Synthesis and anticancer activity of some novel indolo[3,2-b]andrographolide derivatives as apoptosis-inducing agents

Synthetic Modifications of Andrographolide Targeting New Potential Anticancer Drug Candidates: A Comprehensive Overview

This review collects the synthetic modifications performed on andrographolide, a natural molecule derived from Andrographis paniculata, for oncology applications. Various pharmacomodulations were carried out, and the products were tested on different cancer cell lines. The impact of these modifications was analyzed with the aim of mapping the positions essential for activity to facilitate future research in this field. However, this study makes it clear that, in addition to structural modifications of the molecule, which can result in varying degrees of effectiveness in targeting interactions, the lipophilic capacity of the structures obtained through hemisynthesis is of significant importance.

Research status of indole-modified natural products

Indole is a heterocyclic compound formed by the fusion of a benzene ring and pyrrole ring, which has rich biological activity. Many indole-containing compounds have been sold on the market due to their excellent pharmacological activity. For example, vincristine and reserpine have been widely used in clinical practice. The diverse structures and biological activities of natural products provide abundant resources for the development of new drugs. Therefore, this review classifies natural products by structure, and summarizes the research progress of indole-containing natural product derivatives, their biological activities, structure-activity relationship and research mechanism which has been studied in the past 13 years, so as to provide a basis for the development of new drug development.

Advances in ameliorating inflammatory diseases and cancers by andrographolide: Pharmacokinetics, pharmacodynamics, and perspective

Andrographolide, a well-known natural lactone having a range of pharmacological actions in traditional Chinese medicine. It has long been used to cure a variety of ailments. In this review, we cover the pharmacokinetics and pharmacological activity of andrographolide which supports its further clinical application in cancers and inflammatory diseases. Growing evidence shows a good therapeutic effect in inflammatory diseases, including liver diseases, joint diseases, respiratory system diseases, nervous system diseases, heart diseases, inflammatory bowel diseases, and inflammatory skin diseases. As a result, the effects of andrographolide on immune cells and the processes that underpin them are discussed. The preclinical use of andrographolide to different organs in response to malignancies such as colorectal, liver, gastric, breast, prostate, lung, and oral cancers has also been reviewed. In addition, several clinical trials of andrographolide in inflammatory diseases and cancers have been summarized. This review highlights recent advances in ameliorating inflammatory diseases as well as cancers by andrographolide and its analogs, providing a new perspective for subsequent research of this traditional natural product.

Andrographolide and its derivatives: Current achievements and future perspectives

Natural product andrographolide isolated from the plant Andrographis paniculata shows a plethora of biological activities, including anti-tumor, anti-bacterial, anti-inflammation, anti-virus, anti-fibrosis, anti-obesity, immunomodulatory and hypoglycemic activities. Based on extensive chemical structural modifications, a series of andrographolide derivatives with improved bioavailability and druggability has been developed. Moreover, greater understanding of their mechanisms of action at the molecular and cellular level has been thoroughly investigated. In this review, we give an outlook for the therapeutical potential of andrographolide and its derivatives in diverse diseases and highlighted the drug design, pharmacokinetic and mechanistic studies for the past ten years, together with a brief overview of the pharmacological effects. Notably, we focused to provide a critical enlightenment of the area of andrographolide and its derivatives with the intent of indicating the future perspectives, challenges and limitations. We believe that this review paper will benefit drug discovery where andrographolide was used as a template, shed light on the identification of drug targets for andrographolide and its analogs, as well as increase our knowledge for using them for therapeutic application, including the treatment for various forms of cancers.

Design, synthesis, and anticancer evaluation of novel andrographolide derivatives bearing an α,β-unsaturated ketone moiety

A series of 1,2-didehydro-3-ox-andrographolide derivatives based on two Michael acceptors were designed, synthesized and evaluated for their anticancer activity against two human cancer cell lines (HCT116 and MCF-7). All tested compounds exhibited significant growth inhibitory effect on HCT116 and moderate to good inhibitory effect on MCF-7 cell proliferation. Compound 10b displayed the best inhibitory activities against both HCT116 and MCF-7 cell lines, with IC₅₀ values of 2.49 and 7.80 μM respectively. Preliminary anticancer mechanistic investigation was performed in terms of the cell cycle arrest and cell apoptosis assays of compound 10b against HCT116 using flow cytometry, and the results indicated that 10b blocked the proliferation of HCT116 cells by inducing cell apoptosis in a concentration-dependent manner and arresting cell cycle in G₂/M phase.

Synthesis, anticancer evaluation and mechanism studies of novel indolequinone derivatives of ursolic acid

A series of novel indolequinone derivatives of ursolic acid bearing ester, hydrazide, or amide moieties were designed, synthesized, and screened for their in vitro antiproliferative activities against three cancer cell lines (MCF-7, HeLa, and HepG2) and a normal gastric mucosal cell line (Ges-1). A number of compounds showed significant activity against tested cancer cell lines. Among them, compound 6t exhibited the most potent activity against three cancer cell lines with IC50 values of 1.66 ± 0.21, 3.16 ± 0.24, and 10.35 ± 1.63 µM, respectively, and considerably lower cytotoxicity to Ges-1 cells. Especially, compound 6t could arrest cell cycle at S phase, suppress the migration of MCF-7 cells, elevate intracellular reactive oxygen species (ROS) level, and decrease mitochondrial membrane potential. Western blot analysis showed that compound 6t upregulated Bax, cleaved caspase-3/9, cleaved PARP levels and downregulated Bcl-2 level of MCF-7 cells. All these results indicated that compound 6t could significantly induce the apoptosis of MCF-7 cells. Meanwhile, compound 6t markedly decreased p-AKT and p-mTOR expression, which revealed that compound 6t probably exerted its cytotoxicity through targeting PI3K/AKT/mTOR signaling pathway. Therefore, compound 6t could be a promising lead for the discovery of novel anticancer agents.

The importance of indole and azaindole scaffold in the development of antitumor agents

With some indoles and azaindoles being successfully developed as anticancer drugs, the design and synthesis of indole and azaindole derivatives with remarkable antitumor activity has received increasing attention and significant progress has been made. This paper reviews the recent progress in the study of tumorigenesis, mechanism of actions and structure activity relationships about anticancer indole and azindole derivatives. Combining structure activity relationships and molecular targets-related knowledge, this review will help researchers design more effective, safe and cost-effective anticancer indoles and azindoles agents.

Synthesis and biological evaluation of diaryl urea derivatives designed as potential anticarcinoma agents using de novo structure-based lead optimization approach

To develop inhibitors blocking VEGFR2 and the Raf/MEK/ERK mitogen-activated protein kinase signaling pathway new compounds based on sorafenib were designed, synthesized and biologically evaluated. Using de novo design method, a library of new ligands was generated and expanded. Considering in silico binding affinity towards VEGFR2, synthetic feasibility, and drug-likeness property, some of the designed ligands were selected for synthesis and screening for their in vitro antiproliferative activities against two cancer cell lines (HT-29 and A549). Four compounds (13a, 14a, 14l and 15b) exhibited stronger antiproliferative activity (with IC₅₀ values of 13.27, 6.62, 12.74, 3.38 μM, respectively) against HT-29 cells compared to that of the positive reference drug sorafenib (IC₅₀ = 17.28 μM). Notably, compound 15b demonstrated the highest activity, and in particular, it induced HT-29 apoptosis, increased intracellular reactive oxygen species level, arrested cell cycle at G0/G1 phase, and influenced the expression of apoptosis- and cell cycle-related proteins. 15b compound can effectively block the Raf/MEK/ERK pathway and inhibit VEGFR2 phosphorylation. Molecular docking revealed that 15b can bind well to the active site of VEGFR2 receptor. Collectively, 15b may be considered as a promising compound amenable for further investigation for the development of new anticancer agents.

Synthesis of ent-Cleistanthane Diterpenoid Spruceanol: Construction of an Aromatic C Ring via Lewis Acid-Controlled Regioselective Diels-Alder Cycloaddition

The first synthesis of ent-cleistanthane-type diterpenoid spruceanol with significant anticancer activity is described. A chiral pool approach was employed with a linear sequence of 13 steps beginning from readily available and inexpensive andrographolide. The approach features the construction of an aromatic ring with hydroxyl and methyl groups at C-12 and C-13 of the target compound, respectively, via Lewis acid-controlled regioselective Diels-Alder cycloaddition and the regioselective removal of the primary hydroxyl group of the Diels-Alder adduct.

Design, synthesis, and anticancer evaluation of novel quinoline derivatives of ursolic acid with hydrazide, oxadiazole, and thiadiazole moieties as potent MEK inhibitors

In this article, a series of novel quinoline derivatives of ursolic acid (UA) bearing hydrazide, oxadiazole, or thiadiazole moieties were designed, synthesised, and screened for their in vitro antiproliferative activities against three cancer cell lines (MDA-MB-231, HeLa, and SMMC-7721). A number of compounds showed significant activity against at least one cell line. Among them, compound 4d exhibited the most potent activity against three cancer cell lines with IC50 values of 0.12 ± 0.01, 0.08 ± 0.01, and 0.34 ± 0.03 μM, respectively. In particular, compound 4d could induce the apoptosis of HeLa cells, arrest cell cycle at the G0/G1 phase, elevate intracellular reactive oxygen species level, and decrease mitochondrial membrane potential. In addition, compound 4d could significantly inhibit MEK1 kinase activity and impede Ras/Raf/MEK/ERK transduction pathway. Therefore, compound 4d may be a potential anticancer agent and a promising lead worthy of further investigation.

Biodegradable andrographolide-eluting nanofibrous membranes for the treatment of cervical cancer

BACKGROUND

In this study, we developed biodegradable andrographolide (AG)-eluting nanofibrous mats and evaluated their efficacy in treating cervical cancer.

MATERIALS AND METHODS

Membranes of two different poly[(d,l)-lactide-co-glycolide] (PLGA)-to-AG ratios (6:1 and 3:1) were prepared via electrospinning technology. The liberation behavior of AG was evaluated. A cervical cancer model with C57BL/6J mice was created and employed for an in vivo efficacy assessment of the drug-eluting nanofibers. Twelve mice with cervical cancer were stochastically divided into three different groups (four animals per group): group A received no treatment as the control, group B was treated with pure PLGA mats, and group C was treated with AG-loaded nanofibrous membranes. The changes in tumor sizes were recorded.

RESULTS

All membranes eluted high concentrations of AG at the target area for three weeks, while the systemic drug concentration in the blood remained low. Histological analysis showed no obvious tissue inflammation. Compared with the mice in groups A and B, the tumor size of the mice in group C decreased with time until day 25, when the daily drug concentration reduced to 3 µg/mL.

CONCLUSION

Biodegradable nanofibers with a sustainable release of AG exhibit adequate efficacy and durability for the treatment of mice with cervical cancer.

Synthesis of new ent-labdane diterpene derivatives from andrographolide and evaluation of their anti-inflammatory activities

Two series of andrographolide derivatives with nitrogen-containing heterocycles, phenols and aromatic acids as bioisostere moiety of lactone ring were synthesized. 8 from 18 tested compounds showed stronger inhibitory effect on LPS-induced NO production in RAW264.7 macrophage than hydrocortisone. Among them, compound 8m exhibited the most potent inhibition with IC₅₀ of 3.38 ± 1.03 μM. The structure-activity relationships (SARs) suggested that the replacement of lactone ring with small-molecule phenols could improve the anti-inflammatory efficacy. Furthermore, compound 8m significantly reduced the levels of pro-inflammatory cytokine IL-1β and IL-6 with no influence on cell survival, decreased the expression of iNOS and COX-2, and down-regulated the level and phosphorylation of IκBα, as well as the expression of NF-κB. Also it blocked the nuclear translocation of NF-κB in LPS-induced macrophage. Therefore, the anti-inflammation mechanism of compound 8m was related to the inhibition of COX-2, iNOS and NF-κB signal pathway.

Synthesis and antiproliferative activity of flavonoid triazolyl glycosides

Sixteen flavonoid triazolyl glycosides4–19were synthesized in good yieldsviaCu(I)-catalyzed azide-alkyne cycloadditions of terminal alkynes of flavonoids1–3with acetylated sugar azides followed by deacetylation with sodium methoxide in anhydrous methanol. The antiproliferative activity of the synthesized compounds against three human cancer cell lines (Hela, HCC1954 and SK-OV-3)in vitrowas evaluated. Flavonoids1,2and flavonoid triazolyl glycosides7,12,17exhibit potent antiproliferative activity against these cancer cell lines.

Andrographolide, a diterpene lactone from Andrographis paniculata and its therapeutic promises in cancer

The diterpene lactone andrographolide, isolated from Andrographis paniculata, has been proven to possess several important protective biological activities, including antioxidant, anti-inflammatory, immunomodulatory, antiseptic, antimicrobial, cytotoxic, hypolipidemic, cardioprotective, hepatoprotective, and neuroprotective effects. In addition, it has been reported to play a therapeutic role in the treatment of major human diseases, such as Parkinson's disease, rheumatoid arthritis, and colitis. This systematic review aims to highlight andrographolide as a promising agent in cancer treatment. To this purpose, a number of databases were used to search for the cytotoxic/anticancer effects of andrographolide in pre-clinical and clinical studies. Among 1703 identified literature articles, 139 were included in this review; 109 were investigated as non-clinical, whereas 24, 3, and 3 were pre-clinical, clinical, and non-pre-clinical trials, respectively. Among the model systems, cultured cell lines appeared as the most frequently (79.14%) used, followed by in vivo models using rodents, among others. Furthermore, andrographolide was found to exert cytotoxic/anticancer effects on almost all types of cell lines with the underlying mechanisms involving oxidative stress, cell cycle arrest, anti-inflammatory and immune system mediated effects, apoptosis, necrosis, autophagy, inhibition of cell adhesion, proliferation, migration, invasion, anti-angiogenic activity, and other miscellaneous actions. After careful consideration of the relevant evidence, we suggest that andrographolide can be one of the potential agents in the treatment of cancer in the near future.

Synthesis and antiproliferative activities of aminoalkylated polymethoxyflavonoid derivatives

A series of novel aminoalkylated polymethoxyflavonoid derivatives 3-11 was synthesised from 5-hydroxy-3,7,3',4'-tetramethoxyflavonoid (1) through extending alkoxy chain at the 5-position, and introducing amine hydrogen bond receptor at the end of the side chain. Their antiproliferative activities were evaluated in vitro on a panel of three human cancer cell lines (Hela, HCC1954 and SK-OV-3). The results showed that all the target compounds exhibited antiproliferative activities against investigated cancer cells with IC₅₀ values of 9.51-53.33 μM. Compounds 5, 7, 8, 11 on Hela cells and compounds 4-9, 11 on HCC1954 exhibited more potency as compared to positive control cis-Platin.

Andrographolide Suppresses MV4-11 Cell Proliferation through the Inhibition of FLT3 Signaling, Fatty Acid Synthesis and Cellular Iron Uptake

Background: Andrographolide (ADR), the main active component of Andrographis paniculata, displays anticancer activity in various cancer cell lines, among which leukemia cell lines exhibit the highest sensitivity to ADR. In particular, ADR was also reported to have reduced drug resistance in multidrug resistant cell lines. However, the mechanism of action (MOA) of ADR’s anticancer and anti-drug-resistance activities remain elusive. Methods: In this study, we used the MV4-11 cell line, a FLT3 positive acute myeloid leukemia (AML) cell line that displays multidrug resistance, as our experimental system. We first evaluated the effect of ADR on MV4-11 cell proliferation. Then, a quantitative proteomics approach was applied to identify differentially expressed proteins in ADR-treated MV4-11 cells. Finally, cellular processes and signal pathways affected by ADR in MV4-11 cell were predicted with proteomic analysis and validated with in vitro assays. Results: ADR inhibits MV4-11 cell proliferation in a dose- and time-dependent manner. With a proteomic approach, we discovered that ADR inhibited fatty acid synthesis, cellular iron uptake and FLT3 signaling pathway in MV4-11 cells. Conclusions: ADR inhibits MV4-11 cell proliferation through inhibition of fatty acid synthesis, iron uptake and protein synthesis. Furthermore, ADR reduces drug resistance by blocking FLT3 signaling.

Synthesis of thioether andrographolide derivatives and their inhibitory effect against cancer cells

A series of novel thioether andrographolide derivatives were synthesized by incorporating various aromatic (or heteroaromatic) substituents into C-12 or 14-OH. A total of 38 andrographolide derivatives were prepared and evaluated for their in vitro inhibitory activity against cancer cells. All the derivatives exhibited better activity against prostate cancer cells (PC-3) than the parent compound. Among these, compounds 6a, 8, 9, 17, 19, 31, and 32 demonstrated good activity. These compounds were further evaluated for their anticancer activities against other cancer cell lines including MCF-7, MDA-MB-231, and A549. Compounds 31 and 32 showed excellent activity against MCF-7 with an IC₅₀ value of 0.7 and 0.6 μM, respectively. The absolute configuration of 15a was determined via single-crystal X-ray diffraction. The activity of 6a (12S), which was the precursor of 15a, was better than that of the diastereoisomer 6b (12R). Moreover, the preliminary structure-activity relationship has been summarized. The results obtained herein are very important for further optimization of andrographolide.

Synthesis and biological evaluation of new C-12(α/β)-(N-) sulfamoyl-phenylamino-14-deoxy-andrographolide derivatives as potent anti-cancer agents

Andrographolide, the major diterpenoidal constituent of Andrographis paniculata (Acanthaceae) and its derivatives have been reported to possess plethora of biological properties including potent anti-cancer activity. In this work, synthesis and in-vitro anti-cancer evaluation of new C-12-substituted aryl amino 14-deoxy-andrographolide derivatives (III a-f) are reported. The substitutions include various sulfonamide moieties -SO₂-NH-R¹. The new derivatives (III a-e) exhibited improved cytotoxicity (GI₅₀, TGI and LC₅₀) compared to andrographolide (I) and the corresponding 3,14,19-O-triacetyl andrographolide (II) when evaluated against 60 NCI cell line panel. Compounds III c and III e are found to be non-toxic to normal human dermal fibroblasts (NHDF) cells compared to reference drug THZ-1.

Diterpenes and Their Derivatives as Potential Anticancer Agents

As therapeutic tools, diterpenes and their derivatives have gained much attention of the medicinal scientists nowadays. It is due to their pledging and important biological activities. This review congregates the anticancer diterpenes. For this, a search was made with selected keywords in PubMed, Science Direct, Web of Science, Scopus, The American Chemical Society and miscellaneous databases from January 2012 to January 2017 for the published articles. A total 28, 789 published articles were seen. Among them, 240 were included in this study. More than 250 important anticancer diterpenes and their derivatives were seen in the databases, acting in the different pathways. Some of them are already under clinical trials, while others are in the nonclinical and/or pre-clinical trials. In conclusion, diterpenes may be one of the lead molecules in the treatment of cancer. Copyright © 2017 John Wiley & Sons, Ltd.

Brønsted acidic ionic liquid-promoted direct C3-acylation of N-unsubstituted indoles with acid anhydrides under microwave irradiation

A green and efficient method for the synthesis of 3-acylindoles using a Brønsted acidic ionic liquid under microwave irradiation has been developed.

Structure-activity relationship (SAR) study and design strategies of nitrogen-containing heterocyclic moieties for their anticancer activities

The present review article offers a detailed account of the design strategies employed for the synthesis of nitrogen-containing anticancer agents. The results of different studies describe the N-heterocyclic ring system is a core structure in many synthetic compounds exhibiting a broad range of biological activities. Benzimidazole, benzothiazole, indole, acridine, oxadiazole, imidazole, isoxazole, pyrazole, triazoles, quinolines and quinazolines including others drugs containing pyridazine, pyridine and pyrimidines are covered. The following studies of these compounds suggested that these compounds showed their antitumor activities through multiple mechanisms including inhibiting protein kinase (CDK, MK-2, PLK1, kinesin-like protein Eg5 and IKK), topoisomerase I and II, microtubule inhibition, and many others. Our concise representation exploits the design and anticancer potency of these compounds. The direct comparison of anticancer activities with the standard enables a systematic analysis of the structure-activity relationship among the series.

Synthesis and in vitro cytotoxicity of novel C-12 substituted-14-deoxy-andrographolide derivatives as potent anti-cancer agents

Andrographolide, the major labdane diterpenoid from Andrographis paniculata has been reported to be cytotoxic against various cancer cells in vitro. Our research efforts led to the discovery of novel 12-phenyl thio and 12-aryl amino-14-deoxy-andrographolide derivatives (III q and III r) with potent cytotoxic activity, 12-benzyl amino-14-deoxy-andrographolide analogues showing broad range of cytotoxic activity against most of the cell lines and 12-alkyl amino-14-deoxy-andrographolide derivatives being selective to few cell lines (PC-3 and HOP-92), when the selected analogues were evaluated against 60 human cancer cell line panel at National Cancer Institute (N.C.I.), USA. The SAR (structure activity relationship) studies demonstrated potent activity for the compounds containing the following functionalities at C-12: substituted aryl amino/phenyl thio>benzylamine>alkyl amine. The significant cytotoxic activity observed for compounds III q and III r suggest that these could serve as templates for further optimization.

Synthesis, Fluorescence Properties, and Antiproliferative Potential of Several 3-Oxo-3H-benzo[f]chromene-2-carboxylic Acid Derivatives

In this study, two series of 3-oxo-3H-benzo[f]chromene-2-carboxylic acid derivatives (compounds 5a–i and 6a–g) were synthesized. Their in vitro proliferation inhibitory activities against the A549 and NCI-H460 human non-small cell lung cancer (NSCLC) cell lines were evaluated. Their photophysical properties were measured. Among these target compounds, 5e exhibited the strongest antiproliferative activity by inducing apoptosis, arresting cell cycle, and elevating intracellular reactive oxygen species (ROS) level, suggesting that it may be a potent antitumor agent. In addition, compound 6g with very low cytotoxicity, demonstrated excellent fluorescence properties, which could be used as an effective fluorescence probe for biological imaging.