Natural Products as a Vital Source for the Discovery of Cancer Chemotherapeutic and Chemopreventive Agents

Psiadin and plectranthone selectively inhibit colorectal carcinoma cells proliferation via modulating cyclins signaling and apoptotic pathways

Three scarce terpenes, psiadin, plectranthone and saudinolide, were obtained after chromatographic isolation and purification from the aerial parts of the respective plants. Their identities were established based on their spectral data. Their anticancer effects against two human colorectal carcinoma cell lines, CCL233 and CCL235, along with the potential molecular mechanisms of action, were explored. Psiadin and plectranthone exhibited marked growth inhibition on both cell lines in a time- and dose-dependent manner with minimal cytotoxicity against normal breast cells (HB2). The terpenes even showed superior activities to the tested standards. Flow cytometry showed apoptosis induction and alteration in the cell cycle in colorectal cancer cells treated with both compounds. Nevertheless, it was also found that both compounds inhibited NF-κB transcriptional activity, induced mitochondrial membrane potential depolarization and increased the percentage of reactive oxygen species in the treated cancer cells in a dose-dependent manner as well. Since the anticancer effect of psiadin on cancer cells was higher than that produced by plectranthone, only psiadin was tested to determine its possible targets. The results suggested a high degree of specificity of action affecting particular cellular processes in both cancer cells. In conclusion, both terpenes, in particular psiadin, showed significant discriminative therapeutic potential between cancer and normal cells, a value that is missing in current chemotherapies.

Immunoregulatory properties of a crude extraction fraction rich in polysaccharide from Chrysanthemum zawadskii Herbich var. latilobum and its potential role as a vaccine adjuvant

The objective of the current study was to demonstrate the immunostimulatory effects of a polysaccharide isolated from Chrysanthemum zawadskii Herbich var. latilobum leaves (CP) and evaluate its potential as a vaccine adjuvant. Results showed that CP induced maturation of the dendritic cells (DCs). In addition, CP-treated DCs activated naïve T cells to polarized CD4+ and CD8+ T cells and substantially induced the production of IFN-γ and IL-2 in vitro. Furthermore, CP initiated the maturation of DCs via the activation of MAPK and NF-κB signaling pathways. Interestingly, systemic administration of CP-treated DCs pulsed with ovalbumin (OVA) peptides significantly enhanced the immune response in vivo, which included the generation of antigen (OVA)-specific polyfunctional T cells, increased cytotoxic T lymphocyte activity, induction of Th1-mediated humoral immunity, and suppression of tumor growth. Taken together, our study highlighted the immunoregulatory activity of CP as well as its potential as a candidate vaccine adjuvant.

Natural Lignans Honokiol and Magnolol as Potential Anticarcinogenic and Anticancer Agents. A Comprehensive Mechanistic Review

Plant lignans constitute an important group of polyphenols, which have been demonstrated to significantly induce cancer cell death and suppress cancer cell proliferation with minimal toxicity against non-transformed cells. Numerous epidemiological studies have shown that the intake of lignans is associated with lower risk of several cancers. These natural compounds have the potential to inhibit carcinogenesis, tumor growth, and metastasis by targeting various signaling molecules and pathways. Growing evidence indicates that honokiol and magnolol as natural lignans possess potent anticancer activities against various types of human cancer. The aim of present review is to provide the reader with the newest findings in understanding the cellular and molecular mechanisms mediating anticancer effects of honokiol and magnolol. This review comprehensively elucidates the effects of honokiol and magnolol on the molecular targets and signal transduction pathways implicated in cancer cell proliferation and metastasis. The findings of current review indicate that honokiol and magnolol can be considered as promising carcinopreventive and anticancer agents.

Phlorizin from sweet tea inhibits the progress of esophageal cancer by antagonizing the JAK2/STAT3 signaling pathway

Phlorizin, an important member of the dihydrochalcone family, has been widely used as a Chinese Traditional Medicine for treatment of numerous diseases. The present study aimed to investigate the potential therapeutic effects of phlorizin on esophageal cancer. Phlorizin, extracted from sweet tea, was used to treat esophageal cancer cells. Cell proliferation, migration and invasion were determined using Cell Counting Kit-8 and colony formation assays, and wound healing and Transwell assays, respectively. RNA sequencing and bioinformatics analysis was used to investigate the potential mechanism of phlorizin in the development of esophageal cancer. Fluorescent staining and flow cytometry was used to measure the level of apoptosis. The expression level of the proteins, P62/SQSTM1 and LC3 І/II, and the effect of phlorizin on the JAK2/STAT3 signaling pathway was detected using western blot analysis. The results demonstrated that phlorizin could inhibit cell proliferation, migration and invasion. Bioinformatics analysis showed that phlorizin might be involved in pleiotropic effects, such as the ‘JAK/STAT signaling pathway’ (hsa04630), ‘MAPK signaling pathway’(hsa04010) and ‘apoptosis’ (hsa04210). It was also confirmed that phlorizin promoted apoptosis and inhibited autophagy in the esophageal cancer cells. Notably, phlorizin might inhibit the proteins in the JAK/STAT signaling pathway, which would affect cancer cells. Taken together, the present data showed that phlorizin inhibited the progression of esophageal cancer by antagonizing the JAK2/STAT3 signaling pathway.

Bacterial diterpene synthases prenylate small molecules

The biosynthesis of terpenoid natural products begins with a carbocation-based cyclization or prenylation reaction. While these reactions are mechanistically similar, there are several families of enzymes, namely terpene synthases and prenyltransferases, that have evolved to specifically catalyze terpene cyclization or prenylation reactions. Here, we report that bacterial diterpene synthases, enzymes that are traditionally considered to be specific for cyclization, are capable of efficiently catalyzing both diterpene cyclization and the prenylation of small molecules. We investigated this unique dual reactivity of terpene synthases through a series of kinetic, biocatalytic, structural, and bioinformatics studies. Overall, this study unveils the ability of terpene synthases to catalyze C-, N-, O-, and S-prenylation on small molecules, proposes a substrate decoy mechanism for prenylation by terpene synthases, supports the physiological relevance of terpene synthase-catalyzed prenylation in vivo, and addresses questions regarding the evolution of prenylation function and its potential role in natural products biosynthesis.

Sphagneticola Trilobata (L.) Pruski (Asteraceae) Methanol Extract Induces Apoptosis in Leukemia Cells through Suppression of BCR/ABL

We will study the effects of the methanol extract of Sphagneticola trilobata (L.) Pruski (Asteraceae) (MeST) on the growth of leukemia cells that may contain the BCR/ABL gene. This study also clarifies the mechanism of this effect on these cells. For this purpose, the cells harboring wild-type BCR/ABL, imatinib-resistant BCR/ABL (K562 and TCCYT315I), or Ba/F3 cells transfected with wild-type or mutant BCR/ABL genes were used. The results showed that MeST effectively inhibited the viability of leukemia cells in both a dose- and time-dependent manner. The effect of MeST seems to be more sensitive in the cells that carry imatinib-resistant BCR/ABL (especially the T315I BCR/ABL mutation) than those with wild-type BCR/ABL. Furthermore, we have demonstrated that the death caused by MeST is apoptosis and the treatment with MeST could suppress the expression of BCR/ABL, subsequently altering the downstream cascade of BCR/ABL such as AKT and MAPK signaling. In conclusion, MeST has been able to suppress the growth of leukemia cells harboring BCR/ABL. The mechanism of the anti-leukemic effect of MeST on cells harboring imatinib-resistant BCR/ABL mutations could be due to the disruption of the BCR/ABL oncoprotein signaling cascade.

A study of deregulated MMR pathways and anticancer potential of curcuma derivatives using computational approach

Plant derived products have steadily gained momentum in treatment of cancer over the past decades. Curcuma and its derivatives, in particular, have diverse medicinal properties including anticancer potential with proven safety as supported by numerous in vivo and in vitro studies. A defective Mis-Match Repair (MMR) is implicated in solid tumors but its role in haematologic malignancies is not keenly studied and the current literature suggests that it is limited. Nonetheless, there are multiple pathways interjecting the mismatch repair proteins in haematologic cancers that may have a direct or indirect implication in progression of the disease. Here, through computational analysis, we target proteins that are involved in rewiring of multiple signaling cascades via altered expression in cancer using various curcuma derivatives (Curcuma longa L. and Curcuma caesia Roxb.) which in turn, profoundly controls MMR protein function. These biomolecules were screened to identify their efficacy on selected targets (in blood-related cancers); aberrations of which adversely impacted mismatch repair machinery. The study revealed that of the 536 compounds screened, six of them may have the potential to regulate the expression of identified targets and thus revive the MMR function preventing genomic instability. These results reveal that there may be potential plant derived biomolecules that may have anticancer properties against the tumors driven by deregulated MMR-pathways.

Exploring safe and potent bioactives for the treatment of non-small cell lung cancer

Activating and suppressing mutations in the MAPK pathway receptors are the primary causes of NSCLC. Of note, MEK inhibition is considered a promising strategy because of the diverse structures and harmful effects of upstream receptors in MAPK pathway. Thus, we explore a total of 1574 plant-based bioactive compounds activity against MEK using an energy-based virtual screening strategy. Molecular docking, binding free energy, and drug-likeness analysis were performed through GLIDE, Prime MM-GBSA, and QikProp module, respectively. The findings indicate that 5-O-caffeoylshikimic acid has an increased binding affinity to MEK protein. Further, molecular dynamic simulations and MM-PBSA analysis were performed to explore the ligand activity in real-life situations. In essence, compounds inhibitory activity was validated across 77 lung cancer cell lines using multimodal attention-based neural network algorithm. Eventually, our analysis highlight that 5-O-caffeoylshikimic acid obtained from the bark of Rhizoma smilacis glabrae would be developed as a potential compound for treating NSCLC.

Chemoprevention and therapeutic role of essential oils and phenolic compounds: Modeling tumor microenvironment in glioblastoma

Glioblastoma (GBM) is the most common primary tumor of the central nervous system. Current treatments available for GBM entails surgical resection followed by temozolomide chemotherapy and/or radiotherapy, which are associated with multidrug resistance and severe side effects. While this treatment could yield good results, in almost all cases, patients suffer from relapse, which leads to reduced survival rates. Thus, therapeutic approaches with improved efficiency and reduced off-target risks are needed to overcome these problems. Regarding this, natural products appear as a safe and attractive strategy as chemotherapeutic agents or adjuvants in the treatment of GBM. Besides the increasing role of natural compounds for chemoprevention of GBM, it has been proposed to prevent carcinogenesis and metastasis of GBM. Numerous investigations showed that natural products are able to inhibit proliferation and angiogenesis, to induce apoptosis, and to target GBM stem cells, which are associated with tumor development and recurrence. This review gives a timely and comprehensive overview of the current literature regarding chemoprevention and therapy of GBM by natural products with a focus on essential oils and phenolic compounds and their molecular mechanisms.

A comprehensive mechanistic insight into the dietary and estrogenic lignans, arctigenin and sesamin as potential anticarcinogenic and anticancer agents. Current status, challenges, and future perspectives

A large body of evidence indicates that lignans as polyphenolic compounds are beneficial against life-threatening diseases such as cancer. Plant lignans have the potential to induce cancer cell death and interfere with carcinogenesis, tumor growth, and metastasis. Epidemiological studies have revealed that the intake of lignans is inversely associated with the risk of several cancers. Moreover, numerous experimental studies demonstrate that natural lignans significantly suppress cancer cell proliferation with minimal toxicity against non-transformed cells. Dietary lignans arctigenin and sesamin have been found to have potent antiproliferative activities against various types of human cancer. The purpose of this review is to provide the reader with a deeper understanding of the cellular and molecular mechanisms underlying anticancer effects of arctigenin and sesamin. Our review comprehensively describes the effects of arctigenin and sesamin on the signaling pathways and related molecules involved in cancer cell proliferation and invasion. The findings of present review show that the dietary lignans arctigenin and sesamin seem to be promising carcinopreventive and anticancer agents. These natural lignans can be used as dietary supplements and pharmaceuticals for prevention and treatment of cancer.

Recent Advances in Improved Anticancer Efficacies of Camptothecin Nano-Formulations: A Systematic Review

Camptothecin (CPT), a natural plant alkaloid, has indicated potent antitumor activities via targeting intracellular topoisomerase I. The promise that CPT holds in therapies is restricted through factors that include lactone ring instability and water insolubility, which limits the drug oral solubility and bioavailability in blood plasma. Novel strategies involving CPT pharmacological and low doses combined with nanoparticles have indicated potent anticancer activity in vitro and in vivo. This systematic review aims to provide a comprehensive and critical evaluation of the anticancer ability of nano-CPT in various cancers as a novel and more efficient natural compound for drug development. Studies were identified through systematic searches of PubMed, Scopus, and ScienceDirect. Eligibility checks were performed based on predefined selection criteria. Eighty-two papers were included in this systematic review. There was strong evidence for the association between antitumor activity and CPT treatment. Furthermore, studies indicated that CPT nano-formulations have higher antitumor activity in comparison to free CPT, which results in enhanced efficacy for cancer treatment. The results of our study indicate that CPT nano-formulations are a potent candidate for cancer treatment and may provide further support for the clinical application of natural antitumor agents with passive targeting of tumors in the future.

Anticancer activity of limonene: A systematic review of target signaling pathways

Limonene (LIM) is a monoterpene, which is abundant in essential oils of Citrus fruits peels (Rutaceae). More recently, LIM, as a potential natural anticancer compound, has attracted major attention and exerted a chemopreventive activity, stimulating the detoxification of carcinogenic compounds and limiting tumor growth and angiogenesis in various cancer models. Twenty-six (26) articles were selected based on previously established criteria. Anticancer activity of LIM was related to the inhibition of tumor initiation, growth, and angiogenesis and the induction of cancer cells apoptosis. LIM was able to increase Bax expression, release cytochrome c, and activate the caspase pathway. In addition, LIM increased the expression of p53 and decreased the activity of Ras/Raf/MEK/ERK and PI3K/Akt pathways. LIM also decreased the expression of VEGF and increased the activities of the Man-6-P / IGF2R and TGF-βIIR receptors. These results highlight LIM as an abundant natural molecule with low toxicity and pleiotropic pharmacological activity in cancer cells, targeting various cell-signaling pathways critically involved in the initiation, growth, and chemoresistance of cancer cells.

Cytotoxicity of Moringa oleifera fruits on human liver cancer and molecular docking analysis of bioactive constituents against caspase-3 enzyme

Moringa oleifera is an excellent source of phenolics and flavonoids comprise various pharmacological activities. The fourth widespread leading cause of the patients' death is liver cancer. This study was formulated to perform the antiproliferative activity of Moringa oleifera fruit (MOF) extract on human liver cancer HepG2 cells and computational validation of cell death. HepG2 cell line was treated with 25, 50, 75, 100, and 200 µg/ml of MOF extract for 48 hr, and antiproliferative activity was analyzed using MTT assay, nuclear condensation, annexin V-FITC/PI double stain, ROS generation, and apoptosis executioner enzyme caspase-3. MOF extract reduced the cell viability significantly (p ˂ .05) by increasing cellular apoptosis which was confirmed by annexin V-FITC/PI staining assay. In addition, MOF stimulated intracellular ROS production and subsequently induced caspase-3 activity depending upon dose. In silico analysis revealed the good binding interaction between amino acid residues of caspase-3 (PDB ID: 1GFW) protein and selected active constituents of MOF. PASS analyses of the phytoconstituents showed no violation of Lipinski's rule of five. Analysis of drug-likeness and toxicity measurement exhibited drug-like candidates with no predicted toxicity. In conclusion, this study showed the potential anticancer activity of MOF extract which may be valuable source for anticancer drug development. PRACTICAL APPLICATIONS: Moringa oleifera fruit extract induced the anti-proliferative activity against human hepatocellular carcinoma HepG2 cells through ROS-mediated apoptosis and activation of caspase-3 enzyme. Structure-based virtual screening study between bioactive components of Moringa oleifera fruits and apoptosis executioner caspase-3 enzyme has validated the anti-proliferative activity of Moringa oleifera fruit extract. Interestingly, active phytoconstituents of Moringa oleifera fruit exhibited drug-like candidates with no predicted toxicity. Thus, Moringa oleifera fruit could be used as valuable source for anticancer drug development against human liver cancer with relatively non-toxic to healthy cells.

Bergamottin and 5-Geranyloxy-7-methoxycoumarin Cooperate in the Cytotoxic Effect of Citrus bergamia (Bergamot) Essential Oil in Human Neuroblastoma SH-SY5Y Cell Line

The plant kingdom has always been a treasure trove for valuable bioactive compounds, and Citrus fruits stand out among the others. Bergamottin (BRG) and 5-geranyloxy-7-methoxycoumarin (5-G-7-MOC) are two coumarins found in different Citrus species with well-acknowledged pharmacological properties. Previously, they have been claimed to be relevant in the anti-proliferative effects exerted by bergamot essential oil (BEO) in the SH-SY5Y human neuroblastoma cells. This study was designed to verify this assumption and to assess the mechanisms underlying the anti-proliferative effect of both compounds. Our results demonstrate that BRG and 5-G-7-MOC are able to reduce the proliferation of SH-SY5Y cells, inducing apoptosis and increasing cell population in sub-G0/G1 phase. Moreover, we demonstrated the pro-oxidant activity of the two coumarins that increased reactive oxygen species and impaired mitochondrial membrane potential. From a molecular point of view, BRG and 5-G-7-MOC were able to modulate apoptosis related factors at both protein and gene levels. Lastly, we evaluated the synergistic effect of their combination, finding that the highest synergy was observed at a concentration ratio similar to that occurring in the BEO, supporting our initial hypothesis. Taken together, our results deepen the knowledge regarding the effect of BRG and 5-G-7-MOC in SH-SY5Y cells, emphasizing the relevance of their cooperation in achieving this effect.

Studies on the Mechanism of Alloimperatorin on the Proliferation and Apoptosis of HeLa Cells

Alloimperatorin is a compound extracted from the traditional Chinese medicine (Angelica dahurica), which has exhibited anticancer activity. However, its precise molecular mechanism of anticancer remains unclear. Alloimperatorin-induced apoptosis of cervical cancer cells and its molecular mechanism were investigated in the present study. Cholecystokinin octapeptide (CCK-8) was employed to evaluate the cytotoxicity of alloimperatorin on HeLa, SiHa, and MS-751 cells. Flow cytometry was used to assess apoptosis induced by alloimperatorin. The mechanism of apoptosis was verified by mitochondrial membrane potential, Western blotting, and fluorescent PCR. The results of the study showed that alloimperatorin reduced the activity of HeLa cells. The calculated IC50 at 48 hours was 116.9 μM. Compared with the control group, alloimperatorin increased the apoptotic rate of HeLa cells and reduced the mitochondrial membrane potential of HeLa cells. The Western blot results showed that alloimperatorin promotes the expression of caspase3, 8, 9 and that Bax apoptotic proteins reduce PARP expression, procaspase3, 8, 9, and BCL-2 proteins and reduces the cyt-c in the mitochondria expression. The results demonstrated that alloimperatorin can induce HeLa cell apoptosis through mitochondria and extrinsic apoptotic pathways.

Characterizing the cytotoxic effects and several antimicrobial phytocompounds of Argemone mexicana

Commonly called the Mexican prickly poppy, Argemone mexicana is a stress-resistant member of the Papaveraceae family of plants that has been used in traditional medicine for centuries by indigenous communities in Mexico and Western parts of the United States. This plant has been exploited to treat a wide variety of ailments, with reported antimicrobial and antioxidant properties, as well as cytotoxic effects against some human cancer cell lines. Due to its various therapeutic uses and its abundance of secondary metabolites, A. mexicana has great potential as a drug discovery candidate. Herein, the germination conditions of A. mexicana are described and the cytotoxic activities of different parts (seeds, leaves, inner vs. outer roots) of the plant from methanol or hexane extracts are preliminarily characterized against cells of seven unique organisms. When comparing 1 mg of each sample normalized to background solvent alone, A. mexicana methanol outer root and leaf extracts possessed the strongest antimicrobial activity, with greatest effects against the Gram-positive bacteria tested, and less activity against the Gram-negative bacteria and fungi tested. Additionally, using the MTT colorimetric assay, the outer root methanol and seed hexane extracts displayed pronounced inhibitory effects against human colon cancer cells. Quantification of c-MYC (oncogene) and APC (tumor suppressor) mRNA levels help elucidate how the A. mexicana root methanol extract may be affecting colon cancer cells. After ultra-performance liquid chromatography coupled with mass spectrometry and subsequent nuclear magnetic resonance analysis of the root and leaf methanol fractions, two main antibacterial compounds, chelerythrine and berberine, have been identified. The roots were found to possess both phytocompounds, while the leaf lacked chelerythrine. These data highlight the importance of plants as an invaluable pharmaceutical resource at a time when antimicrobial and anticancer drug discovery has plateaued.

Deguelin targets multiple oncogenic signaling pathways to combat human malignancies

Cancer is an anomalous growth and differentiation of cells known to be governed by oncogenic factors. Plant-based natural metabolites have been well recognized to possess chemopreventive properties. Deguelin, a natural rotenoid, is among the class of bioactive phytoconstituents from a diverse range of plants with potential antineoplastic effects in different cancer subtypes. However, the precise mechanisms of how deguelin inhibits tumor progression remains elusive. Deguelin has shown promising results in targeting the hallmarks of tumor progression via inducing tumor apoptosis, cell cycle arrest, and inhibition of angiogenesis and metastasis. Based on initial scientific excerpts, deguelin has been reported to inhibit tumor growth via different signaling pathways, including mitogen-activated protein kinase, phosphoinositide 3-kinase, serine/threonine protein kinase B (also known as Akt), mammalian target of rapamycin, nuclear factor-κB, matrix metalloproteinase (MMP)-2, MMP-9 and caspase-3, caspase-8, and caspase-9. This review summarizes the mechanistic insights of antineoplastic action of deguelin to gain a clear understanding of its therapeutic effects in cancer. The anticancer potential of deguelin with respect to its efficacy in targeting tumorigenesis via nanotechnological approaches is also investigated. The initial scientific findings have presented deguelin as a promising antitumorigenic agent which can be used for monotherapy as well as synergistically to augment efficacy of chemotherapeutic treatment regimes.

Anticancer Activity of Combretum fragrans F. Hoffm on Glioblastoma and Prostate Cancer Cell Lines

BACKGROUND

Cancer incidence has been growing in an alarming rate worldwide and new therapeutics are needed, particularly for intractable and chemoresistant cases. We evaluated the cytotoxic effects of Combretum fragrans F. Hoffm (Combretaceae) on glioblastoma (U87MG and C6) and prostate (PC-3) cancer cell lines.

METHODS

The cytotoxic effect of the methanolic extract of the stem bark of Combretum fragrans was assessed using XTT (2,3-bis (2-methoxy-4-nitro-5-sulfophenyl)-5-[(phenylamino) carbonyl]-2H-tetrazolium hydroxide) test. Expressions of Akt and ERK1/2 were determined using Western blot technique, while Caspase-3/7 kits were used to evaluate caspase-3/7 activity.

RESULTS

C. fragrans extract inhibited the proliferation of U87 (IC50 = 20.13 µg/mL), C6 (IC50 = 12.17 µg/mL), and PC-3 (IC50 = 11.50 µg/mL) cells. Treatment with the extract resulted in lower levels (p < 0.001) of phospho-ERK1/2 and phospho-Akt in U87 cells, and instead, higher levels of phospho-ERK1/2 (p < 0.001) in C6 and PC-3 cells. An increase in caspase-3/7 activity was observed, mainly after 24 hours of treatment, indicating the activation of apoptotic processes.

CONCLUSION

Altogether, these results suggest that C. fragrans have potent anticancer properties. This plant should be further investigated for developing new anticancer drugs.

A Systematic Review of the Preventive and Therapeutic Effects of Naringin Against Human Malignancies

Background: Natural product-based cancer preventive and therapeutic entities, such as flavonoids and their derivatives, are shown to have a noticeable capability to suppress tumor formation and cancer cell growth. Naringin, a natural flavanone glycoside present in various plant species, has been indicated to modulate different signaling pathways and interact with numerous cell signaling molecules, which allows for an extensive variety of pharmacological actions, such as amelioration of inflammation, oxidative stress, metabolic syndromes, bone disorders, and cancer. The purpose of this systematic review is to present a critical and comprehensive assessment of the antitumor ability of naringin and associated molecular targets in various cancers. Methods: Studies were identified through systematic searches of Science Direct, PubMed, and Scopus as well as eligibility checks according to predefined selection criteria. Results: Eighty-seven studies were included in this systematic review. There was strong evidence for the association between treatment with naringin alone, or combined with other drugs and antitumor activity. Additionally, studies showed that naringin-metal complexes have greater anticancer effects compared to free naringin. It has been demonstrated that naringin employs multitargeted mechanisms to hamper cancer initiation, promotion, and progression through modulation of several dysregulated signaling cascades implicated in cell proliferation, autophagy, apoptosis, inflammation, angiogenesis, metastasis, and invasion. Conclusion: The results of our work show that naringin is a promising candidate for cancer prevention and treatment, and might offer substantial support for the clinical application of this phytocompound in the future. Nevertheless, further preclinical and clinical studies as well as drug delivery approaches are needed for designing novel formulations of naringin to realize the full potential of this flavonoid in cancer prevention and intervention.

Marine-Derived Natural Products as ATP-Competitive mTOR Kinase Inhibitors for Cancer Therapeutics

The mammalian target of rapamycin (mTOR) is a serine/threonine kinase portraying a quintessential role in cellular proliferation and survival. Aberrations in the mTOR signaling pathway have been reported in numerous cancers including thyroid, lung, gastric and ovarian cancer, thus making it a therapeutic target. To attain this objective, an in silico investigation was designed, employing a pharmacophore modeling approach. A structure-based pharmacophore (SBP) model exploiting the key features of a selective mTOR inhibitor, Torkinib directed at the ATP-binding pocket was generated. A Marine Natural Products (MNP) library was screened using SBP model as a query. The retrieved compounds after consequent drug-likeness filtration were subjected to molecular docking with mTOR, thus revealing four MNPs with better scores than Torkinib. Successive refinement via molecular dynamics simulations demonstrated that the hits formed crucial interactions with key residues of the pocket. Furthermore, the four identified hits exhibited good binding free energy scores through MM-PBSA calculations and the subsequent in silico toxicity assessments displayed three hits deemed essentially non-carcinogenic and non-mutagenic. The hits presented in this investigation could act as potent ATP-competitive mTOR inhibitors, representing a platform for the future discovery of drugs from marine natural origin.

Synthesis and Pharmacological In Vitro Investigations of Novel Shikonin Derivatives with a Special Focus on Cyclopropane Bearing Derivatives

Melanoma is the deadliest form of skin cancer and accounts for about three quarters of all skin cancer deaths. Especially at an advanced stage, its treatment is challenging, and survival rates are very low. In previous studies, we showed that the constituents of the roots of Onosma paniculata as well as a synthetic derivative of the most active constituent showed promising results in metastatic melanoma cell lines. In the current study, we address the question whether we can generate further derivatives with optimized activity by synthesis. Therefore, we prepared 31, mainly novel shikonin derivatives and screened them in different melanoma cell lines (WM9, WM164, and MUG-Mel2 cells) using the XTT viability assay. We identified (R)-1-(1,4-dihydro-5,8-dihydroxy-1,4-dioxonaphthalen-2-yl)-4-methylpent-3-enyl 2-cyclopropyl-2-oxoacetate as a novel derivative with even higher activity. Furthermore, pharmacological investigations including the ApoToxGlo^TM Triplex assay, LDH assay, and cell cycle measurements revealed that this compound induced apoptosis and reduced cells in the G1 phase accompanied by an increase of cells in the G2/M phase. Moreover, it showed hardly any effects on the cell membrane integrity. However, it also exhibited cytotoxicity against non-tumorigenic cells. Nevertheless, in summary, we could show that shikonin derivatives might be promising drug leads in the treatment of melanoma.

Strobilanthes crispus bioactive subfraction inhibits tumor progression and improves hematological and morphological parameters in mouse mammary carcinoma model

ETHNOPHARMACOLOGICAL RELEVANCE

Locally known as 'pecah batu', 'bayam karang', 'keci beling' or 'batu jin', the Malaysian medicinal herb, Strobilanthes crispus (S. crispus), is traditionally used by the local communities as alternative or adjuvant remedy for cancer and other ailments and to boost the immune system. S. crispus has demonstrated multiple anticancer therapeutic potential in vitro and in vivo. A pharmacologically active fraction of S. crispus has been identified and termed as F3. Major constituents profiled in F3 include lutein and β-sitosterol.

AIM OF THE STUDY

In this study, the effects of F3, lutein and β-sitosterol on tumor development and metastasis were investigated in 4T1-induced mouse mammary carcinoma model.

MATERIALS AND METHODS

Tumor-bearing mice were fed with F3 (100 mg/kg/day), lutein (50 mg/kg/day) and β-sitosterol (50 mg/kg/day) for 30 days (n = 5 each group). Tumor physical growth parameters, animal body weight and development of secondary tumors were investigated. The safety profile of F3 was assessed using hematological and histomorphological changes on the major organs in normal control mice (NM).

RESULTS

Our findings revealed significant reduction of physical tumor growth parameters in all tumor-bearing mice treated with F3 (TM-F3), lutein (TM-L) or β-sitosterol (TM-β) as compared with the untreated group (TM). Statistically significant reduction in body weight was observed in TM compared to the NM or treated (TM-F3, TM-L and TM-β) groups. Histomorphological examination of tissue sections from the F3-treated group showed normal features of the vital organs (i.e., liver, kidneys, lungs and spleen) which were similar to those of NM. Administration of F3 to NM mice (NM-F3) did not cause significant changes in full blood count values.

CONCLUSION

F3 significantly reduced the total tumor burden and prevented secondary tumor development in metastatic breast cancer without significant toxicities in 4T1-induced mouse mammary carcinoma model. The current study provides further support for therapeutic development of F3 with further pharmacokinetics studies.

Resveratrol as Chemosensitizer Agent: State of Art and Future Perspectives

Resistance to chemotherapy still remains a major challenge in the clinic, impairing the quality of life and survival rate of patients. The identification of unconventional chemosensitizing agents is therefore an interesting aspect of cancer research. Resveratrol has emerged in the last decades as a fascinating molecule, able to modulate several cancer-related molecular mechanisms, suggesting a possible application as an adjuvant in cancer management. This review goes deep into the existing literature concerning the possible chemosensitizing effect of resveratrol associated with the most conventional chemotherapeutic drugs. Despite the promising effects observed in different cancer types in in vitro studies, the clinical translation still presents strong limitations due to the low bioavailability of resveratrol. Recently, efforts have been moved in the field of drug delivery to identifying possible strategies/formulations useful for a more effective administration. Despite the necessity of a huge implementation in this research area, resveratrol appears as a promising molecule able to sensitize resistant tumors to drugs, suggesting its potential use in therapy-refractory cancer patients.

Plant-Derived Anticancer Compounds as New Perspectives in Drug Discovery and Alternative Therapy

Despite the recent advances in the field of chemically synthetized pharmaceutical agents, nature remains the main supplier of bioactive molecules. The research of natural products is a valuable approach for the discovery and development of novel biologically active compounds possessing unique structures and mechanisms of action. Although their use belongs to the traditional treatment regimes, plant-derived compounds still cover a large portion of the current-day pharmaceutical agents. Their medical importance is well recognized in the field of oncology, especially as an alternative to the limitations of conventional chemotherapy (severe side effects and inefficacy due to the occurrence of multi-drug resistance). This review offers a comprehensive perspective of the first blockbuster chemotherapeutic agents of natural origin’s (e.g. taxol, vincristine, doxorubicin) mechanism of action using 3D representation. In addition is portrayed the step-by-step evolution from preclinical to clinical evaluation of the most recently studied natural compounds with potent antitumor activity (e.g. resveratrol, curcumin, betulinic acid, etc.) in terms of anticancer mechanisms of action and the possible indications as chemotherapeutic or chemopreventive agents and sensitizers. Finally, this review describes several efficient platforms for the encapsulation and targeted delivery of natural compounds in cancer treatment

Natural product-based nanoformulations for cancer therapy: Opportunities and challenges

Application of natural product-based nanoformulations for the treatment of different human diseases, such as cancer, is an emerging field. The conventional cancer therapeutic modalities, including surgery, chemotherapy, immunotherapy, radiotherapy has limited achievements. A larger number of drawbacks are associated with these therapies, including damage to proliferating healthy tissues, structural deformities, systemic toxicity, long-term side effects, resistance to the drug by tumor cells, and psychological problems. The advent of nanotechnology in cancer therapeutics is recent; however, it has progressed and transformed the field of cancer treatment at a rapid rate. Nanotherapeutics have promisingly overcome the limitations of conventional drug delivery system, i.e., low aqueous solubility, low bioavailability, multidrug resistance, and non-specificity. Specifically, natural product-based nanoformulations are being intentionally studied in different model systems. Where it is found that these nanoformulations has more proximity and reduced side effects. The nanoparticles can specifically target tumor cells, enhancing the specificity and efficacy of cancer therapeutic modalities which in turn improves patient response and survival. The integration of phytotherapy and nanotechnology in the clinical setting may improve pharmacological response and better clinical outcome of patients.

New Antiproliferative Triflavanone from Thymelaea hirsuta-Isolation, Structure Elucidation and Molecular Docking Studies

In this study isolates from Thymelaea hirsuta, a wild plant from the Sinai Peninsula of Egypt, were identified and their selective cytotoxicity levels were evaluated. Phytochemical examination of the ethyl acetate (EtOAc) fraction of the methanolic (MeOH) extract of the plant led to the isolation of a new triflavanone compound (1), in addition to the isolation of nine previously reported compounds. These included five dicoumarinyl ethers found in Thymelaea: daphnoretin methyl ether (2), rutamontine (3), neodaphnoretin (4), acetyldaphnoretin (5), and edgeworthin (6); two flavonoids: genkwanin (7) and trans-tiliroside (8); p-hydroxy benzoic acid (9) and β sitosterol glucoside (10). Eight of the isolated compounds were tested for in vitro cytotoxicity against Vero and HepG2 cell lines using a sulforhodamine-B (SRB) assay. Compounds 1, 2 and 5 exhibited remarkable cytotoxic activities against HepG2 cells, with IC₅₀ values of 8.6, 12.3 and 9.4 μM, respectively, yet these compounds exhibited non-toxic activities against the Vero cells. Additionally, compound 1 further exhibited promising cytotoxic activity against both MCF-7 and HCT-116 cells, with IC₅₀ values of 4.26 and 9.6 μM, respectively. Compound 1 significantly stimulated apoptotic breast cancer cell death, resulting in a 14.97-fold increase and arresting 40.57% of the cell population at the Pre-G1 stage of the cell cycle. Finally, its apoptosis-inducing activity was further validated through activation of BAX and caspase-9, and inhibition of BCL2 levels. In silico molecular docking experiments revealed a good binding mode profile of the isolates towards Ras activation/pathway mitogen-activated protein kinase (Ras/MAPK); a common molecular pathway in the development and progression of liver tumors.

Ethyl acetate subfractions from ethanol extracts of fermented oats (Avena sativa L.) exert anti-cancer properties in vitro and in vivo through G2/M and S Phase arrest and apoptosis

Background: Cancer is a major public problem and poses a long-term impact on patients' life, work, and study. Oats are widely recognized as healthy food and fermented oats were rich in the higher contents of polyphenols. However, the role of fermented oats in cancer remains elusive.

Methods: The effect of ethyl acetate subfractions (EASs) from ethanol extracts of oats fermented by Rhizopus oryzae 3.2751 on cancer cells was verified by series experiments in vitro and in vivo. The cell viability, colony formation, cell cycle, apoptosis, reactive oxygen species (ROS), mitochondrial membrane potential (MMP), and western blot were determined in vitro. The toxicity of EASs and xenograft mouse model were performed in vivo.

Results: MTT assay indicated that EASs interference suppressed the proliferation of four human cancer cells in a dose-dependent manner without a significant impact on two normal cells. EASs (0.2, 0.4, and 0.8 μg/mL) resulted in the G2/M and S phase arrest, apoptosis, depolarization of MMP, and ROS generation in HepG2 cells by flow cytometry. p53, JNK, caspase-9, and caspase-3 were activated and the expression of Bax was promoted, while the expression of Bcl-2 was reduced in HepG2 cells exposed to EASs via western blot. Furthermore, the in vivo study using a xenograft mouse model demonstrated that EASs attenuated the tumor growth with low systemic toxicity.

Conclusions: EASs exhibited anti-cancer activities in vitro and in vivo via cell cycle arrest and apoptosis. This finding suggests that polyphenol-enriched composition from fermented oats might become a promising candidate for impeding the development and progression of liver cancer.

Synergistic anticancer effect of docosahexaenoic acid and isoliquiritigenin on human colorectal cancer cells through ROS-mediated regulation of the JNK and cytochrome c release

A large body of research has demonstrated a synergistic anticancer effect between docosahexaenoic acid (DHA) and standard chemotherapy regimens against colorectal cancer (CRC). In this study, we investigated the chemotherapeutic potential of cotreatment with DHA and isoliquiritigenin (ISL) against CRC HCT-116 cells. Apoptosis was confirmed by Annexin V/PI staining and expression of apoptosis-associated proteins. The synergistic effect of DHA and ISL combination on apoptosis was detected using combination index approaches. Flow cytometry was carried out using fluorescent probes to measure the production of reactive oxygen species (ROS). DHA and ISL in combination synergistically enhanced the decrease in cell viability versus the compounds used alone. Moreover, we demonstrated that the synergistic anti-CRC activity of cotreatment with these two compounds was achieved by inducing the apoptosis caspase-dependently mediated through augmented ROS generation followed by increased Fas ligand mRNA expression and cytochrome c release. Our data also demonstrated that cotreating with DHA and ISL strongly upregulated the phosphorylation of ERK and JNK, which are functionally associated with ROS induced by the two compounds in combination. Interestingly, further study revealed that inhibiting ERK phosphorylation strongly enhanced Fas ligand mRNA expression and the combination of the two compounds induced stronger cytotoxicity, whereas inhibiting JNK phosphorylation significantly reduced the apoptotic signals mediated by cotreatment with these two compounds. Excessive ROS-induced JNK activation and cytochrome c release from mitochondria played a key role in the synergistic anticancer activity of CRC cells by cotreating with DHA and ISL.

Natural Compounds of Marine Origin as Inducers of Immunogenic Cell Death (ICD): Potential Role for Cancer Interception and Therapy

Regulated cell death (RCD) has always been considered a tolerogenic event. Immunogenic cell death (ICD) occurs as a consequence of tumour cell death accompanied by the release of damage-associated molecular patterns (DAMPs), triggering an immune response. ICD plays a major role in stimulating the function of the immune system in cancer during chemotherapy and radiotherapy. ICD can therefore represent one of the routes to boost anticancer immune responses. According to the recommendations of the Nomenclature Committee on Cell Death (2018), apoptosis (type I cell death) and necrosis (type II cell death) represent are not the only types of RCD, which also includes necroptosis, pyroptosis, ferroptosis and others. Specific downstream signalling molecules and death-inducing stimuli can regulate distinct forms of ICD, which develop and promote the immune cell response. Dying cells deliver different potential immunogenic signals, such as DAMPs, which are able to stimulate the immune system. The acute exposure of DAMPs can prime antitumour immunity by inducing activation of antigen-presenting cells (APC), such as dendritic cells (DC), leading to the downstream response by cytotoxic T cells and natural killer cells (NK). As ICD represents an important target to direct and develop new pharmacological interventions, the identification of bioactive natural products, which are endowed with low side effects, higher tolerability and preferentially inducing immunogenic programmed cell death, represents a priority in biomedical research. The ability of ICD to drive the immune response depends on two major factors, neither of which is intrinsic to cell death: ‘Antigenicity and adjuvanticity’. Indeed, the use of natural ICD-triggering molecules, alone or in combination with different (immuno)therapies, can result in higher efficacy and tolerability. Here, we focused on natural (marine) compounds, particularly on marine microalgae derived molecules such as exopolysaccharides, sulphated polysaccharides, glycopeptides, glycolipids, phospholipids, that are endowed with ICD-inducing properties and sulfavants. Here, we discuss novel and repurposed small-molecule ICD triggers, as well as their ability to target important molecular pathways including the IL-6, TNF-α and interferons (IFNs), leading to immune stimulation, which could be used alone or in combinatorial immunotherapeutic strategies in cancer prevention and therapies.

Delivery of Natural Agents by Means of Mesoporous Silica Nanospheres as a Promising Anticancer Strategy

Natural prodrugs derived from different natural origins (e.g., medicinal plants, microbes, animals) have a long history in traditional medicine. They exhibit a broad range of pharmacological activities, including anticancer effects in vitro and in vivo. They have potential as safe, cost-effective treatments with few side effects, but are lacking in solubility, bioavailability, specific targeting and have short half-lives. These are barriers to clinical application. Nanomedicine has the potential to offer solutions to circumvent these limitations and allow the use of natural pro-drugs in cancer therapy. Mesoporous silica nanoparticles (MSNs) of various morphology have attracted considerable attention in the search for targeted drug delivery systems. MSNs are characterized by chemical stability, easy synthesis and functionalization, large surface area, tunable pore sizes and volumes, good biocompatibility, controlled drug release under different conditions, and high drug-loading capacity, enabling multifunctional purposes. In vivo pre-clinical evaluations, a significant majority of results indicate the safety profile of MSNs if they are synthesized in an optimized way. Here, we present an overview of synthesis methods, possible surface functionalization, cellular uptake, biodistribution, toxicity, loading strategies, delivery designs with controlled release, and cancer targeting and discuss the future of anticancer nanotechnology-based natural prodrug delivery systems.

Natural Products as Inducers of Non-Canonical Cell Death: A Weapon against Cancer

Simple Summary

Anticancer therapeutic approaches based solely on apoptosis induction are often unsuccessful due to the activation of resistance mechanisms. The identification and characterization of compounds capable of triggering non-apoptotic, also called non-canonical cell death pathways, could represent an important strategy that may integrate or offer alternative approaches to the current anticancer therapies. In this review, we critically discuss the promotion of ferroptosis, necroptosis, and pyroptosis by natural compounds as a new anticancer strategy.

Abstract

Apoptosis has been considered the main mechanism induced by cancer chemotherapeutic drugs for a long time. This paradigm is currently evolving and changing, as increasing evidence pointed out that antitumor agents could trigger various non-canonical or non-apoptotic cell death types. A considerable number of antitumor drugs derive from natural sources, both in their naturally occurring form or as synthetic derivatives. Therefore, it is not surprising that several natural compounds have been explored for their ability to induce non-canonical cell death. The aim of this review is to highlight the potential antitumor effects of natural products as ferroptosis, necroptosis, or pyroptosis inducers. Natural products have proven to be promising non-canonical cell death inducers, capable of overcoming cancer cells resistance to apoptosis. However, as discussed in this review, they often lack a full characterization of their antitumor activity together with an in-depth investigation of their toxicological profile.

A comprehensive review of anticancer mechanisms of action of Alantolactone

Cancer is considered as the main challenge of human communities, and it annually imposes a significant economic burden on society. Natural products have been used for treatment of many diseases including inflammation, infections, neurological disorders, atherosclerosis, asthma and cancer for many years. Sesquiterpene lactones (STLs) refers to a group of natural products with different biological activities. A type of STL that has recently attracted much attention is Alantolactone (ALT). In recent years, many studies have investigated the molecular mechanism of this compound affecting cancer cells and results suggest that this compound exerts its anticancer effects by providing free radicals and inhibiting some of the signaling pathways that are effective in progression of cancer cells. The present study is aimed to introduce the latest molecular mechanisms of ALT proposed by researchers in recent years.

Anticancer potential of rhizome extract and a labdane diterpenoid from Curcuma mutabilis plant endemic to Western Ghats of India

Zingiberaceae plants are well known for their use in ethnomedicine. Curcuma mutabilis Škorničk., M. Sabu & Prasanthk., is an endemic Zingiberaceae species from Western Ghats of Kerala, India. Here, we report for the first time, the anticancer potential of petroleum ether extract from C. mutabilis rhizome (CMRP) and a novel labdane diterpenoid, (E)-14, 15-epoxylabda-8(17), 12-dien-16-al (Cm epoxide) isolated from it. CMRP was found to be a mixture of potent bioactive compounds including Cm epoxide. Both the extract and the compound displayed superior antiproliferative activity against several human cancer cell lines, without any display of cytotoxicity towards normal human cells such as peripheral blood derived lymphocytes and erythrocytes. CMRP treatment resulted in phosphatidylserine externalization, increase in the levels of intracellular ROS, Ca²⁺, loss of mitochondrial membrane potential as well as fragmentation of genomic DNA. Analyses of transcript profiling and immunostained western blots of extract-treated cancer cells confirmed induction of apoptosis by both intrinsic and extrinsic pathways. The purified compound, Cm epoxide, was also found to induce apoptosis in many human cancer cell types tested. Both CMRP and the Cm epoxide were found to be pharmacologically safe in terms of acute toxicity assessment using Swiss albino mice model. Further, molecular docking interactions of Cm epoxide with selected proteins involved in cell survival and death were also indicative of its druggability. Overall, our findings reveal that the endemic C. mutabilis rhizome extract and the compound Cm epoxide isolated from it are potential candidates for development of future cancer chemotherapeutics.

Synergistic cytotoxicity of erianin, a bisbenzyl in the dietetic Chinese herb Dendrobium against breast cancer cells

Erianin (ER), a dietary compound extracted from Dendrobium, a traditional Chinese medicinal edible herb, is well recognized for its potential anti-cancer activity. Nevertheless, its limitations, regarding its complex isolation procedure, low yield and low water solubility, limit large scale application. Combinatorial therapeutic regimen that combines several drugs to target different pathways in a characteristically synergistic manner at lower doses of drugs proved effective in several diseases treatment. Besides, new knowledge aimed at improving drug delivery into the intracellular environment is essential. In this study, ER was assessed for its cytotoxic effect in combination with doxorubicin hydrochloride (DOX·HCl) against breast cancer cells. Drug synergy was calculated by using combination index (CI) index and we discovered that they had positive effects. To ensure uniform delivery of both drugs to cells for a desired synergistic action, a dual drug loaded liposomes was developed using thin-film dispersion, and coated by a layer of folate-chitosan. Cytotoxicity and cell proliferation based assays revealed the increase of cell inhibition rate by more than 30% compared with free drugs. Fluorescence imaging revealed that liposomes can aid faster drugs accumulate in cancer cells. The study presented a novel strategy for the treatment of breast cancer.

Adipogenesis as a Potential Anti-Obesity Target: A Review of Pharmacological Treatment and Natural Products

Obesity is recognized as a severe threat to overall human health and is associated with type 2 diabetes mellitus, dyslipidemia, hypertension, and cardiovascular diseases. Abnormal expansion of white adipose tissue involves increasing the existing adipocytes' cell size or increasing the number through the differentiation of new adipocytes. Adipogenesis is a process of proliferation and differentiation of adipocyte precursor cells in mature adipocytes. As a key process in determining the number of adipocytes, it is a possible therapeutic approach for obesity. Therefore, it is necessary to identify the molecular mechanisms involved in adipogenesis that could serve as suitable therapeutic targets. Reducing bodyweight is regarded as a major health benefit. Limited efficacy and possible side effects and drug interactions of available anti-obesity treatment highlight a constant need for finding novel efficient and safe anti-obesity ingredients. Numerous studies have recently investigated the inhibitory effects of natural products on adipocyte differentiation and lipid accumulation. Possible anti-obesity effects of natural products include the induction of apoptosis, cell-cycle arrest or delayed progression, and interference with transcription factor cascade or intracellular signaling pathways during the early phase of adipogenesis.

Targeted inhibition of c-MET by podophyllotoxin promotes caspase-dependent apoptosis and suppresses cell growth in gefitinib-resistant non-small cell lung cancer cells

BACKGROUND

Lung cancer has the highest incidence and cancer-related mortality of all cancers worldwide. Its treatment is focused on molecular targeted therapy. c-MET plays an important role in the development and metastasis of various human cancers and has been identified as an attractive potential anti-cancer target. Podophyllotoxin (PPT), an aryltetralin lignan isolated from the rhizomes of Podophyllum species, has several pharmacological activities that include anti-viral and anti-cancer effects. However, the mechanism of the anti-cancer effects of PPT on gefitinib-sensitive (HCC827) or -resistant (MET-amplified HCC827GR) non-small cell lung cancer (NSCLC) cells remains unexplored.

PURPOSE

In the present study, we investigated the underlying mechanisms of PPT-induced apoptosis in NSCLC cells and found that the inhibition of c-MET kinase activity contributed to PPT-induced cell death.

METHODS

The regulation of c-MET by PPT was examined by pull-down assay, ATP-competitive binding assay, kinase activity assay, molecular docking simulation, and Western blot analysis. The cell growth inhibitory effects of PPT on NSCLC cells were assessed using the MTT assay, soft agar assay, and flow cytometry analysis.

RESULTS

PPT could directly interact with c-MET and inhibit kinase activity, which further induced the apoptosis of HCC827GR cells. In contrast, PPT did not significantly affect EGFR kinase activity. PPT significantly inhibited the cell viability of HCC827GR cells, whereas the PPT-treated HCC827 cells showed a cell viability of more than 80%. PPT dose-dependently induced G2/M cell cycle arrest, as shown by the downregulation of cyclin B1 and cdc2, and upregulation of p27 expression in HCC827GR cells. Furthermore, PPT treatment induced Bad expression and downregulation of Mcl-1, survivin, and Bcl-xl expression, subsequently activating multi-caspases. PPT thereby induced caspase-dependent apoptosis in HCC827GR cells.

CONCLUSION

These results suggest the potential of PPT as a c-MET inhibitor to overcome tyrosine kinase inhibitor resistance in lung cancer.

Anti-glioblastoma Activity of Kaempferol via Programmed Cell Death Induction: Involvement of Autophagy and Pyroptosis

Glioblastoma is one of the most common and lethal intracranial malignant, and is still lack of ideal treatments. Kaempferol is a major nutrient found in various edible plants, which has exhibited the potential for the treatment of glioblastoma. However, the specific anti-glioma mechanism of kaempferol is yet to be studied. Herein, we aim to explore the mechanisms underlying the anti-glioma activity of kaempferol. Our results demonstrated that kaempferol suppresses glioma cell proliferation in vitro and inhibits tumor growth in vivo. Moreover, kaempferol raises ROS and decreases mitochondrial membrane potential in glioma cells. The high levels of ROS induce autophagy then ultimately trigger the pyroptosis of glioma cells. Interestingly, when we used 3-MA to inhibit autophagy, we found that the cleaved form of GSDME was also decreased, suggesting that kaempferol induces pyroptosis through regulating autophagy in glioma cells. In conclusion, this study revealed kaempferol possesses good anti-glioma activity by inducing ROS, and subsequently leads to autophagy and pyroptosis, highlighting its clinical potentials as a natural nutrient against glioblastoma.

Anticancer potential of garlic and its bioactive constituents: A systematic and comprehensive review

Vegetables of the Allium genus, such as garlic (Allium sativum L.), onions, shallots, leaks, and chives, have been used for many years for food consumption and for medicinal purposes. Historical medical texts have indicated the therapeutic applications of garlic as an antitumor, laxative, diuretic, antibacterial and antifungal agent. Specifically, garlic's antitumor abilities have been traced back 3500 years as a chemotherapeutic agent used in Egypt. Other beneficial effects of garlic consumption include lowering blood pressure, blood cholesterol, sugar and lipids. The processing and aging of garlic result in the production of non-toxic organosulfur by-products. These sulfur-containing compounds, such as allicin, diallyl sulfide, diallyl disulfide, diallyl trisulfide, alliin, S-allylcysteine, and S-allylmercaptocysteine, impact various stages of carcinogenesis. The anticancer mechanisms of action of these garlic-derived phytochemicals include altering mitochondrial permeability, inhibiting angiogenesis, enhancing antioxidative and proapoptotic properties, and regulating cell proliferation. All these effects of garlic's sulfur-compounds have been demonstrated in various human cancers. The intent of this literature research is to explore the potential of garlic-derived products and bioactive organosulfur compounds as cancer chemopreventive and chemotherapeutic agents. This investigation employs criteria for systematic review and critically analyzes published in vitro, in vivo and clinical studies. Concerns and limitations that have arisen in past studies regarding standards of measurement, bioavailability, and method of delivery are addressed. Overall, it is hoped that through this systematic and comprehensive review, future researchers can be acquainted with the updated data assembled on anticancer properties of garlic and its phytoconstituents.

Effect of aqueous extracts of Ficus vogeliana Miq and Tieghemella africana Pierre in 7,12-Dimethylbenz(a)anthracene -induced skin cancer in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Skin cancer is the most common form of cancer responsible for considerable morbidity and mortality. Tieghemella africana and Ficus vogeliana are used in traditional medicine to treat cancers.

AIM OF THE STUDY

Therefore, the aim of this study was to investigate the antioxidant, antiangiogenic and anti-tumor activities of these plant extracts.

MATERIALS AND METHODS

To achieve it, phytochemical screening, antioxidant activity and antiangiogenic activity were assessed. Thereafter, the anti-tumor activity was determined using skin tumorigenesis induced by 7,12-dimethylbenz[a]anthracene.

RESULTS

The phytochemical result analysis showed that both plant extracts were rich in polyphenols, alkaloids and terpene compounds and possessed good antioxidant activity based on DPPH radical scavenging (IC₅₀ = 9.70 μg/mL and 4.60 μg/mL and AAI values of 5.20 and 10.88) and strong total antioxidant capacity (115.44 VtCE (mg)/g of dry plant extract and 87.37 VtCE (mg)/g of dry plant extract, respectively). Additionally, both plant extracts possessed antiangiogenic activities (IC₅₀ = 53.43 μg/mL and 92.68 μg/mL, respectively), which correlated with significant antitumor activities when using 35 mg/kg (65.02% and 77.54%) and 70 mg/kg of extracts (81.07% and 88.18%).

CONCLUSIONS

In summary, this study illustrates the promising usage of Tieghemella africana and Ficus vogeliana plant extracts in treating skin cancer. However, further characterization of the extracts must be performed to isolate the most active anticancer compound.

The pleiotropic role of transcription factor STAT3 in oncogenesis and its targeting through natural products for cancer prevention and therapy

Signal transducer and activator of transcription 3 (STAT3) is one of the crucial transcription factors, responsible for regulating cellular proliferation, cellular differentiation, migration, programmed cell death, inflammatory response, angiogenesis, and immune activation. In this review, we have discussed the classical regulation of STAT3 via diverse growth factors, cytokines, G-protein-coupled receptors, as well as toll-like receptors. We have also highlighted the potential role of noncoding RNAs in regulating STAT3 signaling. However, the deregulation of STAT3 signaling has been found to be associated with the initiation and progression of both solid and hematological malignancies. Additionally, hyperactivation of STAT3 signaling can maintain the cancer stem cell phenotype by modulating the tumor microenvironment, cellular metabolism, and immune responses to favor drug resistance and metastasis. Finally, we have also discussed several plausible ways to target oncogenic STAT3 signaling using various small molecules derived from natural products.

Polyphenolic Fraction Obtained From Thalassia testudinum Marine Plant and Thalassiolin B Exert Cytotoxic Effects in Colorectal Cancer Cells and Arrest Tumor Progression in a Xenograft Mouse Model

Marine plants are important sources of pharmacologically active metabolites. The aim of the present work was to evaluate the cytotoxic and antitumor activity of a polyphenolic fraction obtained from Thalassia testudinum marine plant and thalassiolin B in human colorectal cancer cells. Human cancer cell lines, including HCT15, HCT116, SW260, and HT29 were treated with tested products for cytotoxicity evaluation by crystal violet assay. The potential proapoptotic effect of these natural products was assessed by flow cytometry in HCT15 cells at 48 h using Annexin V-FITC/propidium iodide. In addition, reactive oxygen species (ROS) generation was measured by fluorescence using DCFH-DA staining, and sulfhydryl concentration by spectrophotometry. The in vivo antitumor activity of the polyphenolic fraction (25 mg/kg) was evaluated in a xenograft model in nu/nu mice. In vivo proapoptotic effect was also evaluated by immunohistochemistry using anti-caspase 3 and anti-Bcl-2 antibodies. The results showed that tested products exert colorectal cancer cell cytotoxicity. Besides, the tested products induced a significant increase (p < 0.05) of intracellular ROS generation, and a depletion of sulfhydryl concentration in HCT15 cells. The polyphenolic fraction arrested tumor growth and induced apoptosis in the xenograft mice model. These results demonstrate the cytotoxic activity of T. testudinum metabolites associated, at least, with ROS overproduction and pro-apoptotic effects. Here we demonstrated for the first time the antitumor activity of a T. testudinum polar extract in a xenograft mice model. These results suggest the potential use of T. testudinum marine plant metabolites as adjuvant treatment in cancer therapy.

Apoptotic effect of berberine via Bcl-2, ROR1, and mir-21 in patients with B-chronic lymphocytic leukemia

Berberine is a natural isoquinoline alkaloid that has been shown to inhibit the proliferation and induce apoptosis in a wide variety of tumor cells. However, the action mechanism of berberine in CLL cells is unknown. The previous study has shown that berberine leads to reduced viability and elevated levels of apoptosis in PBMCs of CLL patients. CLL cells are characterized by remarkable expression of Bcl-2 and ROR1 which leads to activation and survival and increases disease progression in patients. High-level expression of miR-21 in patients with CLL is associated with a higher risk of death. Here we investigated the anticancer effects of berberine upon peripheral blood mononuclear cells (PBMCs) of CLL patients. To evaluate the expression of anti-apoptotic proteins and ROR1 using flow cytometry and western blot, PBMCs were treated with 25 μM of berberine for 24 hr. The expression levels of mir-21 were evaluated by real-time PCR. Examination of treated cells demonstrated that berberine decreased Bcl-2 and ROR1 levels. Although western blot results did not show any change in Bax as a pro-apoptotic protein, an increased Bax/Bcl-2 ratio indicated that mitochondrial pathway is involved in berberine-induced apoptosis of CLL cells. Interestingly, berberine could reduce the expression of miR-21 in comparison to the untreated group. Our findings describe some of the molecular mechanisms of berberine by decreasing Bcl-2, ROR1, and mir-21 which may be considered as a novel apoptosis inducer in CLL cells.

Carotenoid isolates of Spondias mombin demonstrate anticancer effects in DMBA-induced breast cancer in Wistar rats through X-linked inhibitor of apoptosis protein (XIAP) antagonism and anti-inflammation

Breast cancer is the most prevalent cancer in women. X-linked inhibitor of apoptosis protein (XIAP) that is constantly overexpressed in cancer is a promising therapeutic target in cancer treatments. The mechanisms of the anticancer effects of carotenoid isolates of Spondias mombim in DMBA-induced breast cancer in Wistar rats through XIAP antagonism were investigated in the present study. Carotenoids isolated from the leaves of Spondias mombim were subjected to Liquid Chromatography/Mass Spectrometry (LC/MS) and Electrospray Ionization (ESI) for characterization. The characterized carotenoid isolates were docked against XIAP BIR2 domain and XIAP BIR3 domain. The anticancer effects of the carotenoid isolates of Spondias mombim in DMBA-induced breast cancer in Wistar rats were also investigated through the expression of XIAP, COX-2, TNF, BCl-2 mRNAs by qRT-PCR and biochemical parameters of catalase, lipid peroxidation, LDH, ALP, and ALT. These show the carotenoid isolates demonstrate anticancer effects by antagonism of XIAP, proapoptotic, and anti-inflammatory properties. PRACTICAL APPLICATIONS: The present study showed that carotenoids (astaxanthin, β-carotene-15,15'-epoxide, and 7,7',8,8'-tetrahydro-β, β-carotene) isolated from the leaves of Spondias mombim are proapoptotic, it further gives credence to the chemopreventive abilities of carotenoids. This study validated XIAP as a druggable target in cancer treatment and hence more phytochemicals should be screened against it, for possible lead compounds of plant origin. Cancer cells often explore XIAP for antiapoptotic and resistance tendencies, hence, β-carotene-15,15'-epoxide and 7,7',8,8'-tetrahydro-β, β-carotene (XIAP antagonists) are promising drug candidates that can withstand resistant and prone cancer cells to apoptotic cell death. There is a need to synthesize β-carotene-15,15'-epoxide and 7,7',8,8'-tetrahydro-β for further investigation in clinical studies.

Isolinderalactone Induces Cell Death via Mitochondrial Superoxide- and STAT3-Mediated Pathways in Human Ovarian Cancer Cells

The mortality rate of ovarian cancer (OC) worldwide increases with age. OC is an often fatal cancer with a curative rate of only 20-30%, as symptoms often appear after disease progression. Studies have reported that isolinderalactone (ILL), a furanosesquiterpene derivative extracted from the dried root of Lindera aggregata, can inhibit several cancer cell lines' growth. However, the molecular mechanisms underlying ILL activities in human OC cells remain unexplored. This study investigated the antitumor activities of ILL in human OC cells by inducing mitochondrial superoxide (mtSO) and JAK-signal transducer and activator of transcription 3 (STAT3)-dependent cell death. ILL caused cell death in SKOV-3 and OVCAR-3 cells and increased the cell proportion in the subG1 phase. Additionally, ILL significantly induced mtSO production and reduced ROS production. Moreover, ILL downregulated mitochondrial membrane potential and the expression levels of anti-apoptotic Bcl-2 family proteins and superoxide dismutase (SOD)2. Results showed that ILL decreased phosphorylation of serine 727 and tyrosine 705 of STAT3 and expression of survivin, a STAT3-regulated gene. Furthermore, ILL-induced cell death was reversed by pretreatment of Mito-TEMPO, a mitochondria-specific antioxidant. These results suggest that ILL induces cell death by upregulation of mtSO, downregulation of mitochondrial SOD2, and inactivation of the STAT3-mediated pathway.