BackgroundAlizarin and purpurin are di- and trihydroxyanthraquinones derived from Rubia tinctorum L. Previous pharmacological studies have demonstrated that they exhibit certain degree of selective inhibitory effects towards cancer cells suggesting their application as a targeted drug for cancer. Our present work was aimed to investigate the suitability of hydroxyanthraquinones of Rubia tinctorum L. for targeted tumor therapy. The effects of alizarin, purpurin and an aqueous extract from transformed hairy root culture of Rubia tinctorum L. were examined on (1) cell proliferation, (2) apoptosis, (3) cell adhesion/morphology and (4) migration (chemotaxis, chemokinesis) of human melanoma cell lines (A2058, HT168-M1) and human fibroblast cells (MRC-5), as well as (5) the aqueous extract was analytically characterized.MethodsThe aqueous extract was prepared from R. tinctorum hairy root culture and qualitatively analyzed by HPLC and ESI–MS methods. The cell growth inhibitory activity of anthraquinones was evaluated by MTT-assay and by flow cytometry. The effect of anthraquinones on cell adhesion was measured by an impedance based technique, the xCELLigence SP. For the chemotaxis assay NeuroProbe® chamber was used. Computer based holographic microscopy was applied to analyze chemokinetic responses as well as morphometry. Statistical significance was determined by the one-way ANOVA test.ResultsIn the aqueous extract, munjistin (Mr = 284, tR = 18.4 min) as a principal component and three minor anthraquinones (pseudopurpurin, rubiadin and nordamnacanthal) were identified. The purpurin elicited a stronger but not apoptosis-mediated antitumor effect in melanoma cells (A2058: 10−6–10−5 M: 90.6–64.1 %) than in normal fibroblasts (10−6–10−5 M: 97.6–84.8 %). The aqueous extract in equimolar concentrations showed the most potent cytotoxicity after 72 h incubation (A2058: 10−6–10−5 M: 87.4–55.0 %). All tested substances elicited chemorepellent effect in melanoma cells, while in MRC-5 fibroblasts, only the alizarin exhibited such a repellent character. Indices of chemokinesis measured by holographic microscopy (migration, migration directness, motility and motility speed) were significantly enhanced by alizarin and purpurin as well, while morphometric changes were weak in the two melanoma cell lines.ConclusionsOur results highlight the effective and selective inhibitory activity of purpurin towards melanoma cells and its possible use as a targeted anticancer agent. The anthraquinones of the cytotoxic extract are suggested to apply in drug delivery systems as an anticancer drug.Electronic supplementary materialThe online version of this article (doi:10.1186/s12935-015-0271-4) contains supplementary material, which is available to authorized users.
Lobelia inflata L. a native North-American species is reported to possess pharmaceutically significant properties. Our experiments aimed at introducing this species to Hungary and implemented in randomized blocks with 4 repetitions, indicate the favourable effects of Mg-fertilization. Based on our results, it can be estimated that under the influence of Mg treatment an established population of Indian tobacco can produce some 3.2 kg*ha-1 total alkaloids.
We have studied the biomass and alkaloid production of genetically transformed hairy root cultures of Lobelia inflata L.. The hairy root clone 8009/h7 transformed with Agrobacterium rhizogenes strain R1601 was cultivated on B5 liquid media containing 3% sucrose. The bioactive compounds were analysed by HPLC, the total alkaloid content was determined by spectrophotometry in the hairy roots and in the liquid medium. The bioreactor cultures produced an increased biomass and quantity of total alkaloids, but lobeline was not measurable in the tissues and in the medium. 1.7 mg/g total alkaloid content was found in the hairy root tissues. The total alkaloid production in the culture medium (14.3 mg) was higher than in the tissues (10.46 mg). Polyacetylenes were detected both in the tissues and in the liquid medium.
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