Cytotoxic and Antiangiogenetic Xanthones Inhibiting Tumor Proliferation and Metastasis from Garcinia xipshuanbannaensis.

Eight prenylated xanthones including four new analogues were extracted and purified from the leaves of Garcinia xipshuanbannaensis. Multiple techniques including UV, 1D and 2D NMR, and HRESIMS were used to determine the structures of the isolated xanthones. These xanthones were evaluated for their cytotoxicity toward human cancer cells, and compound 4 exhibited activity against HeLa cells. A cytotoxic mechanism examination revealed the active compound induced cell apoptosis by arresting the cell cycle, increasing the levels of ROS, and inhibiting the expression of p-STAT3 in HeLa cells. In in vivo zebrafish experiments, compound 4 was found to block tumor proliferation and migration and have antiangiogenetic activity, and thus seems worthy of further laboratory evaluation.

An evaluation of the genotoxicity and subchronic toxicity of the peel extract of Ponkan cultivar 'Ohta ponkan' (Citrus reticulata Blanco) that is rich in nobiletin and tangeretin with anti-dementia activity.

Nobiletin and tangeretin are major components of polymethoxylated flavones in the peels of citrus fruits such as Citrus reticulata. Because nobiletin and tangeretin have attracted attention due to their beneficial health properties, citrus peel extracts, in which they are concentrated, have the potential to serve as a functional food ingredient to prevent diseases. In this study, a series of toxicological studies on the peel extract of Ponkan cultivar 'Ohta ponkan' (Citrus reticulata Blanco), was conducted. No mutagenic activity was observed in a bacterial reverse mutation test, whereas chromosomal aberrations were induced in an in vitro mammalian chromosomal aberration test. No genotoxicity was observed in an in vivo mammalian micronucleus test. In a 90-day study at daily doses of 54, 180, or 540 mg/kg body weight (bw)/day, hyaline droplet nephropathy, which specifically occurs in adult male rats, was observed in males of 540 mg/kg bw/day group. No other adverse effects were observed in the 90-day study. The no adverse effect level in the 90-day study was considered to be 540 mg/kg bw/day for female rats and less than 540 mg/kg bw/day for male rats.

Bioactive Diterpenoids from the Stems of Euphorbia royleana.

Two ingenane- (1 and 2), two ent-atisane- (3 and 4), two ent-kaurane- (5 and 6), two ent-abietane- (7 and 8), and one ent-isopimarane-type (9) diterpenoid and 12 known analogues have been isolated from the methanolic extract of the stems of Euphorbia royleana. Their structures, including absolute configurations, were determined by extensive spectroscopic methods and ECD data analysis. The nitric oxide inhibitory activities of those diterpenoids were examined biologically in lipopolysaccharide-stimulated BV-2 cells, with compounds 1, 2, 5-7, 10, and 12 having IC50 values lower than 40 µM. Molecular docking was used to investigated the possible mechanism of compounds 1, 2, 5-7, 10, and 12.

Bioactive Diterpenoids from the Stems of Euphorbia antiquorum.

A total of 18 diterpenoids, including 10 new analogues (1-10), were isolated from Euphorbia antiquorum. The structures were characterized by spectroscopic techniques, and circular dichroism data analysis was adopted to confirm the absolute configurations of 1-10. Compounds 1-9 were classified as ent-atisane diterpenoids, and 10 was assigned as an ent-kaurane diterpenoid. The biological evaluation of nitric oxide (NO) production inhibition was conducted, and all of these isolates showed the property of inhibiting NO generation in lipopolysaccharide-induced BV-2 cells. Further research on molecular docking disclosed the affinities between the diterpenoids obtained and inducible nitric oxide synthase.

Withanolides from Physalis peruviana showing nitric oxide inhibitory effects and affinities with iNOS.

A phytochemical study to obtain new nitric oxide (NO) inhibitors resulted in the isolation of five new withanolides from the whole plants of Physalis peruviana. The structures were determined on the basis of extensive NMR spectroscopic data analysis as well as the time-dependent density functional theory (TDDFT) electronic circular dichroism (ECD) calculations. The NO inhibitory effects were examined by inhibiting NO release in lipopolysaccharide-stimulated murine microglial BV-2 cells. Molecular docking studies showed the strong interactions of bioactive compounds with the inducible nitric oxide synthase (iNOS) protein, revealing the potential mechanism of NO inhibition of bioactive compounds.

Bioactive terpenoids from Euonymus verrucosus var. pauciflorus showing NO inhibitory activities.

In our continuous search for new nitric oxide (NO) inhibitory compounds as potential anti-inflammatory agents or lead compounds for inflammatory diseases, the chemical constituents of Euonymus verrucosus var. pauciflorus were investigated, leading to the isolation of eleven terpenoids including six new diterpenoids, designated as euonymupenes A-F. The structures were elucidated on the basis of NMR and ECD data analysis. Euonymupenes A, C, and F feature rare labdane-type norditerpenoid skeletons. The NO inhibitory effects were evaluated and all of the isolates were found to inhibit lipopolysaccharide (LPS)-induced NO production in murine microglial BV-2 cells. Western blotting analysis indicated that the most active compound (5) can regulate iNOS (inducible nitric oxide synthase) expression. The further molecular docking studies exhibited the affinities of bioactive compounds with iNOS.

NO inhibitory phytochemicals as potential anti-inflammatory agents from the twigs of Trigonostemon heterophyllus.

Studies on the relationship of nitric oxide (NO) and inflammation have revealed that compounds with NO inhibitory effects are potentially useful for inflammation and related inflammatory disorders. A phytochemical investigation to obtain new NO inhibitors resulted in the isolation of two new cleistanthane diterpenoids (1 and 2) and 11 known terpenoids (3-13) from Trigonostemon heterophyllus. The structures of these terpenoids were established by analysis of their NMR, MS, and electronic circular dichroism (ECD) data. Compounds 1 and 2 possess rare 3,4-seco-cleistanthane diterpenoid skeletons. All of the isolates were evaluated biologically for their NO inhibitory effects in lipopolysaccharide (LPS)-induced murine microglial BV-2 cells and compounds 1, 6, and 8-10 showed strong NO inhibitory effects with IC50 values less than 40 µM. Using Western blotting experiments and molecular docking, the possible mechanism of NO inhibition was investigated.

Cytotoxic clerodane diterpenoids from the leaves of Casearia kurzii.

A phytochemical investigation to obtain bioactive substances as lead compounds or agents for cancer led to the obtainment of six new clerodane diterpenoids, designated as kurzipenes A-F (1-6), from the leaves of Casearia kurzii. Their structures were elucidated on the basis of NMR spectroscopic data analysis and the absolute configurations were confirmed by the time-dependent density functional theory (TDDFT) electronic circular dichroism (ECD) calculations. The cytotoxic activities of compounds 1-6 were evaluated against human lung cancer A549 cell line, human cervical cancer Hela cell line, and human hepatocellular carcinoma HepG2 cell line. Most diterpenoids showed potent cytotoxicities against the three selected cancer cell lines. The preliminary mechanism studies revealed that the most active compound 2, with an IC50 value of 5.3 µM against Hela cells, induced apoptosis and arrested the Hela cell cycle at the G0/G1 stage to exert cytotoxic effects.

Nitric oxide inhibitory limonoids as potential anti-neuroinflammatory agents from Swietenia mahagoni.

Recent studies have revealed that there is a close relationship between neuroinflammation and Alzheimer's disease (AD) and compounds with anti-neuroinflammatory effects are potentially useful for the treatment of AD. A phytochemical investigation to obtain new neuroinflammatory inhibitors resulted in the isolation of four new and three known limonoids from Swietenia mahagoni. The structures of these limonoids were established by NMR, MS, and electronic circular dichroism (ECD) data analysis. Compounds 1-3 feature complicated polycyclic caged structures of limonoid orthoester and represent new examples of phragmalin-type limonoids. All of the isolates showed anti-neuroinflammatory activities by inhibiting nitric oxide (NO) release in LPS-induced murine microglial BV-2 cells with compounds 1 and 3-6 having IC50 values of 26.8, 26.1, 26.0, 37.1, and 16.5 µM, respectively. The possible mechanism of NO inhibition of some bioactive compounds was also investigated using molecular docking, which revealed the interactions of bioactive compounds with the inducible nitric oxide synthase (iNOS) protein.

Cytotoxic diterpenoids as potential anticancer agents from the twigs of Casearia kurzii.

A search for bioactive natural products as anticancer lead compounds has led to the isolation of five new clerodane diterpenoids (1-5) from the twigs of Casearia kurzii. Their structures were elucidated by extensive analysis of their NMR, IR, and HRESIMS data, and the absolute configurations were determined by experimental and calculated electronic circular dichroism (ECD) data analysis. The isolates were biologically evaluated and showed cytotoxic activities toward human lung cancer cells (A549), human cervical cancer cells (HeLa), and human hepatocellular carcinoma cells (HepG2). The most active compound (5) with an IC50 value of 5.3 µM against HeLa cells, was found to induce apoptosis and arrest the HeLa cell cycle at G0/G1 stage to exert cytotoxic effects.

Potential Benefits of Nobiletin, A Citrus Flavonoid, against Alzheimer's Disease and Parkinson's Disease.

Alzheimer's disease (AD), which is characterized by the presence of amyloid-ß (Aß) plaques and neurofibrillary tangles, accompanied by neurodegeneration, is the most common form of age-related neurodegenerative disease. Parkinson's disease (PD) is the second most common neurodegenerative disease after AD, and is characterized by early prominent loss of dopaminergic neurons in the substantia nigra pars compacta. As currently available treatments are not able to significantly alter the progression of these diseases, successful therapeutic and preventive interventions are strongly needed. In the course of our survey of substances from natural resources having anti-dementia and neuroprotective activity, we found nobiletin, a polymethoxylated flavone from the peel of Citrus depressa. Nobiletin improved cognitive deficits and the pathological features of AD, such as Aß pathology, hyperphosphorylation of tau, and oxidative stress, in animal models of AD. In addition, nobiletin improved motor and cognitive deficits in PD animal models. These observations suggest that nobiletin has the potential to become a novel drug for the treatment and prevention of neurodegenerative diseases such as AD and PD.

NO inhibitory constituents as potential anti-neuroinflammatory agents for AD from Blumea balsamifera.

Our continuous search for new nitric oxide (NO) inhibitory substances as anti-neuroinflammatory agents for AD resulted in the isolation of one new labdane diterpenoid and three new guaiane sesquiterpenoids, as well as ten known compounds from Blumea balsamifera. Their structures were elucidated by NMR spectroscopic data analysis and the time-dependent density functional theory (TDDFT) electronic circular dichroism (ECD) calculations. The anti-neuroinflammatory effects were examined by inhibiting NO release in LPS-induced murine microglial BV-2 cells. The possible mechanism of NO inhibition of some bioactive compounds was also investigated using molecular docking, which revealed the interactions of bioactive compounds with the iNOS protein.

Nitric oxide inhibitors with a spiro diterpenoid skeleton from Scutellaria formosana: Structures, NO inhibitory effects, and interactions with iNOS.

A phytochemical investigation to obtain new NO inhibitors resulted in the isolation of five new spiro diterpenoids (1 -5) from the aerial parts of Scutellaria formosana. The structures were elucidated on the basis of extensive 1D and 2D NMR spectroscopic data analysis, and the absolute configurations of these compounds were established via comparison of experimental and calculated electronic circular dichroism (ECD) spectra. The nitric oxide (NO) inhibitory effects were evaluated and all of the compounds showed inhibitory effects on lipopolysaccharide-induced NO production in murine microglial BV-2 cells. The possible mechanism of NO inhibition of bioactive compounds was also investigated using molecular docking, which revealed the interactions of bioactive compounds with the iNOS protein.

NO inhibitors function as potential anti-neuroinflammatory agents for AD from the flowers of Inula japonica.

The extensive pathology studies revealed that Alzheimer's disease (AD) is closely related to neuroinflammation and anti-neuroinflammatory agents may be potentially useful for the treatment of AD. Inula japonica is a member of the Asteraceae plant family and its flowers have been used as a healthy tea and a traditional Chinese medicine. Our continuous search for new nitric oxide (NO) inhibitory substances as anti-neuroinflammatory agents for AD resulted in the isolation of two new sesquiterpenes and ten known terpenes from the flowers of I. japonica. Their structures were established on the basis of extensive analysis of NMR and MS spectroscopic data, as well as calculated and experimental electronic circular dichroism (ECD) spectra. Among these isolates, compound 1 is a new sesquiterpene with a rare tricyclic fused skeleton, and 2 processes a 1,10-seco-eudesmane skeleton. The anti-neuroinflammatory effects were examined by inhibiting NO release in LPS-induced murine microglial BV-2 cells. The possible mechanism of NO inhibition was also investigated using molecular docking, which revealed the interactions of bioactive compounds with the iNOS protein. The present study disclosed that the flowers of I. japonica as a healthy tea are potentially useful for AD and related neuroinflammatory diseases.

Nobiletin Reduces Intracellular and Extracellular ß-Amyloid in iPS Cell-Derived Alzheimer's Disease Model Neurons.

Alzheimer's disease (AD) is the most common cause of dementia, with progressive memory impairment. Recently, neprilysin, a ß-amyloid (Aß)-degrading enzyme has become featured as a drug target for AD. Previously, we identified nobiletin from citrus peels as a natural compound possessing anti-dementia activity. In addition, we demonstrated that nobiletin improved memory in memory-impaired animals and, further, that Aß levels were markedly decreased in the brains of these animals. We demonstrated in vitro that nobiletin up-regulates neprilysin expression and activity in human neuroblastoma cells. However, the action of nobiletin with regard to Aß degradation under in vitro AD pathological conditions remains unclear. In this study, we examined whether nobiletin could enhance the degradation of intra- and extracellular Aß using human induced pluripotent stem cell-derived AD model neurons, which generate an excess of Aß1-42 due to the familial AD presenilin-1 mutation. The neurons were treated in the presence or absence of nobiletin. The results of real-time quantitative RT-PCR indicated that neprilysin mRNA levels were significantly up-regulated by nobiletin. Furthermore, immunostaining with an anti-Aß antibody revealed that nobiletin substantially reduced the intraneuronal content of Aß. Interestingly, the results of Aß1-42 immunoassays confirmed that nobiletin also significantly decreased the levels of Aß1-42 released into the cellular medium. These results suggest that nobiletin enhanced the reduction of intra- and that extracellular Aß levels under AD pathologic conditions, and this is associated with the up-regulation of neprilysin expression. Collectively, nobiletin appears to be a promising novel prophylactic seed drug or functional food for AD.

Natural NO inhibitors from the leaves of Callicarpa kwangtungensis: Structures, activities, and interactions with iNOS.

A phytochemical investigation to obtain new NO inhibitors resulted in the isolation of a new diterpenoid with a rare 9,10-seco-abietane skeleton (1) and twelve known terpenoids (2-13) from Callicarpa kwangtungensis. Their structures were elucidated on the basis of extensive 1D and 2D NMR spectroscopic data analyses, and the absolute configuration of compound 1 was established by comparison of the calculated and experimental electronic circular dichroism (ECD) spectra. The inhibitory activities on lipopolysaccharide-induced NO production in murine microglial BV-2 cells of these terpenoids were evaluated, and all of the compounds showed inhibitory effects. The following molecular docking studies showed interactions of the bioactive compounds with the iNOS protein.

Phytochemicals with NO inhibitory effects and interactions with iNOS protein from Trigonostemon howii.

A phytochemical investigation to obtain new NO inhibitors led to the isolation of nine compounds including one new guaiane-type sesquiterpenoid (1) and two new cleistanthane diterpenoids (2 and 3) from the stems of Trigonostemon howii. Their structures were elucidated on the basis of extensive 1D and 2D NMR spectroscopic data analysis, and the absolute configurations of new compounds 1-3 were established via comparison of experimental and calculated electronic circular dichroism (ECD) spectra. Compounds 2 and 3 possess a rare 3,4-seco-cleistanthane diterpenoid skeleton. All of the compounds showed inhibitory effects on lipopolysaccharide-induced NO production in murine microglial BV-2 cells. The further molecular docking studies indicated the strong interactions between some bioactive compounds with the iNOS protein, which revealed the possible and potential mechanism of NO inhibition of bioactive compounds.

Nitric oxide inhibitory daphnane diterpenoids as potential anti-neuroinflammatory agents for AD from the twigs of Trigonostemon thyrsoideus.

The extensive pathology studies revealed that Alzheimer's disease (AD) is closely related to neuroinflammation and anti-neuroinflammatory agents may be potentially useful for the treatment of AD. A continuous search for new nitric oxide (NO) inhibitory compounds as anti-neuroinflammatory agents for AD resulted in the isolation of four new (1-4) and eight known (5-12) daphnane diterpenoids from the twigs of Trigonostemon thyrsoideus. Their structures were elucidated on the basis of extensive nuclear magnetic resonance (NMR) spectroscopic data analysis and the time-dependent density functional theory (TDDFT) electronic circular dichroism (ECD) calculations. Compounds 1-4 represent new examples of daphnane diterpenoid orthoesters and 4 features a rare and complex macroring diterpenoid structure. The anti-neuroinflammatory effects were examined by inhibiting NO release in lipopolysaccharide (LPS)-induced murine microglial BV-2 cells. The possible mechanism of NO inhibition of some bioactive compounds was also investigated using molecular docking, which revealed the interactions of bioactive compounds with the inducible nitric oxide synthase (iNOS) protein.

Polycyclic phloroglucinols as PTP1B inhibitors from Hypericum longistylum: Structures, PTP1B inhibitory activities, and interactions with PTP1B.

Protein tyrosine phosphatase 1B (PTP1B) has been regarded asa target for the research and development of new drugs to treat type II diabetes and PTP1B inhibitors are potential lead compounds for this type of new drugs. A phytochemical investigation to obtain new PTP1B inhibitors resulted in the isolation of four new phloroglucinols, longistyliones A-D (1-4) from the aerial parts of Hypericum longistylum. The structures of 1-4 were elucidated on the basis of extensive 1D and 2D NMR spectroscopic data analysis, and the absolute configurations of these compounds were established by comparing their experimental electronic circular dichroism (ECD) spectra with those calculated by the time-dependent density functional theory method. Compounds 1-4 possess a rare polycyclic phloroglucinol skeleton. The following biological evaluation revealed that all of the compounds showed PTP1B inhibitory effects. The further molecular docking studies indicated the strong interactions between these bioactive compounds with the PTP1B protein, which revealed the possible mechanism of PTP1B inhibition of bioactive compounds. All of the results implied that these compounds are potentially useful for the treatment of type II diabetes.

Bioactive diterpenoids from Trigonostemon chinensis: Structures, NO inhibitory activities, and interactions with iNOS.

A phytochemical investigation to obtain new NO inhibitors led to the isolation of two new (1 and 2) and four known (3-6) diterpenoids from Trigonostemon chinensis. Their structures were elucidated on the basis of extensive 1D and 2D NMR spectroscopic data analyses, and the absolute configurations of new compounds were established by experimental and calculated ECD spectra. The inhibitory activities on lipopolysaccharide-induced NO production in murine microglial BV-2 cells of these diterpenoids were evaluated, and all of the compounds showed inhibitory effects. The interactions of bioactive compounds with iNOS protein were also studied by molecular docking.