Anti-HIV and cytotoxic biphenyls, benzophenones and xanthones from stems, leaves and twigs of Garcinia speciosa.

Eleven previously undescribed compounds, including four benzophenones (garciosones A-D), four xanthones (garciosones E-H) and three biphenyls (garciosines A-C), along with eighteen known compounds were isolated from the stems, leaves and twigs of Garcinia speciosa Wall. (Clusiaceae). Their structures were established by extensive spectroscopic analysis. For garciosines A-C, the structures were confirmed by single crystal X-ray diffraction analysis. Most of the isolated compounds were evaluated for their cytotoxic activity and anti-HIV-1 activity using the syncytium inhibition assay and HIV-1 reverse transcriptase (RT) assay. The known compounds, 4,6,3',4'-tetrahydroxy-2-methoxybenzophenone and macluraxanthone, displayed significant cytotoxic activity with the ED50 in the range of 1.85-11.76 µM. 1,5-Dihydroxyxanthone exhibited the most potent anti-HIV activity against syncytium formation with EC50 < 17.13 µM (SI > 25.28) and 2-(3,3-dimethylallyl)-1,3,7-trihydroxyxanthone was the most active compound in the HIV-1 reverse transcriptase assay with IC50 value of 58.24 µM. Structure-activity relationship of some isolated compounds were also discussed.

Polycyclic polyprenylated acylphloroglucinols and biphenyl derivatives from the roots of Garcinia nuntasaenii Ngerns. & Suddee.

Seven previously undescribed compounds, including three polycyclic polyprenylated acylphloroglucinols (garcinuntins A-C), three biphenyl derivatives (garcinuntabiphenyls A-C) and a lanostane triterpene (garcinuntine), along with thirteen known compounds were isolated from the root of Garcinia nuntasaenii Ngerns. & Suddee. Their structures were elucidated on the basis of spectroscopic techniques. For garcinuntins A-C, the absolute configurations were confirmed by the combination of single X-ray crystallography and ECD calculations. Anti-HIV activity using anti-HIV-1 reverse transcriptase and syncytium inhibition assays, and cytotoxic activity against a panel of cultured mammalian cancer cell lines of isolated compounds were investigated.

Cytotoxic lanostanes from fruits of Garcinia wallichii Choisy (Guttiferae).

Five new lanostanes, wallichinanes A-E (1-5) together with a known lanostane derivative 6 were isolated from the cytotoxic hexanes extract of fruits of Garcinia wallichii Choisy (Guttiferae). The structures of the isolated compounds were established by analysis of spectroscopic data, X-ray diffraction technique as well as comparison with the literature data. The cytotoxicity of all isolated compounds against a panel of cultured cancer cell lines was evaluated. Compound 4 exhibited good cytotoxicity with ED50 values ranging from 3.91 to 7.63µM.

A New Neolignan, and the Cytotoxic and Anti-HIV-1 Activities of Constituents from the Roots of Dasymaschalon sootepense.

Bioassay-guided isolation from the ethyl acetate extract of Dasymaschalon sootepense roots led to the isolation of twelve compounds including a new dihydrobenzo-furan neolignan, (+)-(2S,3S)-2,3-dihydro-2-(3,4-dimethoxyphenyl)-3-methylbenzofuran-5-carbaldehyde (5), and eleven known compounds (1-4, and 6-12). The chemical structures and stereochemistry of all the isolated compounds were established by spectroscopic techniques. The known compounds 4 and 6 have been fully characterized spectroscopically, including their absolute configurations. Cytotoxic and anti-HIV-1 reverse transcriptase (RT) activities of compounds 1-3, 5 and 8-12 were determined. Among compounds screened, compounds 2, 3 and 10 displayed weak cytotoxic activity with ED50 values ranging from 9.6-47.5 µM and only compound 2 was found weakly active against HIV-1 RT with an IC50 value of 323.2 µM.

Protective effect of diarylheptanoids from Curcuma comosa on primary rat hepatocytes against t-butyl hydroperoxide-induced toxicity.

CONTEXT: Curcuma comosa Roxb. (Zingiberaceae) has traditionally been used as an anti-inflammatory agent in liver, and recent study has shown its hepatoprotective effect against CCl4-induced liver injury in vivo. OBJECTIVE: This study further assesses the protective effect of C. comosa extracts and its isolated compounds against tert-butyl hydroperoxide (t-BHP)-induced hepatotoxicity in isolated primary rat hepatocytes. MATERIALS AND METHODS: Isolated primary hepatocytes were pretreated with either ethanol (5-50 µg/ml) or hexane extract (1-50 µg/ml), or two diarylheptanoids (4-35 µM): compound D-91 [1-(4-hydroxyphenyl)-7-phenyl-(6E)-6-hepten-3-ol] and compound D-92 [(3S)-1-(3,4-dihydroxyphenyl)-7-phenyl-(6E)-6-hepten-3-ol], from C. comosa for 2 h prior to exposure to 1.5 mM t-BHP for 15 and 30 min. Their hepatoprotective activities were then determined. RESULTS: t-BHP markedly caused the formation of MDA and ALT leakage from the hepatocytes. Pretreatment with the C. comosa ethanol extract showed greater protective effect than the hexane extract, and the effect was concentration related. Treating the hepatocytes with compound D-92 provided greater protective effect than compound D-91. IC50 values of compounds D-91, D-92, and silymarin for the protection of ALT leakage at 30 min were 32.7 ± 1.1, 9.8 ± 0.7, and 160 ± 8 µM, respectively. Further investigation showed that compound D-92 was more effective in maintaining the intracellular glutathione content in the t-BHP treated group, whereas the reduction in antioxidant enzymes, glutathione peroxidase and glutathione-S-transferase activities, were not improved. DISCUSSION AND CONCLUSION: Results suggest that diarylheptanoids are the active principles that provide protection against t-BHP-induced injury. Their ability to maintain intracellular glutathione content is the main mechanisms underlying the protective action.

Polyoxygenated cyclohexene derivatives isolated from Dasymaschalon sootepense and their biological activities.

Six new naturally occurring polyoxygenated cyclohexene derivatives together with eight related known derivatives, two known alkaloids, and two known flavonoid derivatives were isolated from bioassay-guided fractionation of the ethyl acetate extract of the leaves and twigs of Dasymaschalon sootepense. The structure elucidation and determination of absolute configurations were established by various spectroscopic methods, X-ray diffraction techniques as well as comparison with the literature data. Several isolated compounds were evaluated for their cytotoxic, anti-HIV-1 RT and anti-inflammatory activities.

Autophagy inhibition by caffeine increases toxicity of methamphetamine in SH-SY5Y neuroblastoma cell line.

Methamphetamine (METH) is a highly addictive CNS stimulant that its long-term use is associated with the loss of neurons in substantia nigra and development of Parkinson's disease later in life. Common form of METH is Ya-Ba tablet, in which, large portion of caffeine is added to the mass to enhance the stimulatory effect. Previous study demonstrated that caffeine potentiates the toxic effect of METH in association with the production of reactive oxygen species and the induction of apoptosis. Since METH causes induction of autophagy, the question was raised whether this pathway participates in the potentiating effect of caffeine on METH neurotoxicity. We used SH-SY5Y, a neuroblastoma cell line, as an in vitro model to study the effect of METH and caffeine. Co-treatment of non-toxic concentrations of METH, at 0.5 mM, and caffeine, at 1 mM, caused reduction of the cell viability. Reduction of the cell viability was associated with attenuation of autophagy, demonstrated by reduction of LC3-II levels and the number of autophagosome puncta, together with increase of caspase-3 activation. Similar effect was produced by treatment with autophagy inhibitors, 3-MA and wortmanin. Our results suggested that caffeine potentiates METH toxicity through inhibition of autophagy and that autophagy serves as a protective mechanism. In conclusion, we proposed the augmented hazard associated with caffeine and METH combination in Ya-Ba abusers.

Cytotoxic alkaloids from leaves and twigs of Dasymaschalon sootepense.

Bioassay-guided fractionation of the cytotoxic ethyl acetate fraction of the sequential methanol extract from the leaves and twigs of Dasymaschalon sootepense led to the isolation of a new 7-hydroxy aporphine alkaloid, 6a,7-dehydrodasymachaline (1) along with the five known compounds (-)-nordicentrine (2), dicentrinone (3), (-)-sinactine (4), aristolactam AII (5) and epiberberine (6). Their structures were elucidated by spectroscopic methods. This is the first report of alkaloids 1-2 and 5-6 from the genus Dasymaschalon. Compounds 1 and 5 showed cytotoxicity against a panel of cancer cell lines.

Zederone, a sesquiterpene from Curcuma elata Roxb, is hepatotoxic in mice.

The present study aimed to investigate the hepatotoxicity of zederone isolated from Curcuma elata in mice. Adult male mice were intraperitoneally injected with a single dose of zederone (50-300 mg/kg body weight [BW]). Twenty-four hours after the injection, zederone induced liver enlargement with scattered white foci over the organ. The medium lethal dose (LD50) value at 24 hours of zederone was approximately 223 mg/kg BW. Hepatic centrilobular necrosis with marked increases in plasma alanine transaminase activity and total bilirubin levels was observed. Zederone at a dose of 200 mg/kg BW markedly decreased the activity of superoxide dismutase and the hepatic glutathione content, whereas the activity of catalase was not altered. The compound at this dose also increased the messenger RNA (mRNA) expression of Cyp2b10 and Cyp3a11, which are the main drug-metabolizing enzymes in the liver. The mRNA expression of proinflammatory cytokine tumor necrosis factor α was increased. The nuclear factor-E2-related factor 2 protein, which is the transcription factor regulating the antioxidant gene expression, was decreased. The histopathology of massive hepatic centrilobular necrosis with an increase in the expression of cytochrome P450 (Cyp) suggests that the possible potentiation of zederone-induced hepatotoxicity implicated the induction of Cyps, which leads to the formation of biological reactive metabolites and that cause the oxidative stress and liver cell injuries.

Cytotoxic, antitopoisomerase IIα, and anti-HIV-1 activities of triterpenoids isolated from leaves and twigs of Gardenia carinata.

Eight new cycloartane triterpenoids (1-8), named carinatins A-H, and the known compounds secaubryolide (9) and dikamaliartane D (10) were isolated from the leaves and twigs of Gardenia carinata. Their structures were determined on the basis of spectroscopic methods. Cytotoxic, antitopoisomerase IIα, and anti-HIV-1 activities of compounds 1-7, 9, and 10 were investigated.

Inhibition of topoisomerase II α activity and induction of apoptosis in mammalian cells by semi-synthetic andrographolide analogues.

Topoisomerase II α enzyme plays a critical role in DNA replication process. It controls the topologic states of DNA during transcription and is essential for cell proliferation. Human DNA topoisomerase II α (hTopo II α) is a promising chemotherapeutic target for anticancer agents against a variety of cancer types. In the present study, andrographolide and its structurally modified analogues were investigated for their inhibitory activities on hTopo II α enzyme. Five out of nine andrographolide analogues potently reduced hTopo II α activity and inhibited cell proliferation in four mammalian cell lines (Hela, CHO, BCA-1 and HepG2 cells). IC50 values for cytotoxicity of analogues 3A.1, 3A.2, 3A.3, 1B and 2C were 4 to 7 µM. Structure-activity relationship studies revealed that both core structure of andrographolide and silicon based molecule of functional group were important for the inhibition of hTopo II α activity whereas position C-19 of analogues was required for anti-proliferation. In addition, the analogue 2C at 10 µM concentration inhibited hTopo II α, and induced apoptosis with nuclear fragmentation and formation of apoptotic bodies in HepG2 cells. The analogue 2C may, therefore, have a therapeutic potential as effective anticancer agent targeting the hTopo II α functions.

Cleistanthoside A tetraacetate-induced DNA damage leading to cell cycle arrest and apoptosis with the involvement of p53 in lung cancer cells.

Lung cancer is the leading cause of cancer-related death worldwide and resistance to chemotherapeutic drugs is the major obstacle for effective treatment. The present study investigated the anticancer potential of cleistanthoside A tetraacetate (CAT), a derivative of cleistanthoside A from Phyllanthus taxodiifolius Beille on human lung cancer cells, LU-1. Multiple molecular approaches were used in this study and include measuring the anti-proliferative effect of CAT in LU-1 cells using flow cytometry; evaluating the induction of apoptosis by monitoring DNA fragmentation, phosphatidylserine externalization and activation of caspase-3 activity; and assaying the expression of regulatory proteins involved in cell cycle arrest and apoptosis using immunoblots. CAT potently inhibited LU-1 proliferation through an early G1 arrest with down-regulation of cdk4/6 and cyclin D1 proteins. CAT also inhibited DNA topoisomerase IIα activity resulting in DNA damage and increased the expression of the p53 protein with the subsequent induction of apoptosis. A decrease in the Bcl-2/Bax ratio, activation of caspase-3 activity and cleavage of PARP accompanied apoptosis. CAT is highly toxic to lung cancer and its primary targets are the inhibition of topoisomerase IIα activity and inducing apoptosis through a G1 arrest. These properties indicate that CAT is a promising anticancer agent for treatment of lung cancer.

DNA topoisomerase IIα inhibitory and anti-HIV-1 flavones from leaves and twigs of Gardenia carinata.

Four new flavones, 5,2'-dihydroxy-7,3',4',5'-tetramethoxyflavone (1), 5,2',5'-trihydroxy-7,3',4'-trimethoxyflavone (2), 5,7,2',5'-tetrahydroxy-6,3',4'-trimethoxyflavone (3) and 5,2',5'-trihydroxy-6,7,3',4'-tetramethoxyflavone (4), along with the known 5,3'-dihydroxy-6,7,4',5'-tetramethoxyflavone (5), 5,7,3',5'-tetrahydroxy-6,4'-dimethoxyflavone (6), syringaldehyde, vanillic acid and scopoletin were isolated from the leaves and twigs of Gardenia carinata (Rubiaceae). Their structures were determined by spectroscopic methods. Flavone 2 exhibited cytotoxic activity against P-388 and MCF-7 cell lines, while 3, 5 and 6 were active only in P-388 cell line. All active compounds were found to inhibit DNA topoisomerase IIα activity, which may be responsible for the observed cytotoxicity. Flavones 1-3, 5 and 6 also exhibited anti-HIV-1 activity in the anti-syncytium assay using (∆Tat/rev)MC99 virus and 1A2 cell line system; 2 was most potent. Only flavones 1 and 6 showed considerably activity against HIV-1 reverse transcriptase.

Induction of apoptosis in murine leukemia by diarylheptanoids from Curcuma comosa Roxb.

Diarylheptanoids, isolated from the rhizome of Curcuma comosa Roxb., have several biological activities including anti-oxidant and anti-inflammation. The present study investigated the effect of five diarylheptanoids isolated from C. comosa rhizome on the proliferation of murine P388 leukemic cells. Compound-092, (3S)-1-(3,4-dihydroxyphenyl)-7-phenyl-(6E)-6-hepten-3-ol, bearing a catechol moiety, was the most potent diarylheptanoid (IC(50) of 4 µM) in inhibiting P388 leukemic cell viability by causing DNA breakage and inducing apoptosis. Apoptotic cell death was characterized by the presence of chromatin condensation, formation of apoptotic bodies, DNA fragmentation, and externalization of plasma membrane phosphatidylserine. This compound increased caspase-3 activity about fivefold above the untreated control, decreased the intracellular reduced glutathione level, and impaired mitochondrial transmembrane potential. In the presence of Cu(II) ion, the compound exhibited a pro-oxidant activity causing DNA strand breakage and enhancing the anti-proliferative activity. The results provide evidence for the pro-oxidant activity of the diarylheptanoid bearing a catechol moiety in the induction of apoptosis in murine P388 leukemia.

Cytotoxic alkaloids from stems, leaves and twigs of Dasymaschalon blumei.

Bioassay-guided fractionation of the cytotoxic ethyl acetate extract from the stems of Dasymaschalon blumei (Annonaceae) led to the isolation of four aristololactam alkaloids, including the hitherto unknown 3,5-dihydroxy-2,4-dimethoxyaristolactam (1), as well as the three known compounds, aristolactam BI, goniopedaline, and griffithinam. Additionally, the cytotoxic extract from the combined leaves and twigs of the same plant yielded three known oxoaporphine alkaloids, oxodiscoguattine, dicentrinone, and duguevalline. The structures of aristolactams and oxoaporphine alkaloids were elucidated on the basis of spectroscopic methods. All isolates were evaluated for cytotoxicity against a panel of mammalian cancer cell lines and a noncancerous human embryonic kidney cell Hek 293.

Protection of centrilobular necrosis by Curcuma comosa Roxb. in carbon tetrachloride-induced mice liver injury.

AIM OF THE STUDY: To investigate the protective effect and possible mechanism of Curcuma comosa hexane extract on CCl(4)-induced liver injury in adult male mice. MATERIALS AND METHODS: Hepatotoxicity was induced by an intraperitoneal injection of CCl(4) and was evaluated after 24 h from the elevations of plasma alanine transaminase (ALT) and aspartate transaminase (AST) activities, and histological analysis of liver injuries. Hexane extract of Curcuma comosa was given at different time points from 1 to 72 h, prior to CCl(4) administration and the protection from liver injury was assessed. RESULTS: CCl(4)-induced damage to liver cells was resulted in elevations of plasma ALT and AST activities. Pretreatment with Curcuma comosa hexane extract 24 h at a dose of 100, 250, and 500 mg/kg BW resulted in a dose-dependent prevention of the increases in plasma ALT and AST activities as well as time dependent. The protective effect of the extract at a dose of 500 mg/kg BW was seen at 12-24 h. Pretreatment of the extract completely prevented elevation of plasma ALT and AST activities, and centrilobular necrosis. The protective effect of Curcuma comosa was associated with restoration of hepatic glutathione content, and CYP2E1 catalytic activity, and its mRNA and protein levels as well as increase in activity of glutathione-S-transferase (GST). CONCLUSION: Curcuma comosa has a potent protective property against CCl(4)-induced hepatic injuries via the activation of detoxifying mechanisms (GST) as well as reduction of the bioactive toxic metabolites. Therefore, Curcuma comosa may be beneficial for prevention of hepatotoxicity.

Protection against cisplatin-induced nephrotoxicity in mice by Curcuma comosa Roxb. ethanol extract.

The protective effect of an ethanol extract of Curcuma comosa against cisplatin-induced renal toxicity in mice was studied. Adult male mice were pretreated for 4 days with the ethanol extract of C. comosa [100-200 mg/kg body weight (BW), orally (p.o.)] before injection of cisplatin (12.5 mg/kg BW, intraperitoneally (i.p.)). Five days later the mice were killed, and blood samples were collected to determine blood urea nitrogen (BUN) and plasma creatinine levels. Kidneys were examined histopathologically and levels of lipid peroxidation, gluthathione (GSH) content, and superoxide dismutase (SOD), gluthathione peroxidase (GPx), and catalase (CAT) activities were determined. Histological examinations revealed degenerative changes and tubular necrosis in mice treated with cisplatin, which were improved by pretreatment with C. comosa ethanol extract. Cisplatin raised BUN, creatinine, and kidney lipid peroxidation levels, and lowered kidney GSH content and levels of GPx, SOD, and CAT activities, all of which (except SOD and CAT) could be restored to normal values by pretreatment with 200 mg/kg BW of C. comosa ethanol extract. In addition, the ethanol extract of C. comosa and its isolated diarylheptanoid compound also exhibited radical scavenging activities. The results suggest that the ethanol extract of C. comosa exhibits effective protection against cisplatin-induced nephrotoxicity mediated through its antioxidant activity.

Interactions of organic anion transporters and organic cation transporters with mycotoxins.

Mycotoxins are secondary metabolites of moulds that which exert adverse effects in humans and animals. It is known that direct cellular toxicity is often associated with increased cellular accumulation of toxic compounds, and membrane transport may be the first fundamental stage in the development of the cytotoxicity. To elucidate the entry pathway for mycotoxins into cells, we have investigated the interactions of human and rat organic anion transporters (hOATs/rOats) and human organic cation transporters (hOCTs) with mycotoxins using cells stably expressing hOATs/rOats/hOCTs. The mycotoxins tested were aflatoxin B1, alpha-zearalenol, citrinin, citrioveridine, cyclopiazonic acid, fumonisin B1, gliotoxin, patulin, penicillic acid, rubratoxin B, and zearalenone. These mycotoxins inhibited organic anion uptake mediated by hOAT1-4, and organic cation uptake mediated by hOCT1-2. By comparing the IC(50) values of mycotoxins for hOATs, it was found that hOAT1 and hOAT3 exhibited higher affinity interactions with mycotoxins than hOAT2 and hOAT4. There was no interspecies difference between humans and rats for the interactions of OATs with mycotoxins except that of OAT3 with rubratoxin B. Finally, we observed that hOAT1-4 and hOCT1-2 mediated the uptake of aflatoxin B1. In conclusion, hOATs and hOCTs interacted with various mycotoxins. Considering the localization of hOATs/rOats and hOCTs, it was suggested that these transporters were the possible entrance pathway for mycotoxins in kidney and liver, leading to the induction of adverse effects in humans and rats.