In Vitro Metabolism of Phenstatin: Potential Pharmacological Consequences

Abstract

Phenstatin and its derivatives are potential anticancer drug candidates according to their inhibitory properties on tubulin polymerization, cell growth and antivascular activity. However, at the present time, neither pharmacological nor metabolic studies have been conducted in order to strengthen the relevance of phenstatine as a drug discovery candidate. In the present work, the metabolic fate of phenstatin in rat and human microsomal preparations was studied to investigate the stability of this tubulin polymerization inhibitor and any effects of the metabolites on polymerization and on PC3 cancer cell proliferation. The metabolites were separated by high-performance liquid chromatography and, after their synthesis, characterized by simultaneous LC-DAD-UV and LC-ESI-MS analyses. Thus, eight metabolites were identified. The major biotransformation pathways are carbonyl reduction, O-methylation at C-3', O-methylation after aromatic hydroxylation at the position C-2' on phenyl B ring and O-demethylation on A ring. Four of the identified metabolites were as active or more active, than phenstatin in vitro. Moreover, the better stability of phenstatin versus CA-4 and the lack of quinone formation could justify the design of new analogues which could include various substituents on phenyl rings or linker group in order to modulate the metabolism of phenstatin toward even more active metabolites and so up-regulate the pharmacological activity.

Methoxy and bromo scans onN-(5-methoxyphenyl) methoxybenzenesulphonamides reveal potent cytotoxic compounds, especially against the human breast adenocarcinoma MCF7 cell line

“…Melting points were determined on a B€ uchi 510 apparatus and are uncorrected. 1 H NMR and 13 C NMR spectra were recorded in CDCl 3 or CD 3 OD on a Bruker WP 200-SY spectrometer operating at 200/50 MHz, or Varian Mercury or Bruker SY spectrometers operating at 400/ 100 MHz. Chemical shifts (d) are given in ppm downfield from tetramethylsilane and coupling constants (J values) are given in Hz.…”

“…1 H NMR (400 MHz, CDCl 3 ): d 3.62 (6H, s), 3.87 (3H, s), 4.65 (2H, s), 6.12 (2H, d, J ¼ 2), 6.28 (1H, t, J ¼ 2), 6.94 (2H, d, J ¼ 8.8), 7.22 (5H, m), 7.63 (2H, d, J ¼ 8.8). 13…”

“…Diarylsulphonamides are privileged scaffolds in medicinal chemistry and well-known anticancer agents 3 , with benzenesulphonamides carrying 3,4,5-trimethoxyphenyl (TMP) rings acting as tubulin inhibitors, such as N- (3,4,5-trimethoxyphenyl)-4-methoxybenzenesulphonamides 3 . The TMP ring has long been considered important for strong tubulin-binding through interactions with the sidechain of Cys241b amongst others and potent cytotoxic effects 4,9,10 , but it is also a bulky hydrophobic moiety that lowers the aqueous solubility and suffers from metabolic inactivation by O-demethylation reactions of the aromatic methoxy groups [11][12][13] . Recently, successful substitutions of the TMP ring have appeared in several tubulin inhibitory structural families, such as the combretastatins, the isocombretastatins, and the phenstatins, some of them even featuring polar azines replacing the phenyl ring [14][15][16][17] .…”

Cytotoxic substituted indolizines as new colchicine site tubulin polymerisation inhibitors

“…Phenstatin is also known for its outstanding antitumor activities on a wide variety of human cancer cells 14,15 . Its biological properties are comparable to CA-4, currently investigated in clinical trials 16 , but in contrast to CA-4, Phenstatin has a greater pharmacological potential due to improved metabolic stability and requires an easier synthesis for large-scale production 17 . In the process of drug discovery, this kind of compounds are lead scaffolds for the development of improved bioactive analogues, and Phenstatin continues to be a source of inspiration for researchers in designing new potential anticancer drugs [18][19][20][21][22][23][24][25] .…”

Colchicine-Binding Site Inhibitors from Chemistry to Clinic: A Review

“…This inhibitor is structurally related to the known CBSI, podophyllotoxin [58]. Phenstatin is more stable than CA-4 in vivo as it cannot isomerize to an inactive trans configuration [59]. It mirrors CA-4's biological mechanism of action and both phenstatin and its corresponding water-soluble prodrug salt demonstrate pronounced cytotoxicity against human cancer cell lines [60].…”