Anthraquinones from the roots of Morinda scabrida Craib exhibit antiproliferative activity against A549 lung cancer cells and antitubulin polymerization.

Six anthraquinones were isolated from Morinda scabrida Craib, an unexplored species of Morinda found in the tropical forest of Thailand. All six anthraquinones showed cytotoxicity against A549 lung cancer cells, with the most active compound, nordamnacanthal (MS01), exhibiting the IC50 value of 16.3 ± 2.5 µM. The cytotoxic effect was dose-dependent and led to cell morphological changes characteristic of apoptosis. In addition, flow cytometric analysis showed dose-dependent apoptosis induction and the G2/M phase cell cycle arrest, which was in agreement with the tubulin polymerization inhibitory activity of MS01. Molecular docking analysis illustrated the binding between MS01 and the α/ß-tubulin heterodimer at the colchicine binding site, and UV-visible absorption spectroscopy revealed the DNA binding capacity of MS01.

A Comprehension into Target Binding and Spatial Fingerprints of Noscapinoid Analogues as Inhibitors of Tubulin.

BACKGROUND: Owing to its potential to interfere in microtubule dynamics in the mitotic phase of cell cycle and selectively induce apoptosis in cancer cells without affecting normal cells, noscapine and its synthetic analogues have been investigated by other research groups in different cell lines for their capability to be used as anti-cancer agents. OBJECTIVE: The present study is focused on the investigation of the mode of binding of noscapinoids with tubulin, prediction of target binding affinities and mapping of their spatial fingerprints (shape and electrostatic). METHODS: Molecular docking assisted alignment based 3D-QSAR was used on a dataset (43 molecules) having an inhibitory activity (IC50 = 1.2-250 µM) against human lymphoblast (CEM) cell line. RESULTS AND CONCLUSION: Key amino acid residues of target tubulin were mapped for the binding of most potent noscapine analogue (Compound 11) and were compared with noscapine. Spatial fingerprints of noscapinoids for favorable tubulin inhibitory activity were generated and are proposed herewith for further pharmacophoric amendments of noscapine analogues to design and develop novel potent noscapine based anti-cancer agents that may enter into drug development pipeline.

1,3,4-oxadiazole and its derivatives: A review on recent progress in anticancer activities.

The 1,3,4-oxadiazole nucleus is a biologically imperative scaffold possesses numerous biological activities. The broad and potent activity of 1,3,4-oxadiazole and their derivatives has established them as important pharmacological scaffolds especially in the treatment of cancer disease. Several di-, tri-, aromatic, and heterocyclic substituted 1,3,4-oxadiazole derivatives have been reported to possess potent anticancer activity. These substituted 1,3,4-oxadiazoles had shown different mechanism of action and participated in anticancer drug discovery and development. This review is complementary to earlier reviews and aims to review the work reported on anticancer activities of 1,3,4-oxadiazole derivatives from year 2000 to the beginning of 2020.

Algae metabolites: from in vitro growth inhibitory effects to promising anticancer activity.

Covering: 1957 to 2017 Algae constitute a heterogeneous group of eukaryotic photosynthetic organisms, mainly found in the marine environment. Algae produce numerous metabolites that help them cope with the harsh conditions of the marine environment. Because of their structural diversity and uniqueness, these molecules have recently gained a lot of interest for the identification of medicinally useful agents, including those with potential anticancer activities. In the current review, which is not a catalogue-based one, we first highlight the major biological events that lead to various types of cancer, including metastatic ones, to chemoresistance, thus to any types of current anticancer treatment relating to the use of chemotherapeutics. We then review algal metabolites for which scientific literature reports anticancer activity. Lastly, we focus on algal metabolites with promising anticancer activity based on their ability to target biological characteristics of cancer cells responsible for poor treatment outcomes. Thus, we highlight compounds that have, among others, one or more of the following characteristics: selectivity in reducing the proliferation of cancer cells over normal ones, potential for killing cancer cells through non-apoptotic signaling pathways, ability to circumvent MDR-related efflux pumps, and activity in vivo in relevant pre-clinical models.

Antimitotic and antivascular activity of heteroaroyl-2-hydroxy-3,4,5-trimethoxybenzenes.

This study reports the synthesis of a series of heteroaroyl-2-hydroxy-3,4,5-trimethoxybenzenes, which are potent antitubulin agents. Compound 13, (2-hydroxy-3,4,5-trimethoxyphenyl)-(6-methoxy-1H-indol-3-yl)-methanone exhibits marked antiproliferative activity against KB and MKN45 cells with IC50 values of 8.8 and 10.5 nM, respectively, binds strongly to the colchicine binding site and leads to inhibition of tubulin polymerization. It also behaves as a vascular disrupting agent which suppresses the formation of capillaries. The C2-OH group in the A-ring of this compound not only retains the biological activity but has valuable physicochemical properties.

Safranal as a novel anti-tubulin binding agent with potential use in cancer therapy: An in vitro study.

Safranal, a component of saffron, indicates anti-tumor activities; however, the precise mechanism of this effect has remained elusive. In this study we investigated tubulin assembly and structure in the presence of safranal to open the new horizons about the potential of safranal as an anti-tumor agent via microtubule disfunction. Anti-microtubule activity of safranal was evaluated by turbidimetric method and transmission electron microscopy (TEM). Safranal (0.1-70µM) was incubated with tubulin (5µM) and tubulin structural changes was surveyed using fluorometry. Tubulin binding site with safranal was estimated by molecular docking. Microtubule polymerization decreased significantly in the presence of safranal, regardless of its concentration and the IC50 value was obtained 72.19µM. Safranal was situated between α and ß tubulin closer to α-tubulin and hydrogen bond with Gly 142 and hydrophobic interactions played critical roles for safranal molecule stabilization in binding site. It seems that decline of tubulin assembly could result from tubulin structural changes through safranal bindings between alpha and beta tubulin with ΔG(0) of -5.63kcal/mol. Safranal can be taken into account as an anticancer agent; however, in vivo experiments are required to confirm this conclusion.

Synthesis and evaluation of the cell cycle arrest and CT DNA interaction properties of 4ß-amino-4'-O-demethyl-4-deoxypodophyllotoxins.

A series of 4ß-amino-4'-O-demethyl-4-deoxypodophyllotoxin derivatives were synthesized, and their cytotoxicities against several human cancer cell lines, including HepG2, A549, HeLa and HCT-8 cells, evaluated. Some of these compounds exhibited higher levels of cytotoxicity than the anticancer drug etoposide. 4ß-N-(4-Nitrophenyl piperazinyl)-4'-O-demethyl-4-deoxypodophyllotoxin (11) was found to be the most potent synthesized compound in the current study, and induced cell cycle arrest in the G2/M phase in HeLa cells, which was accompanied by apoptosis. Furthermore, this compound activated the expression of cdc2, cyclin B1, p53 and caspase-3 in HeLa cells, leading to changes in the conformation of calf thymus DNA from the B-form to a more compact C-form.

Measurement of ligand binding to tubulin by sulfhydryl reactivity.

Ligand binding can induce shifts in protein conformation. In the case of tubulin, these drug-induced confirmational changes can prevent or stabilize microtubule polymerization. 5',5'-Dithiobis(2-nitrobenzoate) (DTNB) reacts with free and accessible sulfhydryls and stoichiometrically produces a detectable product, which allows an exact measurement of reacted thiols. Since binding of small ligands may alter conformational dynamics, it may also affect the reactivity of thiols on tubulin. Differences in DTNB reactivity with thiols upon ligand binding can therefore be used to deduce binding characteristics. We will describe two methods that use tubulin cysteine reactivity with DTNB in the presence of drug to define ligand-binding characteristics.

Anti-microtubule activity of tubeimoside I and its colchicine binding site of tubulin.

BACKGROUND: Tubeimoside I (TBMS1) was isolated from the tubers of Bolbostemma paniculatum (Maxim.) Franquet. TBMS1 shows potent anti-tumor activity. The present study was conducted to investigate the anti-microtubule role of TBMS1 and its binding site of tubulin. METHODS: Cell growth inhibition was measured by MTT after treatment with TBMS1. Uptake kinetics of TBMS1 by human nasopharyngeal carcinoma CNE-2Z cell line (CNE-2Z) was assayed by HPLC. Microtubule protein (MTP) was prepared from porcine brain through two cycles of polymerization-depolymerization in a high molarity buffer. Inhibition of MTP polymerization induced by TBMS1 was determined by a turbidity measurement and a sedimentation assay; the interactions of TBMS1 with tubulin within CNE-2Z cells were investigated by immunofluorescence microscopy and immunoblotting. TBMS1 was tested for its ability to inhibit binding of known tubulin ligands through competitive binding assay. RESULTS: TBMS1 displayed growth inhibitory activity against CNE-2Z cells with IC(50) value of 16.7 microM for 72 h. HPLC analysis of TBMS1 uptake by CNE-2Z cells displayed the initial slow TBMS1 uptake and then gradually reaching an maximum uptake near 18 h. CNE-2Z cells treated with TBMS1 (25 microM, 3 h) were sufficient to cause the microtubular network disruption. Immunoblot analysis showed that the proportion of cytosolic tubulin of cells treated with TBMS1 increased in a time- and concentration-dependent manner. TBMS1 did not inhibit the binding of vinblastine to tubulin. Colchicine binding to tubulin was inhibited in the presence of TBMS1. CONCLUSIONS: TBMS1 is an anti-microtubule agent, and its binding site of tubulin is the colchicine binding site of tubulin.

Eribulin, a simplified ketone analog of the tubulin inhibitor halichondrin B, for the potential treatment of cancer.

Eisai Co Ltd is developing eribulin, a simplified synthetic macrocyclic ketone analog of the tubulin inhibitor halichondrin B, for the potential treatment of cancer. Phase III trials are underway in the US and Europe for patients with breast cancer. Eribulin is currently in phase II trials for NSCLC and soft tissue sarcoma, and pancreatic, prostate, ovarian, fallopian tube, peritoneal and head and neck cancer, and phase I/II trials for urothelial cancers.

Biological evaluation of tubulysin A: a potential anticancer and antiangiogenic natural product.

Tubulysin A (tubA) is a natural product isolated from a strain of myxobacteria that has been shown to depolymerize microtubules and induce mitotic arrest. The potential of tubA as an anticancer and antiangiogenic agent is explored in the present study. tubA shows potent antiproliferative activity in a panel of human cancer cell lines irrespective of their multidrug resistance properties. It induces apoptosis in cancer cells but not in normal cells and shows significant potential antiangiogenic properties in several in vitro assays. It is efficacious in initial animal studies using a hollow fibre assay with 12 different human tumour cell lines. This study suggests that both in vitro and preclinical profiles of tubA may translate into clinically useful anticancer properties.