Dauferulins A-L, daucane-type sesquiterpenes from the roots of Ferula communis: Their structures and biological activities.

Phytochemical study on the roots of a medicinal plant Ferula communis L. (Apiaceae) resulted in the isolation of 20 sesquiterpenes including 12 previously undescribed compounds, dauferulins A-L (1-12). The detailed spectroscopic analysis revealed 1-12 to be daucane-type sesquiterpenes with a p-methoxybenzoyloxy group at C-6. The absolute configurations of 1-12 were deduced by analysis of the ECD spectra. Dauferulins A-L (1-12), known sesquiterpenes (13-20), and analogues (14a-14l) derived from 6-O-p-methoxybenzoyl-10α-angeloyloxy-jeaschkeanadiol (14) were evaluated for their effects on AMPK phosphorylation in human hepatoma HepG2 cells as well as inhibitory activities against erastin-induced ferroptosis on human hepatoma Hep3B cells and IL-1ß production from LPS-treated murine microglial cells.

Methanol extraction fraction from Citrus Sudachi peel exerts lipid reducing effects in cultured cells.

Ectopic fat accumulation is associated with insulin resistance and type 2 diabetes mellitus. Citrus sudachi is an evergreen tree that is found mainly in Tokushima Prefecture in Japan. Previously, it was demonstrated that Citrus sudachi could inhibit the rising trend of blood glucose and fatty acid in human subjects. In the current study, we illustrated the function of methanol extracts from sudachi peel and investigated the mechanism of this effect. We got the five kinds of methanol extracts by using diaion HP-20, and those were named by hydrophobicity from M-F1 to M-F5. Among the 5 kinds of sudachi methanol extracts, only M-F4 significantly decreased the intracellular triglyceride of C2C12 cells. It augmented the AMPK activity and increased the transcription of PPARα and its downstream targets CPT-1b and UCP2. In conclusion, M-F4 improved the lipid metabolism possibly through AMPK, PPARα and their downstream targets like CPT-1b and UCP2. Furthermore, this extract may be useful for preventing obesity and diabetes related diseases. J. Med. Invest. 65:225-230, August, 2018.

Mechanisms of the pH- and Oxygen-Dependent Oxidation Activities of Artesunate.

Artemisinin was discovered in 1971 as a constituent of the wormwood genus plant (Artemisia annua). This plant has been used as an herbal medicine to treat malaria since ancient times. The compound artemisinin has a sesquiterpene lactone bearing a peroxide group that offers its biological activity. In addition to anti-malarial activity, artemisinin derivatives have been reported to exert antitumor activity in cancer cells, and have attracted attention as potential anti-cancer drugs. Mechanisms that might explain the antitumor activities of artemisinin derivatives reportedly induction of apoptosis, angiogenesis inhibitory effects, inhibition of hypoxia-inducible factor-1α (HIF-1α) activation, and direct DNA injury. Reactive oxygen species (ROS) generation is involved in many cases. However, little is known about the mechanism of ROS formation from artemisinin derivatives and what types of ROS are produced. Therefore, we investigated the iron-induced ROS formation mechanism by using artesunate, a water-soluble artemisinin derivative, which is thought to be the underlying mechanism involved in artesunate-mediated cell death. The ROS generated by the coexistence of iron(II), artesunate, and molecular oxygen was a hydroxyl radical or hydroxyl radical-like ROS. Artesunate can reduce iron(III) to iron(II), which enables generation of ROS irrespective of the iron valence. We found that reduction from iron(III) to iron(II) was activated in the acidic rather than the neutral region and was proportional to the hydrogen ion concentration.

Iron suppresses erythropoietin expression via oxidative stress-dependent hypoxia-inducible factor-2 alpha inactivation.

Renal anemia is a major complication in chronic kidney disease (CKD). Iron supplementation, as well as erythropoiesis-stimulating agents, are widely used for treatment of renal anemia. However, excess iron causes oxidative stress via the Fenton reaction, and iron supplementation might damage remnant renal function including erythropoietin (EPO) production in CKD. EPO gene expression was suppressed in mice following direct iron treatment. Hypoxia-inducible factor-2 alpha (HIF-2α), a positive regulator of the EPO gene, was also diminished in the kidney of mice following iron treatment. Anemia-induced increase in renal EPO and HIF-2α expression was inhibited by iron treatment. In in vitro experiments using EPO-producing HepG2 cells, iron stimulation reduced the expression of the EPO gene, as well as HIF-2α. Moreover, iron treatment augmented oxidative stress, and iron-induced reduction of EPO and HIF-2α expression was restored by tempol, an antioxidant compound. HIF-2α interaction with the Epo promoter was inhibited by iron treatment, and was restored by tempol. These findings suggested that iron supplementation reduced EPO gene expression via an oxidative stress-HIF-2α-dependent signaling pathway.

Iron chelation by deferoxamine prevents renal interstitial fibrosis in mice with unilateral ureteral obstruction.

Renal fibrosis plays an important role in the onset and progression of chronic kidney diseases (CKD). Although several mechanisms underlying renal fibrosis and candidate drugs for its treatment have been identified, the effect of iron chelator on renal fibrosis remains unclear. In the present study, we examined the effect of an iron chelator, deferoxamine (DFO), on renal fibrosis in mice with surgically induced unilateral ureter obstruction (UUO). Mice were divided into 4 groups: UUO with vehicle, UUO with DFO, sham with vehicle, and sham with DFO. One week after surgery, augmented renal tubulointerstitial fibrosis and the expression of collagen I, III, and IV increased in mice with UUO; these changes were suppressed by DFO treatment. Similarly, UUO-induced macrophage infiltration of renal interstitial tubules was reduced in UUO mice treated with DFO. UUO-induced expression of inflammatory cytokines and extracellular matrix proteins was abrogated by DFO treatment. DFO inhibited the activation of the transforming growth factor-ß1 (TGF-ß1)-Smad3 pathway in UUO mice. UUO-induced NADPH oxidase activity and p22(phox) expression were attenuated by DFO. In the kidneys of UUO mice, divalent metal transporter 1, ferroportin, and ferritin expression was higher and transferrin receptor expression was lower than in sham-operated mice. Increased renal iron content was observed in UUO mice, which was reduced by DFO treatment. These results suggest that iron reduction by DFO prevents renal tubulointerstitial fibrosis by regulating TGF-ß-Smad signaling, oxidative stress, and inflammatory responses.

Nitrosonifedipine ameliorates the progression of type 2 diabetic nephropathy by exerting antioxidative effects.

Diabetic nephropathy (DN) is the major cause of end-stage renal failure. Oxidative stress is implicated in the pathogenesis of DN. Nitrosonifedipine (NO-NIF) is a weak calcium channel blocker that is converted from nifedipine under light exposure. Recently, we reported that NO-NIF has potential as a novel antioxidant with radical scavenging abilities and has the capacity to treat vascular dysfunction by exerting an endothelial protective effect. In the present study, we extended these findings by evaluating the efficacy of NO-NIF against DN and by clarifying the mechanisms of its antioxidative effect. In a model of type 2 DN (established in KKAy mice), NO-NIF administration reduced albuminuria and proteinuria as well as glomerular expansion without affecting glucose metabolism or systolic blood pressure. NO-NIF also suppressed renal and systemic oxidative stress and decreased the expression of intercellular adhesion molecule (ICAM)-1, a marker of endothelial cell injury, in the glomeruli of the KKAy mice. Similarly, NO-NIF reduced albuminuria, oxidative stress, and ICAM-1 expression in endothelial nitric oxide synthase (eNOS) knockout mice. Moreover, NO-NIF suppressed urinary angiotensinogen (AGT) excretion and intrarenal AGT protein expression in proximal tubular cells in the KKAy mice. On the other hand, hyperglycemia-induced mitochondrial superoxide production was not attenuated by NO-NIF in cultured endothelial cells. These findings suggest that NO-NIF prevents the progression of type 2 DN associated with endothelial dysfunction through selective antioxidative effects.

Morus alba leaf extract stimulates 5'-AMP-activated protein kinase in isolated rat skeletal muscle.

AIM OF THE STUDY: Morus alba (mulberry) leaf is a natural therapeutic agent that has been shown to have an antidiabetic effect. We explored the possibility that 5'-AMP-activated protein kinase (AMPK) is involved in metabolic enhancement by the Morus alba leaf. MATERIALS AND METHODS: Isolated rat epitrochlearis muscle was incubated in a buffer containing Morus alba leaf hot water extract (MLE) and the AMPK activation and related events were examined. RESULTS: In response to MLE treatment, the Thr(172) phosphorylation of the catalytic alpha subunit of AMPK, an essential step for full kinase activation increased in a dose- and time-dependent manner. Ser(79) phosphorylation of acetyl CoA carboxylase, an intracellular substrate of AMPK, increased similarly. Analysis of isoform-specific AMPK activity revealed that MLE activated both the alpha1 and alpha2 isoforms of the catalytic subunit. This increase in enzyme activity was associated with an increased rate of 3-O-methyl-D-glucose transport in the absence of insulin and with phosphorylation of AS160, a signaling intermediary leading to glucose transporter 4 translocation. The intracellular energy status, estimated from the ATP and phosphocreatine concentrations, was not affected by MLE. CONCLUSION: MLE stimulates skeletal muscle AMPK activity acutely without changing the intracellular energy status.