Mohamed B. Khadeer Ahamed

The Anticancer, Antioxidant and Antimicrobial Properties of the Sesquiterpene β-Caryophyllene from the Essential Oil of Aquilaria crassna.

The present study reports a bioassay-guided isolation of β-caryophyllene from the essential oil of Aquilaria crassna. The structure of β-caryophyllene was confirmed using FT-IR, NMR and MS. The antimicrobial effect of β-caryophyllene was examined using human pathogenic bacterial and fungal strains. Its anti-oxidant properties were evaluated by DPPH and FRAP scavenging assays. The cytotoxicity of β-caryophyllene was tested against seven human cancer cell lines. The corresponding selectivity index was determined by testing its cytotoxicity on normal cells. The effects of β-caryophyllene were studied on a series of in vitro antitumor-promoting assays using colon cancer cells. Results showed that β-caryophyllene demonstrated selective antibacterial activity against S. aureus (MIC 3 ± 1.0 µM) and more pronounced anti-fungal activity than kanamycin. β-Caryophyllene also displayed strong antioxidant effects. Additionally, β-caryophyllene exhibited selective anti-proliferative effects against colorectal cancer cells (IC50 19 µM). The results also showed that β-caryophyllene induces apoptosis via nuclear condensation and fragmentation pathways including disruption of mitochondrial membrane potential. Further, β-caryophyllene demonstrated potent inhibition against clonogenicity, migration, invasion and spheroid formation in colon cancer cells. These results prompt us to state that β-caryophyllene is the active principle responsible for the selective anticancer and antimicrobial activities of A. crassnia. β-Caryophyllene has great potential to be further developed as a promising chemotherapeutic agent against colorectal malignancies.

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).

BackgroundSince 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.ResultsN-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.ConclusionsAll 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.

Cat's whiskers tea (orthosiphon stamineus) extract inhibits growth of colon tumor in nude mice and angiogenesis in endothelial cells via suppressing VEGFR phosphorylation

Cats whiskers (Orthosiphon stamineus) is commonly used as Java tea to treat kidney stones including a variety of angiogenesis-dependent diseases such as tumorous edema, rheumatism, diabetic blindness, and obesity. In the present study, antitumor potential of standardized 50% ethanol extract of O. stamineus leaves (EOS) was evaluated against colorectal tumor in athymic mice and antiangiogenic efficacy of EOS was investigated in human umbilical vein endothelial cells (HUVEC). EOS at 100 mg/kg caused 47.62 ± 6.4% suppression in tumor growth, while at 200 mg/kg it caused 83.39 ± 4.1% tumor regression. Tumor histology revealed significant reduction in extent of vascularization. Enzyme-linked immunosorbent assay showed EOS (200 mg/kg) significantly reduced the vascular endothelial growth factor (VEGF) level in vitro (211 ± 0.26 pg/ml cell lysate) as well as in vivo (90.9 ± 2 pg/g tissue homogenate) when compared to the control (378 ± 5 and 135.5 ± 4 pg, respectively). However, EOS was found to be noncytotoxic to colon cancer and endothelial cells. In vitro, EOS significantly inhibited the migration and tube formation of human umbilical vein endothelial cells (HUVECs). EOS suppressed VEGF-induced phosphorylation of VEGF receptor-2 in HUVECs. High performance liquid chromatography (HPLC) analysis of EOS showed high rosmarinic acid contents, whereas phytochemical analysis revealed high protein and phenolic contents. These results demonstrated that the antitumor activity of EOS may be due to its VEGF-targeted antiangiogenicity.

Design, synthesis and structural studies of meta-xylyl linked bis-benzimidazolium salts: potential anticancer agents against 'human colon cancer'.

BackgroundBenzimidazole derivatives are structurally bioisosteres of naturally occurring nucleotides, which makes them compatible with biopolymers of living systems. This property gives benzimidazole a biological and clinical importance. In the last decade, this class of compounds has been reported to possess anti-allergic, anti-diabatic, anti-HIV, anti-hypertensive, anti-inflammatory, anti-mycobacterial, anti-oxidant, anti-protozoal, and anti-viral properties. The researchers are now interested to explore their potential as anti-cancer agents. In the present study, an effort was made to further explore this area of research. Furthermore, in order to increase the solubility and efficacy of these heterocycles, the interest is now shifted to the salts of these compounds. With this background, we planned to synthesize a series of meta-xylyl linked bis-benzimidazolium salts to assess their anti-proliferation efficacy on human colon cancer cell line (HCT 116).ResultsA number of N-alkylbenzimidazoles were synthesized by reactions of benzimidazole with alkyl halides (i-PrBr, PrBr, EthBr, Pent-2-ylBr, BuBr, BenzCl, HeptBr). The subsequent treatment of the resulting N-alkylbenzimidazoles with 1,3-(bromomethylene)benzene afforded corresponding bis-benzimidazolium salts. All synthesized compounds were characterized by spectroscopic techniques (Additional file 1: NMR & FT-IR) and microanalysis. Molecular structures of selected compounds were established through single crystal x-ray diffraction studies. All the compounds were assessed for their anti-proliferation test on human colorectal cancer cell line (HCT 116). Results showed that the compounds exhibited dose dependent cytotoxicity towards the colon cancer cells with IC50 ranges between 0.1 to 17.6 μM. The anti-proliferation activity of all compounds was more pronounced than that of standard reference drug 5-flourouracil (IC50 =19.2 μM).ConclusionsAll the synthesized bis-benzimidazolium salts showed potential anticancer activity. Out of them, some of these salts showed IC50 value as low as 0.1–0.2 μM. Based on the results it can be concluded that, the bis-benzimidazolium salts could probably be the potential source of chemotherapeutic drugs.

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.

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.

Correlation between enzymes inhibitory effects and antioxidant activities of standardized fractions of methanolic extract obtained from Ficus deltoidea leaves

Recently, there has been increasing interest in Ficus deltoidea (Moracea) due to its chemical composition and the potential health benefits. The leaves of the plant have been suggested to have potential antidiabetic effects. Inhibition of carbohydrate-hydrolysing enzymes, such as α-glucosidase and α-amylase is one of the therapeutic approaches to control postprandial hyperglycemia. In this study, enzymes inhibitory effect and antioxidant properties of different fractions of methanolic extract obtained from F. deltoidea leaves was evaluated. Further, the possible relationship between pharmacological properties and phytochemical content of fractions was investigated. The n-butanol fraction showed significant α-glucosidase and α-amylase inhibitory effects (IC 50 values 15.1 and 39.42 μg/ml, respectively) along with the remarkable antioxidant activity when compared to the other fractions. High performance liquid chromatography (HPLC) chemical profiling of the n-butanol fraction revealed that the contents of isovitexin (24.63 mg/g) and vitexin (8.3 mg/g) were found to be significantly higher than the other fractions. These results indicate that F. deltoidea could be the potential source of promising anti-diabetic drug. Key words : Ficus deltoidea, enzymes, phytochemical, high performance liquid chromatography (HPLC), isovitexin, vitexin.

Synthesis, crystal structures, in vitro anticancer, and in vivo acute oral toxicity studies of bis-imidazolium/benzimidazolium salts and respective dinuclear Ag(I)-N-heterocyclic carbene complexes

The synthesis, spectral (FT-IR and NMR), and structural studies of 1,1′-methylene linked 3,3′-2-cyanobenzyl bis-imidazolium salt (L1) and respective dinuclear Ag(I)-NHC complex (C1) are reported. The structures of both compounds were established through single-crystal X-ray diffraction. C1 has a short Ag–Ag separation of 3.16 Å. Both L1 and C1 were tested for potential against leukemia (k562) cell line. For comparison, para-xylyl linked bis-benzimidazolium salts (L2–L4) and their dinuclear Ag(I)-NHC complexes (C2–C4) were synthesized and tested against the same cell line (K562). The IC50 values proved that L2–L4 and C2–C4 are many fold more active than L1 and C1. The mechanism of action and structure activity relationship are discussed. In vivo oral acute toxicity study (sighting study) was carried out which depicts that 2000 mg/kg dose of selected compounds is an appropriate and safe dose for conducting main study on animals.

Antiangiogenic properties of Koetjapic acid, a natural triterpene isolated from Sandoricum koetjaoe Merr

BackgroundAngiogenesis, the formation of new blood vessels, has become an important target in cancer therapy. Angiogenesis plays an important role in tumor growth and metastasis. Koetjapic acid (KA) is a seco-A-ring oleanene triterpene isolated from S. koetjape. The solvent extract of this plant species was shown previously to have strong antiangiogenic activity; however the active ingredient(s) that conferred the biological activity and the mode of action was not established. Given the high concentration of KA in S. koetjape, an attempt has been made in this study to investigate the antiangiogenic properties of KA.ResultsTreatment with 10-50 μg/ml KA resulted in dose dependent inhibition of new blood vessels growth in ex vivo rat aortic ring assay. KA was found to be non-cytotoxic against HUVECs with IC50 40.97 ± 0.37 μg/ml. KA inhibited major angiogenesis process steps, endothelial cell migration and differentiation as well as VEGF expression.ConclusionsThe non-cytotoxic compound, KA, may be a potent antiangiogenic agent; its activity may be attributed to inhibition of endothelial cells migration and differentiation as well VEGF suppression.

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.