The Biological Assessment of Shikonin and ß,ß-dimethylacrylshikonin Using a Cellular Myxofibrosarcoma Tumor Heterogeneity Model.

Myxofibrosarcoma (MFS) is a subtype of soft tissue sarcoma of connective tissue, which is characterized by large intra-tumor heterogeneity. Therapy includes surgical resection. Additional chemotherapy is of limited effect. In this study, we demonstrated the potent anticancer activity of shikonin derivatives in our MFS cellular model of tumor heterogeneity for developing a new therapeutic approach. The impact of shikonin and ß,ß-dimethylacrylshikonin (DMAS) on viability, apoptotic induction, MAPK phosphorylation, and DNA damage response were analyzed by means of two human MFS cell lines, MUG-Myx2a and MUG-Myx2b, derived from a singular tumor tissue specimen. MFS cells showed a dose-dependent inhibition of cell viability and a significant induction of apoptosis. Treatment with shikonin derivatives caused an inhibition of pSTAT3 and an increase in pAKT, pERK, pJNK, and pp38. DMAS and shikonin inhibited the activation of the two master upstream regulators of the DNA damage response, ATR and ATM. MUG-Myx2b, which contains an additional PTEN mutation, was more sensitive in some targets. These data demonstrate the significant antitumorigenic effect of shikonin derivatives in MFS and highlight the importance of intra-tumor heterogeneity in treatment planning.

Cytotoxicity of Carvotacetones from Sphaeranthus africanus Against Cancer Cells and Their Potential to Induce Apoptosis.

Three carvotacetones (1 - 3: ) isolated from Sphaeranthus africanus were screened in 60 cancer cell lines at the National Cancer Institute (NCI) within the Developmental Therapeutics Program (DTP). At the concentration of 10-5 M, compound 1: (3,5-diangeloyloxy-7-hydroxycarvotacetone) turned out to be the most active compound against ACHN and UO-31 renal cancer cell lines with growth percent values of - 100% (all cells dead). Compound 2: (3-angeloyloxy-5-[2″,3″-epoxy-2″-methylbutanoyloxy]-7-hydroxycarvotacetone) showed strong effects in SK-MEL-5 melanoma and ACHN renal cancer cells with inhibition values of 93% and 97%, respectively. Compound 3: (3-angeloyloxy-5-[3″-chloro-2″-hydroxy-2″-methylbutanoyloxy]-7-hydroxy-carvotacetone) exhibited a quite strong effect on renal cancer cells with a growth inhibitory effect of 96% against ACHN and UO-31 cells. When treated with five different concentrations of 1: (1 × 10-8, 1 × 10-7, 1 × 10-6, 1 × 10-5, and 1 × 10-4 M), HOP-92 cells were found to be most sensitive with GI50, TGI, and LC50 values of 0.17, 0.40, and 0.96 µM, respectively. When using the ApoTox-Glo triplex assay to evaluate the apoptosis inducing effects of seven carvotacetones isolated from S. africanus in CCRF-CEM cells, compounds 1:  - 6: increased caspase-3/7 activity with 1, 2: , and 4: (3-angeloyloxy-5,7-dihydroxycarvotacetone) exhibiting the highest activitiy, indicating induction of caspase-dependent apoptosis.

Shikonin derivatives cause apoptosis and cell cycle arrest in human chondrosarcoma cells via death receptors and MAPK regulation.

BACKGROUND: Although chondrosarcoma is the second most common primary malignant bone tumor, treatment options are limited due to its extensive resistance to a chemo- and radiation therapy. Since shikonin has shown potent anticancer activity in various types of cancer cells, it represents a promising compound for the development of a new therapeutic approach. METHODS: The dose-relationships of shikonin and its derivatives acetylshikonin and cyclopropylshikonin on two human chondrosarcoma cell lines were measured using the CellTiter-Glo®. The changes in the cell cycle were presented by flow cytometry. Protein phosphorylation and expression apoptotic markers, MAPKs and their downstream targets were analyzed using western blotting and gene expression were evaluated using RT-qPCR. RESULTS: Chondrosarcoma cells showed a dose-dependent inhibition of cell viability after treatment with shikonin and its derivatives, with the strongest effect for shikonin and IC50 values of 1.3 ± 0.2 µM. Flow cytometric measurements revealed a G2/M arrest of the cells after treatment. Protein and gene expression analysis demonstrated a dose-dependent downregulation of survivin and XIAP, and an upregulation of Noxa, γH2AX, cleaved caspase-8, -9, -3, and -PARP. Furthermore, the expression of various death receptors was modulated. As MAPK signaling pathways play a key role in tumor biology, their phosphorylation pattern and their corresponding downstream gene regulation were analyzed. Treatment with shikonin derivatives caused an inhibition of pSTAT3 and an increase of pAKT and the MAPKs pERK, pJNK, and pp38 in a dose-dependent manner. CONCLUSIONS: These data demonstrated the significant anti-tumorigenic effect of shikonin derivatives in chondrosarcoma and encourage further research.

SK119, a Novel Shikonin Derivative, Leads to Apoptosis in Melanoma Cell Lines and Exhibits Synergistic Effects with Vemurafenib and Cobimetinib.

Melanoma is a complex and heterogenous disease, displays the deadliest form of skin cancer, and accounts for approx. 80% of all skin cancer deaths. In this study, we reported on the synthesis and pharmacological effects of a novel shikonin derivative (SK119), which is active in a nano-molar range and exhibits several promising in vitro effects in different human melanoma cells. SK119 was synthesized from shikonin as part of our search for novel, promising shikonin derivatives. It was screened against a panel of melanoma and non-tumorigenic cell lines using XTT viability assays. Moreover, we studied its pharmacological effects using apoptosis and Western blot experiments. Finally, it was combined with current clinically used melanoma therapeutics. SK119 exhibited IC50 values in a nano-molar range, induced apoptosis and led to a dose-dependent increase in the expression and protein phosphorylation of HSP27 and HSP90 in WM9 and MUG-Mel 2 cells. Combinatorial treatment, which is highly recommended in melanoma, revealed the synergistic effects of SK119 with vemurafenib and cobimetinib. SK119 treatment changed the expression levels of apoptosis genes and death receptor expression and exhibited synergistic effects with vemurafenib and cobimetinib in human melanoma cells. Further research indicates a promising potential in melanoma therapy.

Structural Diversity of Complex Phloroglucinol Derivatives from Eucalyptus Species.

Several species of the genus Eucalyptus are used in many traditional medicine systems for the treatment of respiratory tract infections, colds, flu, sore throats, and bronchitis. The genus Eucalyptus (Myrtaceae) is a well-known natural source of bioactive phloroglucinols. These polyphenolic compounds bear an aromatic phenyl ring with three hydroxy groups (1,3,5-trihydroxybenzene) which have been exhibiting a variety of biological activities such as antimicrobial, anticancer, anti-allergic, anti-inflammatory, and antioxidant activities. This review summarizes the literature published from 1997 until the end of 2021 and addresses the structure diversity of phloroglucinols isolated from Eucalyptus species and their biological activities. Phloroglucinol-terpene adducts are the main class of compounds that have been reported in this genus.

MUG Mel3 Cell Lines Reflect Heterogeneity in Melanoma and Represent a Robust Model for Melanoma in Pregnancy.

Melanomas are aggressive tumors with a high metastatic potential and an increasing incidence rate. They are known for their heterogeneity and propensity to easily develop therapy-resistance. Nowadays they are one of the most common cancers diagnosed during pregnancy. Due to the difficulty in balancing maternal needs and foetal safety, melanoma is challenging to treat. The aim of this study was to provide a potential model system for the study of melanoma in pregnancy and to illustrate melanoma heterogeneity. For this purpose, a pigmented and a non-pigmented section of a lymph node metastasis from a pregnant patient were cultured under different conditions and characterized in detail. All four culture conditions exhibited different phenotypic, genotypic as well as tumorigenic properties, and resulted in four newly established melanoma cell lines. To address treatment issues, especially in pregnant patients, the effect of synthetic human lactoferricin-derived peptides was tested successfully. These new BRAF-mutated MUG Mel3 cell lines represent a valuable model in melanoma heterogeneity and melanoma pregnancy research. Furthermore, treatment with anti-tumor peptides offers an alternative to conventionally used therapeutic options-especially during pregnancy.

Synthesis and Pharmacological In Vitro Investigations of Novel Shikonin Derivatives with a Special Focus on Cyclopropane Bearing Derivatives.

Melanoma is the deadliest form of skin cancer and accounts for about three quarters of all skin cancer deaths. Especially at an advanced stage, its treatment is challenging, and survival rates are very low. In previous studies, we showed that the constituents of the roots of Onosma paniculata as well as a synthetic derivative of the most active constituent showed promising results in metastatic melanoma cell lines. In the current study, we address the question whether we can generate further derivatives with optimized activity by synthesis. Therefore, we prepared 31, mainly novel shikonin derivatives and screened them in different melanoma cell lines (WM9, WM164, and MUG-Mel2 cells) using the XTT viability assay. We identified (R)-1-(1,4-dihydro-5,8-dihydroxy-1,4-dioxonaphthalen-2-yl)-4-methylpent-3-enyl 2-cyclopropyl-2-oxoacetate as a novel derivative with even higher activity. Furthermore, pharmacological investigations including the ApoToxGloTM Triplex assay, LDH assay, and cell cycle measurements revealed that this compound induced apoptosis and reduced cells in the G1 phase accompanied by an increase of cells in the G2/M phase. Moreover, it showed hardly any effects on the cell membrane integrity. However, it also exhibited cytotoxicity against non-tumorigenic cells. Nevertheless, in summary, we could show that shikonin derivatives might be promising drug leads in the treatment of melanoma.

Preparation of new 1,3-dibenzyl tetrahydropyridinylidene ammonium salts and their antimicrobial and anticellular activities.

New 1,3 dibenzyl -tetrahydropyridinylidene ammonium salts have been prepared from unsubstituted or N-benzylated tetrahydropyridinylidene ammonium salts. The antiplasmodial and antitrypanosomal activities as well as their cytotoxic effects were determined using microplate assays. In addition, their activities against two gram positive and two gram negative bacteria strains and a yeast strain were examined. Furthermore, anticancer effects against two cell lines were investigated. Physicochemical parameters were calculated and structure-activity-relationships discussed. One compound showed antiplasmodial activity against a multiresistant strain of Plasmodium falciparum in subnanomolar concentration. Antitrypanosomal activities were detected in low nanomolar concentrations. A single compound was active against grampositive and gramnegative bacteria, as well as yeast. One compound inhibited the growth of a HCT cell line in low concentration.

Naphthoquinone Derivatives Isolated from Plants: Recent Advances in Biological Activity.

Naturally occurring naphthoquinones (NQs) comprising highly reactive small molecules are the subject of increasing attention due to their promising biological activities such as antioxidant, antimicrobial, apoptosis-inducing activities, and especially anticancer activity. Lapachol, lapachone, and napabucasin belong to the NQs and are in phase II clinical trials for the treatment of many cancers. This review aims to provide a comprehensive and updated overview on the biological activities of several new NQs isolated from different species of plants reported from January 2013 to January 2020, their potential therapeutic applications and their clinical significance.

Periplocin mediates TRAIL-induced apoptosis and cell cycle arrest in human myxofibrosarcoma cells via the ERK/p38/JNK pathway.

BACKGROUND: Periploca sepium is traditionally used in Chinese medicine to treat particularly rheumatic disorders and as a tonic. Periplocin was found as the most cytotoxic compound of its root bark and induced death receptor mediated apoptosis in liposarcoma cells. Sarcomas are a rare type of cancer with only a few treatment options. The five-year survival rate of advanced tumors is low. PURPOSE: In this study, we investigated the effects of periplocin in two myxofibrosarcoma (MFS)cell lines, MUG-Myx2a and MUG-Myx2b, which are subclones of the same tumor and reflect the tumor´s heterogeneity, and in T60 primary myxofibrosarcoma cells. METHODS: The xCELLigence system and the CellTiter 96® AQueous assay were used for studying cell viability. FACS and Western blot experiments were used to investigate the effects of periplocin on apoptosis induction, cell cycle distribution, and the expression of cleaved PARP, caspase 3, p53, phospho-histone γH2AX, ERK/phospho ERK, p38/phospho p38, and, finally, JNK/phospho JNK. Additionally, the expression of the apoptotic markers Bim, NOXA, Bak, Bcl-2, Bcl-xl, and the death receptors IGFR, FADD, TRADD, TNFR1A, TRAIL-R1, and TRAIL-R2 were evaluated using reversed real-time PCR. RESULTS: Periplocin decreased dose-dependently the viability of all MFS cell lines and was more effective than the standard chemotherapeutic doxorubicin. It arrested the cells in the G2/M phase and led to caspase activation. Moreover, periplocin increased the mRNA expression of NOXA, Bak, Bcl-2, and death receptors such as TRAIL-R1 and TRAIL-R2 and the protein expression of ERK/phospho ERK, p38/phospho p38, and JNK/phospho JNK. In all cases, differences in the effects in the different subclones were observed. CONCLUSION: Periplocin showed promising effects in MFS cells. The higher effectiveness compared to doxorubicin is an important aspect for further research with regard as a treatment option. The different effects of periplocin in the two subclones showed the great importance of intratumoral heterogeneity in MFS therapy.

ß,ß-Dimethylacrylshikonin Induces Apoptosis in Melanoma Cell Lines by NOXA Upregulation.

Melanoma is the most aggressive form of skin cancer, with high metastasis rates and poor prognosis. Survival rates and possible therapies depend on the state of the tumor and its mutational profile. BRAF and NRAS are the most frequent driver mutations. Currently, there is no efficient therapy for NRAS-mutated or late-stage melanoma. In this study, the therapeutic potential of ß,ß-dimethylacrylshikonin (DMAS) was investigated on melanoma. The influence of DMAS was determined in five different melanoma cell lines with different mutational profiles. The effects of this compound on cell viability, apoptosis, and gene and protein expression were examined. The results obtained were validated in vivo. DMAS significantly reduced the viability of several melanoma cell lines in a concentration- and time-dependent manner. Furthermore, DMAS induced caspase-3-dependent apoptosis via NOXA upregulation, as confirmed by NOXA knockdown experiments. This is the first time that NOXA-dependent apoptosis was shown with respect to a shikonin derivative and melanoma. Additionally, tumor regression and necrosis under DMAS treatment were demonstrated in vivo. Importantly, BRAF as well as NRAS-mutated metastatic human melanoma cell lines were treated successfully in vitro and in vivo. Taken together, DMAS showed promising results and is worthy of further study.

Anti-inflammatory and antiproliferative compounds from Sphaeranthus africanus.

BACKGROUND: Sphaeranthus africanus has been used in traditional Vietnamese medicine to treat sore throat, and to relieve pain and swelling. However, the anti-inflammatory activity of this plant had not yet been investigated. Previously, we isolated five carvotacetones (1-5) from this plant that displayed cytotoxicity against several cancer cell lines. PURPOSE: The objective of this study was to isolate further constituents from S. africanus and to investigate the anti-inflammatory activity of all constituents. Furthermore, the anti-proliferative activity of the newly isolated compounds was evaluated. STUDY DESIGN AND METHODS: Compounds were isolated from the upper parts of S. africanus by chromatographic methods. Structures were determined using spectroscopic techniques, like NMR and MS. All nine compounds isolated from S. africanus were evaluated for inhibitory activity against COX-1 and COX-2 isoenzymes in-vitro, COX-2 mRNA expression and influence on NO production. The anti-proliferative activities of newly isolated compounds (6-9) were evaluated by XTT viability assay with four cancer cell lines, namely CCRF-CEM, MDA-MB-231, HCT-116, and U-251 cells. RESULTS: Two diastereomeric carvotacetones (3-angeloyloxy-5-[2″S,3″R-dihydroxy-2″-methyl-butanoyloxy]-7-hydroxycarvotacetone (6) and 3-angeloyloxy-5-[2″R,3″R-dihydroxy-2″-methyl-butanoyloxy]-7-hydroxycarvotacetone (7), asperglaucide (8) and chrysoplenol D (9) were isolated from S. africanus. COX-1 and COX-2 assays of compounds 1-9 revealed that compounds 1 and 2 possess potent and selective COX-2 inhibitory activity with IC50 values of 3.6 and 0.5 µM, respectively. COX-2 gene expression assay showed that some carvotacetones exhibited inhibitory effects on COX-2 gene expression in THP-1 macrophages. Compound 4 is the most active compound inhibiting the synthesis of COX-2 by 55% at 2.06 µM. In the iNOS assay, all seven carvotacetones inhibited NO production in BV2 and RAW cell lines with IC50 values ranging from 0.2 to 2.9 µM. Compound 4 showed potent inhibitory activity with IC50 values of 0.2 µM in both BV2 and RAW cell lines. Molecular docking studies revealed the binding orientations of 1 and 2 in the active sites of COX-2. XTT assay of the newly isolated compounds revealed that the two isomeric carvotacetones (6-7) exhibited considerable anti-proliferative activity against four cancer cell lines (CCRF-CEM, MDA-MB-231, HCT-116, U-251) with IC50 values ranging from 1.23 to 8 µM. CONCLUSION: For the first-time, the diastereomeric carvotacetones (6-7) were isolated as separate compounds, and their anti-proliferative activity was determined. Selective COX-2 inhibitory, COX-2 mRNA expression and NO production inhibitory activities by some of the major constituents of S. africanus supports the traditional medical application of this plant for the treatment of inflammation-related disorders.

Synthesis of Jacaranone-Derived Nitrogenous Cyclohexadienones and Their Antiproliferative and Antiprotozoal Activities.

The cytotoxic and antiprotozoal activities of the phytoquinoide, jacaranone, and related compounds have been an ongoing topic in recent drug discovery. Starting from the natural product-derived cyclohexadienone scaffold, a series of nitrogen-containing derivatives were synthesized and subsequently evaluated for their antiproliferative and antiprotozoal activity. Anticancer potency was analyzed using different types of cancer cell lines: MDA-MB-231 breast cancer, CCRF-CEM leukemia, HCT-116 colon cancer, U251 glioblastoma, and, in addition, non-tumorigenic MRC-5 lung fibroblasts. Antiproliferative activities at micromolar concentrations could be shown. Antiprotozoal activity was assessed against Plasmodium falciparum NF54 and Trypanosoma brucei rhodesiense STIB900. For all compounds, selectivity indices (SI) were calculated based on assessed cytotoxicity towards L6 cells. In addition, the structure-activity-relationships and physicochemical parameters of these compounds are discussed.

Periplocin, the most anti-proliferative constituent of Periploca sepium, specifically kills liposarcoma cells by death receptor mediated apoptosis.

BACKGROUND: During a screening of Chinese plants traditionally used for the treatment of cancer and related diseases, extracts of the root bark of Periploca sepium Bunge showed strong cytotoxic activity. PURPOSE: Isolate and identify cytotoxic compounds from P. sepium and investigate the effects and mechanism of action on different cancer cell lines. METHODS: Extracts obtained with solvents of different polarities of the root bark of P. sepium were tested for their anti-proliferative effects. The most active extract was subjected to activity-guided fractionation using different chromatographic methods. The most active compound was further investigated on sarcoma cell lines regarding its effects concerning apoptosis, DNA damage and death receptor expression. RESULTS: We isolated the cardiac glycosides periplocin, glucosyl divostroside, periplogenin, periplocymarin and periplocoside M with periplocin exhibiting the lowest IC50 value against leukemia and liposarcoma cells. Liposarcomas are rare tumors within the heterogeneous group of soft tissue sarcomas and respond poorly to conventional treatments. Periplocin led to growth inhibition and apoptosis induction by changing the expression of death receptors and inducing DNA double strand breaks in SW-872 cells. CONCLUSION: Periplocin displays a promising mechanism of action in sarcoma cells because altering the death receptor expression is an interesting target in sarcoma treatment especially to overcome TRAIL resistance.

Synthesis of Novel Shikonin Derivatives and Pharmacological Effects of Cyclopropylacetylshikonin on Melanoma Cells.

Despite much research in the last centuries, treatment of malignant melanoma is still challenging because of its mostly unnoticeable metastatic spreading and aggressive growth rate. Therefore, the discovery of novel drug leads is an important goal. In a previous study, we have isolated several shikonin derivatives from the roots of Onosma paniculata Bureau & Franchet (Boraginaceae) which evolved as promising anticancer candidates. ß,ß-Dimethylacrylshikonin (1) was the most cytotoxic derivative and exhibited strong tumor growth inhibitory activity, in particular, towards melanoma cells. In this study, we synthesized eighteen novel shikonin derivatives in order to obtain compounds which exhibit a higher cytotoxicity than 1. We investigated their cytotoxic potential against various melanoma cell lines and juvenile skin fibroblasts. The most active compound was (R)-1-(1,4-dihydro-5,8-dihydroxy-1,4-dioxonaphthalen-2-yl)-4-methylpent-3-enyl cyclopropylacetate (cyclopropylacetylshikonin) (6). It revealed significant stronger tumor growth inhibitory activity towards two melanoma cell lines derived from metastatic lesions (WM164 and MUG-Mel2). Further investigations have shown that 6 induced apoptosis caspase-dependently, increased the protein levels of cleaved PARP, and led to double-stranded DNA breaks as shown by phosphorylation of H2AX. Cell membrane damage and cell cycle arrest were not observed.

Comparative Gene Expression Analysis in WM164 Melanoma Cells Revealed That ß-ß-Dimethylacrylshikonin Leads to ROS Generation, Loss of Mitochondrial Membrane Potential, and Autophagy Induction.

Skin cancer is currently diagnosed as one in every three cancers. Melanoma, the most aggressive form of skin cancer, is responsible for 79% of skin cancer deaths and the incidence is rising faster than in any other solid tumor type. Previously, we have demonstrated that dimethylacrylshikonin (DMAS), isolated from the roots of Onosma paniculata (Boraginaceae), exhibited the lowest IC50 values against different tumor types out of several isolated shikonin derivatives. DMAS was especially cytotoxic towards melanoma cells and led to apoptosis and cell cycle arrest. In this study, we performed a comprehensive gene expression study to investigate the mechanism of action in more detail. Gene expression signature was compared to vehicle-treated WM164 control cells after 24 h of DMAS treatment; where 1192 distinct mRNAs could be identified as expressed in all replicates and 89 were at least 2-fold differentially expressed. DMAS favored catabolic processes and led in particular to p62 increase which is involved in cell growth, survival, and autophagy. More in-depth experiments revealed that DMAS led to autophagy, ROS generation, and loss of mitochondrial membrane potential in different melanoma cells. It has been reported that the induction of an autophagic cell death represents a highly effective approach in melanoma therapy.

Phytochemical analysis and anti-inflammatory effects of Filipendula vulgaris Moench extracts.

Filipendula vulgaris Moench (dropwort) is used in traditional medicine for relieving various inflammation-related diseases. In the present study, the phytochemical profile of F. vulgaris aerial part (FVA) and root (FVR) methanolic extracts was evaluated by LC-DAD-HRMS analysis. Furthermore, their in vitro and in vivo anti-inflammatory effects, as well as their potential cytotoxicity, were assessed. Results showed that the extracts mainly contain phenolics like flavonoids, hydrolyzable tannins, procyanidins, and phenolic acid derivatives, including gaultherin. No in vitro cytotoxicity was found at the highest concentration (50 µg/mL). FVA extract (50 µg/mL) significantly inhibited cyclooxygenase-1 and -2 (COX-1 and COX-2) activities in vitro (>50% inhibition), and FVR extract considerably inhibited COX-2 activity (52.5 ±â€¯2.7%) without affecting COX-2 gene expression in LPS-stimulated THP-1 cells. The extracts demonstrated prominent in vivo anti-inflammatory potential upon oral administration in rats. Especially FVA extract at 100 and 200 mg/kg significantly inhibited carrageenan-induced edema formation. From these results, it can be concluded that F. vulgaris extracts possess interesting anti-inflammatory properties.

Influence of silibinin and ß-ß-dimethylacrylshikonin on chordoma cells.

BACKGROUND: Chordoma, slow growing bone tumours originating from remnants of the notochord, leave affected patients with a median survival of six years. The high recurrence rate of chordoma, together with limited treatment options and bad overall prognosis, make the development of new treatment options urgently necessary. PURPOSE: In this study, the potential of two natural products, silibinin and ß-ß-dimethylacrylshikonin (DMAS), was tested on clival (MUG-CC1 and UM-Chor1) as well as sacral (MUG-Chor1 and U-CH2) chordoma cell lines. The treatment was administered both as single- and combined therapy. METHODS: For investigation of cell viability, the Cell Titer 96 Aqueous Non-Radioactive Cell Proliferation Assay Kit was used. Apoptosis induction was studied by flow cytometry, (Annexin V/SYTOX Green, caspase-3) and RT-qPCR. Pathway analyses were performed by western blot. RESULTS: Both drugs were found to reduce cell viability alone as well as in combination in a dose dependent manner, with DMAS being more efficient than silibinin. The mode of cell death was mainly apoptosis in DMAS treated samples, while the combination therapy led to apoptosis as well as late-apoptosis/necrosis. Silibinin therapy alone, although reducing cell viability, did not lead to significant apoptotic effects in the performed assays. Focussing on the molecular mechanism of DMAS induced apoptosis, it was found that major genes of the mitochondrial apoptosis pathway, like NOXA and PUMA were overexpressed. Additionally, western blot experiments showed a decrease of ERK/pERK, STAT3/pSTAT3 (Tyr705) and AKT/pAKT expression/activation levels under DMAS treatment. CONCLUSION: DMAS is a promising new candidate for chordoma therapy, while silibinin or a combination of both is less favourable.

Antiproliferative Carvotacetones from Sphaeranthus africanus.

Five carvotacetone derivatives, including two known ones, 3,5-diangeloyloxy-7-hydroxycarvotacetone (1) and 3-angeloyloxy-5-[2″,3″-epoxy-2″-methylbutanoyloxy]-7-hydroxycarvotacetone (2), along with three new compounds, 3-angeloyloxy-5-[3″-chloro-2″-hydroxy-2″-methylbutanoyloxy]-7-hydroxycarvotacetone (3), 5-angeloyloxy-7-hydroxy-3-tigloyloxycarvotacetone (4), and 3-angeloyloxy-5,7-dihydroxycarvotacetone (5), were isolated from the aerial parts of Sphaeranthus africanus collected in Vietnam. Bioassay-guided fractionation was monitored by the antiproliferative activity on CCRF-CEM human cancer cells. The structures of compounds 1-5 were determined on the basis of NMR spectroscopic and mass spectrometric data. Activities of compounds 1-5 were evaluated in vitro against the human cancer cell lines CCRF-CEM, MDA-MB-231, U-251, and HCT-116. All compounds exhibited significant antiproliferative activity against all four cancer cell lines. CCRF-CEM was most sensitive to the compounds, with IC50 values ranging from 0.6 to 1.5 µM. Compounds 3 and 4 possessed the highest activity, with IC50 values in the four cell lines ranging from 0.6 to 2.9 µM and 1.3 to 2.5 µM, respectively. These compounds also showed inhibitory activity toward the HEK-293 human embryonic kidney cells with IC50 values ranging from 2.5 to 5.5 µM. This is the first time that antiproliferative activity of S. africanus has been reported, and 1-5 are the most cytotoxic carvotacetone derivatives reported so far.

Synthesis of new 1-benzyl tetrahydropyridinylidene ammonium salts and their antimicrobial and anticellular activities.

A series of N-benzyl tetrahydropiperidinylidene pyrrolidinium salts have been synthesized and investigated for their antiplasmodial and antitrypanosomal activities as well as for their cytotoxic effects. The antibacterial, antimycobacterial and anticancer potencies of selected compounds were examined, too. Physicochemical parameters were calculated and structure-activity-relationships are discussed.