Anticancer drugs from nature--natural products as a unique source of new microtubule-stabilizing agents

Semisynthesis and biological evaluation of novel honokiol thioethers against colon cancer cells HCT116 via inhibiting the transcription and expression of YAP protein

Honokiol, derived from Magnolia officinalis (a traditional Chinese medicine), has been reported to have anticancer activity. Here, a series of novel honokiol thioethers bearing a 1,3,4-oxadiazole moiety were prepared and evaluated for their anticancer activities against three types of digestive system tumor cells. Biological evaluation showed that honokiol derivative 3k exhibited the best antiproliferative activity against HCT116 cells with an IC50 value of 6.1 μmol/L, superior to the reference drug 5-fluorouracil (IC50: 9.63 ± 0.27 µmol/L). The structure-activity relationships (SARs) indicated that the introduction of -(4-NO2)Ph, 3-pyridyl, -(2-F)Ph, -(4-F)Ph, -(3-F)Ph, -(4-Cl)Ph, and -(3-Cl)Ph groups was favorable for enhancing the anticancer activity of the title honokiol thioethers. Further study revealed that honokiol thioether 3k can well inhibit the proliferation of colon cancer cells HCT116, arresting the cells in G1 phase and inducing cell death. Moreover, a preliminary mechanism study indicated that 3k directly inhibits the transcription and expression of YAP protein without activating the Hippo signaling pathway. Thus, honokiol thioether 3k could be deeply developed for the development of honokiol-based anticancer candidates.

Daurisoline inhibits proliferation, induces apoptosis, and enhances TRAIL sensitivity of breast cancer cells by upregulating DR5

Daurisoline (DS) is an isoquinoline alkaloid that exerts anticancer activities in various cancer cells. However, the underlying mechanisms through which DS affects the survival of breast cancer cells remain poorly understood. Therefore, the present study was undertaken to investigate the potential anticancer effect of DS on breast cancer cells and reveal the mechanism underlying the enhanced tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-mediated apoptosis by DS. Cell counting kit-8 (CCK-8) and 5-ethynyl-2-deoxyuridine (EdU) assay were used to evaluate the ability of cell proliferation. Flow cytometry was selected to examine the cell cycle distribution. TUNEL assay was used to detect the cell apoptosis. The protein expression was measured by Western blot analysis. DS was found to reduce the cell viability and suppress the proliferation of MCF-7 and MDA-MB-231 cells by causing G1 phase cell cycle arrest. DS could trigger apoptosis by promoting the cleavage of caspase-8 and PARP. The phosphorylation of ERK, JNK, and p38MAPK was upregulated clearly following DS treatment. Notably, SP600125 (JNK inhibitor) pretreatment significantly abrogated DS-induced PARP cleavage. DS inactivated Akt/mTOR and Wnt/β-catenin signaling pathway and upregulated the expression of ER stress-related proteins. Additionally, DS amplified TRAIL-caused viability reduction and apoptosis in breast cancer cells. Mechanismly, DS upregulated the protein level of DR4 and DR5, and knockdown of DR5 attenuated the cotreatment-induced cleavage of PARP. Inhibition of JNK could block DS-induced upregulation of DR5. This study provides valuable insights into the mechanisms of DS inhibiting cell proliferation, triggering apoptosis, and enhancing TRAIL sensitivity of breast cancer cells.

Novel Anti-tumor Strategy for Breast Cancer: Synergistic Role of Oleuropein with Paclitaxel Therapeutic in MCF-7 Cells

BACKGROUND

The side effects of conventional therapeutics pose a problem for cancer treatment. Recently, combination treatments with natural compounds have attracted attention regarding limiting the side effects of treatment. Oleuropein is a natural polyphenol in olives that has antioxidant and anticancer effects.

OBJECTIVES

This study aimed to investigate the oxidative stress effect of a combination of Paclitaxel, a chemotherapeutic agent, and Oleuropein in the MCF-7 cell line.

METHODS

The xCELLigence RTCA method was used to determine the cytotoxic effects of Oleuropein and Paclitaxel in the MCF-7 cell line. The Total Oxidant and Total Antioxidant Status were analyzed using a kit. The Oxidative Stress Index was calculated by measuring Total Oxidant and Total Antioxidant states. The levels of superoxide dismutase, reduced glutathione and malondialdehyde, which are oxidative stress markers, were also measured by ELISA assay kit.

RESULTS

As a result of the measurement, IC50 doses of Oleuropein and Paclitaxel were determined as 230 μM and 7.5 μM, respectively. Different percentages of combination ratios were generated from the obtained IC50 values. The effect of oxidative stress was investigated at the combination rates of 10%, 20%, 30%, and 40% which were determined to be synergistic. In terms of the combined use of Oleuropein and Paclitaxel on oxidative stress, antioxidant defense increased, and Oxidative Stress Index levels decreased.

CONCLUSION

These findings demonstrate that the doses administered to the Oleuropein+Paclitaxel combination group were lower than those administered to groups using one agent alone (e.g. Paclitaxel), the results of which reduce the possibility of administering toxic doses.

Bioactive compounds from Actinidia arguta fruit as a new strategy to fight glioblastoma

In recent years, there has been a significant demand for natural products as a mean of disease prevention or as an alternative to conventional medications. The driving force for this change is the growing recognition of the abundant presence of valuable bioactive compounds in natural products. On recent years Actinia arguta fruit, also known as kiwiberry, has attracted a lot of attention from scientific community due to its richness in bioactive compounds, including phenolic compounds, organic acids, vitamins, carotenoids and fiber. These bioactive compounds contribute to the fruit's diverse outstanding biological activities such as antioxidant, anti-inflammatory, neuroprotective, immunomodulatory, and anti-cancer properties. Due to these properties, the fruit may have the potential to be used in the treatment/prevention of various types of cancer, including glioblastoma. Glioblastoma is the most aggressive form of brain cancer, displaying 90 % of recurrence rate within a span of 2 years. Despite the employment of an aggressive approach, the prognosis remains unfavorable, emphasizing the urgent requirement for the development of new effective treatments. The preclinical evidence suggests that kiwiberry has potential impact on glioblastoma by reducing the cancer self-renewal, modulating the signaling pathways involved in the regulation of the cell phenotype and metabolism, and influencing the consolidation of the tumor microenvironment. Even though, challenges such as the imprecise composition and concentration of bioactive compounds, and its low bioavailability after oral administration may be drawbacks to the development of kiwiberry-based treatments, being urgent to ensure the safety and efficacy of kiwiberry for the prevention and treatment of glioblastoma. This review aims to highlight the potential impact of A. arguta bioactive compounds on glioblastoma, providing novel insights into their applicability as complementary or alternative therapies.

Mukaiyama aldol reaction: an effective asymmetric approach to access chiral natural products and their derivatives/analogues

The Mukaiyama aldol reaction is generally a Lewis-acid catalyzed cross-aldol reaction between an aldehyde or ketone and silyl enol ether. It was first described by Mukaiyama in 1973, almost 5 decades ago, to achieve the enantioselective synthesis of β-hydroxy carbonyl compounds in high percentage yields. Mukaiyama aldol adducts play a pivotal role in the synthesis of various naturally occurring and medicinally important organic compounds such as polyketides, alkaloids, macrolides, etc. This review highlights the significance of the Mukaiyama aldol reaction towards the asymmetric synthesis of a wide range of biologically active natural products reported recently (since 2020).

4-(3-Alkyl-2-oxoimidazolidin-1-yl)-N-phenylbenzenesulfonamide salts: Novel hydrosoluble prodrugs of antimitotics selectively bioactivated by the cytochrome P450 1A1 in breast cancer cells

4-(3-Alkyl-2-oxoimidazolidin-1-yl)-N-phenylbenzenesulfonamides (PAIB-SAs) are members of a new family of prodrugs bioactivated by cytochrome P450 1A1 (CYP1A1) in breast cancer cells into their potent 4-(2-oxoimidazolidin-1-yl)-N-phenylbenzenesulfonamide metabolites (PIB-SAs). One of the predominant problems for the galenic formulation and administration of PAIB-SAs in animal studies is their poor hydrosolubility. To circumvent that difficulty, we report the design, the synthesis, the chemical characterization, the evaluation of the aqueous solubility, the antiproliferative activity and the mechanism of action of 18 new Na+, K+ and Li+ salts of PAIB-SAs. Our results evidenced that the latter exhibited highly selective antiproliferative activity toward MCF7 and MDA-MB-468 breast cancer cells expressing endogenously CYP1A1 compared to insensitive MDA-MB-231 and HaCaT cells. Moreover, PAIB-SA salts 1-18 are significantly more hydrosoluble (3.9-9.4 mg/mL) than their neutral counterparts (< 0.0001 mg/mL). In addition, the most potent PAIB-SA salts 1-3 and 10-12 arrested the cell cycle progression in the G2/M phase and disrupted the cytoskeleton's dynamic assembly. Finally, PAIB-SA salts are N-dealkylated by CYP1A1 into their corresponding PIB-SA metabolites, which are potent antimitotics. In summary, our results show that our water-soluble PAIB-SA salts, notably the sodium salts, still exhibit potent antiproliferative efficacy and remain prone to CYP1A1 bioactivation. In addition, these PAIB-SA salts will allow the development of galenic formulations suitable for further biopharmaceutical and pharmacodynamic studies.

Isothiocyanates as Tubulin Polymerization Inhibitors-Synthesis and Structure-Activity Relationship Studies

Among the various substances that interfere with the microtubule formation process, isothiocyanates (ITCs) are the group of compounds for which the binding mode and mechanism of action have not yet been explained. To better understand the structure-activity relationship of tubulin-isothiocyanate interactions, we designed and synthesized a series of sixteen known and novel, structurally diverse ITCs, including amino acid ester-derived isothiocyanates, bis-isothiocyanates, analogs of benzyl isothiocyanate, and phosphorus analogs of sulforaphane. All synthesized compounds and selected natural isothiocyanates (BITC, PEITC, AITC, and SFN) were tested in vitro to evaluate their antiproliferative activity, tubulin polymerization inhibition potential, and influence on cell cycle progression. The antiproliferative activity of most of the newly tested compounds exceeded the action of natural isothiocyanates, with four structures being more potent as tubulin polymerization inhibitors than BITC. As a confirmation of anti-tubulin activity, the correlation between polymerization inhibition and cell cycle arrest in the G2/M phase was observed for the most active compounds. In light of the biological results indicating significant differences in the impact of structurally diverse isothiocyanate on tubulin polymerization, in silico analysis was conducted to analyze the possible mode of isothiocyanate-tubulin binding and to show how it can influence the polymerization reaction.

Self-assembled nanoformulations of paclitaxel for enhanced cancer theranostics

Chemotherapy has occupied the critical position in cancer therapy, especially towards the post-operative, advanced, recurrent, and metastatic tumors. Paclitaxel (PTX)-based formulations have been widely used in clinical practice, while the therapeutic effect is far from satisfied due to off-target toxicity and drug resistance. The caseless multi-components make the preparation technology complicated and aggravate the concerns with the excipients-associated toxicity. The self-assembled PTX nanoparticles possess a high drug content and could incorporate various functional molecules for enhancing the therapeutic index. In this work, we summarize the self-assembly strategy for diverse nanodrugs of PTX. Then, the advancement of nanodrugs for tumor therapy, especially emphasis on mono-chemotherapy, combinational therapy, and theranostics, have been outlined. Finally, the challenges and potential improvements have been briefly spotlighted.

Silymarin, an antioxidant flavonoid, protects the liver from the toxicity of the anticancer drug paclitaxel

One of the biggest factors that negatively affect the cancer treatment plan is the toxic effects of chemotherapeutics on non-target cells and tissues. This information prompted us to investigate the protective effects of silymarin (SL), a hepatoprotective agent, against the hepatotoxic effects of the anticancer drug paclitaxel (PAC). Four groups were formed from 28 rats as control, PAC (2 mg/kg), SL (100 mg/kg) and PAC + SL (combination of PAC with SL). After completing the experimental procedures, the tissues collected after anesthesia were analyzed by Western blot, qRT-PCR, biochemical, stereological, immunohistochemical, and histopathological techniques. Administration of PAC significantly increased the expression of tumor necrosis factor-alpha (TNF-α), Bax, cytochrome-c (cyt-c), and active caspase-3, as well as malondialdehyde (MDA) levels in liver tissue and decreased glutathione (GSH) levels compared with the control group. PAC also resulted in a significant increase in serum triglyceride (TG), cholesterol (CH), alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels compared with the control group. Pathological changes such as microvesicular steatosis, the formation of Councilman bodies, an increase in total sinusoidal volume, and a decrease in the total number of hepatocytes were observed in the liver tissue of the PAC group. Almost all analysis results in the PAC + SL group were similar to those in the control group, and no significant pathological alterations were observed in this group. The data obtained show that SL protects the liver from the harmful effects of PAC, especially thanks to its TNF-α suppressor, anti-inflammatory, anti-apoptotic and antioxidant effects. Based on this result, in cases where PAC is used in cancer treatment, it can be recommended to be used together with SL to prevent harmful effects on healthy liver tissue and to continue treatment uninterruptedly and effectively.

Garcinia kola: a critical review on chemistry and pharmacology of an important West African medicinal plant

Garcinia kola Heckel (Clusiaceae) is a tree indigenous to West and Central Africa. All plant parts, but especially the seeds, are of value in local folklore medicine. Garcinia kola is used in treatment of numerous diseases, including gastric disorders, bronchial diseases, fever, malaria and is used to induce a stimulating and aphrodisiac effect. The plant is now attracting considerable interest as a possible source of pharmaceutically important drugs. Several different classes of compounds such as biflavonoids, benzophenones, benzofurans, benzopyran, vitamin E derivatives, xanthones, and phytosterols, have been isolated from G. kola, of which many appears to be found only in this species, such as garcinianin (found in seeds and roots), kolanone (fruit pulp, seeds, roots), gakolanone (stem bark), garcinoic acid, garcinal (both in seeds), garcifuran A and B, and garcipyran (all in roots). They showed a wide range of pharmacological activities (e.g. analgesic, anticancer, antidiabetic, anti-inflammatory, antimalarial, antimicrobial, hepatoprotective and neuroprotective effects), though this has only been confirmed in animal models. Kolaviron is the most studied compound and is perceived by many studies as the active principle of G. kola. However, its research is associated with significant flaws (e.g. too high doses tested, inappropriate positive control). Garcinol has been tested under better conditions and is perhaps showing more promising results and should attract deeper research interest (especially in the area of anticancer, antimicrobial, and neuroprotective activity). Human clinical trials and mechanism-of-action studies must be carried out to verify whether any of the compounds present in G. kola may be used as a lead in the drug development.

From Natural Sources to Synthetic Derivatives: The Allyl Motif as a Powerful Tool for Fragment-Based Design in Cancer Treatment

Since the beginning of history, natural products have been an abundant source of bioactive molecules for the treatment of different diseases, including cancer. Many allyl derivatives, which have shown anticancer activity both in vitro and in vivo in a large number of cancers, are bioactive molecules found in garlic, cinnamon, nutmeg, or mustard. In addition, synthetic products containing allyl fragments have been developed showing potent anticancer properties. Of particular note is the allyl derivative 17-AAG, which has been evaluated in Phase I and Phase II/III clinical trials for the treatment of multiple myeloma, metastatic melanoma, renal cancer, and breast cancer. In this Perspective, we compile extensive literature evidence with descriptions and discussions of the most recent advances in different natural and synthetic allyl derivatives that could generate cancer drug candidates in the near future.

Paclitaxel-Loaded Lipid-Coated Magnetic Nanoparticles for Dual Chemo-Magnetic Hyperthermia Therapy of Melanoma

Melanoma is the most aggressive and metastasis-prone form of skin cancer. Conventional therapies include chemotherapeutic agents, either as small molecules or carried by FDA-approved nanostructures. However, systemic toxicity and side effects still remain as major drawbacks. With the advancement of nanomedicine, new delivery strategies emerge at a regular pace, aiming to overcome these challenges. Stimulus-responsive drug delivery systems might considerably reduce systemic toxicity and side-effects by limiting drug release to the affected area. Herein, we report the development of paclitaxel-loaded lipid-coated manganese ferrite magnetic nanoparticles (PTX-LMNP) as magnetosomes synthetic analogs, envisaging the combined chemo-magnetic hyperthermia treatment of melanoma. PTX-LMNP physicochemical properties were verified, including their shape, size, crystallinity, FTIR spectrum, magnetization profile, and temperature profile under magnetic hyperthermia (MHT). Their diffusion in porcine ear skin (a model for human skin) was investigated after intradermal administration via fluorescence microscopy. Cumulative PTX release kinetics under different temperatures, either preceded or not by MHT, were assessed. Intrinsic cytotoxicity against B16F10 cells was determined via neutral red uptake assay after 48 h of incubation (long-term assay), as well as B16F10 cells viability after 1 h of incubation (short-term assay), followed by MHT. PTX-LMNP-mediated MHT triggers PTX release, allowing its thermal-modulated local delivery to diseased sites, within short timeframes. Moreover, half-maximal PTX inhibitory concentration (IC50) could be significantly reduced relatively to free PTX (142,500×) and Taxol® (340×). Therefore, the dual chemo-MHT therapy mediated by intratumorally injected PTX-LMNP stands out as a promising alternative to efficiently deliver PTX to melanoma cells, consequently reducing systemic side effects commonly associated with conventional chemotherapies.

Switching cell fate by the actin-auxin oscillator in Taxus: cellular aspects of plant cell fermentation

Paclitaxel synthesis in Taxus cells correlates with a cell-fate switch that leads to vacuoles of a glossy appearance and vermiform mitochondria. This switch depends on actin and apoplastic respiratory burst. Plant cell fermentation, the production of valuable products in plant cell culture, has great potential as sustainable alternative to the exploitation of natural resources for compounds of pharmaceutical interest. However, the success of this approach has remained limited, because the cellular aspects of metabolic competence are mostly unknown. The production of the anti-cancer alkaloid Paclitaxel has been, so far, the most successful case for this approach. In the current work, we map cellular aspects of alkaloid synthesis in cells of Taxus chinensis using a combination of live-cell imaging, quantitative physiology, and metabolite analysis. We show evidence that metabolic potency correlates with a differentiation event giving rise to cells with large vacuoles with a tonoplast that is of a glossy appearance, agglomerations of lipophilic compounds, and multivesicular bodies that fuse with the plasma membrane. Cellular features of these glossy cells are bundled actin, more numerous peroxisomes, and vermiform mitochondria. The incidence of glossy cells can be increased by aluminium ions, and this increase is significantly reduced by the actin inhibitor Latrunculin B, and by diphenylene iodonium, a specific inhibitor of the NADPH oxidase Respiratory burst oxidase Homologue (RboH). It is also reduced by the artificial auxin Picloram. This cellular fingerprint matches the implications of a model, where the differentiation into the glossy cell type is regulated by the actin-auxin oscillator that in plant cells acts as dynamic switch between growth and defence.

Alkaloids from Phaeanthus vietnamensis with inhibitory effect on nitric oxide production lipopolysaccharide-stimulated in RAW264.7 macrophages

The chemical study of the acidic extract of Phaeanthus vietnamensis leaves led to the isolation of one new alkaloid, vietnamine A (1) and eight known alkaloids (R,S)-2N-norberbamunine (2), grisabine (3), 1S,1'R,O,O'-dimethylgrisabine (4), dauricine (5), neothalibrine (6), vietnamine (7), xylopine (8), and argentinine (9) by NMR and MS and comparing with the data reported in the literature. Compounds 1-9 were evaluated for inhibitory NO production in RAW 264.7 macrophages, LPS-stimulated. Compounds 1-3 significantly inhibited on NO production with the IC₅₀ values of 6.8 ± 0.9, 9.8 ± 1.0, and 7.1 ± 0.4 µg/ml, respectively.

A synthetic prostaglandin E1 analogue, misoprostol, ameliorates paclitaxel-induced oxidative damage in rat brain

The main objective of our study was to examine the protection of misoprostol (MP) on paclitaxel (PAX) side effects in rat brains. Twenty-eight female Sprague-Dawley rats were provided to form 4 groups, each containing seven rats: the control group was given 1 mL of 0.9% NaCl intraperitoneally (i.p.) and 1 mL of 0.9% NaCl orally for six days. In treatment groups, each rat was injected with 2 mg/kg PAX i.p. on days 0, 2, 4, and 6 of the study, and 0.2 mg/kg/day MP was given by oral gavage for six days. Levels of malondialdehyde (MDA) and glutathione (GSH), activities of superoxide dismutase (SOD), and catalase (CAT) of tissue samples were measured. In immunohistochemical analyzes, it was observed that tumor necrosis factor-alpha (TNF-α) and cleaved caspase-3 expression in the cerebellum hippocampus and cerebral cortex were increased in the PAX group compared to the other groups. The increase in TNF-α and cleaved caspase-3 expression detected in PAX group rats were significantly decreased in the PAX + MP group. The results obtained in this study confirm the hypotheses that PAX can increase apoptosis in brain tissue both directly and through cytokines such as TNF-α. It also shows that MP can be used as a protective and therapeutic pharmacological agent against the harmful effects of PAX on brain tissue. In addition, it seems that the use of MP can improve PAX-induced brain damage by preventing oxidative damage.

Understanding of cell death induced by the constituents of Taxus yunnanensis wood

The ethanol extract from the wood of Taxus Yunnanensis (TY) induced apoptosis in all cancer cell lines tested, which was mainly due to activation of an extrinsic pathway in human colon cancer DLD-1 cells. The extrinsic pathway was activated by the upregulation of the expression levels of Fas and TRAIL/DR5, which led to the activation of caspase-8. Of note, the machinery of this increase in expression was promoted by the upregulation of MIR32a expression, which silenced MIR34a-targeting E2F3 transcription factor. Furthermore, ectopic expression of MIR32a or siR-E2F3 silencing E2F3 increased Fas and TRAIL/DR5 expression. Thus, the extract activated the extrinsic pathway through the MIR34a/E2F3 axis, resulting in the autocrine and paracrine release of TRAIL, and upregulated expression of death receptors Fas and DR5 in the treated DLD-1 cells, which were functionally validated by Fas immunocytochemistry, and using anti-Fas and anti-TRAIL antibodies, respectively. In vivo, TY showed significant anti-tumor effects on xenografted and syngeneic model mice. The extract may also aid in chemoprevention by selectively making marked tumor cells susceptible to the tumor immunosurveillance system.

Paclitaxel Drug Delivery Systems: Focus on Nanocrystals' Surface Modifications

Paclitaxel (PTX) is a chemotherapeutic agent that belongs to the taxane family and which was approved to treat various kinds of cancers including breast cancer, ovarian cancer, advanced non-small-cell lung cancer, and acquired immunodeficiency syndrome (AIDS)-related Kaposi’s sarcoma. Several delivery systems for PTX have been developed to enhance its solubility and pharmacological properties involving liposomes, nanoparticles, microparticles, micelles, cosolvent methods, and the complexation with cyclodextrins and other materials that are summarized in this article. Specifically, this review discusses deeply the developed paclitaxel nanocrystal formulations. As PTX is a hydrophobic drug with inferior water solubility properties, which are improved a lot by nanocrystal formulation. Based on that, many studies employed nano-crystallization techniques not only to improve the oral delivery of PTX, but IV, intraperitoneal (IP), and local and intertumoral delivery systems were also developed. Additionally, superior and interesting properties of PTX NCs were achieved by performing additional modifications to the NCs, such as stabilization with surfactants and coating with polymers. This review summarizes these delivery systems by shedding light on their route of administration, the methods used in the preparation and modifications, the in vitro or in vivo models used, and the advantages obtained based on the developed formulations.

Anti-microtubule activity of the traditional Chinese medicine herb Northern Ban Lan (Isatis tinctoria) leads to glucobrassicin

Traditional Chinese medicine (TCM) belongs to the most elaborate and extensive systems of plant-based healing. The herb Northern Ban Lan (Isatis tinctoria) is famous for its antiviral and anti-inflammatory activity. Although numerous components isolated from I. tinctoria have been characterized so far, their modes of action have remained unclear. Here, we show that extracts from I. tinctoria exert anti-microtubular activity. Using time-lapse microscopy in living tobacco BY-2 (Nicotiana tabacum L. cv Bright Yellow 2) cells expressing green fluorescent protein-tubulin, we use activity-guided fractionation to screen out the biologically active compounds of I. tinctoria. Among 54 fractions obtained from either leaves or roots of I. tinctoria by methanol (MeOH/H₂ O 8:2), or ethyl acetate extraction, one specific methanolic root fraction was selected, because it efficiently and rapidly eliminated microtubules. By combination of further purification with ultra-high-performance liquid chromatography and high-resolution tandem mass spectrometry most of the bioactivity could be assigned to the glucosinolate compound glucobrassicin. Glucobrassicin can also affect microtubules and induce apoptosis in HeLa cells. In the light of these findings, the antiviral activity of Northern Ban Lan is discussed in the context of microtubules being hijacked by many viral pathogens for cell-to-cell spread.

Synthesis of Ferulenol by Engineered Escherichia coli: Structural Elucidation by Using the In Silico Tools

4-Hydroxycoumarin (4HC) has been used as a lead compound for the chemical synthesis of various bioactive substances and drugs. Its prenylated derivatives exhibit potent antibacterial, antitubercular, anticoagulant, and anti-cancer activities. In doing this, E. coli BL21(DE3)pLysS strain was engineered as the in vivo prenylation system to produce the farnesyl derivatives of 4HC by coexpressing the genes encoding Aspergillus terreus aromatic prenyltransferase (AtaPT) and truncated 1-deoxy-D-xylose 5-phosphate synthase of Croton stellatopilosus (CstDXS), where 4HC was the fed precursor. Based on the high-resolution LC-ESI(±)-QTOF-MS/MS with the use of in silico tools (e.g., MetFrag, SIRIUS (version 4.8.2), CSI:FingerID, and CANOPUS), the first major prenylated product (named compound-1) was detected and ultimately elucidated as ferulenol, in which information concerning the correct molecular formula, chemical structure, substructures, and classifications were obtained. The prenylated product (named compound-2) was also detected as the minor product, where this structure proposed to be the isomeric structure of ferulenol formed via the tautomerization. Note that both products were secreted into the culture medium of the recombinant E. coli and could be produced without the external supply of prenyl precursors. The results suggested the potential use of this engineered pathway for synthesizing the farnesylated-4HC derivatives, especially ferulenol.

Natural Small Molecules Targeting NF-κB Signaling in Glioblastoma

Nuclear factor-κB (NF-κB) is a transcription factor that regulates various genes that mediate various cellular activities, including propagation, differentiation, motility, and survival. Abnormal activation of NF-κB is a common incidence in several cancers. Glioblastoma multiforme (GBM) is the most aggressive brain cancer described by high cellular heterogeneity and almost unavoidable relapse following surgery and resistance to traditional therapy. In GBM, NF-κB is abnormally activated by various stimuli. Its function has been associated with different processes, including regulation of cancer cells with stem-like phenotypes, invasion of cancer cells, and radiotherapy resistance identification of mesenchymal cells. Even though multimodal therapeutic approaches such as surgery, radiation therapy, and chemotherapeutic drugs are used for treating GBM, however; the estimated mortality rate for GBM patients is around 1 year. Therefore, it is necessary to find out new therapeutic approaches for treating GBM. Many studies are focusing on therapeutics having less adverse effects owing to the failure of conventional chemotherapy and targeted agents. Several studies of compounds suggested the involvement of NF-κB signaling pathways in the growth and development of a tumor and GBM cell apoptosis. In this review, we highlight the involvement of NF-κB signaling in the molecular understanding of GBM and natural compounds targeting NF-κB signaling.

Total Synthesis of Leiodermatolide A via Transfer Hydrogenative Allylation, Crotylation, and Propargylation: Polyketide Construction beyond Discrete Allyl- or Allenylmetal Reagents

The total synthesis of leiodermatolide A was accomplished in 13 steps (LLS). Transfer hydrogenative variants of three carbonyl additions that traditionally rely on premetalated reagents (allylation, crotylation, and propargylation) are deployed together in one total synthesis.

Management of Glioblastoma Multiforme by Phytochemicals: Applications of Nanoparticle-Based Targeted Drug Delivery System

The Glioblastoma Multiforme (GBM; grade IV astrocytoma) exhorts tumors of star-shaped glial cells in the brain. It is a fast-growing tumor that spreads to nearby brain regions specifically to cerebral hemispheres in frontal and temporal lobes. The etiology of GBM is unknown, but major risk factors are genetic disorders like neurofibromatosis and schwannomatosis, which develop the tumor in the nervous system. The management of GBM with chemo-radiotherapy leads to resistance, and current drug regimen like Temozolomide (TMZ) is less efficacious. The reasons behind the failure of drugs are due to DNA alkylation in the cell cycle by enzyme DNA guanidase and mitochondrial dysfunction. Naturally occurring bioactive compounds from plants referred as phytochemicals, serve as vital sources for anti-cancer drugs. Some prototypical examples include taxol analogs, vinca alkaloids (vincristine, vinblastine), podophyllotoxin analogs, camptothecin, curcumin, aloe-emodin, quercetin, berberine etc. These phytochemicals often regulate diverse molecular pathways, which are implicated in the growth and progression of cancers. However, the challenges posed by the presence of BBB/BBTB to restrict the passage of these phytochemicals, culminates in their low bioavailability and relative toxicity. In this review, we integrated nanotech as a novel drug delivery system to deliver phytochemicals from traditional medicine to the specific site within the brain for the management of GBM.

Retracted Article: The synthesis and biological activity of marine alkaloid derivatives and analogues

The ocean is the origin of life, with a unique ecological environment, which has given birth to a wealth of marine organisms. The ocean is an important source of biological resources and tens of thousands of monomeric compounds have been separated from marine organisms using modern separation technology. Most of these monomeric compounds have some kind of biological activity that has attracted extensive attention from researchers. Marine alkaloids are a kind of compound that can be separated from marine organisms. They have complex and special chemical structures, but at the same time, they can show diversity in biological activities. The biological activities of marine alkaloids mainly manifest in the form of anti-tumor, anti-fungus, anti-viral, anti-malaria, and anti-osteoporosis properties. Many marine alkaloids have good medicinal prospects and can possibly be used as anti-tumor, anti-viral, and anti-fungal clinical drugs or as lead compounds. The limited amounts of marine alkaloids that can be obtained by separation, coupled with the high cytotoxicity and low selectivity of these lead compounds, has restricted the clinical research and industrial development of marine alkaloids. Marine alkaloid derivatives and analogues have been obtained via rational drug design and chemical synthesis, to make up for the shortcomings of marine alkaloids; this has become an urgent subject for research and development. This work systematically reviews the recent developments relating to marine alkaloid derivatives and analogues in the field of medical chemistry over the last 10 years (2010-2019). We divide marine alkaloid derivatives and analogues into five types from the point-of-view of biological activity and elaborated on these activities. We also briefly discuss the optimization process, chemical synthesis, biological activity evaluation, and structure-activity relationship (SAR) of each of these compounds. The abundant SAR data provides reasonable approaches for the design and development of new biologically active marine alkaloid derivatives and analogues.

Unexpected synthesis of novel 2-pyrone derivatives: crystal structures, Hirshfeld surface analysis and computational studies

Here we report synthesis of three new compounds namely, 1-acetyl-1H-benzimidazolo-2(3H)-one (I), N-(5-acetyl-6-methyl-2-oxo-2H-pyran-4-yl)-N-(2-acetamidophenyl)acetamide (II) and N-(2-acetamidophenyl)-N-2-oxo-2H-pyran-4-yl)acetamide (III) have been synthesized and characterized by single crystal X-ray diffraction. Compounds I and II crystallize in the monoclinic space groups P21/n, and P21/c, respectively, while III crystallizes in the triclinic space group P-1. The theoretical parameters of I-III have been calculated through density functional theory (DFT) by using the hybrid functional B3LYP and basis set 6-311++G**. These theoretical parameters have been compared with the experimental ones obtained by XRD. The significant intermolecular interactions arising in crystal packing are rationalized by means of the Hirshfeld surface analysis method. The major intermolecular contacts in the Hirshfeld surfaces of I-III are from H…H contacts. In addition, binding modes of I-III within Tyrosine-protein kinase JAK2 were investigated using molecular docking and molecular dynamics simulation studies.Communicated by Ramaswamy H. Sarma.

Toxicity of secondary metabolites

Secondary metabolites, commonly referred to as natural products, are produced by living organisms and usually have pharmacological or biological activities. Secondary metabolites are the primary source for the discovery of new drugs. Furthermore, secondary metabolites are also used as food preservatives, biopesticides or as research tools. Although secondary metabolites are mainly used by their beneficial biological activity, the toxicity of some of them may limit their use. The toxicity assessment of any compound that is prone to be used in direct contact with human beings is of vital importance. There is a vast spectrum of experimental methods for toxicity evaluation, including in vitro and in vivo methodologies. In this work, we present an overview of the different sources, bioactivities, toxicities and chemical classification of secondary metabolites, followed by a sketch of the role of toxicity assessment in drug discovery and agrochemistry.

Gamma-Irradiated Chrysin Improves Anticancer Activity in HT-29 Colon Cancer Cells Through Mitochondria-Related Pathway

Irradiation technology can improve the biological activities of natural molecules through a structural modification. This study was conducted to investigate the enhancement of the anticancer effects of chrysin upon exposure to gamma irradiation. Gamma irradiation induces the production of new radiolytic peaks simultaneously with the decrease of the chrysin peak, which increases the cytotoxicity in HT-29 human colon cancer cells. An isolated chrysin derivative (CM1) exhibited a stronger apoptotic effect in HT-29 cells than intact chrysin. The apoptotic characteristics induced by CM1 in HT-29 cells was mediated through the intrinsic signaling pathway, including the excessive production of included reactive oxygen species, the dissipation of the mitochondrial membrane potential, regulation of the B cell lymphoma-2 family, activation of caspase-9, 3, and cleavage of poly (adenosine diphosphate-ribose) polymerase. Our findings suggest that CM1 can be a potential anticancer candidate for the treatment of colon cancer.

One new xanthenone from the marine-derived fungus Aspergillus versicolor MF160003

A new xanthenone derivative, 3-hydroxy pinselin (1), together with five known analogues (2-6) were isolated from the marine-derived fungus Aspergillus versicolor MF160003. Their structures were identified by extensive 1D- and 2D-NMR, and high-resolution mass spectrometry data. Compounds 5 and 6 showed moderate bioactivities against BCG with MIC values of 40 and 20 μg/mL, respectively.

Bioactivity Profile of the Diterpene Isosteviol and its Derivatives

Steviosides, rebaudiosides and their analogues constitute a major class of naturally occurring biologically active diterpene compounds. The wide spectrum of pharmacological activity of this group of compounds has developed an interest among medicinal chemists to synthesize, purify, and analyze more selective and potent isosteviol derivatives. It has potential biological applications and improves the field of medicinal chemistry by designing novel drugs with the ability to cope against resistance developing diseases. The outstanding advancement in the design and synthesis of isosteviol and its derivative has proved its effectiveness and importance in the field of medicinal chemical research. The present review is an effort to integrate recently developed novel drugs syntheses from isosteviol and potentially active pharmacological importance of the isosteviol derivatives covering the recent advances.

Identification of narciclasine from Lycoris radiata (L'Her.) Herb. and its inhibitory effect on LPS-induced inflammatory responses in macrophages

Lycoris radiata (L'Her.) Herb. (L. radiata) was traditionally used as a folk medicine in China for treatment of Alzheimer's disease. However, the specific component responsible for its considerable toxicity remained unclear thus restricting its clinical trials. Narciclasine (NCS) was isolated from L. radiata and treatment of NCS for 72 h exhibited significant antiproliferative effects against L02, Hep G2, HT-29 and RAW264.7 cells. However, what needs to be emphasized is that at safe working concentrations of 0.001-0.016 μM, administration of NCS for 24 h inhibited the mRNA expression of inducible nitric oxide synthase (iNOS), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-ɑ), interleukin-1beta (IL-1β) and cyclooxygenase-2 (COX-2) in lipopolysaccharide (LPS)-induced macrophages thereby suppressing production of nitric oxide (NO), IL-6, TNF-ɑ and IL-1β. NCS supplementation also inhibited nuclear factor-kappa B (NF-κB) activation by suppressing NF-κB P65 phosphorylation and nuclear translocation, IκBɑ degradation and phosphorylation, and IκKɑ/β phosphorylation. The phosphorylation of c-Jun N-terminal kinase (JNK) and P38, and expression of COX-2 was also attenuated by NCS. These results suggested that NCS might exert anti-inflammatory effects through inhibiting NF-κB and mitogen-activated protein kinase (MAPK) pathways even at very low doses.

Understanding the co-loading and releasing of doxorubicin and paclitaxel using chitosan functionalized single-walled carbon nanotubes by molecular dynamics simulations

Two widely used anticancer drugs, doxorubicin (DOX) and paclitaxel (PTX), possess distinct physical properties and chemotherapy specificity. In order to investigate their interaction mechanism with single-walled carbon nanotubes (SWCNTs), co-loading and releasing from the SWCNTs, all-atom molecular dynamics (MD) simulations were firstly carried out for different SWCNT systems, followed by binding free energy calculation with MM-PBSA. The results indicate that the co-loading of DOX and PTX onto the pristine SWCNT is exothermic and spontaneous. The DOX molecules predominantly interact with the SWCNT via π-π stacking through the conjugated aromatic rings, while the separated aromatic rings of PTX also primarily interact with the SWCNT through π-π stacking yet supplemented by an X-π (X = C-H, N-H and C[double bond, length as m-dash]O) interaction. Moreover, the strongest binding of DOX and PTX with the pristine SWCNT shows similar strength (ΔG: -32.0 vs. -33.8 kcal mol-1). For the chitosan functionalized SWCNT (f-SWCNT), the DOX and PTX molecules still prefer binding to the sidewall of the CNT rather than binding with the polymer, and the non-covalent functionalization of the SWCNT with chitosan decreases the binding of DOX and PTX with the sidewall of the f-SWCNT as compared with the DOX/PTX-SWCNT system (ΔG: -24.0 and -21.9 kcal mol-1). The protonation of chitosan and drug molecules further weakens the interaction between DOX/PTX and the f-SWCNT, and shows a consequent displacement of the drug molecules, triggering the release of the drugs. The variation of binding strength of the three systems (DOX/PTX-SWCNT, DOX/PTX-f-SWCNT, and DOXH+/PTXH+-f-SWCNT) was also discussed in terms of the histogram or frequency of the distance from the drugs to the SWCNT. In addition, the encapsulation of two DOX molecules by the f-SWCNT is considerably stronger than the binding of the other six drug molecules to the sidewall, indicating that the encapsulation of anticancer drugs may also play a very important role and should be considered in the drug delivery.

Alcyonacea: A Potential Source for Production of Nitrogen-Containing Metabolites

Alcyonacea (soft corals and gorgonia) are well known for their production of a wide array of unprecedented architecture of bioactive metabolites. This diversity of compounds reported from Alcyonacea confirms its productivity as a source of drug leads and, consequently, indicates requirement of further chemo-biological investigation. This review can be considered a roadmap to investigate the Alcyonacea, particularly those produce nitrogen-containing metabolites. It covers the era from the beginning of marine nitrogen-containing terpenoids isolation from Alcyonacea up to December 2018. One hundred twenty-one compounds with nitrogenous moiety are published from fifteen genera. Their prominent biological activity is evident in their antiproliferative effect, which makes them interesting as potential leads for antitumor agents. For instance, eleutherobin and sarcodictyins are in preclinical or clinical stages.

Basic principles of drug delivery systems - the case of paclitaxel

Cancer is the second cause of death worldwide, exceeded only by cardiovascular diseases. The prevalent treatment currently used against metastatic cancer is chemotherapy. Among the most studied drugs that inhibit neoplastic cells from acquiring unlimited replicative ability (a hallmark of cancer) are the taxanes. They operate via a unique molecular mechanism affecting mitosis. In this review, we show this mechanism for one of them, paclitaxel, and for other (non-taxanes) anti-mitotic drugs. However, the use of paclitaxel is seriously limited (its bioavailability is <10%) due to several long-standing challenges: its poor water solubility (0.3 μg/mL), its being a substrate for the efflux multidrug transporter P-gp, and, in the case of oral delivery, its first-pass metabolism by certain enzymes. Adequate delivery methods are therefore required to enhance the anti-tumor activity of paclitaxel. Thus, we have also reviewed drug delivery strategies in light of the various physical, chemical, and enzymatic obstacles facing the (especially oral) delivery of drugs in general and paclitaxel in particular. Among the powerful and versatile platforms that have been developed and achieved unprecedented opportunities as drug carriers, microemulsions might have great potential for this aim. This is due to properties such as thermodynamic stability (leading to long shelf-life), increased drug solubilization, and ease of preparation and administration. In this review, we define microemulsions and nanoemulsions, analyze their pertinent properties, and review the results of several drug delivery carriers based on these systems.

Synephrine Hydrochloride Suppresses Esophageal Cancer Tumor Growth and Metastatic Potential through Inhibition of Galectin-3-AKT/ERK Signaling

A library consisting of 429 food-source compounds was used to screen the natural products with anticancer properties in esophageal squamous cell carcinoma (ESCC). We demonstrated for the first time that synephrine, an active compound isolated from leaves of citrus trees, markedly suppressed cell proliferation (inhibition rate with 20 μM synephrine at day 5:71.1 ± 5.8% and 75.7 ± 6.2% for KYSE30 and KYSE270, respectively) and colony formation (inhibition rate with 10 μM synephrine: 86.5 ± 5.9% and 82.3 ± 4.5% for KYSE30 and KYSE270, respectively), as well as migration (inhibition rate with 10 μM synephrine: 76.9 ± 4.4% and 62.2 ± 5.8% for KYSE30 and KYSE270, respectively) and invasion abilities (inhibition rate with 10 μM synephrine: 73.3 ± 7.5% and 75.3 ± 3.4% for KYSE30 and KYSE270, respectively) of ESCC cells in a dose-dependent manner, without significant toxic effect on normal esophageal epithelial cells. Mechanistically, quantitative proteomics and bioinformatics analyses were performed to explore the synephrine-regulated proteins. Western blot and qRT-PCR data indicated that synephrine may downregulate Galectin-3 to inactivate AKT and ERK pathways. In addition, we found that the sensitivity of ESCC to fluorouracil (5-FU) could be enhanced by synephrine. Furthermore, in vivo experiments showed that synephrine had significant antitumor effect on ESCC tumor xenografts in nude mice (inhibition rate with 20 mg/kg synephrine is 61.3 ± 20.5%) without observed side effects on the animals. Taken together, synephrine, a food-source natural product, may be a potential therapeutic strategy in ESCC.

The inhibitory effect of kokusaginine on the growth of human breast cancer cells and MDR-resistant cells is mediated by the inhibition of tubulin assembly

The emergence of multidrug resistance (MDR) is a significant challenge in breast carcinoma chemotherapy. Kokusaginine isolated from Dictamnus dasycarpus Turcz. has been reported to show cytotoxicity in several human cancer cell lines including breast cancer cells MCF-7. In this study, kokusaginine showed the potent inhibitory effect on MCF-7 multidrug resistant subline MCF-7/ADR and MDA-MB-231 multidrug resistant subline MDA-MB-231/ADR. Kokusaginine markedly induced apoptosis in a concentration-dependent manner in MCF-7/ADR cells. Furthermore, kokusaginine reduced P-gp mRNA and protein levels, and suppressed P-gp function especially in MCF-7/ADR cells. In addition, kokusaginine showed to inhibit tubulin assembly and the binding of colchicine to tubulin by binding directly to tubulin and affects tubulin formation in vitro. Taken together, these results support the potential therapeutic value of kokusaginine as an anti-MDR agent in chemotherapy for breast carcinoma.

Natural products: a hope for glioblastoma patients

Glioblastoma (GBM) is one of the most aggressive malignant tumors with an overall dismal survival averaging one year despite multimodality therapeutic interventions including surgery, radiotherapy and concomitant and adjuvant chemotherapy. Few drugs are FDA approved for GBM, and the addition of temozolomide (TMZ) to standard therapy increases the median survival by only 2.5 months. Targeted therapy appeared promising in in vitro monolayer cultures, but disappointed in preclinical and clinical trials, partly due to the poor penetration of drugs through the blood brain barrier (BBB). Cancer stem cells (CSCs) have intrinsic resistance to initial chemoradiation therapy (CRT) and acquire further resistance via deregulation of many signaling pathways. Due to the failure of classical chemotherapies and targeted drugs, research efforts focusing on the use of less toxic agents have increased. Interestingly, multiple natural compounds have shown antitumor and apoptotic effects in TMZ resistant and p53 mutant GBM cell lines and also displayed synergistic effects with TMZ. In this review, we have summarized the current literature on natural products or product analogs used to modulate the BBB permeability, induce cell death, eradicate CSCs and sensitize GBM to CRT.

7α,8α-Epoxynagilactones and their glucosides from the twigs of Podocarpus nagi: Isolation, structures, and cytotoxic activities

A phytochemical investigation of twigs of Podocarpus nagi resulted in the identification of eight new type B nagilactones (1-8), all bearing a 7α,8α-epoxy-9(11)-enolide substructure, along with two known analogs (9-10). Their structures were determined on the basis of spectroscopic analysis, including HRESIMS, IR and NMR experiments, and X-ray crystallographic analysis. In vitro cytotoxic assay exhibited that compounds 1, 2, 9 and 10 could induce antiproliferation against three different types of human cancer cells while compounds 3 and 5 were inactive. Notably, the IC₅₀ value of compound 1 is 0.208μM for A431 human epidermoid carcinoma cells, reaching the same level as the positive control combretastatin A-4 (0.104μM). Furthermore, compound 1 performed a strong inhibition of cancer cells by triggering apoptosis and arresting the cell cycle at G₁ phase. These results unfold potential anticancer therapeutic applications of type B nagilactones.

Characteristics, Properties and Analytical Methods of Paclitaxel: A Review

Paclitaxel is a diterpenoid pseudoalkaloid, isolated from Taxus brevifolia, and is largely used as an antitumoral drug. The formulation of paclitaxel known as Taxol® employs a mixture of Cremophor EL and dehydrated ethanol, due the low drug water solubility. However, Taxol® causes some unwanted side effects due to the presence of Cremophor EL and ethanol in the formulation. Based on this, there is a need for the development of drug delivery systems to enhance the solubility, permeability and stability of paclitaxel and to promote a controlled and targeted delivery for better therapeutic effect and reduced side effects. In addition, the drug has been qualitatively and quantitatively analyzed in different delivery systems. In this context, several approaches were reported focusing on the optimization of analytical methods and development of new ones, considering the need of a fast, simple, with enough sensibility and selectivity assay, which can be a problem in some analysis. This review presents a summary of methods used in quantification of paclitaxel in different matrices, such as plasma, urine, plant extract, cells and delivery systems.

Therapeutic targeting of oncogenic transcription factors by natural products in eye cancer

Carcinogenesis has a multifactorial etiology, and the underlying molecular pathogenesis is still not entirely understood, especially for eye cancers. Primary malignant intraocular neoplasms are relatively rare, but delayed detection and inappropriate management contribute to poor outcomes. Conventional treatment, such as orbital exenteration, chemotherapy, or radiotherapy, alone results in high mortality for many of these malignancies. Recent sequential multimodal therapy with a combination of high-dose chemotherapy, followed by appropriate surgery, radiotherapy, and additional adjuvant chemotherapy has helped dramatically improve management. Transcription factors are proteins that regulate gene expression by modulating the synthesis of mRNA. Since transcription is a dominant control point in the production of many proteins, transcription factors represent key regulators for numerous cellular functions, including proliferation, differentiation, and apoptosis, making them compelling targets for drug development. Natural compounds have been studied for their potential to be potent yet safe chemotherapeutic drugs. Since the ancient times, plant-derived bioactive molecules have been used to treat dreadful diseases like cancer, and several refined pharmaceutics have been developed from these compounds. Understanding targeting mechanisms of oncogenic transcription factors by natural products can add to our oncologic management toolbox. This review summarizes the current findings of natural products in targeting specific oncogenic transcription factors in various types of eye cancer.

The Forty-Sixth Euro Congress on Drug Synthesis and Analysis: Snapshot †

The 46th EuroCongress on Drug Synthesis and Analysis (ECDSA-2017) was arranged within the celebration of the 65th Anniversary of the Faculty of Pharmacy at Comenius University in Bratislava, Slovakia from 5-8 September 2017 to get together specialists in medicinal chemistry, organic synthesis, pharmaceutical analysis, screening of bioactive compounds, pharmacology and drug formulations; promote the exchange of scientific results, methods and ideas; and encourage cooperation between researchers from all over the world. The topic of the conference, "Drug Synthesis and Analysis," meant that the symposium welcomed all pharmacists and/or researchers (chemists, analysts, biologists) and students interested in scientific work dealing with investigations of biologically active compounds as potential drugs. The authors of this manuscript were plenary speakers and other participants of the symposium and members of their research teams. The following summary highlights the major points/topics of the meeting.