Anti-Cancer Agents in Medicinal Chemistry (Formerly Current Medicinal Chemistry - Anti-Cancer Agents) - Volume 18, Issue 13, 2018

Camptothecin (CPT), obtained from Camptotheca acuminata (Nyssaceae), is a quinoline type of alkaloid. Apart from various traditional uses, it is mainly used as a potential cytotoxic agent acting against a variety of cancer cell lines. Though searches have been continued for last six decades, still it is a demanding task to design potent and cytotoxic CPTs. Different CPT analogs are synthesized to enhance the cytotoxic potential as well as to increase the pharmacokinetic properties of these analogs. Some of these analogs were proven to be clinically effective in different cancer cell lines. In this article, different CPT analogs have been highlighted extensively to get a detail insight about the structure-property relationships as well as different quantitative structure-activity relationships (QSARs) modeling of these analogs are also discussed. This study may be beneficial for designing newer CPT analogs in future.

Background: Essential oils (EOs) are aromatic, volatile and concentrated hydrophobic liquids extracted from plant material. EOs are also called as ethereal oils, volatile oils or aetherolea. EOs also play a crucial role in plant defence and signalling processes. They are mostly used in perfumes, cosmetics, soaps and other products for flavouring food, drinks, adding scents to incense and household cleaning products. EOs have a long medicinal history. Methods: Reported research literature and online contents related to the use of EOs for their biochemical pharmacological applications in cancer prevention therapy were reviewed. The most relevant and updated citations were included in this review. Results: This review elaborates the various types of EOs, their biochemical characteristics, and pharmacology. Medicinal benefits of essential oil products range from various skin treatments to different types of therapies for cancer and are dependent entirely on historical backgrounds of use of EOs for these properties. EOs have antimicrobial, anticancer, antioxidant, antiparasitical, insecticidal, anti-inflammatory, viricidal, fungicidal, wound healing, antihypertensive, analgesic properties and other medicinal properties. The efficiency of EOs in medical treatments and treatment of cancers are these days a subject of interest in most countries. Conclusion: This review elaborated the potentials of EOs in regulating cancer cell growth and have explored the probable EOs that can be used in drug development.

Background: Phytol have various pharmacological activities such as antimicrobial, cytotoxic, antitumoral, antimutagenic, anti-atherogenic, antidiabetic, lipid-lowering, antispasmodic, antiepileptic, antinociceptive, antioxidant, anti-inflammatory, anxiolytic, antidepressant and immunoadjuvant. Several studies point to an association of phytol with implications for apoptosis and necrosis at cellular levels in cancer, yet no clear conclusions were drawn. Method: To clarify this, we conducted a meta-analysis of non-clinical studies of phytol and its associations with toxicity and cytotoxicity emphasizing the mechanisms of apoptosis and necrosis induction and its importance in tumor therapy. Relevant studies were systematically searched in PubMed and Web of Science. The association between phytol and cyto-/toxicity was assessed by odds ratio (ORs) and 95% confidence intervals (CI). Twentythree studies were finally included in the meta-analysis. A significant association between phytol and toxicity (OR: 1.47; 95% CI = 0.86–2.48) was found among in vivo studies and cytotoxicity (OR: 1.81; 95% CI = 1.12– 2.65, p<0.05) in in vitro and ex vivo studies. In in vitro studies, 24% of them indicate that phytol at high doses induces apoptosis by several mechanisms; while about 40% of ex vivo studies indicate that phytol induces reactive oxygen species generation. But, Phytol does not act as a direct oxidant, unlike its metabolite phytanic acid. The 24% of in vivo studies also highlighted the mechanisms for apoptosis-like including expression of Bcl2 protein or mutations in pro-apoptotic protein Bax. Of them, 8% studies show necrosis and hepatotoxicity. However, in 24% of the articles, the mechanisms of toxicity and cytotoxicity are still not well elucidated. Conclusion: This study confirms that the association between phytol and cyto-/toxicity depends on the dose/concentration used in the given experimental conditions. Thus, there are still great prospects for new research aimed at the use of phytol and its metabolite as anticancer agents.

Background: Liver cancer is the fifth most commonly diagnosed cancer and the second leading cause of cancer-related deaths worldwide. Among the liver cancers, hepatocellular carcinoma has been reported to be responsible for 85-90% of primary liver cancer and it is the second most common cause of cancer mortality with 700,000 deaths documented annually. The major risk factors of HCC include chronic infections with the hepatitis B (HBV) or hepatitis C (HCV) virus, chronic liver diseases, alcoholism as well as dietary carcinogens, such as aflatoxins. Highest incidence rates are estimated to occur in Asia and Africa. Objective: The effectiveness of current man-made agents in treating chronic liver disease is not satisfactory and they have uninvited side effects. Herbal medicines are extensively used all over the world; however, there is still a vast gap in their acceptance by the scientific community. Plants are rich in secondary metabolites and phytochemicals obtained from both, dietary and non-dietary sources. Natural plant products are potent therapeutic as well as chemopreventive agents for numerous chronic diseases like cardiovascular, metabolic, neurodegenerative and neoplastic diseases. Results: Dietary phytochemicals such as curcumin, resveratrol, quercetin, silibinin, N-trans-feruloyl octopamine, lycopene, emodin, caffeine, urolithin A and Phloretin have been found to be useful for the treatment of HCC and other diseases. According to recent reports 60% of the anticancer medication in current use has been obtained from natural sources. Conclusion: Thus, derivatives from plants have played an essential role in cancer prevention due to their pleiotropic abilities to scavenge free radicals, inhibit cell growth and induce apoptosis.

Background: Novel bioactive plant secondary metabolites, including flavonoids, offer a spectrum of chemo-protective responses against a range of human tumor models. However, the clinical translation of these promising anti-cancer agents has been hindered largely by their poor solubility, rapid metabolism, or a combination of both, ultimately resulting in poor bioavailability upon oral administration. Objective: To circumvent the challenges associated with herbal drug development and for effective integration into clinical setting, nano-engineering is one of the emerging pragmatic strategies which has promise to deliver therapeutic concentrations of bio-actives upon oral administration. Method: We assessed the nano-encapsulated flavonoid-rich fraction isolated from a traditional Indian herb Selaginella bryopteris (Sanjeevani) (NP.SB). Both in vitro and in vivo studies were performed to evidence the epigenetic protection mechanisms of NP.SB through a mitochondrial-targeted pre-clinical validation strategy. Results: The mito-protective activity of NP.SB revealed a dose-dependent effect when tested in GC-1 spg (mouse spermatogonial epithelial) and B/CMBA.Ov (mouse ovarian epithelial) following exposure to Nsuccinimidyl N-methylcarbamate, a potential human carcinogen. Smaller size, rapid internalization, faster mobility and site specific delivery conferred significant cancer protection in cultured cells. Notably, this encapsulated flavonoid supplementation; prevented emergence of neoplastic daughter clones from senescent mother phenotypes in pro-oxidant treated GC-1 spg and B/CMBA.Ov cells by selective abrogation of mitochondrial oxidative stress-induced aberrant epigenetic modifications. In vivo studies using a diethylnitrosamine and 2- acetylaminofluorene mouse model demonstrated that NP.SB has a significant inhibitory effect on tumor growth which clearly substantiated our in vitro findings. Conclusion: Anti-carcinogenic property in conjunction with low toxicity of NP.SB, underscores the translational significance of dietary flavonoids as cancer-protective agents for preferential application in clinical settings.

Background: Colon cancer is the most aggressive form of cancers, that causes 0.5 million deaths per year around the globe. Targeting colon cancer by conventional therapeutic options elicits toxicity. Traditional medicines take a lead to alleviate the existing clinical challenges. Objective: To investigate antibacterial activity against Helicobacter Pylori and in vitro anti-colon cancer activity by Acacia nilotica extract (ACE) and its active constituent pyrogallol. Methods: Pyrogallol isolated from A. nilotica by column chromatography and HPLC and structure was elucidated by spectral analysis. Antibacterial activity was done by flow cytometry. Cytotoxicity was measured by MTT assay. Apoptotic morphology and nuclear fragmentation were assessed with AO/ethidium bromide and DAPI staining. DNA fragmentation was done by electrophoresis. Western blot used to analyze the molecular mechanism of apoptosis. Cell cycle arrest was determined using flow cytometry of propidium iodide stained cells. Cell migration was determined by wound healing assay. Results: ACE (20 μg/ml) and pyrogallol (10 μg/ml) treatment reduced the survival of H.pylori at 61% and 62%, respectively. MTT results show that HT-29 cells are more sensitive to pyrogallol with an IC50 value of 35μg/ml compared to ACE. Pyrogallol treated HT-29 cells reached dead state i.e. late apoptotic state with severe nuclear fragmentation. Pyrogallol elicits dose dependent DNA fragmentation in HT-29 cells. Pyrogallol induced apoptosis by simultaneous down-regulation of Bcl-2 and up-regulation of BAX and cytochrome c. Pyrogallol arrested HT-29 cells in S and G2/M phase of cell cycle. Further pyrogallol exhibited marked antimetastatic potential by inhibiting the migration of HT-29 cells dose dependently. Conclusion: Both ACE and pyrogallol repressed the growth of H.pylori and as significant anti-colon cancer agent.

Background: Recently, we have reported that Fisetin, a natural flavonol, is able to regress Aflatoxin- B1 (AFB1) induced hepatocellular carcinoma (HCC) by suppressing reactive oxygen species (ROS) led proinflammatory factors in rats. In the current study, we aimed to delineate whether Fisetin does so by modulating the cell growth promoting signaling cascade in HCC. The reciprocal interplay of 3-phosphoinositol kinase (PI3K) vs phosphatase and tensin homologue deleted on chromosome 10 (PTEN) displays Akt, a protein kinase B, to get phosphorylated at Thr308 by a 3-phosphoinositol dependent kinase 1 (PDK1). This commits cells of neoplastic niche to undergo rapid proliferation by p-Aktthr308 dependent phosphorylation of glycogen synthase kinase 3β (GSK3β) at Ser 9 position. Method: In this study, the effect of in vivo treatment of 20 mg/kg b.w. Fisetin on relative profile of all these factors were studied in the liver from the HCC rats induced by two doses of 1mg/kg b.w. AFB1 i.p. Result: As compared to the untreated HCC liver, liver from Fisetin treated HCC group rats showed a significant decline in the activity and level of p-Aktthr308 which was consistent with a similar decline in PDK1 level. Concordantly, the level of p-GSK3βSer 9 was also found to be declined significantly in those Fisetin-treated HCC livers. Conclusion: A concomitant decline in immunohistochemically detected number of the proliferating cell nuclear antigen (PCNA), a cell proliferation marker, in the HCC liver, further confirmed anti-cell proliferative role of Fisetin during HCC growth in vivo. These findings suggest that Fisetin is able to suppress Akt dependent cell growth signaling mechanisms in HCC mainly by down regulating PDK1 dependent Akt phosphorylation.

Background: At present, ‘pharmaco-epigenomics’ constitutes the hope in cancer treatment owing to epigenetic deregulation- a reversible process and playing a role in malignancy. Objective: Chemotherapy has many limitations like host-tissue toxicity, drug resistance. Hence, it is imperative to unearth targets to better treat cancer. Here, we intend to repurpose a set of our previously synthesized difluorinated Propanediones (PR) as Histone lysine Methyltransferase inhibitors (HMTi). Methods: The cell lines of leukemic origin viz. histiocytic lymphoma (U937) and acute T-cell leukemia (JURKAT) were treated with PR-1 to 7 after docking studies with active pocket of HMT. The cell cycle analysis, in vitro methylation and cell proliferation assays were carried out to delineate their physiological role. Results: A small molecule PR-4, at 1 and 10μM, has shown to alter the methylation of histone H3 and H4 in both cell lines. Also, treatment shows an increase in G2/M population and a subsequent decrease in the G0/G1 population in U937. In JURKAT, an increase in both G2/M and S phase population was observed. The sub-G1 population showed a steady rise with increase in dose and prolonged time intervals in U937 and JURKAT cell lines. In SRB assay, the PR showed a cell growth of 42.6 and 53.4% comparable to adriamycin; 44.5 and 53.2% in U937 and JURKAT, respectively. The study suggests that PR-4 could emerge as a potential HMT inhibitor. Conclusion: The molecule PR-4 could be a lead in developing more histone lysine methyltransferases inhibitors with potential to be pro-apoptotic agents.

Purpose: To investigate N-succinyl chitosan nanoparticles (NSC NPs) encapsulation with Dunaliella bardawil (D. bardawil) biomass for high utilization enhanced effectiveness and least side effects for anticancer activity. Methods: The potential bioactive compounds from D. bardawil biomass were encapsulated NSC NPs by ionotropic gelation method and to characterize its molecular shape, particle size, stability and polydispersity index using FTIR, XRD, SEM, TEM and Zetasize Nano analyzer. Signaling pathway analysis, molecular docking study and in vitro anticancer screening were performed on chosen H-Ras P21, 721P and liver cancer cell lines (HepG2), respectively. Results: The D. bardawil biomass majorly contains 6 bioactive compounds such as β-carotene, lutein, zeaxanthin, phytoene, canthaxanthin, and phytofluene were identified by LC-MS. The D. bardawil biomass encapsulated NSC NPs showed an average particle size of 80±5.6 nm in spherical shape, crystalline nature, zeta potential of -32±2.7 mV and polydispersity index of 0.51±0.02. Interestingly, the identified target using graph theoretical signaling pathway analysis and molecular docking study showed strong interaction of NSC NPs in binding pockets of H-Ras P21 protooncogene. At 50μg/mL, NPs displayed 95.60% cytotoxicity in HepG2 cell line. The apoptotic cell cycle analysis showed cell death for 24 h and 48 h representing 13.13% and 47.04%, respectively. Conclusion: The highly cross-linked, biocompatible, biodegradable, nontoxic NSC NPs promising carrier for delivery of bioactive molecules present in the D. bardawil biomass was found to be actively involved in deregulation of cellular growth in targeted cancer cells. Thus active NPs serve as a novel nanodrug to enhance the controlled; site specific drug delivery in the management of cancer.

Background: The potential of steroids for development into lead pharmacological molecules lies in the regulation of a variety of biological processes by these molecules and also because of these being a fundamental class of signaling molecules. Steroid based scaffolds have been extensively used as active pharmaceutical agents for the treatment of various diseases including the deadly disease of cancer which despite the recent advances in the early diagnosis, prevention and therapy, remains a clinical challenge affecting millions of people world over and is one of the leading causes of death. It thus warrants the development of new drugs against this dreadful disease through exploitation of emerging molecularly defined targets. Methods: The present study explores the effect of novel steroidal pyrazolines as presumed inhibitors of 5α- reductase (5AR) and 17α-hydroxylase-C17,20-lyase as a target for treatment of prostate cancer. A series of 1,5- diaryl pyrazoline pregnenolones were synthesized and screened for 5α-reductase inhibitory activities. Synthesis of the analogs is multistep and proceeds in good overall yields. The key step in the synthesis of 1,5- disubstituted pyrazolinyl pregnenolones is the heterocyclization of bezylidine derivatives (3) in presence of phenylhydrazines (4) through the initial formation of the phenylhydrazones, which undergo concomitant cyclization to generate the stable pyrazoline derivatives. Results: All the synthesised D-ring 1,5-disubstituted pyrazolinyl pregnenolone derivatives (5a-l) were screened for prostate cancer cell inhibitory, 5α-reductase and 17α-hydroxylase-C17,20-lyase inhibitory activity. Amongst all the compounds screened for their 5α-reductase inhibitory activities, compound 5c, 5e, 5g and 5l were found to be the most active. Further, compounds 5g and 5h were found to have moderate 17α-hydroxylase-C17,20-lyase inhibitory activities. Conclusion: A series of D-ring 1,5-disubstituted pyrazolinyl pregnenolone derivatives (5a-l) were synthesized and screened for their prostate cancer cell inhibitory, 5a-reductase and 17α-hydroxylase-C17,20-lyase inhibitory activity. Amongst all the compounds screened for their 5α-reductase inhibitory activities, compound 5c, 5e, 5g and 5l were found to be the most active whereas compounds 5g and 5h were found to have moderate 17α- hydroxylase-C17,20-lyase inhibitory activities.

Background: Colchicine, a tricyclic alkaloid, is commonly used in treatment due to its antiinflammatory and anti-fibrotic effects. Besides its toxicity at high doses, colchicine is reported for its potential anticancer effects at lower concentrations. The present study aimed to evaluate the anticancer effects of colchicine in SW480 cells. Methods: The effect of colchicine on cell proliferation was determined by MTT assay. The cellular colchicine uptake was measured by HPLC analysis. The apoptotic effects was evaluated by annexin v binding assay and MMP-9 mRNA expression was determined by RT-PCR experiments. Results: Colchicine showed significant cytotoxicity at 10 ng/ml and higher concentrations and caused a cell cycle arrest of SW480 cells at G2/M phase. The results of HPLC analysis showed that colchicine uptake was increased in correlation with treated concentrations. Colchicine concentrations have increased the amount of apoptotic cell population. The elisa and western blot measurements showed that colchicine led to nuclear translocation of NF-ΚB proteins and increased caspase levels. The real time PCR experiments showed that colchicine has inhibitory effect on MMP-9 mRNA expression in a concentration dependent manner. Conclusion: These results illustrated that low dose colchicine efficiently induced cell death and apoptosis of SW480 cells and the inhibition of MMP-9 mRNA levels was significantly correlated with the amount of cellular colchicine uptake, suggesting that colchicine has a potential value in the treatment of human colorectal cancer.