The phosphate ester group in secondary metabolites.

Covering: 2000 to mid-2021The phosphate ester is a versatile, widespread functional group involved in a plethora of biological activities. Its presence in secondary metabolites, however, is relatively rare compared to other functionalities and thus is part of a rather unexplored chemical space. Herein, the chemistry of secondary metabolites containing the phosphate ester group is discussed. The text emphasizes their structural diversity, biological and pharmacological profiles, and synthetic approaches employed in the phosphorylation step during total synthesis campaigns, covering the literature from 2000 to mid-2021.

A canthin-6-one derivative induces cell death by apoptosis/necroptosis-like with DNA damage in acute myeloid cells.

Natural products have long been considered a relevant source of new antitumor agents. Despite advances in the treatment of younger patients with acute myeloid leukemia (AML), the prognosis of elderly patients remains poor, with a high frequency of relapse. The cytotoxicity of canthin-6-one alkaloids has been extensively studied in different cell types, including leukemic strains. Among the canthin-6-one analogs tested, 10-methoxycanthin-6-one (Mtx-C) showed the highest cytotoxicity in the malignant AML cells Kasumi-1 and KG-1. Thus, we evaluated the cytotoxicity and cell death mechanisms related to Mtx-C using the EC50 (80 µM for Kasumi-1 and 36 µM for KG-1) treatment for 24 h. Our results identify reactive oxygen species production, mitochondrial depolarization, annexin V-FITC/7-AAD double staining, caspase cleave and upregulation of mitochondria-dependent apoptosis proteins (Bax, Bim, Bik, Puma and phosphorylation of p53) for both cell lineages. However, downregulation of Bcl-2 and the simultaneous execution of the apoptotic and necroptotic programs associated with the phosphorylation of the proteins receptor-interacting serine/threonine-protein kinase 3 and mixed lineage kinase domain-like pseudokinase occurred only in Kasumi-1 cells. About the lasted events, Kasumi-1 cell death was inhibited by pharmacological agents such as Zvad-FMK and necrostatin-1. The underlying molecular mechanisms of Mtx-C still include participation in the DNA damage and stress-signaling pathways involving p38 and c-Jun N-terminal mitogen-activated protein kinases and interaction with DNA. Thus, Mtx-C represents a promising tool for the development of new antileukemic molecules.

Goniothalamin-Related Styryl Lactones: Isolation, Synthesis, Biological Activity and Mode of Action.

This review covers the chemistry and biological aspects of goniothalamin-related styryl lactones isolated from natural sources. This family of secondary metabolites has been reported to display diverse uses in folk medicine, but only a limited number of these compounds have been throughly investigated regarding their biological profile. Herein, we cover the goniothalamin-related styryl lactones having a C6-C3-C4 framework which appeared in the literature for the first time in the period 2000-2017, and the reports on the synthesis, biological activity and mechanism of action which were published from 2007-2017.

Steroidal hormone and morphological responses in the prostate anterior lobe in different cancer grades after Celecoxib and Goniothalamin treatments in TRAMP mice.

Prostate cancer is the second most diagnosed cancer in the world, and alternative methods to prevent and treat different lesion grades need to be evaluated. The objective was to evaluate the morphological, hormonal, and inflammatory responses in the prostate anterior lobe in transgenic adenocarcinoma of the mouse prostate (TRAMP), following Celecoxib and Goniothalamin (GTN) treatments. All animals were treated for 4 weeks, from 8 weeks of age and euthanized either immediately after treatment (12-week-old mice: immediate response) or later (22-week-old mice: late response). The results showed a significant increase of high-grade prostatic intraepithelial neoplasia (HGPIN) and well-differentiated adenocarcinoma (WDA), according to the age in the control groups. Celecoxib treatment decreased the WDA incidence in the late response group. GTN led to a significant healthy tissue increase, and an LGPIN and HGPIN decrease in the immediate response group. In the late response group, GTN led to healthy area increase and there was no occurrence of WDA. AR and ERα immunoexpressions were reduced by both treatments in the immediate response groups. However, only GTN was able to decrease the ERα level in the late response group. Regarding COX-2 immunoreactivity, both treatments reduced the frequency of this enzyme. We can conclude that the prostate anterior lobe is a good model to study prostate cancer, considering its slow progression. Both treatments led to cancer delay in the prostate anterior lobe. However, GTN pointed towards a better treatment spectrum in the signaling pathways in the prostate microenvironment, particularly in ERα.

Goniothalamin and Celecoxib Effects During Aging: Targeting Pro-Inflammatory Mediators in Chemoprevention of Prostatic Disorders.

BACKGROUND: Prostate is highly affected by aging, which lead to inflammatory disorders that can predispose to cancer development. Chemoprevention has emerged as a new therapeutic approach, intensifying studies evaluating the biological properties of new compounds. The aim of this study was to characterize the inflammatory responses in the prostate ventral lobe from senile mice treated with Goniothalamin (GTN), a promising natural compound with anti-inflammatory and antiproliferative properties. Its activity was compared to Celecoxib, an established nonsteroidal anti-inflammatory drug (NSAID). METHODS: The animals were divided into: Control groups; Young (18-week-old FVB), Senile (52-week-old FVB). Treated groups: Senile-Goniothalamin (150 mg/kg orally), Senile-Celecoxib (10 mg/kg orally). The ventral lobe was collected after 4 weeks for light microscopy, immunohistochemistry, ELISA, and Western blotting analysis. RESULTS: Both treatments were efficient in controlling the inflammatory process in the prostate from senile mice, maintaining the glandular morphology integrity. GTN reduced all inflammatory mediators evaluated (TNF-α, COX-2, iNOS) and different from Celecoxib, it also decreased the protein levels of NF-kB and p-NF-kB. CONCLUSIONS: Finally, GTN and Celecoxib controlled inflammation in the prostate, and sensitized the senescent microenvironment to anti-inflammatory stimuli. Thus, both treatments are indicated as potential drugs in the prostatic diseases prevention during senescence. Prostate 77:838-848, 2017. © 2017 Wiley Periodicals, Inc.

Anti-inflammatory natural product goniothalamin reduces colitis-associated and sporadic colorectal tumorigenesis.

The tumor microenvironment offers multiple targets for cancer therapy, including pro-tumorigenic inflammation. Natural compounds represent an enormous source of new anti-inflammatory and anticancer agents. We previously showed that the styryl lactone goniothalamin (GTN) has promising antiproliferative and anti-inflammatory activities. Because inflammation is a major driver of colorectal cancer (CRC), we therefore evaluated the therapeutic and preventive potentials of GTN in colitis, colitis-associated cancer (CAC) and spontaneous CRC. First, in a simplistic model of inflammation in vitro, GTN was able to inhibit cytokine production in bone marrow-derived macrophages induced by lipopolysaccharide. Next, in dextran sulfate sodium (DSS) induced-colitis model, mice treated with GTN displayed restored tissue architecture, increased cell proliferation in the colonic crypts and reduced epithelial damage. Moreover, colon tissue from GTN-treated mice had significantly less expression of the inflammatory genes interleukin 1ß (IL-1ß), tumor necrosis factor α (TNF-α), interleukin 6 (IL-6), S100A9, interleukin 23A (IL-23A), IL-22 and IL-17A In the azoxymethane/DSS model of CAC, GTN reduced tumor multiplicity, load and size. Additionally, GTN suppressed production of IL-6, IL-17 and TNF-α in tumor tissue, as well as abrogated stromal immune cell activation and nuclear translocation of NF-κB. Finally, in a tamoxifen inducible model of sporadic CRC, GTN-treated mice had significantly fewer tumors and decreased levels of IL-17A, IL-6, S100A9 and TNF-α protein within the tumors. These results suggest that GTN possesses anti-inflammatory and antitumor activities and represents a preventive and therapeutic agent modulating the inflammatory environment in the colon during colitis as well as CAC and CRC development.

Goniothalamin prevents the development of chemically induced and spontaneous colitis in rodents and induces apoptosis in the HT-29 human colon tumor cell line.

Colon cancer is the third most incident type of cancer worldwide. One of the most important risk factors for colon cancer development are inflammatory bowel diseases (IBD), thus therapies focusing on IBD treatment have great potential to be used in cancer prevention. Nature has been a source of new therapeutic and preventive agents and the racemic form of the styryl-lactone goniothalamin (GTN) has been shown to be a promising antiproliferative agent, with gastroprotective, antinociceptive and anti-inflammatory effects. As inflammation is a well-known tumor promoter, the major goal of this study was to evaluate the therapeutic and preventive potentials of GTN on chemically induced and spontaneous colitis, as well as the cytotoxic effects of GTN on a human colon tumor cell line (HT-29). GTN treatments inhibited TNBS-induced acute and chronic colitis development in Wistar rats, reducing myeloperoxidase levels and inflammatory cells infiltration in the mucosa. In spontaneous-colitis using IL-10 deficient mice (C57BL/6 background), GTN prevented colitis development through downregulation of TNF-α, upregulation of SIRT-1 and inhibition of proliferation (PCNA index), without signs of toxicity after three months of treatment. In HT-29 cells, treatment with 10µM of GTN induced apoptosis by increasing BAX/BCL2, p-JNK1/JNK1, p-P38/P38 ratios as well as through ROS generation. Caspase 8, 9 and 3 activation also occurred, suggesting caspase-dependent apoptotic pathway, culminating in PARP-1 cleavage. Together with previous data, these results show the importance of GTN as a pro-apoptotic, preventive and therapeutic agent for IBD and highlight its potential as a chemopreventive agent for colon cancer.

Anti-inflammatory therapies in TRAMP mice: delay in PCa progression.

The aim of this study was to characterize the structural and molecular biology as well as evaluate the immediate and late responses of prostatic cancer in the transgenic adenocarcinoma of the mouse prostate (TRAMP) model after treatment with goniothalamin (GTN) and celecoxib. The treated mice received GTN (150 mg/kg, gavage) or celecoxib (10 mg/kg, gavage) from 8 to 12 weeks of age. They were killed at different ages: the immediate-response groups at 12 weeks and the late-response groups at 22 weeks. The ventral prostate was collected for light microscopy, immunohistochemistry, western blotting, TUNEL, and ELISA. Morphological analyses indicated that GTN treatment delayed the progression of prostatic adenocarcinoma, leading to a significant decrease of prostatic lesion frequency in both experimental period responses to this treatment, mainly high-grade prostatic intraepithelial neoplasia and well-differentiated adenocarcinoma. Also, the celecoxib treatment showed a particular decrease in the proliferative processes (PCNA) in both the experimental periods. Despite celecoxib diminishing the COX2 and IGFR1 levels, GTN presented higher action spectrum considering the decrease of a greater molecular number involved in the proliferative and inflammatory processes in prostatic cancer. Goniothalamin attenuated the pro-inflammatory response in TRAMP prostatic microenvironment, delaying prostate cancer (PCa) progression. Celecoxib treatment was efficient in the regulation of COX2 in the TRAMP mice, mainly in the advanced disease grade. Finally, we concluded that inflammatory process control in early grades of PCa was crucial for the downregulation of the signaling pathways involved in the proliferative processes in advanced cancer grades.

(-)-Tarchonanthuslactone: Design of New Analogues, Evaluation of their Antiproliferative Activity on Cancer Cell Lines, and Preliminary Mechanistic Studies.

Natural products containing the α,ß-unsaturated δ-lactone skeleton have been shown to possess a variety of biological activities. The natural product (-)-tarchonanthuslactone (1) possessing this privileged scaffold is a popular synthetic target, but its biological activity remains underexplored. Herein, the total syntheses of dihydropyran-2-ones modeled on the structure of 1 were undertaken. These compounds were obtained in overall yields of 17-21 % based on the Keck asymmetric allylation reaction and were evaluated in vitro against eight different cultured human tumor cell lines. We further conducted initial investigation into the mechanism of action of selected analogues. Dihydropyran-2-one 8 [(S,E)-(6-oxo-3,6-dihydro-2H-pyran-2-yl)methyl 3-(3,4-dihydroxyphenyl)acrylate], a simplified analogue of (-)-tarchonanthuslactone (1) bearing an additional electrophilic site and a catechol system, was the most cytotoxic and selective compound against six of the eight cancer cell lines analyzed, including the pancreatic cancer cell line. Preliminary studies on the mechanism of action of compound 8 on pancreatic cancer demonstrated that apoptotic cell death takes place mediated by an increase in the level of reactive oxygen species. It appears as though compound 8, possessing two Michael acceptors and a catechol system, may be a promising scaffold for the selective killing of cancer cells, and thus, it deserves further investigation to determine its potential for cancer therapy.

Anti-inflammatory and antinociceptive effects of racemic goniothalamin, a styryl lactone.

AIMS: The present study aimed to further investigate the anti-inflammatory activity of goniothalamin (GTN), a styryl lactone, as well as its antinociceptive effects. MAIN METHODS: The anti-inflammatory activity was evaluated in models of paw edema induced by different mediators in mice and carrageenan-induced peritonitis. Evaluation of the antinociceptive effect was performed through acetic acid-induced writhing test and formalin test. Activity of GTN on gene expression levels of interleukin-1beta (IL-1ß), induced nitric oxidase synthase (iNOS) and cyclooxygenase-2 (COX-2) were evaluated in vitro in lipopolysaccharide (LPS)-stimulated macrophage (RAW 264.7), as well as gene expression and protein levels of tumor necrosis factor-alpha (TNF-α). KEY FINDINGS: Pretreatment with GTN (300 mg/kg) significantly reduced paw edema induced by compound 48/80, prostaglandin E2, phospholipase A2 and bradykinin. GTN (10, 30 and 100mg/kg) inhibited leukocyte migration in the peritonitis model and gene expression levels of IL-1ß, iNOS and TNF-α, as well as TNF-α protein levels, in LPS-stimulated macrophages, without affecting COX-2 gene expression levels. GTN inhibited nociception induced by acetic acid in the writhing model and in the formalin test, when both neurogenic and inflammatory phases were inhibited. SIGNIFICANCE: For the first time the acute anti-inflammatory profile of GTN is characterized and its antinociceptive activity reported. The current study shows that GTN inhibits both vascular and cellular phases of inflammation, with bradykinin and PLA2 induced inflammation being the most affected by GTN. Its anti-inflammatory effects also involved the in vitro inhibition of gene expression of alarm cytokines and mediators as IL-1ß, iNOS and TNF-α.

Gastroprotective effects of goniothalamin against ethanol and indomethacin-induced gastric lesions in rats: Role of prostaglandins, nitric oxide and sulfhydryl compounds.

Goniothalamin (GTN), a styryl-lactone, is a secondary metabolite naturally found in its enantiomeric form (R) in plants of the genus Goniothalamus (Annonaceae). The antiproliferative activity against human tumor cell lines reported in several studies suggest that the α,ß-unsaturated δ-lactone moiety emerges as a key Michael acceptor for cysteine residues or other nucleophilic biological molecules. Our group reported on the in vivo activity of (R)- and (S)-GTN as well as its racemic form (rac-GTN) in both Ehrlich solid tumor and carrageenan-induced paw edema in mice, without side effects in the effective doses. Despite the rich body of data on the in vitro GTN biological activity, much less is known about its in vivo pharmacological action. Herein we describe the gastroprotective activity of rac-GTN on chemical-induced gastric ulcers models in rats. GTN has a potent gastroprotective effect on ethanol-induced ulcers (effective dose50=18mg/kg) and this activity is dependent on sulfhydryl compounds and prostaglandins generation, but independent of nitric oxide (NO), gastric secretion and mucus production. We hypothesize that goniothalamin may act as a mild irritant, inducing the production of sulfhydryl compounds and prostaglandins, in a process known as adaptive cytoprotection. This hypothesis is supported by the fact that Michael acceptors are the most potent inducers of antioxidant response (as activation of Nrf2 pathway) through generation of mild oxidative stress and that gastroprotective activity of goniothalamin is inhibited after pre-treatment with NEM (N-ethylmaleimide) and NSAID (non-steroidal anti-inflammatory drugs), highlighting the importance of sulfhydryl compounds and prostaglandins on GTN activity.

A new goniothalamin N-acylated aza-derivative strongly downregulates mediators of signaling transduction associated with pancreatic cancer aggressiveness.

In this study, a novel concise series of molecules based on the structure of goniothalamin (1) was synthesized and evaluated against a highly metastatic human pancreatic cancer cell line (Panc-1). Among them, derivative 8 displayed a low IC50 value (2.7 µM) and its concentration for decreasing colony formation was 20-fold lower than goniothalamin (1). Both compounds reduced the levels of the receptor tyrosine kinase (AXL) and cyclin D1 which are known to be overexpressed in pancreatic cancer cells. Importantly, despite the fact that goniothalamin (1) and derivative 8 caused pancreatic cancer cell cycle arrest and cell death, only derivative 8 was able to downregulate pro-survival and proliferation pathways mediated by mitogen activated protein kinase ERK1/2. Another interesting finding was that Panc-1 cells treated with derivative 8 displayed a strong decrease in the transcription factor (c-Myc), hypoxia-inducible factor-1α (HIF-1α) and vascular endothelial growth factor (VEGF) protein levels. Notably, the molecular effects caused by derivative 8 might not be related to ROS generation, since no significant production of ROS was observed in low concentrations of this compound (from 1.5 up to 3 µM). Therefore, the downregulation of important mediators of pancreatic cancer aggressiveness by derivative 8 reveals its great potential for the development of new chemotherapeutic agents for pancreatic cancer treatment.

Design and synthesis of N-acylated aza-goniothalamin derivatives and evaluation of their in vitro and in vivo antitumor activity.

Herein we describe the synthesis of a focused library of compounds based on the structure of goniothalamin (1) and the evaluation of the potential antitumor activity of the compounds. N-Acylation of aza-goniothalamin (2) restored the in vitro antiproliferative activity of this family of compounds. 1-(E)-But-2-enoyl-6-styryl-5,6-dihydropyridin-2(1H)-one (18) displayed enhanced antiproliferative activity. Both goniothalamin (1) and derivative 18 led to reactive oxygen species generation in PC-3 cells, which was probably a signal for caspase-dependent apoptosis. Treatment with derivative 18 promoted Annexin V/7-aminoactinomycin D double staining, which indicated apoptosis, and also led to G2 /M cell-cycle arrest. In vivo studies in Ehrlich ascitic and solid tumor models confirmed the antitumor activity of goniothalamin (1), without signs of toxicity. However, derivative 18 exhibited an unexpectedly lower in vivo antitumor activity, despite the treatments being administered at the same site of inoculation. Contrary to its in vitro profile, aza-goniothalamin (2) inhibited Ehrlich tumor growth, both on the ascitic and solid forms. Our findings highlight the importance of in vivo studies in the search for new candidates for cancer treatment.

Design, synthesis and in vitro evaluation against human cancer cells of 5-methyl-5-styryl-2,5-dihydrofuran-2-ones, a new series of goniothalamin analogues.

The present work describes the preparation of a novel series of compounds based on the structure of goniothalamin (1), a natural styryl lactone with known cytotoxic and antiproliferative activities against a variety of cancer cell lines. A focused library of 17 goniothalamin analogues displaying the 5-methyl-2,5-dihydrofuran-2-one motif were prepared, and their cytotoxicity evaluated. While the analogues bearing methoxy and/or hydroxy groups on the aromatic moiety usually were at least three times less potent than the lead compound (1), ortho and para-trifluoromethyl analogues 10 and 11 exhibited levels of cytotoxicity similar to goniothalamin (1) against most cancer cell lines evaluated. One could suggest that the electronic effect of the trifluoromethyl group activates the inhibitor's electrophilic site via reduction of the electron density of the α,ß-unsaturated ester oxygen atom. These results provide new information on the structure activity relationship of these α,ß-unsaturated styryl lactones, thereby further focusing the design of novel candidates.

Knocking down low molecular weight protein tyrosine phosphatase (LMW-PTP) reverts chemoresistance through inactivation of Src and Bcr-Abl proteins.

The development of multidrug resistance (MDR) limits the efficacy of continuous chemotherapeutic treatment in chronic myelogenous leukemia (CML). Low molecular weight protein tyrosine phosphatase (LMW-PTP) is up-regulated in several cancers and has been associated to poor prognosis. This prompted us to investigate the involvement of LMW-PTP in MDR. In this study, we investigated the role of LMW-PTP in a chemoresistant CML cell line, Lucena-1. Our results showed that LMW-PTP is highly expressed and 7-fold more active in Lucena-1 cells compared to K562 cells, the non-resistant cell line. Knocking down LMW-PTP in Lucena-1 cells reverted chemoresistance to vincristine and imatinib mesylate, followed by a decrease of Src and Bcr-Abl phosphorylation at the activating sites, inactivating both kinases. On the other hand, overexpression of LMW-PTP in K562 cells led to chemoresistance to vincristine. Our findings describe, for the first time, that LMW-PTP cooperates with MDR phenotype, at least in part, through maintaining Src and Bcr-Abl kinases in more active statuses. These findings suggest that inhibition of LMW-PTP may be a useful strategy for the development of therapies for multidrug resistant CML.

Synthesis of methoxylated goniothalamin, aza-goniothalamin and γ-pyrones and their in vitro evaluation against human cancer cells.

The present work describes the preparation of three novel series of compounds based on the structure of goniothalamin, a natural styryl lactone which has been found to display cytotoxic and antiproliferative activities against a variety of cancer cell lines. A focused library of 29 novel goniothalamin analogues was prepared and evaluated against seven human cancer cell lines. While the γ-pyrones and the aza-goniothalamin analogues were less potent than the lead compound, 2,4-dimethoxy analogue 88 has shown to be more potent in vitro than goniothalamin against all cancer cell lines evaluated. Furthermore, it was more potent than doxorubicin against NCI-ADR/RES, OVCAR-03 and HT-29 while being less toxic to human keratinocytes (HaCat). The 3,5-dimethoxy analogue 90 and 2,4,5-trimethoxy analogue 92 also displayed promising antiproliferative activity when compared to goniothalamin (1). These results provide new elements for the design and synthesis of novel representatives of this family of natural compounds.

Effect of goniothalamin on the development of Ehrlich solid tumor in mice.

In this work the antiproliferative activity of goniothalamin (1), both in racemic and in its enantiomeric pure forms, in a solid tumor experimental model using laboratory animals is described. The antiedematogenic activity displayed by racemic 1 in the carrageenan edema model in mice together with the reduction of Ehrlich solid tumor model suggest a relationship between anticancer and antiinflammatory activities with the antiinflammatory activity favoring the antiproliferative activity itself.

Trypanocidal activity of 5,6-dihydropyran-2-ones against free trypomastigotes forms of Trypanosoma cruzi.

Sixteen 5,6-dihydro-2H-pyran-2-ones were evaluated in in vitro assay against trypomastigotes forms of Trypanosoma cruzi, the causative agent of Chagas' disease. A structure-activity relationship study (SAR) allowed us to establish the relevant structural features for the trypanocidal activity of goniothalamin analogues against T. cruzi. In fact, non-natural form of goniothalamin (ent-1) was threefold more potent than the natural one (1). In addition, we have identified analogues 9 and 10 (both displaying S configuration) as the highest potent compounds against T. cruzi with IC50=0.12 and 0.09 mM (IC50 value for crystal violet was 0.08 mM) whereas significantly lower toxicities were observed when these compounds were evaluated under LLC-MK2 lineage cells (1.38 and 4.89 mM, respectively). In addition, epoxides derivatives 12 and ent-12 were shown to be more potent than the corresponding stereoisomers 2 and ent-2 and non-natural argentilactone (ent-3, IC50=0.47 mM) was twofold more potent than natural argentilactone (3, IC50=0.94 mM).

(R)-Goniothalamin: total syntheses and cytotoxic activity against cancer cell lines.

The total syntheses of (R)-goniothalamin (1), a styryl lactone isolated from several Goniothalamus species, via catalytic asymmetric allylation of alpha-benzyloxyacetaldehyde (2), followed by ring-closing metathesis and Wittig olefination and via catalytic asymmetric allylation of trans-cinnamaldehyde (12), followed by ring-closing metathesis are reported. The antiproliferative activities of (R)-1 and its Z-isomer 10 as well as of the synthetic dihydropyranone intermediates 7 and 8 against eight different cancer cell lines are also described.