Endogenous enzyme-hydrolyzed fruit of Cirsium brachycephalum: Optimal source of the antiproliferative lignan trachelogenin regulating the Wnt/β-Catenin signaling pathway in the SW480 colon adenocarcinoma cell line

Greasing the Wheels of Pharmacotherapy for Colorectal Cancer: the Role of Natural Polyphenols

PURPOSE OF REVIEW

The main purpose of this review, mainly based on preclinical studies, is to summarize the pharmacological and biochemical evidence regarding natural polyphenols against colorectal cancer and highlight areas that require future research.

RECENT FINDINGS

Typically, colorectal cancer is a potentially preventable and curable cancer arising from benign precancerous polyps found in the colon's inner lining. Colorectal cancer is the third most common cancer, with a lifetime risk of approximately 4 to 5%. Genetic background and environmental factors play major roles in the pathogenesis of colorectal cancer. Theoretically, a multistep process of colorectal carcinogenesis provides enough time for anti-tumor pharmacotherapy of colorectal cancer. Chronic colonic inflammation, oxidative stress, and gut microbiota imbalance have been found to increase the risk for colorectal cancer development by creating genotoxic stress within the intestinal environment to generate genetic mutations and epigenetic modifications. Currently, numerous natural polyphenols have shown anti-tumor properties against colorectal cancer in preclinical research, especially in colorectal cancer cell lines. In this review, the current literature regarding the etiology and epidemiology of colorectal cancer is briefly outlined. We highlight the findings of natural polyphenols in colorectal cancer from in vitro and in vivo studies. The scarcity of human trials data undermines the clinical use of natural polyphenols as anti-colorectal cancer agents, which should be undertaken in the future.

Arylnaphthalene Lignans with Anti-SARS-CoV-2 and Antiproliferative Activities from the Underground Organs of Linum austriacum and Linum perenne

Diphyllin (1) and justicidin B (2) are arylnaphthalene lignans with antiviral and antiproliferative effects. Compound 1 is also known as an effective inhibitor of the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). To evaluate the in vitro antiviral and cytotoxic potency of both lignans in SARS-CoV-2 -infected cells and various cancer cell lines, respectively, 1 and 2 were isolated from the underground organs of Linum austriacum and Linum perenne. Two previously undescribed arylnaphthalene lignans, denominated linadiacin A and B (3 and 4), were also isolated and identified. In acidic media, 3 was converted by a two-step reaction into 2 via the intermediate 4. Optimum acid treatment conditions were determined to isolate lignans by one-step preparative high-performance liquid chromatography (HPLC). The results of the conversion, HPLC-tandem mass spectrometry, nuclear magnetic resonance spectroscopy, and molecular modeling studies allowed complete structure analysis. Compounds 1 and 2 were the most effective against SARS-CoV-2 with a 3-log reduction in the viral copy number at a 12.5 μM concentration. Ten human cancer cell lines showed sensitivity to at least one of the isolated lignans.

Chemical Characterisation-Biological Evaluation of Greek Cultivar Cardoon Seeds (Cynara cardunculus). A By-product with Potential High Added Value

Cynara cardunculus (artichoke) is a perennial plant of the Mediterranean basin, known since antiquity as food and for its therapeutic properties. Cynara is a relatively small genus with two cultivated species and one wild one. Recently, successful efforts have been made to cultivate wild cardoon and monetise it as a bioenergy crop. In this study, the seeds of an established Greek cultivar of C. cardunculus, cultivated in the experimental field and used as biofuel, have been researched for their chemical profile and nutritional value. According to the results, six lignans were isolated [arctigenin, arctiin, trachelogenin, tracheloside, cynarinine, and ethylate of trachelogenin (isolated for the first time from a natural source)] as well as the most characteristic metabolites of the genus (linoleic acid, trilinolein, and 3,5-dicaffeoylquinic acid). Moreover, the total phenolic content (31.18 - 54.51 mg gallic acid equivalents/g extract) and antioxidant and enzyme inhibitory activities of the seeds have been evaluated and showed strong antioxidant properties (44.42 - 516.81 mg gallic acid equivalents/g extract) as well as satisfactory bleaching (enzyme tyrosinase, 16.95 - 23.80 mg kojic acid equivalents/g extract), antidiabetic (enzymes a-amylase, a-glucosidase, 0.14 - 1.75 mmol acarbose equivalents/g extract), and protective against neurodegenerative disease (cholinesterase enzymes, 0.49 - 1.22 mg galanthamine equivalents/g extract) activities. The nutritional evaluation of the seeds confirmed them as a rich source of unsaturated fatty acids, dietary fibre (24.1%), and high protein content (19.3%). It is noteworthy that such a neglected bioactive by-product, with essentially high nutritional value, as the studied seeds could be investigated for its value-added applications towards food and food supplements areas.

Arctigenin, an anti-tumor agent; a cutting-edge topic and up-to-the-minute approach in cancer treatment

Today, herbal-derived compounds are being increasingly studied in cancer treatment. Over the past decade, Arctigenin has been introduced as a bioactive dibenzylbutyrolactone lignan which is found in Chinese herbal medicines. In addition to anti-microbial, anti-inflammatory, immune-modulatory functions, Arctigenin has attracted growing attention due to its anti-tumor capabilities. It has been shown that Arctigenin can induce apoptosis and necrosis and abolish drug resistance in tumor cells by inducing apoptotic signaling pathways, caspases, cell cycle arrest, and the modulating proteasome. Moreover, Arctigenin mediates other anti-tumor functions through several mechanisms. It has been demonstrated that Arctigenin can act as an anti-inflammatory compound to inhibit inflammation in the tumor microenvironment. It also downregulates factors involved in tumor metastasis and angiogenesis, such as matrix metalloproteinases, N-cadherin, TGF-β, and VEGF. Additionally, Arctigenin, through modulation of MAPK signaling pathways and stress-related proteins, is able to abolish tumor cell growth in nutrient-deprived conditions. Due to the limited solubility of Arctigenin in water, it is suggested that modification of this compound through amino acid esterification can improve its pharmacogenetic properties. Collectively, it is hoped that using Arctigenin or its derivates might introduce new chemotherapeutic approaches in future treatment.

Potential Role of Traditional Chinese Medicines by Wnt/β-Catenin Pathway Compared With Targeted Small Molecules in Colorectal Cancer Therapy

Colorectal cancer (CRC) has become a global public health problem because of its high incidence and mortality rate worldwide. The previous clinical treatment for CRC mainly involves conventional surgery, chemotherapy, and radiotherapy. With the development of tumor molecular targeted therapy, small molecule inhibitors present a great advantage in improving the survival of patients with advanced CRC. However, various side effects and drug resistance induced by chemotherapy are still the major obstacles to improve the clinical benefit. Thus, it is crucial to find new and alternative drugs for CRC treatment. Traditional Chinese medicines (TCMs) have been proved to have low toxicity and multi-target characteristics. In the last few decades, an increasing number of studies have demonstrated that TCMs exhibit strong anticancer effects in both experimental and clinical models and may serve as alternative chemotherapy agents for CRC treatment. Notably, Wnt/β-catenin signaling pathway plays a vital role in the initiation and progression of CRC by modulating the stability of β-catenin in the cytoplasm. Targeting Wnt/β-catenin pathway is a novel direction for developing therapies for CRC. In this review, we outlined the anti-tumor effects of small molecular inhibitors on CRC through Wnt/β-catenin pathway. More importantly, we focused on the potential role of TCMs against tumors by targeting Wnt/β-catenin signaling at different stages of CRC, including precancerous lesions, early stage of CRC and advanced CRC. Furthermore, we also discussed perspectives to develop potential new drugs from TCMs via Wnt/β-catenin pathway for the treatment of CRC.

Synthesis of arctigenin derivatives against infectious hematopoietic necrosis virus

Infectious hematopoietic necrosis virus (IHNV) is a common pathogen that causes severe disease and huge economic losses in the salmonid aquaculture industry. Herein, a series of arctigenin derivatives are synthesized to evaluate their antiviral activity against IHNV. The results indicate that the length of linker and imidazole substituent groups play an important role in decreasing IHNV replication. In this study, the arctigenin-imidazole hybrid derivative 15 with an eight carbon atoms length of the linker reduces IHNV replication with an IC₅₀ value of 1.3 μM. In addition, derivative 15 significantly inhibits apoptosis and cellular morphological damage induced by IHNV. Mechanistically, derivative 15 can not damage the viral particle directly. While time-of-addition and viral binding assays reveal that derivative 15 mainly affect the early replication of IHNV but do not interfere with IHNV adsorption. Overall, derivative 15 could be considered to develop as a promising agent to treat IHNV infection.

miRNA-29a inhibits colon cancer growth by regulation of the PTEN/Akt/GSK3β and Wnt/β-catenin signaling pathways

In the present study, the effects of microRNA-29a (miRNA-29a) on colon cancer cell viability and the molecular mechanisms underlying the effects were investigated. The expression of miRNA-29a in colon cancer serum samples was notably downregulated, compared with in the normal group. First, miRNA-29a mimic was used to increase the expression of miRNA-29a in HCT-116 cells. Furthermore, upregulation of miRNA-29a suppressed cell viability, increased lactate dehydrogenase levels and apoptosis, and promoted caspase-3/9 activities and B-cell lymphoma 2-associated X protein and phosphatase and tensin homolog (PTEN) protein expression in colon cancer cells. Furthermore, upregulation of miRNA-29a decreased phosphoinositide 3-kinase, phosphorylated (p)-protein kinase B (Akt) and p-glycogen synthase kinase 3β (GSK3β) protein expression and suppressed the Wnt/β-catenin signaling pathway in colon cancer cells. The results of the present study verified that the protective effects of miRNA-29a suppress the PTEN/Akt/GSK3β and Wnt/β-catenin signaling pathways in colon cancer.

Chemodiversity of Cirsium fruits: Antiproliferative lignans, neolignans and sesquineolignans as chemotaxonomic markers

While analyzing the fruit composition of nine European Cirsium species representing three sections (i.e., Cephalonoplos, Chamaeleon and Eriolepis), four lignans, three neolignans and three sesquineolignans were determined and used as chemotaxonomic markers. Among them, desmethyl balanophonin and desmethyl picrasmalignan were determined for the first time in the plant kingdom, as the main metabolites of the Chamaeleon section. Prebalanophonin and prepicrasmalignan, identified so far exclusively in C. eriophorum, were also confirmed in C. boujartii and C. vulgare, highlighting the chemotaxonomic significance of these compounds in the Eriolepis section. The antiproliferative assay of the compounds isolated from their optimum sources, confirmed a dose-dependent inhibitory effect of the structures bearing the 4',7-epoxy moiety (balanophonin, picrasmalignan, desmethyl balanophonin, desmethyl picrasmalignan) against SW480 colon cancer cells, while those bearing the 4',7-dihydroxy motif (prebalanophonin, prepicrasmalignan) were inactive.

Experimental study of the anti-tumour activity and pharmacokinetics of arctigenin and its valine ester derivative

Arctigenin (ARG) is a functional active component that has important physiological and pharmacological activities. The anti-tumour and anti-inflammatory activities of ARG show good potential for application and development, but this material has the defect of low water solubility. In this experiment, the valine derivative of ARG (ARG-V) was designed and synthesized to overcome this disadvantage. The ARG amino acid, EDCI and DMAP were raw materials in the addition reaction, with a molar ratio of 1:2:2:0.5. The yield of ARG-V was up to 80%. ARG-V has strong anti-tumour activity in vivo and in vitro. The inhibitory rate of ARG-V was 69.2%, with less damage to the immune organs and different degrees of increased serum cytotoxicity. Moreover, the pharmacokinetics of ARG following oral administration and ARG-V following oral administration in rats were also studied. The C_max and AUC values of ARG-V showed significant differences compared to ARG. The relative bioavailabilities of three doses of ARG-V compared to ARG were 664.7%, 741.5% and 812.9%. These pharmacokinetic results may be useful for further studies of the bioactive mechanism of ARG and provide a theoretical basic for clinical use.

Optimized conversion of antiproliferative lignans pinoresinol and epipinoresinol: Their simultaneous isolation and identification by centrifugal partition chromatography and high performance liquid chromatography

High amount of the valuable lignan pinoresinol (PR) was determined in Carduus nutans fruit (7.8mg/g) for the first time. A preparative separation method using two consecutive, identical steps of centrifugal partition chromatography (CPC) was developed in order (i) to isolate PR and (ii) to subsequently isolate PR and its 7' epimer epipinoresinol (EPR) simultaneously after an optimized acid treatment which resulted in PR epimerization forming equal amounts of PR and EPR, from C. nutans fruit. As optimal conditions, a two-phase solvent system consisting of methyl tert-butyl ether:acetone:water (4:3:3, v/v/v) for CPC separation, and an acid treatment performed at 50°C for 30min for the epimerization were applied. Thus, 33.7mg and 32.8mg PR and EPR, in as high as 93.7% and 92.3% purity, were isolated from 10.0gC. nutans fruit, representing 86.4% and 84.1% efficiency, respectively. Conversion characteristic of PR and EPR in acidic medium, determined as a function of time and temperature of acid treatment provides their unambiguous identification by on-line high performance liquid chromatography (HPLC). Antiproliferative assay of isolated PR and EPR in two different types of colon cancer cell lines (HCT116 and SW480) confirmed that both epimers caused a more significant decrease of viability in HCT116 cells than in SW480 cells, suggesting their similar mechanism of antiproliferative action.

Enzyme-hydrolyzed Fruit of Jurinea mollis: A Rich Source of (-)-(8R,8′R)-Arctigenin

In Jurinea mollis fruit, the dibenzylbutyrolactone-type lignan glycoside arctiin and its aglycone arctigenin were determined for the first time using a combination of optimized enzymatic treatment and complementary spectrometric (HPLC-MS, GC-MS) and spectroscopic (CD and NMR) methods. Analysis of separated fruit parts, i.e., the fruit wall and embryo, demonstrated the specific accumulation of arctiin, since it was exclusively found in the embryo. Arctiin in the embryo samples (71.5 mg/g) was found to be quantitatively converted into arctigenin (50.7 mg/g) by endogenous enzymatic hydrolysis, resulting in one of the highest arctigenin-containing plant tissues reported to date and allowing the selective isolation of arctigenin by our recently reported three-step isolation method. The absolute configuration of the isolated arctigenin was determined to be (-)-(8 R,8′ R). Conformational analysis of arctigenin was also performed, resulting in three major low energy conformations.