No abstract

Chronic inflammation is associated with various chronic illnesses including immunity disorders, cancer, neurodegeneration, and vascular diseases. Iridoids are compounds with anti-inflammatory properties. However their anti-inflammatory mechanism remains unclear. Here, we report that scropolioside B, isolated from a Tibetan medicine (Scrophularia dentata Royle ex Benth.), blocked expressions of TNF, IL-1, and IL-32 through NF-κB pathway. Scropolioside B inhibited NF-κB activity in a dose-dependent manner with IC50 values of 1.02 μmol/L. However, catalpol, similar to scropolioside B, was not effective in inhibiting NF-κB activity. Interestingly, scropolioside B and catalpol decreased the expression of NLRP3 and cardiolipin synthetase at both the mRNA and protein level. Our results showed that scropolioside B is superior in inhibiting the expression, maturation, and secretion of IL-1β compared to catalpol. These observations provide further understanding of the anti-inflammatory effects of iridoids and highlight scropolioside B as a potential drug for the treatment of rheumatoid arthritis and atherosclerosis.

Mitochondrial oxidative stress has been suggested as a major etiological factor in cardiovascular diseases. Manganese superoxide dismutase (MnSOD) is an essential antioxidant mitochondrial enzyme. Although polyphenols can induce MnSOD expression, their mechanism of action remains unclear. We examined the effect of bavachalcone, a bioactive compound isolated from Psoralea corylifolia, on MnSOD protein expression and explored whether this effect is mediated through the AMP-activated protein kinase (AMPK) signaling pathway. Our data showed that bavachalcone enhanced the luciferase activity of the MnSOD promoter and increased MnSOD mRNA and protein expressions. Moreover, bavachalcone suppressed the mitochondrial superoxide production in endothelial cells. Conversely, bavachalcone stimulated liver kinase B1 and AMPKα phosphorylation. mRNA interference by using short hairpin RNA (shRNA) of AMPK inhibited bavachalcone-induced MnSOD expression. A-769662, an AMPK activator, also stimulated AMPK activity and increased MnSOD expression. Furthermore, AMPK knockdown by shRNA-AMPK reversed the inhibitory effects of bavachalcone on mitochondrial superoxide production in endothelial cells. These findings indicate that bavachalcone can protect the endothelial function by increasing AMPK activity and MnSOD expression and reducing mitochondrial oxidative stress.

The longevity gene klotho has numerous physiological functions, such as regulating calcium and phosphorus levels, delaying senescence, improving cognition, reducing oxidative stress, and protecting vascular endothelial cells. This study tested whether 2,3,5,4′-Tetrahydroxystilbene-2-O-β-D-glucoside (THSG), a small molecule with antiaging effects, regulates the expression and physiological effects of klotho. Our results showed that THSG dose-dependently increased the luciferase reporter activity of the klotho gene, reversed the decrease in mRNA and protein expression of klotho which was induced by angiotensin II in NRK-52E renal tubular epithelial cells, and increased klotho mRNA expression in the cerebral cortex, hippocampus, testis, and kidney medulla of spontaneously hypertensive rats. THSG also reduced the number of senescent cells induced by angiotensin II and improved the antioxidant capacity and enhanced the bone strength in vivo. Based on klotho's role in promoting cognition, regulating bone metabolism, and improving renal function, the effect of THSG on klotho expression will be beneficial to the functional improvement or enhancement of the expressed organs or tissues.

Resveratrol and pterostilbene, present in fruits, red wine and some Chinese medicine herbs, activate MnSOD expression, and stimulate LKB1, AMPK, ERK5 phosphorylation and HDAC5 and KLF2 expression in endothelial cells. Furthermore, two stilbenes promote KLF2 binding to human MnSOD promoter. These findings reveal a new mechanism underlying the anti-aging effect two stilbenes exert on vascular endothelial cells.