Three new acridone alkaloids from Glycosmis lanceolata (Blume) D.Dietr. and their cytotoxic effects on tumour cell lines.

We separated and structurally elucidated three new acridone alkaloids (glycomontamine A (1), B (2), and C (3)), together with three known compounds (glycofoline, kokusaginine and dictamnine) from the acetone extract of Glycosmis lanceolata (Blume) D.Dietr. branches collected in Thailand. The compounds were assayed for cell viability using human lung adenocarcinoma cell line A549, breast adenocarcinoma cell line T47D, cervix epithelioid carcinoma cell line Hela, acute lymphoid leukaemia B cell line NALM-6, and human dermal fibroblasts. The viability of Hela cells treated with compound 1 (IC50 17.6 µM) and T47D cells treated with compound 2 (IC50 17.4 µM) decreased dose-dependently. Both compounds also showed cytotoxicity against NALM-6 cells (IC50 16.5 and 9.3 µM). Additionally, compound 1 decreased the mitochondrial membrane potential of Hela cells, whereas compound 2 did not change the mitochondrial membrane potential in T47D cells.

Three phlorotannins from Sargassum carpophyllum are effective against the secretion of allergic mediators from antigen-stimulated rat basophilic leukemia cells.

Sargassum carpophyllum (Sargassaceae) is a brown seaweed that contains phlorotannins, which are phloroglucinol polymers with reported anti-inflammatory activities. The phlorotannins 2-[2-(3,5-dihydroxyphenoxy)-3,5-dihydroxyphenoxy]-1,3,5-benzenetriol (1), 2,2'-[[2-(3,5-dihydroxyphenoxy)-5-hydroxy-1,3-phenylene]bis(oxy)]bis(1,3,5-benzenetriol) (2), and 2-[2-[4-[2-(3,5-dihydroxyphenoxy)-3,5-dihydroxyphenoxy]-3,5-dihydroxyphenoxy]-3,5-dihydroxyphenoxy]-1,3,5-benzenetriol (3) were isolated from S. carpophyllum. Here, we evaluated the anti-allergic activities of these compounds and comprehensively explored their effects on intracellular protein levels. Immunoglobulin E-sensitized rat basophilic leukemia cells pretreated with any of these three compounds exhibited reduced ß-hexosaminidase, prostaglandin D2, and tumor necrosis factor-α secretion compared with dinitrophenyl-human serum albumin (DNP-HSA)-stimulated cells. Reduction of ß-hexosaminidase release was dose-dependent but the half-maximal inhibitory concentrations of the compounds were similar (36-51 µM). Proteomics analysis revealed that the three compounds up-regulated 25 proteins and down-regulated 33 proteins compared with DNP-HSA stimulation alone, and slightly suppressed proteasome 5 expression linked to the regulation of IκB. These results demonstrate that these phlorotannins are potentially useful for preventing immediate hypersensitivity. S. carpophyllum may be a functional food.

Four new isoflavones from Derris scandens and their in vitro antiproliferative effects.

Four new compounds (derriscandenon D (1), E (2), F (3), G (4)) and six known isoflavones (warangalone (5), millewanin E (6), rhynedlin A (7), 6,8-diprenylgenistein (8), isolupalbigenin (9), isoscandinone (10)) were isolated from the acetone extract of the branches of Derris scandens. These compounds were assayed for cell viability using the human lung carcinoma cell line A549, colorectal carcinoma cell line Colo205, epidermoid carcinoma cell line KB, the human acute lymphoblastic leukaemia cell line NALM-6, and human dermal fibroblasts. Compounds 2 and 3 significantly decreased the viability of KB cells, with IC50 values of 2.7 and 12.9 µM, respectively. In addition, compounds 2 and 3 reduced the mitochondrial membrane potential in KB cells. Compounds 2 and 3 strongly down-regulated the cell viability of cell lines KB and NALM-6, achieving IC50 values of 2.7 and 0.9 µM, respectively, compared with the positive control staurosporine at 1.25 and 0.01 µM, respectively.

Cytotoxic activity of dimeric acridone alkaloids derived from Citrus plants towards human leukaemia HL-60 cells.

OBJECTIVES: Acridone alkaloids from Citrus and their derivatives show various kinds of biological activity. However, the anticancer activities of dimeric acridone alkaloids with unique structures and the molecular mechanism of these effects are poorly understood. METHODS: We investigated the cytotoxicity effects of dimeric acridone alkaloids isolated from Marsh grapefruit on human myeloid leukaemia HL-60 cells. KEY FINDINGS: Of the six dimeric acridone alkaloids tested, citbismine-E, the most potent, dose- and time-dependently decreased HL-60 cell viability by inducing apoptosis. The treatment of HL-60 cells with citbismine-E yielded a significant increase in levels of intracellular reactive oxygen species (ROS). Citbismine-E lowered the mitochondrial membrane potential and increased the activities of caspase-9 and -3. In addition, citbismine-E-induced apoptosis, decrease in mitochondrial membrane potential and caspase activation were significantly alleviated by pretreatment of the cells with antioxidant N-acetylcysteine (NAC). Citbismine-E induced intrinsic caspase-dependent apoptosis through ROS-mediated c-Jun N-terminal kinase activation. Citbismine-E-induced production of oxidative stress biomarkers, malondialdehyde and 8-hydroxy-2'-deoxyguanosine was also attenuated by pretreatment with NAC. CONCLUSIONS: Citbismine-E is a powerful cytotoxic agent against HL-60 cells that acts by inducing mitochondrial dysfunction-mediated apoptosis through ROS-dependent JNK activation. Citbismine-E also induced oxidative stress damage via ROS-mediated lipid peroxidation and DNA damage in HL-60 cells.

Three isoflavones from Derris scandens (Roxb.) Benth and their cancer chemopreventive activity and in vitro antiproliferative effects.

Three undescribed isoflavones, derriscandenon A, B, and C, together with seven known isoflavones were isolated and structurally characterized during a study of the chemical constituents in the leaves of Derris scandens (Roxb.) Benth (Leguminosae, Fabaceae) collected in Bangladesh. The inhibitory activity of the compounds against activation of Epstein-Barr virus antigen (EBV-EA) by 12-O-tetradecanoylphorbo-13-acetate (TPA) was measured to identify possible chemopreventive agents. Mild inhibitory effects (IC50 278-290 mol ratio/32 pmol TPA) against EBV-EA induction compared with curcumin (IC50 341 mol ratio/32 pmol TPA) were observed for four known compounds (lupalbigenin, isopalbigenin, glyurallin, and isangustone A). Next, we focused on antitumor effects and investigated cell viability, cell proliferation, and mitochondria membrane potential by using an MTT assay, a live cell monitoring system, and fluorescence staining. Of the seven isoflavones tested for cell viability, a dose-dependent decrease in cell viability was observed for four isoflavones (derriscandenon B and C, derrubone, and glyurallin) in KB cells and two compounds (derriscandenon B and isochandaisone) in NALM6-MSH+ cells. In addition, the proliferation of KB cells was significantly inhibited by these four compounds at a concentration of 5 µM. The mitochondria membrane potentials of KB cells treated with derriscandenon C, derrubone, and glyurallin at the IC50 concentration were decreased by about 55%, whereas undescribed compound derriscandenon B had no effect. Our results show that some of the compounds isolated from D. scandens may be suitable as seed compounds for cancer prevention and therapy.

Acrofolione A and B, acetophenone dimers from Acronychia pendunculata, induce an apoptotic effect on human NALM-6 pre-B cell leukaemia cells.

OBJECTIVES: We investigated the apoptotic activities of acrofolione A (1) and B (2) isolated from Acronychia pedunculata against a human pre-B cell leukaemia cell line (NALM-6) to explore the apoptosis-related signalling molecules targeted by 1 and 2. METHODS: The apoptosis effects of 1 and 2 in NALM-6 cells were investigated by TUNEL staining, annexin V, mitochondria membrane potential and caspase 3/7 activity. We carried out a protein array to explore the signalling molecules involved in apoptosis comprehensively. KEY FINDINGS: Acrofolione A (1) suppressed the growth of NALM-6, K562 and HPB-ALL cells (IC50 16.7 ± 1.9, 17.9 ± 0.3 and 10.1 ± 0.2 µm, respectively) more effectively than acrofolione B (2). Both compounds time-dependently increased the number of NALM-6 cells with abnormal nuclei, and increased the number of annexin V-positive cells and decreased the mitochondrial membrane potential of NALM-6 cells. Acrofolione A (1) markedly elevated caspase 3/7 activity and increased the number of TUNEL-positive cells. Cells treated with either compound showed enhanced expression of cleaved PARP and cleaved caspase 3 and 7, and reduced survivin protein levels. CONCLUSIONS: Acrofolione A (1) and B (2) may be useful in the treatment of various types of leukaemia.

Anti-cell proliferation effect of naphthoquinone dimers isolated from Plumbago zeylanica.

Study of the chemical constituents of the roots of Plumbago zeylanica L. collected in Taiwan led to the isolation and identification of a new naphthoquinone dimer, plumzeylanone (1), along with eight known compounds (2-9). Nine naphthoquinones isolated from this plant were assayed for cell growth inhibition activity using NALM-6 (human B cell precursor leukaemia), A549 (human lung adenocarcinoma), Colo205 (human colorectal adenocarcinoma) and KB (human epidermoid carcinoma). Plumzeylanone (1), a novel plumbagin dimer, suppressed cell proliferation in only NALM-6 cells (IC50 3.98 µM). However, maritinone (9) showed strong inhibition of cell growth in all cell lines tested (0.12 < IC50 < 9.06 µM). This compound appeared to affect the cell cycle.

Four New Xanthones from Cratoxylum cochinchinense and Their In Vitro Antiproliferative Effects.

The study of the chemical constituents of branches and twigs of Cratoxylum cochinchinense collected in Singapore led to the isolation and structural elucidation of four new xanthones, named cratoxanthone A (1), B (2), C (3), and D (4), together with six known xanthones (5-10) and one known dihydroanthracenone (11). Eight xanthones (including 1 and 2) and 11 were tested for their antiproliferative activity in three human carcinoma cell lines (lung adenocarcinoma A549, colorectal carcinoma Colo205, and epidermoid carcinoma KB) and a human acute lymphoblastic leukemia B cell line (NALM-6), and the mitochondrial membrane potential was determined in KB cells. New xanthones 1 and 2 attenuated NALM-6 cell proliferation with IC50 values of 17.78 and 8.27 µM, respectively. Furthermore, KB cells treated with these compounds had significantly decreased mitochondrial membrane potentials. Notably, the proliferation of A549 cells was specifically inhibited by 11, but not the xanthones.

Acetophenones Isolated from Acronychia pedunculata and their Anti-proliferative Activities.

Study of the chemical constituents of Acronychia pedunculata (L.) Miq. (Rutaceae) stems collected in Taiwan led to the isolation and identification of eight known and three new acetophenones, named acrophenone A (1), B (2), and C (3). Of them, acrovestone (5), acropyrone (6) and acrovestenol (7), which are dimer compounds, strikingly inhibited the proliferation of human leukemia cell lines.

Acetophenones from Acronychia pedunculata and their Cancer Chemopreventive Activity.

From the roots of Acronychia pedunculata (L.) Miq. (Rutaceae) collected in Taiwan, six known and three new acetophenones have been isolated. The new compounds were named acrophenones D (1), E (2), and F (3). Of the acetophenones isolated in this study, prenylacronylin (4) and acronyculatin D. (10) exhibited significant inhibitory activity against 12-0-tetradecanoylphorbol 13-acetate-induced Epstein-Barr virus early antigen activation in Raji cells.

Licarin A is a candidate compound for the treatment of immediate hypersensitivity via inhibition of rat mast cell line RBL-2H3 cells.

OBJECTIVES: We previously demonstrated that some phenylpropanoids are capable of inhibiting activated mast cells. This study evaluated the anti-allergic effects of licarin A, a neolignan isolated from various plants, on antigen-stimulated rat mast cell line. METHODS: The inhibitory effects of licarin A on histamine release, tumour necrosis factor-α (TNF-α) and prostaglandin D2 (PGD2) production, and cyclooxygenase-2 (COX-2) expression in dinitrophenyl-human serum albumin (DNP-HSA) rat basophilic leukemia cells (DNP-HSA-stimulated RBL-2H3 cells), were investigated by spectrofluorometry, ELISA and immunoblotting. KEY FINDINGS: Licarin A significantly and dose-dependently reduced TNF-α production (IC50 12.6 ± 0.3 µm) in DNP-HSA-stimulated RBL-2H3 cells. Furthermore, the levels of PGD2 secretion in DNP-HSA-stimulated cells pretreated with licarin A were lower than those stimulated with DNP-HSA alone (positive control). Treatment with licarin A at 20 µm produced slight suppression of DNP-HSA-induced increases in COX-2 mRNA and protein levels. We identified several signalling pathways that mediated these pharmacological effects. Licarin A treatment tended to reduce phosphorylated protein kinase C alpha/beta II (PKCα/ßII) and p38 mitogen-activated protein kinase (MAPK) protein levels. CONCLUSIONS: Our results demonstrate that licarin A reduces TNF-α and PGD2 secretion via the inhibition of PKCα/ßII and p38 MAPK pathways; this compound may be useful for attenuating immediate hypersensitivity.

Biphenyl derivatives from Garcinia schomburgkiana and the cytotoxicity of the isolated compounds.

Study of the chemical constituents of the stems of Garcinia schomburgkiana Pierre (Guttiferae), collected in Thailand, led to the isolation and identification of five known compounds and two new biphenyl derivatives, schomburgbiphenyl A (1) and B (2). Six phenolic compounds isolated from this plant were screened for their cell growth inhibition activity using several human leukemia cell lines. One compound, oblongifolin C (7), showed significant cytotoxic activity towards Jurkat, NALM6, K562 and HPB-ALL cells.

Inhibitory effect of carbazolequinone derivatives on lipopolysaccharide and interferon-γ-induced nitric oxide production in mouse macrophage RAW264.7 cells.

OBJECTIVES: The aim of this study was to examine the mechanism underlying the inhibitory effect of our synthesized carbazolequinone derivatives on nitric oxide (NO) production in activated macrophages. METHODS: Lipopolysaccharide (LPS) and interferon-γ (IFN-γ)-stimulated RAW264.7 macrophages were treated with carbazolequinone derivatives. The NO and prostaglandin E2 (PGE2 ) levels in cell culture supernatants fractions were measured by Greiss and ELISA assay, respectively. The expression of inducible NO synthase (iNOS) and cyclooxygenase-2 (COX-2) was assessed by the real-time RT-PCR method. Nuclear factor kappa B (NF-κB) activation was detected by an NF-κB-dependent luciferase reporter assay. KEY FINDINGS: Our synthesized carbazolequinone derivatives (7-methoxy-2-methylcarbazole-1,4-quinone, 6-methoxy-2-methylcarbazole-1,4-quinone and 6-chloro-2-methylcarbazole-1,4-quinone) significantly inhibited LPS/IFN-γ-induced NO production and iNOS expression in RAW264.7 cells. They also inhibited the LPS/IFN-γ-mediated induction of COX-2 expression and PGE2 production. In addition, the LPS/IFN-γ-induced transcription activity of NF-κB was attenuated. Using the RAW264.7-tsAM5NE co-culture system, we found that these carbazolequinone derivatives protected neuronally differentiated tsAM5NE cells from NO-induced cell death by inhibiting the production of NO. CONCLUSIONS: These results suggest that the three carbazolequinone derivatives inhibit LPS/IFN-γ-induced NO production via iNOS and COX-2 downregulation due to NF-κB inhibition. Therefore, these three carbazolequinone derivatives may be useful for developing a new drug against NO-mediated neurodegenerative diseases.

Lansiumamide B and SB-204900 isolated from Clausena lansium inhibit histamine and TNF-α release from RBL-2H3 cells.

AIMS AND OBJECTIVE: Mast cells play a central role in allergic and chronic inflammation. Extracts from Clausena lansium (Lour.) Skeels (Rutaceae) possess many pharmacological effects including anti-inflammatory, anti-oxidant, anti-cancer, and anti-trichomonal activities. In addition, the leaves and fruit are used in Chinese folk medicine. We have isolated and identified four known cinnamamides from this plant: lansiumamide C, lansamide I, lansiumamide B, and SB-204900. However, the biological activities of these compounds are not yet understood. The purpose of this paper is to clarify the pharmacological effects of these compounds on mast cells. METHODS: We measured inflammatory molecules in A23187-stimulated rat basophilic leukemia cells (RBL-2H3) treated with these compounds using HPLC, ELISA, and immunoblotting methods. In addition, some signaling molecules were investigated by immunoblotting. RESULTS: Lansamide I, lansiumamide B, and SB-204900 significantly decreased histamine release. Furthermore, lansiumamide B- and SB-204900-treated cells also reduced the protein and/or mRNA levels of TNF-α. SB-204900 markedly suppressed the phosphorylation of p38 MAPK. CONCLUSION: Our findings suggest that lansiumamide B and SB-204900 attenuate mast-cell-induced inflammation.

A novel trans-4-hydroxycinnamic acid derivative from Meyer lemon (Citrus meyeri).

Isolation and structural elucidation of a new trans-4-hydroxycinnamic acid derivative from Meyer lemon (Citrus meyeri hort. ex Y. Tanaka) was carried out. The derivative exhibited the antioxidative activity by ORAC (oxygen radical absorbance capacity) assay and was found in the flavedo and alvedo of Meyer lemon peel.

Apoptosis of HL-60 leukemia cells induced by carbazole alkaloids isolated from Murraya euchrestifolia.

We carried out primary screening of 13 carbazole alkaloids isolated from the plant species Murraya euchrestifolia (Rutaceae) on cell growth inhibition of the human leukemia cell line HL-60. Among them, murrayafoline-A (1) and murrayazolinine (7) exhibited significant growth suppression due to apoptosis mediated by the activation of the caspase-9/caspase-3 pathway.

Rotenoid derivatives from Derris trifoliata with nitric oxide production inhibitory activity.

Study of the chemical constituents of the stems of Derris trifoliata Lour. (Leguminosae) collected in Singapore led to the isolation and identification of three known and two new rotenoid derivatives. The new derivatives, named derrisfolin A (1) and B (2), inhibited nitric oxide production in murine macrophage-like RAW 264.7 cells stimulated with interferon-gamma and lipopolysaccharide.

Lapachol suppresses cell proliferation and secretion of interleukin-6 and plasminogen activator inhibitor-1 of fibroblasts derived from hypertrophic scars.

OBJECTIVES: The pathogenesis and therapy of hypertrophic scar have not yet been established. Our aim was to investigate the antiproliferative and antisecretory effects of lapachol, isolated from the stem bark of Avicennia rumphiana Hall. f., on hypertrophic scar fibroblasts. METHODS: The effects of lapachol on hypertrophic scar fibroblast proliferation were measured using the MTT assay, cell-cycle analyses and lactate dehydrogenase assays. The type I collagen α-chain (COL1A1), interleukin-6 (IL-6) and plasminogen activator inhibitor-1 (PAI-1) mRNA and/or protein levels of hypertrophic scar-fibroblasts were quantitated by real-time PCR and ELISA. KEY FINDINGS: Lapachol at 25 and 50 µm significantly inhibited the in vitro proliferation of hypertrophic scar fibroblasts, but not fibroblasts from non-lesional skin sites. In addition, lapachol had no apparent effect on cell cycle and lactate dehydrogenase activity in conditioned medium from lapachol-treated hypertrophic scar fibroblasts was nearly equal to that in medium from vehicle-treated cells. Lapachol treatment also inhibited COL1A1 and PAI-1 mRNA levels in hypertrophic scar fibroblasts, but did not affect IL-6 mRNA levels. The protein levels of IL-6 and PAI-1 in conditioned medium from hypertrophic scar fibroblasts treated with 50 µm lapachol were lower than those from vehicle-treated hypertrophic scar fibroblasts. CONCLUSIONS: Lapachol decreased the proliferation rate of hypertrophic scar fibroblasts. As IL-6 and PAI-1 secretion was also lowered in lapachol-treated hypertrophic scar fibroblasts, our findings suggested that lapachol may have suppressed extracellular matrix hyperplasia in wound healing and possibly alleviated the formation of hypertrophic scar.

Evaluation of flavoglaucin, its derivatives and pyranonigrins produced by molds used in fermented foods for inhibiting tumor promotion.

Flavoglaucin, its derivatives, and pyranonigrins, which are antioxidants produced by the molds used in fermented foods, were examined for their inhibition of tumor promotion by the Epstein-Barr virus early antigen activation test. Flavoglaucin and its derivatives exhibited high activity. Flavoglaucin and such a derivative as isodihydroauroglaucin inhibited mouse skin tumor promotion in a two-stage carcinogenesis test and appear to be antitumor promoters.

Antioxidants produced by Eurotium herbariorum of filamentous fungi used for the manufacture of karebushi, dried bonito (Katsuobushi).

Extracts prepared by culturing ten filamentous fungi from Aspergillus and Eurotium species isolated from dried bonito (katsuobushi) were examined for 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging capacity. The extracts prepared by culturing E. herbariorum NE-1 and NE-4, which are used in the molding process for the manufacture of karebushi (a kind of katsuobushi), were shown to have higher activity than the others. Five antioxidants were isolated from the extracts and identified as isodihydroauroglaucin (IDAG), auroglaucin (AG), dihydroauroglaucin (DAG), tetrahydroauroglaucin (TAG), and flavoglaucin (FG) by (1)H-NMR, (13)C-NMR, and EI-MS analyses. Compared with alpha-tocopherol, the isolated antioxidants exhibited high antioxidative activity for the radical scavenging capacity of DPPH and superoxide, but low activity for inhibiting the autoxidation of docosahexaenoic acid (DHA). The isolated antioxidants were produced by the Eurotium species, but not by the Aspergillus species. DAG and TAG exhibited higher radical scavenging capacity than the other antioxidants and were abundantly contained in the extracts of E. herbariorum NE-1 and NE-4.