ABSTRACT
The plants of genus Toona are well known for diverse limonoid secondary metabolites, while polyacetylenes are rarely found from Toona species. In this work, six new polyacetylenes toonasindiynes A-F (1-6) and six known analogues (7-12) were isolated from the root bark of Toona sinensis. Their structures and absolute configurations were elucidated by HRESIMS, 1D and 2D NMR spectroscopic analysis, modified Mosher's method, and biosynthetic consideration. These polyacetylenes share the same 4,6-diyne moiety with different side chain length and different oxidation degree. Bioactivity screening revealed the cytotoxic activity of 3, 5, 9, and 11 against U2OS cells, and the inhibitory effects on nitric oxide (NO) production of 1, 2, 5, 8, 9, and 11 in lipopolysaccharide-induced RAW 264.7 cells.
Subject(s)
Anti-Inflammatory Agents/pharmacology , Antineoplastic Agents, Phytogenic/pharmacology , Polyacetylene Polymer/pharmacology , Toona/chemistry , Animals , Anti-Inflammatory Agents/isolation & purification , Antineoplastic Agents, Phytogenic/isolation & purification , Cell Line, Tumor , China , Humans , Mice , Molecular Structure , Nitric Oxide/metabolism , Phytochemicals/isolation & purification , Phytochemicals/pharmacology , Plant Roots/chemistry , Polyacetylene Polymer/isolation & purification , RAW 264.7 CellsABSTRACT
BACKGROUND: Eucalyptus extracts have anti-cancer activity against various cancer cells. Formyl-phloroglucinol meroterpenoids (FPMs), which are typical secondary metabolites of the genera Eucalyptus, have many important pharmacological activities. PURPOSE: Eucalrobusone C (EC), a new bioactive phytochemical, was first isolated from the leaves of Eucalyptus robusta in our laboratory. EC is a FPM, and our previous research revealed that EC showed strongest cytotoxicity in three cancer models than other compounds isolated from the leaves of E. robusta. This study investigated its anti-tumor effects on human hepatocellular carcinoma (HCC) and its underlying mechanisms. METHODS: Cell viability was measured by MTT assay. Cell cycle, apoptosis and mitochondrial transmembrane potential were determined by flow cytometry. Immunofluorescence was determined by a laser scanning confocal microscope. Protein levels were analyzed by Western blotting. RESULTS: Our results showed that EC exerted strong anti-proliferative activity against HCC cells in a concentration- and time-dependent manner. EC markedly induced apoptosis through the caspase-dependent mitochondrial pathway, and the cell cycle was arrested at S phase. SB203580, a p38 MAPK inhibitor, effectively decreased cell death caused by EC. Moreover, the ROS scavenger N-acetyl cysteine (NAC) significantly attenuated apoptosis induced by EC and reversed EC-induced p38 MAPK activation. CONCLUSION: Our findings indicate that EC induces mitochondrial-dependent apoptosis in HCC cells through ROS generation and p38 MAPK activation, making EC a promising candidate for further development as an anticancer agent for HCC cells.
Subject(s)
Carcinoma, Hepatocellular , Eucalyptus/chemistry , Liver Neoplasms , Mitochondria/drug effects , Plant Extracts/pharmacology , Reactive Oxygen Species/metabolism , p38 Mitogen-Activated Protein Kinases/metabolism , Antineoplastic Agents, Phytogenic/pharmacology , Antineoplastic Agents, Phytogenic/therapeutic use , Apoptosis/drug effects , Carcinoma, Hepatocellular/drug therapy , Carcinoma, Hepatocellular/metabolism , Carcinoma, Hepatocellular/pathology , Cell Cycle/drug effects , Cell Proliferation/drug effects , Enzyme Inhibitors/pharmacology , Hep G2 Cells , Humans , Imidazoles/pharmacology , Liver Neoplasms/drug therapy , Liver Neoplasms/metabolism , Liver Neoplasms/pathology , Membrane Potential, Mitochondrial/drug effects , Mitochondria/metabolism , Phytotherapy , Plant Extracts/therapeutic use , Pyridines/pharmacologyABSTRACT
Nine formyl-phloroglucinolmeroterpenoids (FPMs), namely, eucalrobusonesâ A-I (1-9), were isolated from the leaves of Eucalyptus robusta by tracking the phenolic hydroxyl (1) Hâ NMR peaks. The Snatzke helicity rules for the Cotton effects of twisted benzene rings were applied to elucidate the absolute configurations of the FPMs. These findings, along with NMR spectroscopy, the circular dichroism (CD) exciton chirality method, and CD calculations, allowed complete structures for the FPMs to be assigned. Eucalrobusonesâ A-F (1-6) are novel adducts formed between a formyl-derived carbon atom on the phloroglucinol ring and monoterpene and sesquiterpene components. Eucalrobusonesâ G-I (7-9) are the first examples of FPMs with cubebane part structures connected by an unusual 1-oxaspiro[5.5]undecane subunit. Among these isolates, eucalrobusoneâ C (3) showed significant cytotoxicity against HepG2, MCF-7, and U2OS cancer cell lines, with IC50 values less than 10â µm. Compound 3 significantly blocks cell proliferation in MCF-7 cells and induces MCF-7 cell death through apoptosis.
Subject(s)
Apoptosis/drug effects , Cell Proliferation/drug effects , Eucalyptus/chemistry , Phloroglucinol/chemistry , Plant Leaves/chemistry , Sesquiterpenes/chemistry , Sesquiterpenes/pharmacology , Terpenes/chemistry , Terpenes/pharmacology , Circular Dichroism , Humans , MCF-7 Cells , Magnetic Resonance Imaging , Magnetic Resonance Spectroscopy , Molecular Structure , Sesquiterpenes/isolation & purification , Terpenes/isolation & purificationABSTRACT
Sarglaperoxides A (1) and B (2), a pair of unusual sesquiterpene-normonoterpene conjugates with a peroxide bridge, were isolated from the seeds of Sarcandra glabra. The structures and absolute configurations of 1 and 2 were determined on the basis of spectroscopic data analysis, including MS, NMR, CD, and XRD. The two compounds were screened in antimicrobial, anti-inflammatory, and cytotoxic bioassays and showed moderate bioactivities.