Diabetic retinopathy, a prevalent and vision-threatening microvascular complication of diabetes mellitus, is the leading cause of blindness among middle-aged and elderly individuals. Natural diterpenoids isolated from Siegesbeckia pubescens demonstrate potent anti-inflammatory properties. This study aimed to identify novel bioactive diterpenoids from S. pubescens and investigate their effects on oxidative stress and inflammatory responses in diabetic retinopathy, both in vitro and in vivo. Three new ent-pimarane-type diterpenoids (1-3) and six known compounds (4-9) were isolated from the aerial parts of S. pubescens. Their structures were elucidated through spectroscopic data interpretation, and absolute configurations were determined by comparing calculated and experimental electronic circular dichroism (ECD) spectra. Among these compounds, 14β,16-epoxy-ent-3β,15α,19-trihydroxypimar-7-ene (5) exhibited the most potent protective effect against high glucose and interleukin-1β (IL-1β)-stimulated human retinal endothelial cells. Mechanistically, compound 5 promoted endothelial cell survival while ameliorating oxidative stress and inflammatory response in diabetic retinopathy, both in vivo and in vitro. These findings not only suggest that diterpenoids such as compound 5 are important anti-inflammatory constituents in S. pubescens, but also indicate that compound 5 may serve as a lead compound for preventing or treating vascular complications associated with diabetic retinopathy.
Diabetic Retinopathy/metabolism* ; Humans ; Oxidative Stress/drug effects* ; Animals ; Diterpenes, Kaurane/administration & dosage* ; Asteraceae/chemistry* ; Male ; Endothelial Cells/drug effects* ; Abietanes/administration & dosage* ; Molecular Structure ; Mice ; Anti-Inflammatory Agents/chemistry* ; Plant Extracts/chemistry* ; Mice, Inbred C57BL

This study aims to investigate the mechanism of tanshinone Ⅱ_A(Tan Ⅱ_A) in protecting mice from diethylinitrosamine(DEN)/carbon tetrachloride(CCl_4)/ethanol(C_2H_5OH)-induced hepatocellular carcinoma(HCC) and HepG2 cells from hydrogen peroxide(H_2O_2)-induced oxidative damage via the phosphoinositide 3-kinase(PI3K)/protein kinase B(Akt) and nuclear factor E2-related factor 2(Nrf2)/heme oxygenase 1(HO-1) signaling pathways. Sixty male C57BL/6J mice were grouped as follows: control, model, low, medium, and high-dose(10, 20, 40 mg·kg~(-1), respectively) Tan Ⅱ_A, and colchicine(0.2 mg·kg~(-1)), with 10 mice in each group. The HCC model was established with DEN/CCl_4/C_2H_5OH for 20 weeks, and the mice were then euthanized for collection of blood and liver specimens. A protein-protein interaction(PPI) network of the targets of Tan Ⅱ_A in the prevention of HCC was constructed. HepG2 cells were treated with 150 μmol·L~(-1) H_2O_2 for the modeling of oxidative stress. The cell counting kit-8(CCK-8) was used to assess the effects of different concentrations(1, 2, 4 μmol·L~(-1)) of Tan Ⅱ_A on the relative viability of cells. Hematoxylin-eosin(HE) staining was used to observe the pathological changes in the liver tissue, and an automatic biochemical analyzer was used to measure the levels of alanine aminotransferase(ALT) and aspartate aminotransferase(AST) in the mice serum. Relevant assay kits were used to measure the levels of reactive oxygen species(ROS), malondialdehyde(MDA), superoxide dismutase(SOD), glutathione(GSH), and glutathione peroxidase(GSH-Px) in the liver and cells. Immunohistochemistry, immunofluorescence assay, and Western blot were employed to determine the expression of phosphorylated PI3K(p-PI3K), PI3K, phosphorylated Akt(p-Akt), Akt, Nrf2, and HO-1. Compared with the control group, the model group exhibited typical pathological manifestations of liver cancer in the liver tissue, with elevated levels of ALT and AST in the serum, risen levels of ROS and MDA in the liver, and lowered levels of SOD and GSH in the liver. Compared with the control group, the HepG2 cells treated with H_2O_2 showed significantly decreased activities of SOD and GSH-Px and increased ROS and MDA levels. In the liver tissue and HepG2 cells, the modeling up-regulated the expression of p-PI3K and p-Akt while down-regulating the expression of Nrf2 and HO-1. Compared with the model group, different doses of Tan Ⅱ_A reduced the levels of ALT and AST in the serum, elevated the levels of SOD, GSH, and GSH-Px in the liver tissue and cells, and lowered the ROS and MDA levels, which indicated significant alleviation of oxidative stress. The PPI network showed that Akt was a core target of the PI3K/Akt and Nrf2/HO-1 signaling pathways. Western blot, immunohistochemistry, and immunofluorescence assay results indicated that Tan Ⅱ_A promoted the expression of Nrf2 and HO-1 while inhibiting the phosphorylation of PI3K and Akt. In conclusion, Tan Ⅱ_A may delay the progression of HCC by inhibiting oxidative stress via the PI3K/Akt and Nrf2/HO-1 signaling pathways.
Animals ; NF-E2-Related Factor 2/genetics* ; Oxidative Stress/drug effects* ; Proto-Oncogene Proteins c-akt/genetics* ; Carcinoma, Hepatocellular/genetics* ; Male ; Humans ; Signal Transduction/drug effects* ; Liver Neoplasms/genetics* ; Phosphatidylinositol 3-Kinases/genetics* ; Mice ; Heme Oxygenase-1/genetics* ; Mice, Inbred C57BL ; Abietanes/administration & dosage* ; Hep G2 Cells

Cisplatin and other platinum-based drugs are used frequently for treatment of lung cancer. However, their clinical performance are usually limited by drug resistance or toxic effects. Carnosic acid, a polyphenolic diterpene isolated from Rosemary (Rosemarinus officinalis), has been reported to have several pharmacological and biological activities. In the present study, the combination effect of cisplatin plus carnosic acid on mouse LLC (Lewis lung cancer) xenografts and possible underlying mechanism of action were examined. LLC-bearing mice were treated with intraperitoneal injection with cisplatin, oral gavage with carnosic acid, or combination with cisplatin and carnosic acid, respectively. Combination of carnosic acid and cisplatin yielded significantly better anti-growth and pro-apoptotic effects on LLC xenografts than drugs alone. Mechanistic study showed that carnosic acid treatment boosted the function of CD8 T cells as evidenced by higher IFN-γ secretion and higher expression of FasL, perforin as well as granzyme B. In the meantime, the proportion of MDSC (myeloid-derived suppressor cells) in tumor tissues were reduced by carnosic acid treatment and the mRNA levels of iNOS2, Arg-1, and MMP9, which are the functional markers for MDSC, were reduced. In conclusion, our study proved that the functional suppression of MDSC by carnosic acid promoted the lethality of CD8 T cells, which contributed to the enhancement of anti-lung cancer effect of cisplatin.
Abietanes ; administration & dosage ; Animals ; Antineoplastic Agents ; administration & dosage ; CD8-Positive T-Lymphocytes ; drug effects ; immunology ; Carcinoma, Lewis Lung ; drug therapy ; genetics ; immunology ; Cell Line, Tumor ; Cisplatin ; administration & dosage ; Drug Synergism ; Humans ; Interferon-gamma ; genetics ; immunology ; Lung Neoplasms ; drug therapy ; genetics ; immunology ; Matrix Metalloproteinase 9 ; genetics ; Mice ; Mice, Inbred C57BL ; Myeloid-Derived Suppressor Cells ; drug effects ; immunology ; Plant Extracts ; administration & dosage ; Rosmarinus ; chemistry

Due to ineffectiveness and side effects of existing analgesics, chronic pain has become one of the most complex and difficult problems in the clinic. Monoacylglycerol lipase (MAGL) is an essential hydrolase in the endocannabinoid system and has been identified as a potential target for the treatment of pain. In the present study, we designed and synthesized twelve tanshinone IIA analogs and screened their activity against MAGL. Selected compounds were tested for analgesic activity in vivo, with the acetic acid writhing test model. Among the test compounds, compound III-3 (IC 120 nmol·L) showed significant activity against MAGL and ameliorated the clinical progression in the mouse pain model. Additionally, compound III-3, substitution with N-methyl-2-morpholinoacetamide, demonstrated improved solubility relative to tanshinone IIA.
Abietanes ; administration & dosage ; chemical synthesis ; chemistry ; Analgesics ; administration & dosage ; chemical synthesis ; chemistry ; Animals ; Chronic Pain ; drug therapy ; enzymology ; Drug Evaluation, Preclinical ; Enzyme Inhibitors ; administration & dosage ; chemical synthesis ; chemistry ; Female ; Humans ; Male ; Mice ; Mice, Inbred ICR ; Monoacylglycerol Lipases ; antagonists & inhibitors ; metabolism ; Structure-Activity Relationship