Macrophage and colon tumor cells as targets for a binuclear silver(I) N-heterocyclic carbene complex, an anti-inflammatory and apoptosis mediator

Chronic inflammation intensifies the risk for malignant neoplasm, indicating that curbing inflammation could be a valid strategy to prevent or cure cancer. Cancer and inflammation are inter-related diseases and many anti-inflammatory agents are also used in chemotherapy. Earlier, we have reported a series of novel ligands and respective binuclear Ag(I)-NHC complexes (NHC=N-heterocyclic carbene) with potential anticancer activity. In the present study, a newly synthesized salt (II) and respective Ag(I)-NHC complex (III) of comparable molecular framework were prepared for a further detailed study. Preliminarily, II and III were screened against HCT-116 and PC-3 cells, wherein III showed better results than II. Both the compounds showed negligible toxicity against normal CCD-18Co cells. In FAM-FLICA caspase assay, III remarkably induced caspase-3/7 in HCT-116 cells most probably by tumor necrosis factor-alpha (TNF-α) independent intrinsic pathway and significantly inhibited in vitro synthesis of cytokines, interleukin-1 (IL-1) and TNF-α in human macrophages (U937 cells). In a cell-free system, both the compounds inhibited cyclooxygenase (COX) activities, with III being more selective towards COX-2. The results revealed that III has strong antiproliferative property selectively against colorectal tumor cells which could be attributed to its pro-apoptotic and anti-inflammatory abilities.

Mononuclear dioxomolybdenum(VI) thiosemicarbazonato complexes: Synthesis, characterization, structural illustration, in vitro DNA binding, cleavage, and antitumor properties

Four dioxomolybdenum(VI) complexes were synthesized by reacting [MoO2(acac)2] with N-ethyl-2-(5-bromo-2-hydroxybenzylidene) hydrazinecarbothioamide (1), N-ethyl-2-(5-allyl-3-methoxy-2-hydroxybenzylidene) hydrazinecarbothioamide (2), N-methyl-2-(3-tert-butyl-2-hydroxybenzylidene) hydrazinecarbothioamide (3), and N-ethyl-2-(3-methyl-2-hydroxybenzylidene) hydrazinecarbothioamide (4). The molecular structures of 1, 2, and all the synthesized complexes were determined using single crystal X-ray crystallography. The binding properties of the ligand and complexes with calf thymus DNA (CT-DNA) were investigated via UV, fluorescence titrations, and viscosity measurement. Gel electrophoresis revealed that all the complexes cleave pBR 322 plasmid DNA. The cytotoxicity of the complexes were studied against the HCT 116 human colorectal cell line. All the complexes exhibited more pronounced activity than the standard reference drug 5-fluorouracil (IC50 7.3μM). These studies show that dioxomolybdenum(VI) complexes could be potentially useful in chemotherapy.

Multi-constituent synergism is responsible for anti-inflammatory effect of Azadirachta indica leaf extract

CONTEXT

Azadirachta indica A. Juss. (Meliaceaes) leaves have been used traditionally to treat swelling and rheumatism in Indian cultures.

OBJECTIVE

To fractionate A. indica leaf extracts using bioactivity guided manner for identification of the active anti-inflammatory principles.

MATERIALS AND METHODS

Polarity-gradient sequential extracts (petroleum ether, chloroform, methanol, and water) of A. indica leaves were screened for their anti-inflammatory potential using the carrageenan-induced rat paw edema model (1 g/kg). The chloroform extract was sequentially fractionated to obtain n-hexane (F-1), n-hexane-chloroform (F-2), and chloroform (F-3) fractions and their inhibitory effect on rat paw edema was evaluated (500 mg/kg). Inhibitory effect of F-2 on granuloma formation, plasma interleukin (IL-1), and tumor necrosis factor (TNF-α) was assessed at the doses of 100, 200, and 400 mg/kg using the cotton pellet assay in rats. Three sub-fractions (SF-1, SF-2, and SF-3) were obtained upon chromatography of F-2, and their inhibitory effect on cyclooxygenase was assessed at 200 µg/mL concentration. The sub-fractions were subjected to gas chromatography-mass spectrometry (GC-MS).

RESULTS

All the extracts showed significant anti-inflammatory effect; however, chloroform extract was the most effective against paw edema (53.25% inhibition). The three fractions of chloroform extract showed significant effect, while F-2 being the most potent (51.02%). F-2 demonstrated dose-dependent inhibition of granuloma and cytokines. Interestingly, all the sub-fractions of F-2 inhibited COX-1 and COX-2 with almost equal potential. GC-MS revealed that chemically the sub-fractions were totally different from each other.

DISCUSSION AND CONCLUSION

Anti-inflammatory effect of A. indica is a result of cumulative and synergistic effects of diversified constituents with varying polarities that collectively exert the effect via suppression of cyclo-oxygenases and cytokines (IL-1 and TNF-α).

Correlation of antiangiogenic, antioxidant and cytotoxic activities of some Sudanese medicinal plants with phenolic and flavonoid contents

BACKGROUND

Consumption of medicinal plants to overcome diseases is traditionally belongs to the characteristics of most cultures on this earth. Sudan has been a host and cradle to various ancient civilizations and developed a vast knowledge on traditional medicinal plants. The present study was undertaken to evaluate the antioxidant, antiangiogenic and cytotoxic activities of six Sudanese medicinal plants which have been traditionally used to treat neoplasia. Further the biological activities were correlated with phytochemical contents of the plant extracts.

METHODS

Different parts of the plants were subjected to sequential extraction method. Cytotoxicity of the extracts was determined by dimethylthiazol-2-yl)- 2,5diphenyl tetrazolium bromide (MTT) assay on 2 human cancer (colon and breast) and normal (endothelial and colon fibroblast) cells. Anti-angiogenic potential was tested using ex vivo rat aortic ring assay. DPPH (1,1-diphenyl-2-picrylhydrazyl) assay was conducted to screen the antioxidant capabilities of the extracts. Finally, total phenolic and flavonoid contents were estimated in the extracts using colorimetric assays.

RESULTS

The results indicated that out of 6 plants tested, 4 plants (Nicotiana glauca, Tephrosia apollinea, Combretum hartmannianum and Tamarix nilotica) exhibited remarkable anti-angiogenic activity by inhibiting the sprouting of microvessels more than 60%. However, the most potent antiangiogenic effect was recorded by ethanol extract of T. apollinea (94.62%). In addition, the plants exhibited significant antiproliferative effects against human breast (MCF-7) and colon (HCT 116) cancer cells while being non-cytotoxic to the tested normal cells. The IC50 values determined for C. hartmannianum, N. gluaca and T. apollinea against MCF-7 cells were 8.48, 10.78 and 29.36 μg/ml, respectively. Whereas, the IC50 values estimated for N. gluaca, T. apollinea and C. hartmannianum against HCT 116 cells were 5.4, 20.2 and 27.2 μg/ml, respectively. These results were more or less equal to the standard reference drugs, tamoxifen (IC50 = 6.67 μg/ml) and 5-fluorouracil (IC50 = 3.9 μg/ml) tested against MCF-7 and HCT 116, respectively. Extracts of C. hartmannianum bark and N. glauca leaves demonstrated potent antioxidant effect with IC50s range from 9.4-22.4 and 13.4-30 μg/ml, respectively. Extracts of N. glauca leaves and T apollinea aerial parts demonstrated high amount of flavonoids range from 57.6-88.1 and 10.7-78 mg quercetin equivalent/g, respectively.

CONCLUSIONS

These results are in good agreement with the ethnobotanical uses of the plants (N. glauca, T. apollinea, C. hartmannianum and T. nilotica) to cure the oxidative stress and paraneoplastic symptoms caused by the cancer. These findings endorse further investigations on these plants to determine the active principles and their mode of action.

Proapoptotic and antimetastatic properties of supercritical CO2 extract of Nigella sativa Linn. against breast cancer cells

Nigella sativa, commonly referred as black cumin, is a popular spice that has been used since the ancient Egyptians. It has traditionally been used for treatment of various human ailments ranging from fever to intestinal disturbances to cancer. This study investigated the apoptotic, antimetastatic, and anticancer activities of supercritical carbon dioxide (SC-CO2) extracts of the seeds of N. sativa Linn. against estrogen-dependent human breast cancer cells (MCF-7). Twelve extracts were prepared from N. sativa seeds using the SC-CO2 extraction method by varying pressure and temperature. Extracts were analyzed using FTIR and UV-Vis spectrometry. Cytotoxicity of the extracts was evaluated on various human cancer and normal cell lines. Of the 12 extracts, 1 extract (A3) that was prepared at 60°C and 2500 psi (~17.24 MPa) showed selective antiproliferative activity against MCF-7 cells with an IC50 of 53.34±2.15 μg/mL. Induction of apoptosis was confirmed by evaluating caspases activities and observing the cells under a scanning electron microscope. In vitro antimetastatic properties of A3 were investigated by colony formation, cell migration, and cell invasion assays. The elevated levels of caspases in A3 treated MCF-7 cells suggest that A3 is proapoptotic. Further nuclear condensation and fragmentation studies confirmed that A3 induces cytotoxicity through the apoptosis pathway. A3 also demonstrated remarkable inhibition in migration and invasion assays of MCF-7 cells at subcytotoxic concentrations. Thus, this study highlights the therapeutic potentials of SC-CO2 extract of N. sativa in targeting breast cancer.

Increased aqueous solubility and proapoptotic activity of potassium koetjapate against human colorectal cancer cells

Objectives

Recently, we have isolated koetjapic acid (KA) from Sandoricum koetjape and identified its selective anticancer potentiality against colorectal carcinoma. KA is quite likely to be useful as a systemic anticancer agent against colorectal malignancy. However, with extremely low solubility, KA has to be converted into a biocompatible solubilized form without compromising the bioefficacy. Objective of this study is to enhance solubility of KA and to evaluate anticancer efficacy of potassium koetjapate in human colorectal cancer cells.

Methods

(2-Hydroxypropyl)-β-cyclodextrin inclusion complex and solid dispersions (carboxymethyl cellulose, polyvinylpyrrolidone and sodium lauryl sulphate) of KA were prepared. In addition, a salt of KA, potassium koetjapate was synthesized.

Key findings

Potassium koetjapate demonstrated higher solubility than the other tested formulations with enhanced cytotoxicity against HCT 116 cells. The enhanced efficacy of potassium koetjapate is attributed to apoptotic induction of nuclear condensation and disruption of mitochondrial membrane potential in the cells. Interestingly, potassium koetjapate was found to be safe in rats after oral administration (LD50 > 2000 mg/kg).

Conclusions

The salt formulation of KA appears to modulate the capability of the parent compound by enhancing its solubility and improves its bioefficacy against colon cancer cells, suggesting attractive roles for its applications in medicine.

Standardized extract of Ficus deltoidea stimulates insulin secretion and blocks hepatic glucose production by regulating the expression of glucose-metabolic genes in streptozitocin-induced diabetic rats

BACKGROUND

Recently, there has been increasing interest in Ficus deltoidea Jack. (Moraceae) due to its chemical composition and the potential health benefits. The present study was undertaken to investigate the effect of extracts of F. deltoidea leaves on diabetes.

METHODS

The petroleum ether, chloroform and methanol extracts of F. deltoidea were prepared and subjected to standardization using preliminary phytochemical and HPLC analysis. Dose selection was made on the basis of acute oral toxicity study (50-5000 mg/kg b. w.) as per OECD guidelines. Diabetes mellitus was induced with streptozotocin and rats found diabetic were orally administered with the extract (250, 500 and 1000 mg/kg) for 14 days. Levels of blood glucose and insulin were measured in control as well as diabetic rats on 0, 7 and 14th day. In addition, glucose metabolism regulating gene expression was assessed using RT-PCR.

RESULTS

HPLC analysis revealed that the methanol extract is enriched with C-glycosylflavones particularly, vitexin and isovitexin. In oral glucose tolerance test, oral administration of the methanol extract increased the glucose tolerance. The methanol extract showed significant (P < 0.01) antidiabetic activity. The extract treatment caused significant reduction (p < 0.01) in elevated fasting blood glucose level in streptozotocin-induced diabetic rats. The streptozotocin-related weight loss in rats was noticeably reversed by the extract treatment. Finally, RT-PCR analysis revealed a novel mechanisms for the anti-diabetic action of methanol extract of F. deltoidea. The extract exerted its effect via an increase of insulin secretion which impeded the hepatic glucose production, via down-regulation of phosphoenolpyruvate carboxykinase and glucose-6-phosphatase genes expression on one hand, and up-regulation of hepatic GK and PPARγ genes expression on the other hand. The extract caused an increased expression of GLUT-4 gene expression in skeletal muscles which leads to normalize the hyperglycemia. The extract also nullified the toxic effects of streptozitocin by blocking its entry into the islet β-cells through reducing the expression of GLUT-2 gene.

CONCLUSION

It can be concluded that, F. deltoidea could potentially inhibits the streptozitocin-induced hyperglycemia in rats. Further the herb can be utilized as useful remedy for alleviation of diabetes complications.

Synthesis of isatin thiosemicarbazones derivatives: in vitro anti-cancer, DNA binding and cleavage activities

New derivatives of thiosemicarbazone Schiff base with isatin moiety were synthesized L1-L6. The structures of these compounds were characterized based on the spectroscopic techniques. Compound L6 was further characterized by XRD single crystal. The interaction of these compounds with calf thymus (CT-DNA) exhibited high intrinsic binding constant (k(b)=5.03-33.00×10(5) M(-1)) for L1-L3 and L5 and (6.14-9.47×10(4) M(-1)) for L4 and L6 which reflect intercalative activity of these compounds toward CT-DNA. This result was also confirmed by the viscosity data. The electrophoresis studies reveal the higher cleavage activity of L1-L3 than L4-L6. The in vitro anti-proliferative activity of these compounds against human colon cancer cell line (HCT 116) revealed that the synthesized compounds (L3, L6 and L2) exhibited good anticancer potency.

Crystal structure elucidation and anticancer studies of (-)-pseudosemiglabrin: a flavanone isolated from the aerial parts of Tephrosia apollinea

Tephrosia apollinea is a perennial shrublet widely distributed in Africa and is known to have medicinal properties. The current study describes the bio-assay (cytotoxicity) guided isolation of (-)-pseudosemiglabrin from the aerial parts of T. apollinea. The structural and stereochemical features have been described using spectral and x-ray crystallographic techniques. The cytotoxicity of isolated compound was evaluated against nine cancer cell lines. In addition, human fibroblast was used as a model cell line for normal cells. The results showed that (-)-pseudosemiglabrin exhibited dose-dependent antiproliferative effect on most of the tested cancer cell lines. Selectively, the compound showed significant inhibitory effect on the proliferation of leukemia, prostate and breast cancer cell lines. Further studies revealed that, the compound exhibited proapoptotic phenomenon of cytotoxicity. Interestingly, the compound did not display toxicity against the normal human fibroblast. It can be concluded that (-)-pseudosemiglabrin is worthy for further investigation as a potential chemotherapeutic agent.

Ethyl-p-methoxycinnamate isolated from Kaempferia galanga inhibits inflammation by suppressing interleukin-1, tumor necrosis factor-α, and angiogenesis by blocking endothelial functions

OBJECTIVE

The present study aimed to investigate the mechanisms underlying the anti-inflammatory and anti-angiogenic effects of ethyl-p-methoxycinnamate isolated from Kaempferia galanga.

METHODS

The anti-inflammatory effects of ethyl-p-methoxycinnamate were assessed using the cotton pellet granuloma assay in rats, whereby the levels of interleukin-1 and tumor necrosis factor-α were measured in the animals' blood. In addition, the levels of interleukin, tumor necrosis factor, and nitric oxide were measured in vitro using the human macrophage cell line (U937). The analgesic effects of ethyl-p-methoxycinnamate were assessed by the tail flick assay in rats. The anti-angiogenic effects were evaluated first by the rat aortic ring assay and, subsequently, by assessing the inhibitory effects of ethyl-p-methoxycinnamate on vascular endothelial growth factor, proliferation, migration, and tube formation in human umbilical vein endothelial cells.

RESULTS

Ethyl-p-methoxycinnamate strongly inhibited granuloma tissue formation in rats. It prolonged the tail flick time in rats by more than two-fold compared with the control animals. The inhibition of interleukin and tumor necrosis factor by ethyl-p-methoxycinnamate was significant in both in vivo and in vitro models; however, only a moderate inhibition of nitric oxide was observed in macrophages. Furthermore, ethyl-p-methoxycinnamate considerably inhibited microvessel sprouting from the rat aorta. These mechanistic studies showed that ethyl-p-methoxycinnamate strongly inhibited the differentiation and migration of endothelial cells, which was further confirmed by the reduced level of vascular endothelial growth factor.

CONCLUSION

Ethyl-p-methoxycinnamate exhibits significant anti-inflammatory potential by inhibiting pro-inflammatory cytokines and angiogenesis, thus inhibiting the main functions of endothelial cells. Thus, ethyl-p-methoxycinnamate could be a promising therapeutic agent for the treatment of inflammatory and angiogenesis-related diseases.

Anti-angiogenic quassinoid-rich fraction from Eurycoma longifolia modulates endothelial cell function

Targeting angiogenesis could be an excellent strategy to combat angiogenesis-dependent pathophysiological conditions such as cancer, rheumatoid arthritis, obesity, systemic lupus erythematosus, psoriasis, proliferative retinopathy and atherosclerosis. Recently a number of clinical investigations are being undertaken to assess the potential therapeutic application of various anti-angiogenic agents. Many of these angiogenesis inhibitors are directed against the functions of endothelial cells, which are considered as the building blocks of blood vessels. Similarly, roots of a traditional medicinal plant, Eurycoma longifolia, can be used as an alternative treatment to prevent and treat the angiogenesis-related diseases. In the present study, antiangiogenic potential of partially purified quassinoid-rich fraction (TAF273) of E. longifolia root extract was evaluated using ex vivo and in vivo angiogenesis models and the anti-angiogenic efficacy of TAF273 was investigated in human umbilical vein endothelial cells (HUVEC). TAF273 caused significant suppression in sprouting of microvessels in rat aorta with IC50 11.5μg/ml. TAF273 (50μg/ml) showed remarkable inhibition (63.13%) of neovascularization in chorioallantoic membrane of chick embryo. Tumor histology also revealed marked reduction in extent of vascularization. In vitro, TAF273 significantly inhibited the major angiogenesis steps such as proliferation, migration and differentiation of HUVECs. Phytochemical analysis revealed high content of quassinoids in TAF273. Specially, HPLC characterization showed that TAF273 is enriched with eurycomanone, 13α(21)-epoxyeurycomanone and eurycomanol. These results demonstrated that the antiangiogenic activity of TAF273 may be due to its inhibitory effect on endothelial cell proliferation, differentiation and migration which could be attributed to the high content of quassinoids in E. longifolia.

Genotoxicity and acute and subchronic toxicity studies of a standardized methanolic extract of Ficus deltoidea leaves

OBJECTIVE

Ficus deltoidea leaves have been used in traditional medicine in Southeast Asia to treat diabetes, inflammation, diarrhea, and infections. The present study was conducted to assess the genotoxicity and acute and subchronic toxicity of a standardized methanol extract of F. deltoidea leaves.

METHODS

Sprague Dawley rats were orally treated with five different single doses of the extract and screened for signs of toxicity for two weeks after administration. In the subchronic study, three different doses of the extract were administered for 28 days. Mortality, clinical signs, body weight changes, hematological and biochemical parameters, gross findings, organ weights, and histological parameters were monitored during the study. Genotoxicity was assessed using the Ames test with the TA98 and TA100 Salmonella typhimurium strains. Phytochemical standardization was performed using a colorimeter and high-performance liquid chromatography. Heavy metal detection was performed using an atomic absorption spectrometer.

RESULTS

The acute toxicity study showed that the LD50 of the extract was greater than 5000 mg/kg. In the subchronic toxicity study, there were no significant adverse effects on food consumption, body weight, organ weights, mortality, clinical chemistry, hematology, gross pathology, or histopathology. However, a dose-dependent increase in the serum urea level was observed. The Ames test revealed that the extract did not have any potential to induce gene mutations in S. typhimurium, either in the presence or absence of S9 activation. Phytochemical analysis of the extract revealed high contents of phenolics, flavonoids, and tannins. High-performance liquid chromatography analysis revealed high levels of vitexin and isovitexin in the extract, and the levels of heavy metals were below the toxic levels.

CONCLUSION

The no-observed adverse effect level of F. deltoidea in rats was determined to be 2500 mg/kg.

Potential of silver against human colon cancer: (synthesis, characterization and crystal structures of xylyl (Ortho, meta, &Para) linked bis-benzimidazolium salts and Ag(I)-NHC complexes: In vitro anticancer studies)

BACKGROUND

Since the first successful synthesis of Ag(I)-N-heterocyclic carbene complex in 1993, this class of compounds has been extensively used for transmetallation reactions where the direct synthesis using other metal ions was either difficult or impossible. Initially, silver(I)-NHC complexes were tested for their catalytic potential but could not get fame because of lower potential compare to other competent compounds in this field; however, these compounds proved to have vital antimicrobial activities. These encouraging biomedical applications further convinced researchers to test these compounds against cancer. The current work has been carried out with this aim.

RESULTS

N-ipropylbenzimidazole was synthesized by reaction of benzimidazole with ipropyl bromide. The subsequent treatment of the resulting N-alkylbenzimidazole with ortho/meta/para-(bromomethylene) benzene afforded corresponding bis-benzimidazolium bromides (5-7). The counter anion (Br-) of each salt was replaced by hexaflourophosphate (PF6-) for the ease of handling and further purification (8-10). Each salt (Ligand), in halide form, was further allowed to react with Ag2O with stirring at room temperature for a period of two days to synthesize dinuclear Ag(I)-NHC complexes (11-13). All synthesized compounds were characterized by spectroscopic techniques and microanalysis. Molecular structures of compounds 5, 9 &10 were established through single crystal x-ray diffraction technique. All the compounds were assessed for their anti-proliferation test on human colorectal cancer cell line (HCT 116). Results showed that the ligands (5-10) showed mild to negligible cytotoxicity on HCT 116 cells whereas respective silver complexes (11-13) exhibited dose dependent cytotoxicity towards the colon cancer cells with IC50 ranges between 9.7 to 44.5 μM. Interestingly, the complex 13 having para-xylyl spacer was found the most active (IC50 9.7 μM) that verifies our previously reported results.

CONCLUSIONS

All the bis-benzimidazolium salts (8-10) were found inactive whereas after bonding with silver cations, the Ag(I)-NHC complexes (11-13) showed a dose dependent cytotoxic activity. This proved that silver practice an important role in death of cancer cells. Also, the N-alkyl/aryl substitutions and ortho/metal/para xylyl units regulate the cytotoxicity.