ABSTRACT
During the last decade, maslinic acid has been evaluated for many biological properties, e.g. as an anti-tumor or an anti-viral agent but also as a nutraceutical. The potential of maslinic acid and related derivatives to act as inhibitors of acetyl- or butyryl-cholinesterase was examined in this communication in more detail. Cholinesterases do still represent an interesting group of target enzymes with respect to the investigation and treatment of the Alzheimer's disease and other dementia illnesses as well. Although other triterpenoic acids have successfully been tested for their ability to act as inhibitors of cholinesterases, up to now maslinic acid has not been part of such studies. For this reason, three series of maslinic acid derivatives possessing modifications at different centers were synthesized and subjected to Ellman's assay to determine their inhibitory strength and type of inhibitory action. While parent compound maslinic acid was no inhibitor in these assays, some of the compounds exhibited an inhibition of acetylcholinesterase in the single-digit micro-molar range. Two compounds were identified as inhibitors of butyrylcholinesterase showing inhibition constants comparable to those of galantamine, a drug often used in the treatment of Alzheimer's disease. Furthermore, additional selectivity as well as cytotoxicity studies were performed underlining the potential of several derivatives and qualifying them for further investigations. Docking studies revealed that the different kinetic behavior within the same compound series may be explained by the ability of the compounds to enter the active site gorge of AChE.
Subject(s)
Acetylcholinesterase/metabolism , Cholinesterase Inhibitors/chemical synthesis , Cholinesterase Inhibitors/pharmacology , Triterpenes/pharmacology , Animals , Cells, Cultured , Cholinesterase Inhibitors/chemistry , Dose-Response Relationship, Drug , Electrophorus/metabolism , Fibroblasts/drug effects , Mice , Molecular Docking Simulation , Molecular Structure , NIH 3T3 Cells , Structure-Activity Relationship , Triterpenes/chemical synthesis , Triterpenes/chemistryABSTRACT
Several novel esters and amides of maslinic acid were prepared. Their evaluation for cytotoxic activity with a panel of human cancer cell lines using a sulforhodamine B (SRB) assay revealed for some of them a noteworthy activity. The results from annexinV-FITC and caspase-assays as well as from DNA laddering experiments provided evidence for an apoptotic cell death. A diacetylated benzylamide (15) induced a G1/G0 arrest in tumor cells. It also displayed an extraordinary cytotoxicity against human ovarian cancer cells but a 300 times lower toxicity for non-malignant primary human fibroblasts.
Subject(s)
Triterpenes/chemistry , Amides/chemistry , Animals , Apoptosis , Cell Line, Tumor , Cell Proliferation , Esters/chemistry , Humans , Mice , Molecular StructureABSTRACT
Cancer is one of the most commonly diagnosed diseases worldwide; its mortality rate is high, and there is still a demand for the development of antitumor active drugs. Triterpenoic acids show many pharmacological effects, among them antitumor activity. One of these, maslinic acid-1 is of interest because of its antitumor profile. It is not only cytotoxic but also triggers apoptosis in various human tumor cell lines. To improve the cytotoxicity of parent 1 we set out to synthesize a series of esters and amides differing in structure and lipophilicity. These compounds were tested in a sulforhodamine B assay for cytotoxicity, and screened for their ability to induce apoptosis using an acridine orange/propidium iodide assay, DNA laddering and cell cycle experiments. Esters containing small-chain, lipophilic residues increased the cytotoxicity whereas amides as well long-chain esters led to a decrease in activity. The antitumor activity seems to be independent from the substitution pattern at position C-28 for esters and amides but alters their mode of action.
