDN2 and CLDN7 was enhanced by TEN. Transepithelial electrical resistance was decreased by TEN, but paracellular fluxes of lucifer yellow and dextran were not. In the Ussing chamber assay, TEN increased dilution potential and the ratio of permeability of Cl- to Na+. Both p53 and HNF4α were highly expressed at the surface of mouse colon crypt. We suggest that p53 and HNF4α alter the paracellular permeability of Cl- to Na+ mediated by the inverse regulation of CLDN2 and CLDN7 expression in the colon.

Upregulation of Claudin-7 Expression by Angiotensin II in Colonic Epithelial Cells of Mice Fed with NaCl-Depleted Diets.

Dietary NaCl depletion increases Na+ and Cl- absorption in the colon, but the mechanisms are not fully understood. So far, we reported that the expression of claudin-7 (CLDN7), a tight junction (TJ) protein, was upregulated in the mice fed with NaCl-depleted diets, but the regulatory mechanism has not been clarified. Here, we found that angiotensin II (ANGII) increases the mRNA level of CLDN7, which was inhibited by losartan, a type 1 ANGII (AT1) receptor antagonist. Immunofluorescence measurement showed that CLDN7 is colocalized with zonula occludens-1 at the TJ in untreated and ANGII-treated cells. ANGII decreased transepithelial electrical resistance (TER) and increased permeability to C1- without affecting permeability to lucifer yellow, a paracellular flux marker. In contrast, TER was increased by CLDN7 knockdown in the absence and presence of ANGII. ANGII increased the nuclear distribution of phosphorylated p65 subunit of NF-κB, which was inhibited by losartan. The ANGII-induced elevation of CLDN7 expression was blocked by BAY 11-7082 (BAY), an NF-κB inhibitor. Luciferase reporter assay showed that ANGII increases promoter activity of CLDN7, which was inhibited by the treatment with losartan or BAY, and introduction of mutations in κB-binding motifs in the promoter. The binding of p65 on the promoter region of CLDN7 was increased by ANGII, which was inhibited by losartan and BAY in chromatin immunoprecipitation assay. Our data suggest that ANGII acts on AT1 receptor and increases paracellular permeability to Cl- mediated by the elevation of CLDN7 expression in the colon.