Anti-tumor activity evaluation of novel chrysin–organotin compound in MCF-7 cells

Hive Products: Composition, Pharmacological Properties, and Therapeutic Applications

Beekeeping provides products with nutraceutical and pharmaceutical characteristics. These products are characterized by abundance of bioactive compounds. For different reasons, honey, royal jelly, propolis, venom, and pollen are beneficial to humans and animals and could be used as therapeutics. The pharmacological action of these products is related to many of their constituents. The main bioactive components of honey include oligosaccharides, methylglyoxal, royal jelly proteins (MRJPs), and phenolics compounds. Royal jelly contains jelleins, royalisin peptides, MRJPs, and derivatives of hydroxy-decenoic acid, particularly 10-hydroxy-2-decenoic acid (10-HDA), which possess antibacterial, anti-inflammatory, immunomodulatory, neuromodulatory, metabolic syndrome-preventing, and anti-aging properties. Propolis has a plethora of activities that are referable to compounds such as caffeic acid phenethyl ester. Peptides found in bee venom include phospholipase A2, apamin, and melittin. In addition to being vitamin-rich, bee pollen also includes unsaturated fatty acids, sterols, and phenolics compounds that express antiatherosclerotic, antidiabetic, and anti-inflammatory properties. Therefore, the constituents of hive products are particular and different. All of these constituents have been investigated for their properties in numerous research studies. This review aims to provide a thorough screening of the bioactive chemicals found in honeybee products and their beneficial biological effects. The manuscript may provide impetus to the branch of unconventional medicine that goes by the name of apitherapy.

Anti-cancer Activity of Chrysin in Cancer Therapy: a Systematic Review

Chrysin is a natural bioactive compound that is extracted from many trees, honey, and propolis. Chrysin has several pharmacological activities such as anti-inflammatory, anti-cancer, and antioxidant properties. This study was performed to evaluate the anti-cancer activities of chrysin in cancer therapy. The present study was conducted by systematic review of studies published up to August 2021. Related studies were identified by searching Web of Science (WoS), PubMed, Science Direct, SID, MagIran, Scopus, and Google Scholar databases. The keywords of chrysin, cancer, anti-cancer, and cancer therapy were used for searching. The quality of the studies was assessed by the CONSORT checklist. A total of 21 studies were identified. The results of studies showed that chrysin has an anticancer effect by stimulating apoptosis in a wide range of human cells and rats. Chrysin is also an important factor in inhibiting tumor growth and neoplasticity. Chrysin inhibits the growth and proliferation of cancer cells by inducing cytotoxic effects. Therefore, due to the antitumor effects of chrysin and its safety and non-toxicity towards normal cells, this compound can be considered as an adjuvant along with chemotherapeutic agents in cancer treatment.

New Visions on Natural Products and Cancer Therapy: Autophagy and Related Regulatory Pathways

Macroautophagy (autophagy) has been a highly conserved process throughout evolution and allows cells to degrade aggregated/misfolded proteins, dysfunctional or superfluous organelles and damaged macromolecules, in order to recycle them for biosynthetic and/or energetic purposes to preserve cellular homeostasis and health. Changes in autophagy are indeed correlated with several pathological disorders such as neurodegenerative and cardiovascular diseases, infections, cancer and inflammatory diseases. Conversely, autophagy controls both apoptosis and the unfolded protein response (UPR) in the cells. Therefore, any changes in the autophagy pathway will affect both the UPR and apoptosis. Recent evidence has shown that several natural products can modulate (induce or inhibit) the autophagy pathway. Natural products may target different regulatory components of the autophagy pathway, including specific kinases or phosphatases. In this review, we evaluated ~100 natural compounds and plant species and their impact on different types of cancers via the autophagy pathway. We also discuss the impact of these compounds on the UPR and apoptosis via the autophagy pathway. A multitude of preclinical findings have shown the function of botanicals in regulating cell autophagy and its potential impact on cancer therapy; however, the number of related clinical trials to date remains low. In this regard, further pre-clinical and clinical studies are warranted to better clarify the utility of natural compounds and their modulatory effects on autophagy, as fine-tuning of autophagy could be translated into therapeutic applications for several cancers.

An Insight into Anticancer Effect of Propolis and Its Constituents: A Review of Molecular Mechanisms

Propolis is a natural compound collected by honeybees from different parts of plants. Honeybees produce a sticky component besides honey by mixing the tree resin and other botanical sources with saliva called propolis or bee glue. Propolis was traditionally used as a wound healing substance, cosmetic, medicine, and many other conditions. Till now, there is no definite curable treatment for most cancers and chemotherapeutic drugs and drugs used for targeted therapies have serious side effects. According to a recent research, natural products are becoming increasingly essential in cancer prevention. Natural products are a great source of potential therapeutic agents, especially in the treatment of cancer. Previous studies have reported that the presence of caffeic acid phenethyl ester (CAPE), artepillin C, and chrysin is responsible for the anticancer potential of propolis. Most of the previous studies suggested that propolis and its active compounds inhibit cancer progression by targeting multiple signaling pathways including phosphoinositide 3-kinases (PI3K)/Akt and mitogen-activated protein kinase (MAPK) signaling molecules, and induce cell cycle arrest. Induction of apoptosis by propolis is mediated through extrinsic and intrinsic apoptotic pathways. The aim of this review is to highlight and summarize the molecular targets and anticancer potential of propolis and its active compounds on cell survival, proliferation, metastasis, and apoptosis in cancer cells.

Facile synthesis and biological evaluation of chrysin derivatives

In this paper, novel synthetic methods, including microwave O-alkylation, were used to produce several chrysin derivatives. These compounds were purified, characterised and tested on different cell lines and bacterial strains. From this family, 7-(2,4-dinitrophenoxy)-5-hydroxy-3-phenyl-4H-chromen-4-one (C3) was shown to be extremely active on bacterial strains methicillin-resistant Staphylococcus aureus, Pseudomonas aeruginosa and Klebsiella pneumoniae as well as having anticancer activity on a range of cancer cell lines with IC50 values less than 30 µM. Chrysin has been known for their anticancer and antimicrobial properties, and this study not only corroborates this but also shows that it is possible to synthesise new improved derivatives with therapeutic possibilities.

Apoptosis-related gene expression induced by Colombian propolis samples in canine osteosarcoma cell line

Background and Aim

Osteosarcoma (OSA) is the most common bone tumor in canines and humans. This study aimed to assess the cytotoxic and apoptotic effects of Colombian propolis samples on a canine OSA cell line (OSCA-8) by evaluating the expression of BCL-2, BAX, CASPASE 9, CASPASE 8, and TNFR1 genes involved in the apoptosis pathway.

Materials and Methods

After treating the cells with five Colombian propolis samples (Usm, Met, Fus, Sil, and Caj), we evaluated cell viability and lactate dehydrogenase (LDH) release. Early and late apoptosis was determined by flow cytometry using annexin V/propidium iodide. Furthermore, the effects of three selected samples on gene expression were analyzed by real-time polymerase chain reaction.

Results

The Colombian propolis samples reduced OSCA-8 cell viability and increased LDH release. All samples induced apoptosis significantly and upregulated BCL-2 and CASPASE 8 expression. Usm and Sil increased BAX expression, Met and Sil induced CASPASE 9 expression, and Usm increased TNFR1.

Conclusion

Colombian propolis samples exhibited cytotoxic and apoptotic effects on canine OSA cells, and CASPASE 8 upregulation indicated apoptosis induction by the extrinsic pathway.

Emerging cellular and molecular mechanisms underlying anticancer indications of chrysin

Chrysin has been shown to exert several beneficial pharmacological activities. Chrysin has anti-cancer, anti-viral, anti-diabetic, neuroprotective, cardioprotective, hepatoprotective, and renoprotective as well as gastrointestinal, respiratory, reproductive, ocular, and skin protective effects through modulating signaling pathway involved in apoptosis, oxidative stress, and inflammation. In the current review, we discussed the emerging cellular and molecular mechanisms underlying therapeutic indications of chrysin in various cancers. Online databases comprising Scopus, PubMed, Embase, ProQuest, Science Direct, Web of Science, and the search engine Google Scholar were searched for available and eligible research articles. The search was conducted by using MeSH terms and keywords in title, abstract, and keywords. In conclusion, experimental studies indicated that chrysin could ameliorate cancers of the breast, gastrointestinal tract, liver and hepatocytes, bladder, male and female reproductive systems, choroid, respiratory tract, thyroid, skin, eye, brain, blood cells, leukemia, osteoblast, and lymph. However, more studies are needed to enhance the bioavailability of chrysin and evaluate this agent in clinical trial studies.

Structurally characterized gallium-chrysin complexes with anticancer potential

Chemotherapeutic metal-based compounds are effective anticancer agents; however, their cytotoxic profile and significant side effects limit their wide application. Natural products, especially flavonoids, are a prominent alternative source of anticancer agents that can be used as ligands for the generation of new bioactive complexes with metal ions of known biochemical and pharmacological activities. Herein, we present the synthesis and detailed structural and physicochemical characterizations of three novel complex assemblies of Ga(iii) with the flavonoid chrysin and the ancillary aromatic chelators 1,10-phenanthroline, 2,2'-bipyridine and imidazole. The complexes constitute the only crystallographically characterized structures having a metal core from the boron group elements and a flavonoid as the ligand. The in vitro biological evaluation of the three complexes in a series of cancer cell lines of different origin established their cytotoxicity and ROS generating potential. In particular, the Ga(iii)-chrysin-imidazole complex displayed the highest anticancer efficacy against all cancer cell lines with IC50 values in the low micromolar range (<1.18 μM), a result worth further investigation.

Natural and synthetic retinoid X receptor ligands and their role in selected nuclear receptor action

Important key players in the regulatory machinery within the cells are nuclear retinoid X receptors (RXRs), which compose heterodimers in company with several diverse nuclear receptors, playing a role as ligand inducible transcription factors. In general, nuclear receptors are ligand-activated, transcription-modulating proteins affecting transcriptional responses in target genes. RXR molecules forming permissive heterodimers with disparate nuclear receptors comprise peroxisome proliferator-activated receptors (PPARs), liver X receptors (LXRs), farnesoid X receptor (FXR), pregnane X receptor (PXR) and constitutive androstan receptor (CAR). Retinoid receptors (RARs) and thyroid hormone receptors (TRs) may form conditional heterodimers, and dihydroxyvitamin D₃ receptor (VDR) is believed to form nonpermissive heterodimer. Thus, RXRs are the important molecules that are involved in control of many cellular functions in biological processes and diseases, including cancer or diabetes. This article summarizes both naturally occurring and synthetic ligands for nuclear retinoid X receptors and describes, predominantly in mammals, their role in molecular mechanisms within the cells. A focus is also on triorganotin compounds, which are high affinity RXR ligands, and finally, we present an outlook on human microbiota as a potential source of RXR activators. Nevertheless, new synthetic rexinoids with better retinoid X receptor activity and lesser side effects are highly required.

Broad-Spectrum Preclinical Antitumor Activity of Chrysin: Current Trends and Future Perspectives

Pharmacological profile of phytochemicals has attracted much attention to their use in disease therapy. Since cancer is a major problem for public health with high mortality and morbidity worldwide, experiments have focused on revealing the anti-tumor activity of natural products. Flavonoids comprise a large family of natural products with different categories. Chrysin is a hydroxylated flavonoid belonging to the flavone category. Chrysin has demonstrated great potential in treating different disorders, due to possessing biological and therapeutic activities, such as antioxidant, anti-inflammatory, hepatoprotective, neuroprotective, etc. Over recent years, the anti-tumor activity of chrysin has been investigated, and in the present review, we provide a mechanistic discussion of the inhibitory effect of chrysin on proliferation and invasion of different cancer cells. Molecular pathways, such as Notch1, microRNAs, signal transducer and activator of transcription 3 (STAT3), nuclear factor-kappaB (NF-κB), PI3K/Akt, MAPK, etc., as targets of chrysin are discussed. The efficiency of chrysin in promoting anti-tumor activity of chemotherapeutic agents and suppressing drug resistance is described. Moreover, poor bioavailability, as one of the drawbacks of chrysin, is improved using various nanocarriers, such as micelles, polymeric nanoparticles, etc. This updated review will provide a direction for further studies in evaluating the anti-tumor activity of chrysin.

Novel Chrysin-De-Allyl PAC-1 Hybrid Analogues as Anticancer Compounds: Design, Synthesis, and Biological Evaluation

New chrysin-De-allyl-Pac-1 hybrid analogues, tethered with variable heterocyclic systems (4a–4o), were rationally designed and synthesized. The target compounds were screened for in vitro antiproliferative efficacy in the triple-negative breast cancer (TNBC) cell line, MDA-MB-231, and normal human mammary epithelial cells (HMECs). Two compounds, 4g and 4i, had the highest efficacy and selectivity towards MDA-MB-231 cells, and thus, were further evaluated by mechanistic experiments. The results indicated that both compounds 4g and 4i induced apoptosis by (1) inducing cell cycle arrest at the G2 phase in MDA-MB-231 cells, and (2) activating the intrinsic apoptotic pathways in a concentration-dependent manner. Physicochemical characterizations of these compounds suggested that they can be further optimized as potential anticancer compounds for TNBC cells. Overall, our results suggest that 4g and 4i could be suitable leads for developing novel compounds to treat TNBC.

Autophagy: A Potential Therapeutic Target of Polyphenols in Hepatocellular Carcinoma

Autophagy is a conserved biological phenomenon that maintains cellular homeostasis through the clearing of damaged cellular components under cellular stress and offers the cell building blocks for cellular survival. Aberrations in autophagy subsidize to various human pathologies, such as dementia, cardiovascular diseases, leishmaniosis, influenza, hepatic diseases, and cancer, including hepatocellular carcinoma (HCC). HCC is the fifth common mortal type of liver cancer globally, with an inhomogeneous topographical distribution and highest incidence tripled in men than women. Existing treatment procedures with liver cancer patients result in variable success rates and poor prognosis due to their drug resistance and toxicity. One of the pathophysiological mechanisms that are targeted during the development of anti-liver cancer drugs is autophagy. Generally, overactivated autophagy may lead to a non-apoptotic form of programmed cell death (PCD) or autophagic cell death or type II PCD. Emerging evidence suggests that manipulation of autophagy could induce type II PCD in cancer cells, acting as a potential tumor suppressor. Hence, altering autophagic signaling offers new hope for the development of novel drugs for the therapy of resistant cancer cells. Natural polyphenolic compounds, including flavonoids and non-flavonoids, execute their anticarcinogenic mechanism through upregulating tumor suppressors and autophagy by modulating canonical (Beclin-1-dependent) and non-canonical (Beclin-1-independent) signaling pathways. Additionally, there is evidence signifying that plant polyphenols target angiogenesis and metastasis in HCC via interference with multiple intracellular signals and decrease the risk against HCC. The current review offers a comprehensive understanding of how natural polyphenolic compounds exhibit their anti-HCC effects through regulation of autophagy, the non-apoptotic mode of cell death.

Novel photosensitizing properties of porphyrin–chrysin derivatives with antitumor activity in vitro

Photodynamic therapy is a promising cancer treatment with the advantages of low toxicity, high efficiency, and noninvasiveness. In this study, 23 novel porphyrin–chrysin derivatives are synthesized using alkyl carbon chains as bridges. We use human gastric cancer cells (MGC-803) and human cervical cancer cells to evaluate the in vitro antitumor activity of all the porphyrin–chrysin derivatives, with 5-fluorouracil (5-Fu) as a positive control. Several of the prepared compounds showed effective photodynamic killing effects, among which 5-hydroxy-2-phenyl-7-(2-(4-(10,15,20-tris(4-hydroxyphenyl)porphyrin-5-yl)phenoxy)ethoxy)-4 H-chromen-4-one shows the highest antiproliferation activity on human cervical cancer cells, with a half maximal inhibitory concentration of 26.51 ± 1.15 µM. Flow cytometry analysis showed that human cervical cancer cell apoptosis might be induced by G1 phase arrest.

Diversity of complexes based on p-nitrobenzoylhydrazide, benzoylformic acid and diorganotin halides or oxides self-assemble: Cytotoxicity, the induction of apoptosis in cancer cells and DNA-binding properties

Eight organotin(IV) complexes (C1-C8) have been synthesized and characterized by elemental analysis, fourier transform infrared spectroscopy (FT-IR), multinuclear nuclear magnetic resonance (¹H, ¹³C and ¹¹⁹Sn NMR), high resolution mass spectroscopy (HRMS) and single crystal X-ray structural analysis. Crystallographic data show that C1 was a tetranuclear 16-membered macrocycle complex, C2-C4 and C7 were centrosymmetric dimer distannoxane and there was a Sn₂O₂ four-membered ring in the middle of the molecule, respectively, C5 and C6 are monoorganotin complexes due to the dehydroalkylation effect during the reaction, while C8 forms a one-dimensional chain structure. The cytotoxicity of all complexes were tested by 3-(4,5)-dimethylthiahiazo(-z-y1)-3,5-di-phenytetrazoliumromide (MTT) assays against three human tumor cell lines NCI-H460, MCF-7 and HepG2. The dibutyltin complex C2 has been shown to be more potent antitumor agents than other complexes and carboplatin. Cell apoptosis study of C2 with the high activity on HepG2 and MCF-7 cancer cell lines was investigated by flow cytometry, it was shown that the antitumor activity of C2 was related to apoptosis, but it has different cell cycle arrest characteristics from platinum compounds, and the proliferation was inhibited by blocking cells in S phase. The DNA binding activity of the C2 was studied by UV-visible absorption spectrometry, fluorescence competitive, viscosity measurements and gel electrophoresis, results shown C2 can be well embedded in the double helix of DNA and cleave DNA.

Inclusion complexes between chrysin and amino-appended β-cyclodextrins (ACDs): Binding behavior, water solubility, in vitro antioxidant activity and cytotoxicity

Solid inclusion complexes between chrysin and four amino-appended β-cyclodextrins (ACDs) were prepared by suspension method and characterized in solid and solution states by kinds of analytical methods. The scanning electron microscopy (SEM) showed distinct micro-morphologies of them. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) analysis revealed their unique thermal properties, such as decomposition temperatures and endothermic points. Powder X-ray diffractometry (XRD) analysis disclosed their unique crystal patterns. Their nuclear magnetic resonance (NMR) analyses provided the variations of chemical shifts before and after the formation of inclusion complexes. Their binding stability constants (Ks) were 574, 842, 704, and 474 L·mol^-1, respectively, as determined by spectral titration. A 1:1 inclusion mode with self-assembly of their amino side chains inside the ACD cavity was proposed based on Job plot and 2D-ROESY experiments. Water solubility of chrysin was promoted up to 4411.98 μg·mL^-1 after formation of inclusion complexes with ACDs, better than that of β-CD and its derivatives, i.e., HP- and SBE-β-CD. In vitro antioxidant activity of chrysin was also improved after inclusion complexation by the DPPH scavenging assay. Furthermore, in vitro cytotoxicity of solid inclusion complexes towards three human cancer cell lines, A549, HT-29 and HCT116 were enhanced significantly.

Design, synthesis, and biologic evaluation of novel chrysin derivatives as cytotoxic agents and caspase-3/7 activators

Background

Chrysin (5,7-dihydroxyflavone) is a widely distributed natural flavonoid found in many plant extracts, honey and propolis. Several studies revealed that chrysin possesses multiple biological activities including anti-cancer effects. It has been established that activation of apoptosis is the key molecular mechanism responsible for the cytotoxic potential of chrysin. The objective of this study was to design and synthesize potent chrysin analogues as potential cytotoxic agents.

Methods

A series of chrysin derivatives (3a-m) bearing N'-alkylidene/arylideneacetohydrazide moiety were designed, synthesized, and evaluated for their antiproliferative activity against two human breast cancer cell lines, MDA-MB-231 and MCF-7 by applying the MTT colorimetric assay. Selected compounds were tested for their ability to induce apoptosis through caspase 3/7 activation in MDA-MB-231 cells only since MCF-7 cells lack procaspase 3.

Results

Compounds (3a-m) were obtained as geometrical isomers (E/Z isomers) in good yields upon treatment of hydrazide 5 with different aliphatic and aromatic aldehydes. Most of the synthesized compounds demonstrated moderate-to-good activity against both cell lines. The cytotoxicity results revealed the importance of lipophilic moieties at C-4 position of ring D in imparting the cytotoxic activities to the compounds. Compound 3e with 4-benzyloxy substituent was found to be the most active among the synthesized compounds with IC50 3.3 µM against MDA-MB-231 and 4.2 µM against MCF-7 cell lines. The cytotoxic potential of compound 3e is comparable to that of the well-known anti-cancer agent doxorubicin. In addition, compounds substituted with fluoro (3b), nitro (3h), and dimethylamino (3j) exhibited good cytotoxicity with IC₅₀ <6.5 µM against MDA-MB-231 and <12 µM against MCF-7. Selected compounds were able to induce apoptosis in MDA-MB-231 cells as indicated by caspase-3 and/or -7 activation.

Conclusion

Our results show that the newly designed chrysin derivatives exert anticancer activity in human breast cancer cell lines, MDA-MB-231 and MCF-7. Therefore, they can be considered as leads for further development of more potent and selective cytotoxic agents.

A new clerodane furano diterpene glycoside from Tinospora cordifolia triggers autophagy and apoptosis in HCT-116 colon cancer cells

ETHNOPHARMACOLOGICAL RELEVANCE

Tinospora cordifolia is a miraculous ayurvedic herb used in the treatment of innumerable diseases such as diabetes, gonorrhea, secondary syphilis, anaemia, rheumatoid arthritis, dermatological diseases, cancer, gout, jaundice, asthma, leprosy, in the treatment of bone fractures, liver & intestinal disorders, purifies the blood, gives new life to the whole body; (rejuvenating herb) and many more. Recent studies have revealed the anticancer potential of this plant but not much work has been done on the anticancer chemical constituents actually responsible for its amazing anticancer effects. This prompted us to investigate this plant further for new potent anticancer molecules.

AIM OF THE STUDY

The present study was designed to isolate and identify new promising anticancer candidates from the aqueous alcoholic extract of T. cordifolia using bioassay-guided fractionation.

MATERIALS AND METHODS

The structures of the isolated compounds were determined on the basis of spectroscopic data interpretation and that of new potent anticancer molecule, TC-2 was confirmed by a single-crystal X-ray crystallographic analysis of its corresponding acetate. The in vitro anti-cancer activity of TC-2 was evaluated by SRB assay and the autophagic activity was investigated by immunofluorescence microscopy. Annexin-V FITC and PI dual staining was applied for the detection of apoptosis. The studies on Mitochondrial Membrane potential and ROS (Reactive oxygen species) production were also done.

RESULTS

Bioassay guided fractionation and purification of the aqueous alcoholic stem extract of Tinospora cordifolia led to the isolation of a new clerodane furano diterpene glycoside (TC-2) along with five known compounds i.e. cordifolioside A (β-D-Glucopyranoside,4-(3-hydroxy-1-propenyl)- 2,6-dimethoxyphenyl 3-O-D-apio-β-D-furanosyl) (TC-1), β-Sitosterol(TC-3), 2β,3β:15,16-Diepoxy- 4α, 6β-dihydroxy-13(16),14-clerodadiene-17,12:18,1-diolide (TC-4), ecdysterone(TC-5) and tinosporoside(TC-6). TC-2 emerged as a potential candidate for the treatment of colon cancer.

CONCLUSION

The overall study on the bioassay guided isolation of T.cordifolia identified and isolated a new clerodane furano diterpenoid that exhibited anticancer activity via induction of mitochondria mediated apoptosis and autophagy in HCT116 cells. We have reported a promising future candidate for treating colon cancer.

Triphenyltin derivatives of sulfanylcarboxylic esters

The reaction of 3-(aryl)-2-sulfanylpropenoic acids [H₂xspa; x: p=3-phenyl-, f=3-(2-furyl)-, t=3-(2-thienyl)-] with methanol or ethanol gave the corresponding methyl (Hxspme) or ethyl (Hxspee) esters. The reaction of these esters (HL) with triphenyltin(IV) hydroxide gave compounds of the type [SnPh₃L], which were isolated and characterized as solids by elemental analysis, IR spectroscopy and mass spectrometry and in solution by multinuclear (¹H, ¹³C and ¹¹⁹Sn) NMR spectroscopy. The structures of [SnPh₃(pspme)], [SnPh₃(fspme)] and [SnPh₃(fspee)] were determined by X-ray diffractometry and the antimicrobial activity against E. coli, S. aureus, B. subtilis, P. aeruginosa, Resistant P. aeruginosa (a strain resistant to 'carbapenem'), and C. albicans was tested and the in vitro cytotoxic activity against the HeLa-229, A2780 and A2780cis cell lines was determined for all compounds.

Natural Compounds from Herbs that can Potentially Execute as Autophagy Inducers for Cancer Therapy

Accumulated evidence indicates that autophagy is a response of cancer cells to various anti-cancer therapies. Autophagy is designated as programmed cell death type II, and is characterized by the formation of autophagic vacuoles in the cytoplasm. Numerous herbs, including Chinese herbs, have been applied to cancer treatments as complementary and alternative medicines, supplements, or nutraceuticals to dampen the side or adverse effects of chemotherapy drugs. Moreover, the tumor suppressive actions of herbs and natural products induced autophagy that may lead to cell senescence, increase apoptosis-independent cell death or complement apoptotic processes. Hereby, the underlying mechanisms of natural autophagy inducers are cautiously reviewed in this article. Additionally, three natural compounds—curcumin, 16-hydroxycleroda-3,13-dien-15,16-olide, and prodigiosin—are presented as candidates for autophagy inducers that can trigger cell death in a supplement or alternative medicine for cancer therapy. Despite recent advancements in therapeutic drugs or agents of natural products in several cancers, it warrants further investigation in preclinical and clinical studies.

Chrysin induces death of prostate cancer cells by inducing ROS and ER stress

Chrysin is a natural flavone found in numerous plant extracts, honey, and propolis that has multiple biological activities including anti-cancer effects. Understanding of biological mechanisms mediated in response to chrysin in cancerous cells may provide novel insight into chemotherapeutic approaches with reduced side effects in cancers. In the present study, we investigated functional roles of chrysin in progression of prostate cancer cells using DU145 and PC-3 cell lines. The results showed that chrysin induced apoptosis of cells evidenced by DNA fragmentation and increasing the population of both DU145 and PC-3 cells in the sub-G₁ phase of the cell cycle. In addition, chrysin reduced expression of proliferating cell nuclear antigen in the prostate cancer cell lines compared to untreated prostate cancer cells. Moreover, chrysin induced loss of mitochondria membrane potential (MMP), while increasing production of reactive oxygen species (ROS) and lipid peroxidation in a dose-dependent manner. Also, it induced endoplasmic reticulum (ER) stress through activation of unfolded protein response (UPR) proteins including PRKR-like ER kinase (PERK), eukaryotic translation initiation factor 2α (eIF2α), and 78 kDa glucose-regulated protein (GRP78) in DU145 and PC-3 cells. The chrysin-mediated intracellular signaling pathways suppressed phosphoinositide 3-kinase (PI3K) and the abundance of AKT, P70S6K, S6, and P90RSK proteins, but stimulated mitogen-activated protein kinases (MAPK) and activation of ERK1/2 and P38 proteins in the prostate cancer cells. Collectively, these results indicate that chrysin initiates cell death through induction of mitochondrial-mediated apoptosis and ER stress, and regulation of signaling pathways responsible for proliferation of prostate cancer cells.

Phytochemical Modulation of Apoptosis and Autophagy: Strategies to Overcome Chemoresistance in Leukemic Stem Cells in the Bone Marrow Microenvironment

Advances in scientific research and targeted treatment regimes have improved survival rates for many cancers over the past few decades. However, for some types of leukemia, including acute lymphoblastic and acute myeloid leukemia, mortality rates have continued to rise, with chemoresistance in leukemic stem cells (LSCs) being a major contributing factor. Most cancer drug therapies act by inducing apoptosis in dividing cells but are ineffective in targeting quiescent LSCs. Niches in the bone marrow, known as leukemic niches, behave as "sanctuaries" where LSCs acquire drug resistance. This review explores the role of the bone marrow environment in the maintenance of LSCs and its contribution to chemoresistance and considers current research on the potential use of phytochemicals to overcome chemoresistance through the modulation of signaling pathways involved in the survival and death of leukemic clonal cells and/or leukemic stem cells. Phytochemicals from traditional Chinese medicine, namely baicalein, chrysin, wogonin (constituents of Scutellaria baicalensis; huáng qín; ), curcumin (a constituent of Curcuma longa, jiāng huáng, ), and resveratrol (a constituent of Polygonum cuspidatum; hŭ zhàng, ) have been shown to induce apoptosis in leukemic cell lines, with curcumin and resveratrol also causing cell death via the induction of autophagy (a nonapoptotic pathway). In order to be effective in eliminating LSCs, it is important to target signaling pathways (such as Wnt/β-catenin, Notch, and Hedgehog). Resveratrol has been reported to induce apoptosis in leukemic cells through the inhibition of the Notch and Sonic hedgehog signaling pathways, therefore showing potential to affect LSCs. While these findings are of interest, there is a lack of reported research on the modulatory effect of phytochemicals on the autophagic cell death pathway in leukemia, and on the signaling pathways involved in the maintenance of LSCs, highlighting the need for further work in these areas.

Honey and Cancer: Current Status and Future Directions

Cancer is a leading cause of death worldwide and poses a challenge to treatment. With overwhelming evidence of the role played by diet and lifestyle in cancer risk and prevention, there is a growing interest into the search for chemopreventative or chemotherapeutic agents derived from natural products. Honey is an important source of bioactive compounds derived from plants and recent years have seen an increased interest in its anticancer properties. This review examines the role of honey in targeting key hallmarks of carcinogenesis, including uncontrolled proliferation, apoptosis evasion, angiogenesis, growth factor signalling, invasion, and inflammation. The evidence for honey as an adjunct to conventional cancer therapy is also presented. The review also highlights gaps in the current understanding and concludes that, before translation of evidence from cell culture and animal studies into the clinical setting, further studies are warranted to examine the effects of honey at a molecular level, as well as on cells in the tumour environment.