(3'R)-hydroxytabernaelegantine C: A bisindole alkaloid with potent apoptosis inducing activity in colon (HCT116, SW620) and liver (HepG2) cancer cells

Indole Alkaloids of Rauvolfia ligustrina and Their Anxiolytic Effects in Adult Zebrafish

Rauvolfia species are well known as producers of bioactive monoterpene indole alkaloids, which exhibit a broad spectrum of biological activities. A new vobasine-sarpagan-type bisindole alkaloid (1: ) along with six known monomeric indoles (2, 3/4, 5: , and 6/7: ) were isolated from the ethanol extract of the roots of Rauvolfia ligustrina. The structure of the new compound was elucidated by interpretation of their spectroscopic data (1D and 2D NMR and HRESIMS) and comparison with published data for analog compounds. The cytotoxicity of the isolated compounds was screened in a zebrafish (Danio rerio) model. The possible GABAergic (diazepam as the positive control) and serotoninergic (fluoxetine as the positive control) mechanisms of action in adult zebrafish were also evaluated. No compounds were cytotoxic. Compound 2: and the epimers 3: /4: and 6: /7: showed a mechanism action by GABAA, while compound 1: showed a mechanism action by a serotonin receptor (anxiolytic activity). Molecular docking studies showed that compounds 2: and 5: have a greater affinity by the GABAA receptor when compared with diazepam, whereas 1: showed the best affinity for the 5HT2AR channel when compared to risperidone.

Naturally derived indole alkaloids targeting regulated cell death (RCD) for cancer therapy: from molecular mechanisms to potential therapeutic targets

Regulated cell death (RCD) is a critical and active process that is controlled by specific signal transduction pathways and can be regulated by genetic signals or drug interventions. Meanwhile, RCD is closely related to the occurrence and therapy of multiple human cancers. Generally, RCD subroutines are the key signals of tumorigenesis, which are contributed to our better understanding of cancer pathogenesis and therapeutics. Indole alkaloids derived from natural sources are well defined for their outstanding biological and pharmacological properties, like vincristine, vinblastine, staurosporine, indirubin, and 3,3′-diindolylmethane, which are currently used in the clinic or under clinical assessment. Moreover, such compounds play a significant role in discovering novel anticancer agents. Thus, here we systemically summarized recent advances in indole alkaloids as anticancer agents by targeting different RCD subroutines, including the classical apoptosis and autophagic cell death signaling pathways as well as the crucial signaling pathways of other RCD subroutines, such as ferroptosis, mitotic catastrophe, necroptosis, and anoikis, in cancer. Moreover, we further discussed the cross talk between different RCD subroutines mediated by indole alkaloids and the combined strategies of multiple agents (e.g., 3,10-dibromofascaplysin combined with olaparib) to exhibit therapeutic potential against various cancers by regulating RCD subroutines. In short, the information provided in this review on the regulation of cell death by indole alkaloids against different targets is expected to be beneficial for the design of novel molecules with greater targeting and biological properties, thereby facilitating the development of new strategies for cancer therapy.

Bisindole natural products: A vital source for the development of new anticancer drugs

Currently, the number of new cancer cases and deaths worldwide is increasing year on year. In addition to the requirement for cancer prevention, the top priority is still to seek the effective cure of cancer. In over a half century of constant exploration, increasing attention has been paid to the excellent anticancer activity of natural products, with more and more natural products isolated, identified and detected. For this study, the focus lies the natural products of bisindole, where two indole molecules are indirectly linked or directly polymerized, developing the diversity of structure and mechanism, accompanied with the better anticancer activity than monomers. There has been a long history of applying indirubin and vincristine in cancer treatment, verifying the anticancer effect of bisindoles. Vincribine, midostaurin and other anticancer drugs have also been developed and commercialized. In this paper, a review regarding the potential therapeutic effect of bisindole alkaloids extracted from various natural products was carried out, in which the progress made in research of 242 bisindole alkaloids for cancer treatment was introduced. These compounds may be applicable as medicinal products for clinical research in the future.

Review On Documented Medicinal Plants Used For The Treatment Of Cancer

Background:

Cancer is a frightful disease and it is the second leading cause of death worldwide. Naturally derived compounds are gaining interest of research workers as they have less toxic side effects as compared to currently used treatments such as chemotherapy. Plants are the pool of chemical compounds which provides a promising future for research on cancer.

Objective:

This review paper provides updated information gathered on medicinal plants and isolated phytoconstituents used as anticancer agents and summarises the plant extracts and their isolated chemical constituents exhibiting anticancer potential on clinical trials.

Methods:

An extensive bibliographic investigation was carried out by analysing worldwide established scientific databases like SCOPUS, PUBMED, SCIELO, ScienceDirect, Springerlink, Web of Science, Wiley, SciFinder and Google Scholar etc. In next few decades, herbal medicine may become a new epoch of medical system.

Results:

Many researches are going on medicinal plants for the treatment of cancer but it is a time to increase further experimental studies on plant extracts and their chemical constituents to find out their mechanism of action at molecular level.

Conclusion:

The article may help many researchers to start off further experimentation that might lead to the drugs for the cancer treatment.

Lappaconitine hydrochloride inhibits proliferation and induces apoptosis in human colon cancer HCT-116 cells via mitochondrial and MAPK pathway

Lappaconitine hydrochloride (LH), as a new synthetic alkaloid, exhibits antitumor activity, whereas its antitumor effect on colorectal cancer (CRC) has not been investigated. In this study, the effect of LH on HCT-116 cell proliferation and apoptosis in vivo and in vitro and underlying molecular mechanism were explored. The Cell Counting Kit-8 (CCK-8) was used to assess cell viability. Morphological change was observed by Hoechst 33342 staining. Cell cycle and apoptosis were performed using a flow cytometer. The western blot method was used to screen for related protein expression. The mitochondrial membrane potential (MMP) was confirmed using the 5, 5, 6, 6'-tetrachloro-1, 1', 3, 3'-tetraethylbenzimi-dazolyl carbo cyanine iodide (JC-1) staining assay. Reactive oxygen species (ROS) was evaluated by a 20-70-dichlorofluorescein diacetate (DCFH-DA) staining assay. The antitumor effect was evaluated in vivo by the xenograft HCT-116 model. The results showed that LH significantly inhibited cell viability in a time- and concentration-dependent manner. LH induced apoptosis and S phase cell cycle arrest. LH promoted the reduction of MMP and ROS accumulation. Moreover, LH activated the mitochondrial and MAPK pathway. The experiments in vivo showed that LH had significant antitumor effect in tumor-bearing mice, and had virtually no effect on the weight and internal organs of the mice. In conclusion, LH could induce apoptosis in HCT-116 cells through mitochondrial and MAPK signaling pathways. LH may be a promising treatment for CRC.

Ricinus communis Butanol Fraction Inhibits MCF-7 Breast Cancer Cell Migration, Adhesion, and Invasiveness

In this study, the potential of an n-butanol fraction from Ricinus communis to prevent metastasis in MCF-7 breast cancer cells was investigated. The effect of the fraction on BUD-8 and MCF-7 cell viability was assessed using the MTT assay. Apoptotic cell death was analyzed by Hoechst staining assay. The antimetastatic effect of the fraction on MCF-7 cell was evaluated using the wound healing, adhesion and Boyden chamber invasion assays. Gelatin-zymography was used to assess the effect of the fraction on MMP-2 and MMP-9 activity. The expression profile of proteins implicated in metastasis and angiogenesis was determined using the human angiogenesis antibody array kit, following treatment with the fraction. BUD-8 cell viability was significantly reduced at concentrations between 300 and 500 µg/ml of the extract. In contrast, a significant reduction in cell viability was seen in MCF-7 cells treated with 400 to 500 µg/ml of the fraction. At sub-lethal concentrations (100 and 200 µg/ml) of the fraction, no nuclei morphological changes associated with apoptotic cell death were observed in MCF-7 cells. In addition, the fraction showed to have an inhibitory effect on MCF-7 cell migration, adhesion, invasiveness, and MMP-2 activity. Moreover, the fraction was seen to modulate the expression of several proteins, such as MMP-9, uPA, VEGF, and TGF-β1, playing a role in the metastasis process. This study demonstrates that the n-butanol fraction of R. communis can inhibit major steps of the metastatic cascade and modulate metastasis regulatory proteins. Thus, the fraction can be considered a potential source of antimetastatic agents that could be useful in the treatment of malignant cancers.

Anticancer activity of bisindole alkaloids derived from natural sources and synthetic bisindole hybrids

The bisindole moiety, as a versatile pharmacophore, is one of the widespread heterocycles in naturally occurring and synthetic bioactive compounds. The bisindole alkaloids derived from natural sources possess structural and mechanistic diversity, and they were found to be generally more active than monoindole alkaloids against various cancer cell lines. Moreover, some bisindole alkaloids such as the tubulin inhibitors, vinorelbine and vinblastine, have already been approved for cancer therapy, suggesting that bisindole alkaloids are a significant source of anticancer agents and lead hits. Bisindole hybrids have the potential to overcome drug resistance, enhance efficiency, and reduce severe side effects. The bisindole-lactam hybrid midostaurin has already been approved for the treatment of adult patients with newly diagnosed acute myeloid leukemia who are FLT3 mutation-positive, highlighting the importance of bisindole hybrids in the development of novel anticancer agents. In this review, we present a brief account of the bisindole alkaloids derived from nature and of synthetic hybrids with potential anticancer activity developed in the recent 10 years.

Terpenoids from Euphorbia pedroi as Multidrug-Resistance Reversers

The phytochemical study of Euphorbia pedroi led to the isolation of a new tetracyclic triterpenoid with an unusual spiro scaffold, spiropedroxodiol (1), along with seven known terpenoids (2-8). Aiming at obtaining compounds with improved multidrug-resistance (MDR) reversal activity, compound 8, an ent-abietane diterpene, was derivatized by introducing nitrogen-containing and aromatic moieties, yielding compounds 9-14. The structures of compounds were characterized by detailed spectroscopic analysis, including 2D NMR experiments (COSY, HMQC/HSQC, HMBC, and NOESY). Compounds 1-14 were evaluated for their MDR-reversing activity on human ABCB1 gene transfected mouse lymphoma cells (L5178Y-MDR) through a combination of functional and chemosensitivity assays. The natural compounds 1-8 were further evaluated on resistant human colon adenocarcinoma cells (Colo320), and, additionally, their cytotoxicity was assessed on noncancerous mouse (NIH/3T3) and human (MRC-5) embryonic fibroblast cell lines. While spiropedroxodiol (1) was found to be a very strong MDR reversal agent in both L5178Y-MDR and Colo320 cells, the chemical modifications of helioscopinolide E (8) at C-3 positively contributed to increase the MDR reversal activity of compounds 10, 12, and 13. Furthermore, in combination assays, compounds 1 and 7-14 enhanced synergistically the cytotoxicity of doxorubicin. Finally, by means of molecular docking, the key residues and binding modes by which compounds 1-14 may interact with a murine P-glycoprotein model were identified, allowing additional insights on the efflux modulation mechanism of these compounds.

Discovery of DEBIC to correlate P-selectin inhibition and DNA intercalation in cancer therapy and complicated thrombosis

Arterial thrombosis is one of the major complications of cancer and can seriously worsen the prognosis of the patients. These clinical findings encouraged this paper to correlate P-selectin inhibition and DNA intercalation in cancer therapy and complicated thrombosis. By designing and docking 12 derivatives of bisindole- 2-carboxylic acids into the active sites of P-selectin and d(CGATCG)2 9 derivatives were assigned to receive in vivo anti-tumor assay, and finally provided dimethyl 2,2'-[(2,2'-(ethane-1,1-diyl)bis(1H-indole-3,2-diyl)]diacetate (DEBIC) to receive assays. DEBIC intercalated DNA and inhibited proliferation of tumor cells but not non-tumor cells. It slowed tumor growth of S180 mice at a dose of 0.36 μmol/kg, and slowed tumor growth of A549 bearing BABL/C mice at a dose of 8.9 μmol/kg. DEBIC was also found to inhibit arterial thrombosis by down regulating P-selectin effectively at a dose of 0.36 μmol/kg.

Optimizing the flavanone core toward new selective nitrogen-containing modulators of ABC transporters

Aim: Naringenin (1), isolated in large amount from the aerial parts of Euphorbia pedroi, was chemically derivatized to yield 18 imine derivatives (2–19) and three alkylated derivatives through a Mannich-type reaction (20–22) that were tested as multidrug resistance (MDR) reversers in cancer cells. Results/methodology: While hydrazone (2–4) and azine (5–13) derivatives showed an improvement in their MDR reversal activities against the breast cancer resistance protein, carbohydrazides 14–19 revealed an enhancement in MDR reversal activity toward the multidrug resistance protein 1. Conclusion: The observed activities, together with pharmacophoric analysis and molecular docking studies, identified the spatial orientation of the substituents as a key structural feature toward a possible mechanism by which naringenin derivatives may reverse MDR in cancer.