Abstract
Telomerase, the enzyme responsible for cell immortality, is an important target in anti-cancer drug discovery. Boldine, an abundant aporphine alkaloid of Peumus boldus, is known to inhibit telomerase at non-toxic concentrations. Cytotoxicity of N-benzylsecoboldine hydrochloride (BSB), a synthetic derivative of boldine, was determined using the MTT method in MCF7 and MDA-MB231 cells. Aliquots of cell lysates were incubated with various concentrations of BSB in qTRAP (quantitative telomere repeat amplification protocol)-ligand experiments before substrate elongation by telomerase or amplification by hot-start Taq polymerase. The crystal structure of TERT, the catalytic subunit of telomerase from Tribolium castaneum, was used for docking and molecular dynamics analysis. The qTRAP-ligand data gave an IC50 value of about 0.17 ± 0.1 µM for BSB, roughly 400 times stronger than boldine, while the LD50 in the cytotoxicity assays were 12.5 and 21.88 µM, respectively, in cells treated for 48 h. Although both compounds interacted well with the active site, MD analysis suggests a second binding site with which BSB interacts via two hydrogen bonds, much more strongly than boldine. Theoretical analyses also evaluated the IC50 for BSB as submicromolar. BSB, with greater hydrophobicity and flexibility than boldine, represents a promising structure to inhibit telomerase at non-toxic concentrations.
Highlights
Boldine (1,10-dimethoxy-2,9-dihydroxyaporphine) is an aporphine alkaloid found in several plant species and is the main alkaloid in the bark and a relatively abundant component of the leaves of the boldo tree (Peumus boldus) [1] and Lindera aggregata [2]
The MTT test showed that N-benzylsecoboldine (BSB) hydrochloride has LD50 = 16.25 and 21.88 μM against the MCF7 and MDA-MB-231 lines, respectively
In the molecular dynamics simulation resulting from the blind docking position in two essential subunits; a catalytic protein (TERT), boldine exhibited a binding energy of −6.64 kcal/mol and an inhibition constant of 9.15 μM
Summary
Boldine (1,10-dimethoxy-2,9-dihydroxyaporphine) is an aporphine alkaloid found in several plant species and is the main alkaloid in the bark and a relatively abundant component of the leaves of the boldo tree (Peumus boldus) [1] and Lindera aggregata [2]. Boldine is known for its health promoting properties that include hepatoprotective, cytoprotective, antipyretic and anti-inflammatory effects [3]. The potent antioxidant effects of boldine guarding nitric oxide against reactive oxygen species have been shown to protect the endothelium, supporting its therapeutic role against hypertension and diabetes mellitus [5,6,7]. Boldine has been shown to reduce the viability and proliferation of T24 human bladder carcinoma cells by inducing cell cycle arrest at the G2/M-phase and causes cell death by apoptosis in correlation with AKT inactivation and glycogen synthase kinase-3β (GSK-3β) activation [8]. Boldine showed a strong induction of apoptosis in breast cancer cells [9], and cerebrovascular protective effects against neural apoptosis via inhibition of mitochondrial Bax translocation and cytochrome C release [10]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
