Liriodenine enhances the apoptosis effect of valproic acid in human colon cancer cells through oxidative stress upregulation and Akt inhibition

Rapid identification and pharmacokinetic studies of multiple active alkaloids in rat plasma through UPLC-Q-TOF-MS and UPLC-MS/MS after the oral administration of Zanthoxylum nitidum extract

Zanthoxylum nitidum (Roxb.) DC. (ZN) belongs to the genus Zanthoxylum of Rutaceae and has various chemical ingredients and pharmacologic effects. Alkaloids are its main active constituents responsible for diverse pharmacologic effects, such as anti-tumor, anti-bacterial, anti-inflammatory, and analgesic activities. The chemical and pharmacological effects of ZN are well reported, but the in vivo pharmacokinetic profiles of its main active alkaloids are poorly investigated. This study aims to elucidate the absorbed constituents and pharmacokinetic behavior of main active ingredients in rat plasma after the oral administration of ZN extract. The absorbed constituents in rat plasma were qualitatively analyzed using ultra-high-performance liquid chromatography with quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS). Ultra-high-performance liquid chromatography with triple quadrupole mass spectrometry (UPLC-MS/MS) method was developed for the simultaneous determination and pharmacokinetic studies of dihydrochelerythrine (DHCHE), nitidine chloride (NIT), chelerythrine (CHE), sanguinarine (SAN), liriodenine (LIR), skimmianine (SKI), γ-fagarine (FAG), and dictamnine (DIC) in rat plasma. Eighteen prototypes and metabolites were identified according to exact mass, characteristic diagnostic fragment ions, and reference standards. The established UPLC-MS/MS quantitative method met the requirements of FDA for biological analysis methods. Method validation showed that this method has good linearity (r ≥ 0.9910), precision (RSD ≤ 18.63 %), accuracy (88.11 %-117.50 %), and stability. The limit of detection (LOD) could reach 1 ng/mL, and the limit of quantitation could reach 2 ng/mL. The plasma drug concentration of benzophenanthridine alkaloids, such as NIT, CHE, and DHCHE, were still low even after dose differences were deducted. For the furan quinoline alkaloids (such as SKI, FAG, and DIC), only SKI showed high plasma drug concentration, although SKI content comprised only approximately 1/6 of benzophenanthridine alkaloids. This study is the first to simultaneously determine the above-mentioned active alkaloids in rat plasma and would contribute to the comprehensive understanding of in vivo pharmacokinetic behavior on active alkaloids in ZN extract.

Yellow and green pigments from Calophyllum inophyllum L. seed oil induce cell death in colon and lung cancer cells

Natural compounds have been candidates for anticancer medicine over the last 20 years. During the process of isolating seed oil from Calophyllum inophyllum L., yellow and green pigments containing multiple compounds with an aromatic structure were identified. High-performance liquid chromatography and nuclear magnetic resonance analysis of these pigments revealed that the compounds present were identical, but the concentration of the compounds was different. Treatment with the pigments was able to induce the death of DLD-1 human colon cancer cells and increase the percentage of the cells in the sub-G₁ and sub-G₂/M phases in a dose-dependent manner. Additionally, the pigments were able to exhibit cytotoxic activity on A549 and H1975 human non-small cell lung cancer (NSCLC) cell lines at 24 h, with half-maximal inhibitory concentrations (IC₅₀) values of 0.1206 and 0.0676%, respectively for green pigments, and 0.0434 and 0.0501%, respectively for yellow pigments. Furthermore, a decrease in IC₅₀ value was associated with an increase in the duration of treatment. However, a sharp decrease in IC₅₀ value of the yellow pigment was observed for H1975 cells at 48 h and for A549 cells at 72 h compared with no change in IC₅₀ value for the green pigment with time, suggesting that the pigments function and induce cell death differently in the two cell lines. An investigation was performed into the synergistic effect of the green pigment and gefitinib (Iressa^®, ZD1839), which is a selective epidermal growth factor receptor-tyrosine kinase inhibitor to block growth factor-mediated cell proliferation. The combination of the green pigment and gefitinib resulted in an enhancement of the decrease in viability of A549 and H1975 cells compared with treatment with gefitinib alone, which suggested that treatment with the green pigments was able to enhance the sensitivity of NSCLC cells to gefitinib. In conclusion, these pigments may be considered for development as anti-colon cancer agents.

Xylopine Induces Oxidative Stress and Causes G2/M Phase Arrest, Triggering Caspase-Mediated Apoptosis by p53-Independent Pathway in HCT116 Cells

Xylopine is an aporphine alkaloid that has cytotoxic activity to cancer cells. In this study, the underlying mechanism of xylopine cytotoxicity was assessed in human colon carcinoma HCT116 cells. Xylopine displayed potent cytotoxicity in different cancer cell lines in monolayer cultures and in a 3D model of cancer multicellular spheroids formed from HCT116 cells. Typical morphology of apoptosis, cell cycle arrest in the G₂/M phase, increased internucleosomal DNA fragmentation, loss of the mitochondrial transmembrane potential, and increased phosphatidylserine externalization and caspase-3 activation were observed in xylopine-treated HCT116 cells. Moreover, pretreatment with a caspase-3 inhibitor (Z-DEVD-FMK), but not with a p53 inhibitor (cyclic pifithrin-α), reduced xylopine-induced apoptosis, indicating induction of caspase-mediated apoptosis by the p53-independent pathway. Treatment with xylopine also caused an increase in the production of reactive oxygen/nitrogen species (ROS/RNS), including hydrogen peroxide and nitric oxide, but not superoxide anion, and reduced glutathione levels were decreased in xylopine-treated HCT116 cells. Application of the antioxidant N-acetylcysteine reduced the ROS levels and xylopine-induced apoptosis, indicating activation of ROS-mediated apoptosis pathway. In conclusion, xylopine has potent cytotoxicity to different cancer cell lines and is able to induce oxidative stress and G₂/M phase arrest, triggering caspase-mediated apoptosis by the p53-independent pathway in HCT116 cells.