Structurally related cytotoxic effects of flavonoids on human cancer cells in vitro

Potential of Dietary HDAC2i in Breast Cancer Patients Receiving PD-1/PD-L1 Inhibitors

Breast cancer (BC) is a lethal malignancy with high morbidity and mortality but lacks effective treatments thus far. Despite the introduction of immune checkpoint inhibitors (ICIs) (including PD-1/PD-L1 inhibitors), durable and optimal clinical benefits still remain elusive for a considerable number of BC patients. To break through such a dilemma, novel ICI-based combination therapy has been explored for enhancing the therapeutic effect. Recent evidence has just pointed out that the HDAC2 inhibitor (HDAC2i), which has been proven to exhibit an anti-cancer effect, can act as a sensitizer for ICIs therapy. Simultaneously, dietary intervention, as a crucial supportive therapy, has been reported to provide ingredients containing HDAC2 inhibitory activity. Thus, the novel integration of dietary intervention with ICIs therapy may offer promising possibilities for improving treatment outcomes. In this study, we first conducted the differential expression and prognostic analyses of HDAC2 and BC patients using the GENT2 and Kaplan-Meier plotter platform. Then, we summarized the potential diet candidates for such an integrated therapeutic strategy. This article not only provides a whole new therapeutic strategy for an HDAC2i-containing diet combined with PD-1/PD-L1 inhibitors for BC treatment, but also aims to ignite enthusiasm for exploring this field.

A novel 4'-brominated derivative of fisetin induces cell cycle arrest and apoptosis and inhibits EGFR/ERK1/2/STAT3 pathways in non-small-cell lung cancer without any adverse effects in mice

The therapeutic toxicity and resistance to currently available treatment options are major clinical challenges for the management of lung cancer. As a novel strategy, we synthesized analogues of a known flavonol, fisetin, which has shown anti-tumorigenic potential against cancer in cell culture with no adverse effects in animal models. We studied the synthetic analogues of fisetin for their anti-cancer potential against lung cancer cells, toxicity in mice and efficacy in a xenograft model. Brominated fisetin analogues were screened for their effects on the viability of A549 and H1299 lung cancer cells, and three analogues (3a, 3b, 3c), showed improved activity compared to fisetin. These analogues were more effective in restricting lung cancer cell proliferation, inducing G₂ M phase cell cycle arrest and apoptosis. The fisetin analogues also downregulated EGFR/ERK1/2/STAT3 pathways. Fisetin analogue-induced apoptosis was accompanied by a higher Bax to Bcl-2 expression ratio. Based on the in vitro studies, the most effective fisetin analogue 3b was evaluated for in vivo toxicity, wherein it did not show any hepatotoxicity or adverse health effects in mice. Furthermore, analogue 3b showed greater antitumor efficacy (p < .001) as compared to its parent compound fisetin in a human lung cancer cell xenograft study in athymic mice. Together, our data suggest that the novel fisetin analogue 3b is more effective in restricting lung cancer cell growth, both in vitro as well as in vivo, without any apparent toxicity, supporting its further development as a novel anti-lung cancer agent.

Anticancer and Cytotoxicity Activity of Native and Modified Black Rice Flour on Colon Cancer Cell Lines

This study is intended to evaluate the cytotoxicity of native and dual-modified black rice flour against the colon cancer cell line (HCT116) and mouse embryo cell line (3T3-L1) by using the MTT assay. The modification techniques applied to prepare rice flour samples were enzymatic modification and heat moisture treatment. In this study, the IC50 of native black rice flour and modified black rice flour was 255.78 µg/mL and 340.85 µg/mL, respectively. The result confirms that the native black rice flour has significant cytotoxic and anticancer potential against human colon cancer cells. In addition, the IC50 of native black rice flour and modified black rice flour on the 3T3-L1 cell line was found to be 345.96 µg/mL and 1106.94 µg/mL, respectively. The results showed that the native black rice flour had weak cytotoxicity, and modified black rice flour was nontoxic in both the cell lines. The active component of phytochemicals present in black rice flour has a potential role in preventing colon cancer.

Molecular Mechanism of Chrysin in Hepatocellular Carcinoma Treatment Based on Network Pharmacology and in Vitro Experiments

This study elucidated the potential molecular mechanism of chrysin in hepatocellular carcinoma (HCC) treatment using network pharmacology and in vitro experiments. Chrysin and candidate targets of HCC were obtained from the TCMSP and DrugBank databases, followed by mapping and screening of chrysin and HCC targets to identify the core targets of chrysin in HCC treatment. The interaction of chrysin and its targets, including CDK1, CDK5, as well as MMP9, were evaluated by molecular docking. The STRING database and Cytoscape (version 3.8.2) software were used to construct protein interactions and component-target networks of the core targets. Gene Ontology (GO) annotation and Kyoto Encyclopedia of Genes and Genomes (KEGG) signaling pathway enrichment analysis of the core target genes were performed using the DAVID database. Network pharmacology results showed that chrysin treatment of HCC was mainly related to cell proliferation and cell cycle. Accordingly, the cell counting kit-8 method and flow cytometry were used to detect the cell viability and cell cycle of hepatocarcinoma cells HCCLM3 and BEL-7402 in vitro. A total of 142 compound targets of chrysin, 12,179 HCC-related targets, and 116 intersecting targets were screened. The first 20 GO biological annotations of 17 core targets and the first 20 KEGG pathways mainly involved cell proliferation and cell cycle. In vitro experiments showed that chrysin inhibits the proliferation of human hepatocarcinoma cells (HCCLM3 and BEL-7402) in a dose-dependent manner. Moreover, chrysin induced cell cycle arrest in HCCLM3 and BEL-7402 cells in the G2 phase, and the expression was downregulated of cyclin-dependent kinases (CDKs), CDK2 and CDK4. Chrysin can offset HCC mainly by regulating the cell cycle and inhibiting cell proliferation. The network pharmacology results were verified, providing the basis for further study on the mechanism of chrysin intervention in HCC.

Effects of propolis and its bioactive components on breast cancer cell pathways and the molecular mechanisms involved

BACKGROUND

Breast cancer is a female malignancy that is a significant cause of mortality worldwide. Currently, investigations on natural ingredients as new candidates for chemopreventive agents and breast cancer chemotherapies are increasing. Propolis is a natural resinous material produced by honeybees that exhibit anticancer potential. Several studies have mentioned the major bioactive compounds of propolis, but their mechanism of action is not clearly understood.

OBJECTIVES

The purpose of this review is to collect and summarize the evidence related to the effectiveness of propolis and its bioactive contents as candidates for breast cancer therapy and analyze the molecular mechanisms involved in their therapeutic pathways.

METHODS

We reviewed 94 articles from journals and databases, extracted the results, and produced summaries and conclusions.

RESULTS

Propolis and its bioactive ingredients show cytotoxic, anti-proliferative, pro-autophagic, anti-metastatic, and antioxidant activities, as well as synergistic effects with chemotherapy or radiotherapy in breast cancer. Its therapeutic activity involves various target molecules, including NF-κβ, Fas receptors, p53, TLR4, ANXA7, and voltage-gated Na+ channel (VGSC).

CONCLUSION

The bioactive components of propolis and the target molecules involved need to be explored further to develop new breast cancer therapies and overcome the problem of chemoradiation resistance.

In vitro and in vivo effects of inhibitors on actin and myosin

The interaction of actin and myosin is essential for cell migration. We have identified kaempferol and pentahalogenated pseudilins as efficient inhibitors of migration of MDA-MB-231 breast adenocarcinoma cells. The compounds were studied with respect to possible effects on myosin-2-ATPase activity. The pentahalogenated pseudilins inhibited the enzyme activity in vitro. Flavonoids showed no effect on enzyme activity. The polymerization dynamics of actin was measured to test whether the integrity of F-actin is essential for the migration of MDA-MB-231 cells. Quercetin and kaempferol depolymerized F-actin with similar efficiencies as found for the pentahalogenated pseudilins, whereas epigallocatechin showed the weakest effect. As the inhibitory effect on cell migration may be caused by a toxic effect, we have performed a cytotoxicity test and, furthermore, investigated the influence of the test compounds on cardiac function in eleutheroembryos of medaka (Oryzias latipes). Compared with the pentahalogenated pseudilins, the cytotoxic and cardiotoxic effects of flavonoids on medaka embryos were found to be moderate.

Polyphenols with Anti-Amyloid β Aggregation Show Potential Risk of Toxicity Via Pro-Oxidant Properties

Alzheimer's disease (AD) is the most common form of dementia among older people. Amyloid β (Aβ) aggregation has been the focus for a therapeutic target for the treatment of AD. Naturally occurring polyphenols have an inhibitory effect on Aβ aggregation and have attracted a lot of attention for the development of treatment strategies which could mitigate the symptoms of AD. However, considerable evidence has shown that the pro-oxidant mechanisms of polyphenols could have a deleterious effect. Our group has established an assay system to evaluate the pro-oxidant characteristics of chemical compounds, based on their reactivity with DNA. In this review, we have summarized the anti-Aβ aggregation and pro-oxidant properties of polyphenols. These findings could contribute to understanding the mechanism underlying the potential risk of polyphenols. We would like to emphasize the importance of assessing the pro-oxidant properties of polyphenols from a safety point of view.

A new hexenoic acid glycoside with cytotoxic activity from the leaves of Psychotria luzoniensis

A new hexenoic acid glycoside (1) together with known compounds, flavonol glycosides (2-4), iridoid glycoside (5), megastigmane glycoside (6), and amino acid (7) were isolated from the leaves of P. luzoniensis by resin column chromatography and preparative HPLC. Their structures were determined based on spectroscopic analysis, including HRFABMS and NMR (¹H and ¹³C, ¹H-¹H COSY, HMQC, and HMBC) data. All compounds tested for cytotoxicity were active (IC₅₀ < 50 μM) with IC₅₀ values ranging from 1.97 to 32.85 μM against human colon adenocarcinoma cell line, compared to etoposide (IC₅₀ 1.19 μM).

Human CYP1A1 inhibition by flavonoids

Cytochrome P4501A1 (CYP1A1) is involved in the metabolism of several genotoxic/carcinogenic environmental xenobiotics including polycyclic aromatic hydrocarbons (PAHs) like benzo[a]pyrene. Several authors had proposed CYP1A inhibition as a plausible strategy for cancer chemoprevention. Using ethoxyresorufin O-deethylase activity (EROD), we tested the inhibitory properties of nine flavonoids: quercetin, miricetin, luteolin, fisetin, morin, kaempferol, 5-hydroxyflavone (5-HF), 3-hydroxyflavone (3-HF), and flavone (F) against human recombinant CYP1A1. The last three compounds exerted the highest inhibitory effect with IC₅₀ values of 0.07, 0.10 and 0.08 μM respectively; the more hydroxyl-groups were present, the lower the potency of inhibition was. Biochemical characterization leads to the conclusion that flavone and its hydroxy derivatives are mixed-type inhibitors. In silico studies have shown that, Phe224 and other aromatic residues in the human CYP1A1 active site play an important role in flavonoid-CYP interaction, through a π/π stacking between the aminoacid and the flavonoid C-ring. Outside the active site, the three flavonoids bind preferentially between A and K helices of the enzyme. Results from the Ames test using human S9 fraction revealed that none of the three compounds was mutagenic. We can consider 5-HF, 3-HF, and F as potential chemopreventive agents against genotoxic damage caused by metabolites resulting from CYP1A1 activity.

The Degradation of Deoxynivalenol by Using Electrochemical Oxidation with Graphite Electrodes and the Toxicity Assessment of Degradation Products

Deoxynivalenol (DON) is a common mycotoxin, which is known to be extremely harmful to human and livestock health. In this study, DON was degraded by electrochemical oxidation (ECO) using a graphite electrode and NaCl as the supporting electrolyte. The graphite electrode is advantageous due to its electrocatalytic activity, reusability, and security. The degradation process can be expressed by first-order kinetics. Approximately 86.4% of DON can be degraded within 30 min at a potential of 0.5 V. The degradation rate reached 93.2% within 30 min, when 0.5 V potential was used for electrocatalyzing a 10 mg/L DON solution. The degradation rate of DON in contaminated wet distiller's grain with solubles (WDGS) was 86.37% in 60 min. Moreover, results from the cell counting kit-8 (CCK-8) and 4,6-diamidino-2-phenylindole dihydrochloride (DAPI) staining assay indicated that ECO reduced the DON-induced cytotoxicity and apoptotic bodies in a gastric epithelial cell line (GES-1) compared to the DON-treated group. These findings provide new insights into the application of ECO techniques for degrading mycotoxins, preventing food contamination, and assessing DON-related hazards.

Structure-Antioxidant-Antiproliferative Activity Relationships of Natural C7 and C7-C8 Hydroxylated Flavones and Flavanones

Common food flavonoids: chrysin, apigenin, luteolin, diosmetin, pinocembrin, naringenin, eriodictyol, hesperetin, and their analogues with an additional hydroxyl group at the C-8 position obtained via biotransformation were tested for antioxidant activity using the ABTS, DPPH, and ferric ion reducing antioxidant power (FRAP) methods. They were also tested for antiproliferative activity against selected human cancer cell lines-MV-4-11 (biphenotypic B myelomonocytic leukemia), MCF7 (breast carcinoma), LoVo (colon cancer), LoVo/DX (colon cancer doxorubicin resistant), and DU 145 (prostate cancer)-and two normal human cell lines-MCF 10A (breast cells) and HLMEC (lung microvascular endothelial cells). Flavonoids with a C7-C8 catechol moiety indicated much higher antioxidant activity compared with the C7 hydroxy analogues. However, because they were unstable under the assay conditions, they did not show antiproliferative activity or it was very low.

Synthesis, Biological Evaluation and Docking Studies of Chalcone and Flavone Analogs as Antioxidants and Acetylcholinesterase Inhibitors

Several oxidative processes are related to a wide range of human chronic and degenerative diseases, like Alzheimer’s disease, which also has been related to cholinergic processes. Therefore, search for new or improved antioxidant molecules with acetylcholinesterase activity is essential to offer alternative chemotherapeutic agents to support current drug therapies. A series of chalcone (2a–2k) and flavone (3a–3k) analogs were synthesized, characterized, and evaluated as acetylcholinesterase (AChE) inhibitors, and antioxidant agents using 1,1-diphenyl-2-picrylhydrazyl (DPPH•), 2-2′-azino-bis-(3-ethylbenzothiazoline-6-sulfonate) (ABTS•), and β-carotene/linoleic acid bleaching assay. Compounds more active were 3j and 2k in DPPH with EC50 of 1 × 10−8 and 5.4 × 10−3 μg/mL, respectively; 2g and 3i in ABTS (1.14 × 10−2 and 1.9 × 10−3 μg/mL); 2e, 2f, 3f, 2j, and 3j exceeded the α-tocopherol control in the β-carotene assay (98–99% of antioxidant activity). At acetylcholinesterase inhibition assay, flavones were more active than chalcones; the best results were compounds 2d and 3d (IC50 21.5 and 26.8 µg/mL, respectively), suggesting that the presence of the nitro group enhances the inhibitory activity. The docking of these two structures were made to understand their interactions with the AChE receptor. Although further in vivo testing must be performed, our results represent an important step towards the identification of improved antioxidants and acetylcholinesterase inhibitors.

5'-Chloro-2,2'-dihydroxychalcone and related flavanoids as treatments for prostate cancer

Several flavonoids and their biosynthetic precursor chalcones were designed and synthesized to improve the biological effects of the lead compound 2'-hydroxyflavonone against androgen receptor (AR)-dependent transcriptional stimulation. Newly synthesized chalcones 19 and 26 suppressed AR-dependent transcription as well as DHT-dependent growth stimulation at a low micromolar level. These compounds were also effective against ligand-independent constitutively active mutant AR derived from castration-resistant PCa (CRPC). Compounds 19 and 26 showed broad spectrum antiproliferative activity at 5-10 μM against multiple tumor cell lines including androgen-independent and taxane-resistant prostate cancer as well as a multidrug-resistant subline. Mode of action studies suggested that 19 induced sub-G1 accumulation in PC-3 cells by disrupting the microtubule network without affecting cell cycle progression. Furthermore, the in vivo effectiveness of chalcone 19 was confirmed in a xenograft model antitumor assay. Thus, chalcone 19 has the potential to be a bifunctional lead for treatment of AR-dependent PCa at lower doses as well as AR-independent PCa, including CRPC, at higher doses.

Cytotoxic, analgesic and anti-inflammatory properties of Syzygium calophyllifolium bark

The present study explores the effect of Syzygium calophyllifolium bark methanol (SCBM) extract on pain and inflammation as cancer associated symptoms. The anti-proliferative and cell death-inducing ability of the extract was analysed using MCF-7 breast cancer cells. ATP and LDH levels, along with the cell morphology were noted. The anti-proliferative ability of the extract was examined in relation to pain and inflammation. Analgesic activity was determined using a hot plate, acetic acid and formalin-induced pain models in mice. Acute anti-inflammatory activity was observed in carrageenan and egg albumin induced paw oedema in Wistar rats. Chronic inflammation was induced by placing a cotton pellet under the skin at the axial region of rats. Reduced ATP and increased LDH content indicated the cytotoxic effect of the extract. SCBM at 200 mg/kg dose depicted good activity in acetic acid (77.69%) and formalin (80.81%) induced pain models compared to the standard drug indomethacin. However, only a moderate activity was observed in the hot plate method (53.85%). The higher dose of SCBM was equally effective in anti-inflammatory models. The dose (200 mg/kg) significantly reduced the paw oedema in carrageenan (96.71%) and egg albumin models (54.24%) compared to the control. The chronic inflammation was also inhibited upto 70.46% by SCBM. These activities can be attributed to the phenolic compounds detected in HPLC. The outcome of the study states that the extract can reduce both acute and chronic inflammatory conditions and kill the cancer cells, proposing the dual role of SCBM in treating inflammatory pains in cancer. The result of these studies indicated that wild plants like Syzygium calophyllifolium could be taken forward for a detailed study to accomplish the demand for a better treatment against diseases.

Astragalin-induced cell death is caspase-dependent and enhances the susceptibility of lung cancer cells to tumor necrosis factor by inhibiting the NF-кB pathway

Flavonoids are naturally occurring polyphenolic compounds and are among the most promising anticancer agents. Here, we demonstrate that the flavonoid astragalin (AG), also known as kaempferol-3-O-β-D-glucoside, induces cell death. This was prevented by the caspase inhibitors z-DEVD-FMK and z-LEHD-FMK. AG-induced cell death was associated with an increase in the Bax:Bcl-2 ratio and amplified by the inhibition of extracellular signal-regulated kinase (ERK)-1/2 and Akt signaling. Meanwhile, AG suppressed LPS-induced NF-κB activation. Additional studies revealed that AG inhibited tumor necrosis factor-alpha (TNFα)-induced NF-κB activity. AG also potentiated TNFα-induced apoptosis in A549 cells. Furthermore, using a mouse xenograft model, we demonstrated that AG suppressed tumor growth and induced cancer cell apoptosis in vivo. Taken together, these results suggest that AG may be a promising cancer therapeutic drug that warrants further investigation into its potential clinical applications.

Polyphenols in Colorectal Cancer: Current State of Knowledge including Clinical Trials and Molecular Mechanism of Action

Polyphenols have been reported to have wide spectrum of biological activities including major impact on initiation, promotion, and progression of cancer by modulating different signalling pathways. Colorectal cancer is the second most major cause of mortality and morbidity among females and the third among males. The objective of this review is to describe the activity of a variety of polyphenols in colorectal cancer in clinical trials, preclinical studies, and primary research. The molecular mechanisms of major polyphenols related to their beneficial effects on colorectal cancer are also addressed. Synthetic modifications and other future directions towards exploiting of natural polyphenols against colorectal cancer are discussed in the last section.

Flavonoids Isolated From the Flowers of Limonium bicolor and their In vitro Antitumor Evaluation

BACKGROUND

Limonium bicolor, a halophytic species, can grow in saline or saline-alkali soil, is well known as a traditional Chinese medicine. Recently it attracted much attention for its treatment for cancer.

OBJECTIVE

The present study was performed to evaluate this species from the phytochemical standpoint and the possible relationship between the antitumor activity and its natural products.

MATERIALS AND METHODS

The chemical constituents from the flowers of L. bicolor were investigated through bioassay-guided fractionation and isolation. All the individual compounds were characterized by spectroscopic analysis and their potential antitumor activity was tested against three different human tumor cell lines by MTT assays.

RESULTS

The EtOAc extract was proven as the most potent fraction and further fractionation led to the isolation of 15 natural flavonoids, which were characterized as luteolin (1), acacetin (2), quercetin (3), isorhamnetin (4), kaempferol (5), eriodictyol (6), kaempferol-3-O-α-L-rhamnoside (7), kaempferol-3-O-β-D-glucoside (8), quercetin-3-O-α-L-rhamnoside (9), quercetin-3-O-β-D-glucoside (10), quercetin-3-O-β-D-galactoside (11), myricetin-3-O-α-L-rhamnoside (12), kaempferol-3-O-(6″-O-galloyl)-β-D-glucoside (13), hesperidin (14) and rutin (15). The biotesting results demonstrated that both compounds 1 and 3 showed good cytotoxicity against human colon cancer cells (LOVO). Compound 5 exhibited relative greater growth inhibition against both human breast cancer cells (MCF-7) and osteosarcoma cell lines (U2-OS) at the concentration of 100 μg/mL.

CONCLUSION

On the basis of these findings, the flavonoids were deduced to be potentially responsible for the antitumor activity of L. bicolor. The preliminary structure-activity relationship analysis suggests that the 3-O-glycosylation moiety in natural flavonoids was not essential for the antiproliferative activity on LOVO and U2-OS cells.

SUMMARY

The phytochemical investigation of Limonium bicolor led to the isolation of 15 flavonoids.The biotesting of the isolates against three different human tumor cell lines was evaluated.The structure-antitumor activity relationship between the isolated flavonoids was discussed. Abbreviation used: MTT: 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, EtOAc: Ethyl acetate; LOVO: human colon cancer; MCF-7: human breast, cancer; U2-OS: human osteosarcoma; 5-FU: 5-Fluorouracil; DMSO: dimethyl sulfoxide, NMR: nuclear magnetic resonance; HR-ESI-MS: high resolution electrospray ionization mass chromatography, HPLC: high performance liquid chromatography, EtOH: ethanol; n-BuOH: n-butanol; CC: column chromatography, TLC: thin layer chromatography; PBS: phosphate-buffered saline.

Improved antioxidative and cytotoxic activities of chamomile (Matricaria chamomilla) florets fermented by Lactobacillus plantarum KCCM 11613P

Antioxidative and cytotoxic effects of chamomile (Matricaria chamomilla) fermented by Lactobacillus plantarum were investigated to improve their biofunctional activities. Total polyphenol (TP) content was measured by the Folin-Denis method, and the antioxidant activities were assessed by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) method and β-carotene bleaching method. AGS, HeLa, LoVo, MCF-7, and MRC-5 (normal) cells were used to examine the cytotoxic effects by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium (MTT) assay. The TP content of fermented chamomile reduced from 21.75 to 18.76 mg gallic acid equivalent (mg GAE)/g, but the DPPH radical capturing activity of fermented chamomile was found to be 11.1% higher than that of nonfermented chamomile after 72 h of fermentation. Following the β-carotene bleaching, the antioxidative effect decreased because of a reduction in pH during fermentation. Additionally, chamomile fermented for 72 h showed a cytotoxic effect of about 95% against cancer cells at 12.7 mg solid/ml of broth, but MRC-5 cells were significantly less sensitive against fermented chamomile samples. These results suggest that the fermentation of chamomile could be applied to develop natural antioxidative and anticancer products.

Impact of Phytochemicals and Dietary Patterns on Epigenome and Cancer

Cancer remains one of the leading causes of death around the world. Initially it is recognized as a genetic disease, but now it is known to involve epigenetic abnormalities along with genetic alterations. Epigenetics refers to heritable changes that are not encoded in the DNA sequence itself, but play an important role in the control of gene expression. It includes changes in DNA methylation, histone modifications, and RNA interference. Although it is heritable, environmental factors such as diet could directly influence epigenetic mechanisms in humans. This article will focus on the role of dietary patterns and phytochemicals that have been demonstrated to influence the epigenome and more precisely histone and non-histone proteins modulation by acetylation that helps to induce apoptosis and phosphorylation inhibition, which counteracts with cells proliferation. Recent developments discussed here enhance our understanding of how dietary intervention could be beneficial in preventing or treating cancer and improving health outcomes.

Polyphenol Composition, Antioxidant Activity and Cytotoxicity of Seeds from Two Underexploited Wild Licania Species: L. rigida and L. tomentosa

Studies have shown the benefit of antioxidants in the prevention or treatment of human diseases and promoted a growing interest in new sources of plant antioxidants for pharmacological use. This study aimed to add value to two underexploited wild plant species (Licania rigida) and L. tomentosa) from Brazilian flora. Thus, the phenolic compounds profile of their seed ethanol extract and derived fractions were elucidated by HPLC, the antioxidant capacity was assessed by in vitro chemical tests and the cytotoxicity determined using the human carcinoma cell lines MCF-7 and Caco-2. Eleven phenolic compounds were identified in the extracts of each species. The extracts and fractions showed excellent antioxidant activity in the DPPH assay (SC₅₀, ranging from 9.15 to 248.8 µg/mL). The aqueous fraction of L. rigida seeds was most effective in preventing lipid peroxidation under basal conditions (IC₅₀ 60.80 µg/mL) whereas, in the presence of stress inducer, the methanolic fraction of L. tomentosa performed best (IC₅₀ 8.55 µg/mL). None of the samples showed iron chelating capacity. Ethanolic seed extracts of both species did not reveal any cytotoxicity against MCF-7 and Caco-2 cells. Both plant species showed a promising phenolic profile with potent antioxidant capacity and deserve attention to be sustainably explored.

Flavonoids of Calligonum polygonoides and their cytotoxicity

Context Calligonum polygonoides L. subsp. comosum L' Hér. (Polygonaceae), locally known as "arta", is a slow-growing small leafless desert shrub. Objective Isolation, structure elucidation and evaluation of cytotoxic activity of flavonoids from C. polygonoides aerial parts. Materials and methods Flavonoids in the hydroalcoholic extract of the of C. polygonoides were isolated and purified using column chromatography and preparative HPLC. The structures of the isolated flavonoids were elucidated on the basis of spectroscopic data including 2D NMR techniques. The cytotoxic activity of the isolated flavonoids (6.25, 25, 50 and 100 μg/mL) was evaluated against liver HepG2 and breast MCF-7 cancer cell lines using sulphorhodamine-B assay. Results A new flavonoid, kaempferol-3-O-β-D-(6″-n-butyl glucuronide) (1), and 13 known flavonoids, quercetin 3-O-β-D-(6″-n-butyl glucuronide) (2), kaempferol-3-O-β-D-(6″-methyl glucuronide) (3), quercetin-3-O-β-D-(6″-methyl glucuronide) (4), quercetin-3-O-glucuronide (5), kaempferol-3-O-glucuronide (6), quercetin-3-O-α-rhamnopyranoside (7), astragalin (8), quercetin-3-O-glucopyranoside (9), taxifolin (10), (+)-catechin (11), dehydrodicatechin A (12), quercetin (13), and kaempferol (14), were isolated from the aerial parts of C. polygonoides. Quercetin showed significant cytotoxic activity against HepG2 and MCF-7 cell lines with IC50 values of 4.88 and 0.87 μg/mL, respectively. Structure-activity relationships were analyzed by comparing IC50 values of several pairs of flavonoids differing in one structural element. Discussion and conclusion The activity against breast cancer cell lines decreased by glycosylation at C-3. The presence of 2,3-double bond in ring C, carbonyl group at C-4 and 3',4'-dihydroxy substituents in ring B are essential structural requirements for the cytotoxic activity against breast cancer cells.

The Role of Natural Polyphenols in the Prevention and Treatment of Cervical Cancer-An Overview

Cervical cancer represents the second leading cause of death for women worldwide. The importance of the diet and its impact on specific types of neoplasia has been highlighted, focusing again interest in the analysis of dietary phytochemicals. Polyphenols have shown a wide range of cellular effects: they may prevent carcinogens from reaching the targeted sites, support detoxification of reactive molecules, improve the elimination of transformed cells, increase the immune surveillance and the most important factor is that they can influence tumor suppressors and inhibit cellular proliferation, interfering in this way with the steps of carcinogenesis. From the studies reviewed in this paper, it is clear that certain dietary polyphenols hold great potential in the prevention and therapy of cervical cancer, because they interfere in carcinogenesis (in the initiation, development and progression) by modulating the critical processes of cellular proliferation, differentiation, apoptosis, angiogenesis and metastasis. Specifically, polyphenols inhibit the proliferation of HPV cells, through induction of apoptosis, growth arrest, inhibition of DNA synthesis and modulation of signal transduction pathways. The effects of combinations of polyphenols with chemotherapy and radiotherapy used in the treatment of cervical cancer showed results in the resistance of cervical tumor cells to chemo- and radiotherapy, one of the main problems in the treatment of cervical neoplasia that can lead to failure of the treatment because of the decreased efficiency of the therapy.

Current state of phenolic and terpenoidal dietary factors and natural products as non-coding RNA/microRNA modulators for improved cancer therapy and prevention

The epigenetic regulation of cancer cells by small non-coding RNA molecules, the microRNAs (miRNAs), has raised particular interest in the field of oncology. These miRNAs play crucial roles concerning pathogenic properties of cancer cells and the sensitivity of cancer cells towards anticancer drugs. Certain miRNAs are responsible for an enhanced activity of drugs, while others lead to the formation of tumor resistance. In addition, miRNAs regulate survival and proliferation of cancer cells, in particular of cancer stem-like cells (CSCs), that are especially drug-resistant and, thus, cause tumor relapse in many cases. Various small molecule compounds were discovered that target miRNAs that are known to modulate tumor aggressiveness and drug resistance. This review comprises the effects of naturally occurring small molecules (phenolic compounds and terpenoids) on miRNAs involved in cancer diseases.

Chemical Profile, Antioxidant and Antibacterial Activities of Achillea moschata Wulfen, an Endemic Species from the Alps

Aerial parts of Achillea moschata Wulfen (Asteraceae) growing wild in the Italian Rhaetian Alps were investigated to describe, for the first time, their phenolic content, as well as to characterize the essential oil. Inspection of the metabolic profile combining HPLC-DAD and ESI-MS/MS data showed that the methanol extract contained glycosylated flavonoids with luteolin and apigenin as the main aglycones. Among them, the major compound was 7-O-glucosyl apigenin. Caffeoyl derivates were other phenolics identified. The essential oil obtained by steam distillation and investigated by GC/FID and GC/MS showed camphor, 1,8-cineole, and bornylacetate as the main constituents. The antioxidant capacity of three different extracts with increasing polarity and of the essential oil was evaluated by employing ABTS·+ and DPPH· radical scavenging assays. The methanolic extract was the only significantly effective sample against both synthetic radicals. All samples were also tested against Gram-positive (Bacillus cereus, Enterococcus faecalis, Staphylococcus aureus) and Gram-negative (Escherichia coli, Proteus mirabilis, Pseudomonas aeruginosa) bacterial species using the disk diffusion assay. The non-polar extracts (dichloromethane and petroleum ether) and the essential oil possessed a broad spectrum of antimicrobial activity expressed according to inhibition zone diameter (8–24 mm).

Preparation and Evaluation of Chrysin Encapsulated in PLGA- PEG Nanoparticles in the T47-D Breast Cancer Cell Line

BACKGROUND

Polymeric nanoparticles are attractive materials that have been widely used in medicine for drug delivery, with therapeutic applications. In our study, polymeric nanoparticles and the anticancer drug, chrysin, were encapsulated into poly (D, L-lactic-co-glycolic acid) poly (ethylene glycol) (PLGA-PEG) nanoparticles for local treatment.

MATERIALS AND METHODS

PLGA: PEG triblock copolymers were synthesized by ring-opening polymerization of D, L-lactide and glycolide as an initiator. The bulk properties of these copolymers were characterized using 1H nuclear magnetic resonance spectroscopy and Fourier transform infrared spectroscopy. In addition, the resulting particles were characterized by scanning electron microscopy.

RESULTS

The chrysin encapsulation efficiency achieved for polymeric nanoparticles was 70% control of release kinetics. The cytotoxicity of different concentration of pure chrysin and chrysin loaded in PLGA-PEG (5-640μM) on T47-D breast cancer cell line was analyzed by MTT-assay.

CONCLUSIONS

There is potential for use of these nanoparticles for biomedical applications. Future work should include in vivo investigation of the targeting capability and effectiveness of these nanoparticles in the treatment of breast cancer.

Solubility enhancement of morin and epicatechin through encapsulation in an albumin based nanoparticulate system and their anticancer activity against the MDA-MB-468 breast cancer cell line

Mor-HSA-NPs and EC-HSA-NPs are effective on MDA-MB-468 breast cancer cell lines.

Flavones Inhibit the Activity of AKR1B10, a Promising Therapeutic Target for Cancer Treatment

AKR1B10 is an NADPH-dependent reductase that plays an important function in several physiological reactions such as the conversion of retinal to retinol, reduction of isoprenyl aldehydes, and biotransformation of procarcinogens and drugs. A growing body of evidence points to the important role of the enzyme in the development of several types of cancer (e.g., breast, hepatocellular), in which it is highly overexpressed. AKR1B10 is regarded as a therapeutic target for the treatment of these diseases, and potent and specific inhibitors may be promising therapeutic agents. Several inhibitors of AKR1B10 have been described, but the area of natural plant products has been investigated sparingly. In the present study almost 40 diverse phenolic compounds and alkaloids were examined for their ability to inhibit the recombinant AKR1B10 enzyme. The most potent inhibitors-apigenin, luteolin, and 7-hydroxyflavone-were further characterized in terms of IC50, selectivity, and mode of action. Molecular docking studies were also conducted, which identified putative binding residues important for the interaction. In addition, cellular studies demonstrated a significant inhibition of the AKR1B10-mediated reduction of daunorubicin in intact cells by these inhibitors without a considerable cytotoxic effect. Although these compounds are moderately potent and selective inhibitors of AKR1B10, they constitute a new structural type of AKR1B10 inhibitor and may serve as a template for the development of better inhibitors.

Antioxidative and Anticanceric Activities of Magnolia (Magnolia denudata) Flower Petal Extract Fermented by Pediococcus acidilactici KCCM 11614

In this study, the effects of magnolia (Magnolia (M.) denudata) extract fermentation in increasing the extract's antioxidative and anticancer activities were investigated. Magnolia was fermented by Pediococcus acidilactici KCCM 11614. The total phenolic content was determined by the Folin-Ciocalteu's method and the antioxidative effects by 1,1-diphenyl-2-picrylhydrazy (DPPH) and ferric reducing ability of plasma (FRAP) assay. Anticancer activity against cancer and normal cells was determined using 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT). Total phenolic content during fermentation increased from 38.1 to 47.0 mg gallic acid equivalent (GAE)/g of solid matter. The radical scavenging activity was 91.4% after 72 h fermentation. Fermented magnolia's antioxidative effect was threefold higher than that of the (non-fermented) control. Fermentation (48 h) increased anticanceric activity against AGS, LoVo, and MCF-7 cancer cells 1.29- to 1.36-fold compared with that of the control, but did not affect MRC-5 (normal) cells, suggesting that fermented magnolia could be used as a natural antioxidative and anticancer agent.

Synthesis and anticancer activity of new flavonoid analogs and inconsistencies in assays related to proliferation and viability measurements

Flavonoids have been studied intensely for their ability to act as anti-carcinogenic, anti-inflammatory, anti-viral and anti-aging agents and are often marketed as supplements related to their anti-inflammatory activity. Previous studies have primarily focused on the effects of polar natural flavonoids. We examined the activity of novel hydrophobic and lipophilic flavonols against human DU-145 and PC-3 prostate cancer cell lines. All flavonol analogs were more active than the naturally occurring flavonols quercetin, kaempferol, kaempferide and galangin. The most potent analogs were 6.5-fold more active against DU-145 and PC-3 cells than quercetin and fell within the biologically relevant concentration range (low micromolar). We also evaluated the potential toxic effects of flavonol analogs on normal cells, an assessment that has frequently been ignored when studying the anticancer effects of flavonoids. During these analyses, we discovered that various metabolic and DNA staining assays were unreliable methods for assessing cell viability of flavonoids. Flavonoids reduce colorimetric dyes such as MTT and Alamar Blue in the absence of cells. We showed that flavonol-treated prostate cancer cells were stained less intensely with crystal violet than untreated cells at non-toxic concentrations. The trypan blue exclusion assay was selected as a reliable alternative for measuring cell viability.

In vitro action of flavonoids in the canine malignant histiocytic cell line DH82

Cancer is commonly diagnosed in dogs over the age of 10 and is a leading cause of death due to the lack of effective drugs. Flavonoids possess antioxidant, anti-inflammatory and anticarcinogenic properties and have been studied as chemopreventive agents in human cancer therapy. However, the literature on dogs is sparse. In this study, we analyzed the effect of nine flavonoids on cell viability, DNA damage and topoisomerase IIa/IIb gene expression in a canine tumor cell line (DH82). Apigenin, luteolin, trans-chalcone and 4-methoxychalcone showed the highest degree of cytotoxicity in the absence of considerable DNA damage, whereas genistein exhibited low cytotoxicity but induced a high level of DNA damage. These five flavonoids inhibited topoisomerase IIa and IIb gene expression to variable extents and with variable specificity. Genistein exerted a lower inhibitory effect on the two topoisomerases than luteolin and apigenin. trans-Chalcone and 4-methoxychalcone exerted greater inhibition of topoisomerase IIa expression than topoisomerase IIb. The differences in the effects between genistein and luteolin and apigenin might be explained by the position of ring B, whereas the more specific effect of chalcones on topoisomerase IIa might be due to their open chain structure.

Cytotoxic, genotoxic and antigenotoxic potencies of oligorutins

Rutin has been enzymatically oligomerized by laccase from Trametes versicolor. Five fractions of oligomers were obtained from the monomers having high solubility in water, which can reach 351-times that of rutin. Cytotoxicity of rutin and oligorutin fractions was evaluated towards K562 cells. Oligorutin fractions showed a lower antiproliferative effect compared with its monomer. The genotoxic potential of rutin and oligorutin fractions was assessed, at the limit of the solubility of each molecule, using the comet test. None of the tested concentrations of either rutin or oligorutin fractions has showed a genotoxic effect. Similarly, the antigenotoxic effect of these flavonoids was tested using the same assay. The obtained results showed a higher ability of oligorutin fractions to reduce the genotoxicity induced by hydrogen peroxide compared with monomeric rutin.

Cytotoxic and pro-apoptotic effects of Abrus precatorius L. on human metastatic breast cancer cell line, MDA-MB-231

Abrus precatorius is highly regarded as a universal panacea in the herbal medicine with diverse pharmacological activity spectra. This experimental study on the mechanism of the anticancer activity of A. precatorius leaf extracts, may offer new evidence for A. precatorius in the treatment of breast cancer in clinical practice. Cell death was determined by using MTT assay. Further analyses were carried out by doing DNA laddering, PARP cleavage, FACS, semi-quantitative RT-PCR and detection of cellular reactive oxygen species (ROS) by DCFDA assay. A. precatorius showed very striking inhibition on MDA-MB-231 cells. MTT assay showed more than 75 % inhibition of the cells and treated cells indicated visible laddering pattern with thick compact band. PARP cleavage produced 89 kDa cleavage product which was associated with apoptosis. Flow cytometer exhibited a sub-G0/G1 peak as an indicative of apoptosis. mRNA expression level of apoptosis-related genes p21 and p53 was markedly increased in cells treated with the extract as compared to control. The up-regulation of p21 and p53 may be the molecular mechanisms by which A. precatorius extract which induces apoptosis. An increase in the concentration of A. precatorius extract does not generate ROS, instead it reduces ROS formation in MDA-MB-231 cells, as evident from the shift in fluorescence below untreated control. This is the first report showing that A. precatorius leaf extract exhibits a growth inhibitory effect by induction of apoptosis in MDA-MB-231 cells. Our results contribute towards validation of the A. precatorius extract as a potentially effective chemopreventive or therapeutic agent against breast cancer.

MicroRNA-34a and microRNA-21 play roles in the chemopreventive effects of 3,6-dihydroxyflavone on 1-methyl-1-nitrosourea-induced breast carcinogenesis

Introduction

miRNAs are very important regulators in biological processes such as development, cellular differentiation, and carcinogenesis. Given the important role of miRNAs in tumorigenesis and development, it is worth investigating whether some miRNAs play roles in the anticancer mechanism of flavonoids. However, such a role has not yet been reported. We previously selected the promising anticancer agent 3,6-dihydroxyflavone (3,6-DHF) in pharmacodynamic experiments, which may serve as a leading compound for developing more potent anticancer drugs or chemopreventive supplements. The present study aims to investigate the chemopreventive activities of 3,6-DHF against mammary carcinogenesis.

Methods

The experimental model of breast carcinogenesis was developed by intraperitoneal injection of 1-methyl-1-nitrosourea (MNU). The bioavailability of 3,6-DHF in rats was detected by HPLC. The expression of microRNA-34a (miR-34a) and microRNA-21 (miR-21) was evaluated by real-time quantitative RT-PCR. Cell apoptosis was analyzed by flow cytometry or terminal deoxynucleotidyl transferase dUTP nick end-labeling assay. The mitochondrial membrane potential was assayed using 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethyl-imidacarbocyanine iodide dye by confocal laser scanning microscopy. The level of cytochrome C in cytosol was evaluated by western blotting.

Results

Our study showed that oral administration of 3,6-DHF effectively suppressed MNU-induced breast carcinogenesis in rats, decreasing the cancer incidence by 35.7%. The detection of bioavailability indicated that the concentration of 3,6-DHF was 2.5 ± 0.4 μg/ml in plasma of rats within 2 hours after administration, and was 21.7 ± 3.8 μg/ml in urine within 24 hours. Oral administration of 3,6-DHF to BALB/c nude mice bearing breast cancer cell xenografts also significantly suppressed tumor growth in vivo. Furthermore, our study revealed that the global upregulation of miR-21 and downregulation of miR-34a in breast carcinogenesis could be reversed by 3,6-DHF, which significantly upregulated miR-34a expression and decreased miR-21 expression - inducing apoptosis of breast cancer cells in vitro and in vivo. Overexpression of miR-34a induced by plasmid transfection or inhibition of miR-21 by oligonucleotides markedly promoted the pro-apoptotic effect of 3,6-DHF. Inactivation of miR-34a or overproduction of miR-21 compromised the anticancer effects of 3,6-DHF.

Conclusion

These findings indicate that 3,6-DHF is a potent natural chemopreventive agent, and that miR-34a and miR-21 play roles in MNU-induced breast carcinogenesis and the anticancer mechanism of flavonoids.

Plant HDAC inhibitor chrysin arrest cell growth and induce p21WAF1 by altering chromatin of STAT response element in A375 cells

Background

Chrysin and its analogues, belongs to flavonoid family and possess potential anti-tumour activity. The aim of this study is to determine the molecular mechanism by which chrysin controls cell growth and induce apoptosis in A375 cells.

Methods

Effect of chrysin and its analogues on cell viability and cell cycle analysis was determined by MTT assay and flowcytometry. A series of Western blots was performed to determine the effect of chrysin on important cell cycle regulatory proteins (Cdk2, cyclin D1, p53, p21, p27). The fluorimetry and calorimetry based assays was conducted for characterization of chrysin as HDAC inhibitor. The changes in histone tail modification such as acetylation and methylation was studied after chrysin treatment was estimated by immuno-fluorescence and western blot analysis. The expression of Bcl-xL, survivin and caspase-3 was estimated in chrysin treated cells. The effect of chrysin on p21 promoter activity was studied by luciferase and ChIP assays.

Results

Chrysin cause G1 cell cycle arrest and found to inhibit HDAC-2 and HDAC-8. Chrysin treated cells have shown increase in the levels of H3acK14, H4acK12, H4acK16 and decrease in H3me2K9 methylation. The p21 induction by chrysin treatment was found to be independent of p53 status. The chromatin remodelling at p21^WAF1 promoter induces p21 activity, increased STAT-1 expression and epigenetic modifications that are responsible for ultimate cell cycle arrest and apoptosis.

Conclusion

Chrysin shows in vitro anti-cancer activity that is correlated with induction of histone hyperacetylation and possible recruitment of STAT-1, 3, 5 proteins at STAT (−692 to −684) region of p21 promoter. Our results also support an unexpected action of chrysin on the chromatin organization of p21^WAF1 promoter through histone methylation and hyper-acetylation. It proposes previously unknown sequence specific chromatin modulations in the STAT responsive elements for regulating cell cycle progression negatively via the induction of the CDK inhibitor p21^WAF1.

Geranylated flavanone tomentodiplacone B inhibits proliferation of human monocytic leukaemia (THP-1) cells

BACKGROUND AND PURPOSE

Paulownia tomentosa is a rich source of geranylated flavanones, some of which we have previously shown to have cytotoxic activity. To identify members of this class of compounds with cytostatic effects, we assessed the effects of the geranylated flavanone tomentodiplacone B (TOM B) on cell cycle progression and cell cycle regulatory pathways of THP-1 human monocytic leukaemia cells.

EXPERIMENTAL APPROACH

Cell viability was measured by dye exclusion and proliferation by WST-1 assays; cell cycle was monitored by flow cytometry. Regulatory proteins were assessed by immunoprecipitation and kinase assays, and Western blotting.

KEY RESULTS

Tomentodiplacone B had no effect during the first 24 h of cell growth at concentrations between 1 and 2.5 µM, but inhibited cell growth in a dose-dependent manner at concentrations of 5 µM or higher. Growth inhibition during the first 24 h of exposure to TOM B was not accompanied by cytotoxicity as cells were accumulated in G1 phase dose-dependently. This G1 phase accumulation was associated with down-regulation of cyclin-dependent kinase 2 activity and also protein levels of cyclins E1 and A2. However, key stress-related molecules (γ-H2AX, p53 and p21) were not induced, suggesting that TOM B acts by directly inhibiting the cyclin-dependent kinase 2 signalling pathway rather than initiating DNA damage or cellular stress.

CONCLUSIONS AND IMPLICATIONS

Our study provides the first evidence that TOM B directly inhibits proliferation of human monocytic leukaemia cells, and thus is a potential anticancer agent, preventing leukaemia cells from progressing from G1 phase into DNA synthesis.

Anticancer activities of an anthocyanin-rich extract from black rice against breast cancer cells in vitro and in vivo

Anthocyanins widely present in human diet and have a variety of health effects. This study investigates the anticancer effects of an anthocyanin-rich extract from black rice (AEBR) on breast cancer cells in vitro and in vivo. AEBR reduced the viability of breast cancer cell lines MCF-7 (ER(+), HER2/neu(-)), MDA-MB-231 (ER(-), HER2/neu(-)), and MDA-MB-453 (ER(-), HER2/neu(+)) and induced apoptosis in MDA-MB-453 cells via the intrinsic pathway in vitro by activating caspase cascade, cleaving poly (ADP-ribose) polymerase (PARP), depolarizing mitochondrial membrane potential, and releasing cytochrome C. Oral administration of AEBR (100 mg/kg/day) to BALB/c nude mice bearing MDA-MB-453 cell xenografts significantly suppressed tumor growth and angiogenesis by suppressing the expression of angiogenesis factors MMP-9, MMP-2, and uPA in tumor tissue. Altogether, this study suggests the anticancer effects of AEBR against human breast cancer cells in vitro and in vivo by inducing apoptosis and suppressing angiogenesis.

Activity investigation of pinostrobin towards herpes simplex virus-1 as determined by atomic force microscopy

In the present study, the antiviral activity of pinostrobin towards herpes simplex virus-1 (HSV-1) was investigated by MTT assay and atomic force microscopy. Pinostrobin can inhibit HSV-1 replication with 50% effective concentration (EC(50)) of 22.71 ± 1.72 μg/ml. MTT assay showed HSV-1 was significantly inhibited when pretreated with pinostrobin, with the inhibition of 85.69 ± 2.59%. Significant changes in morphology and size of HSV-1 were observed by atomic force microscopy (AFM) in response to pinostrobin treatment. AFM topography and phase images showed that with increasing time, the envelope was shedded and damaged, finally leading to virus inactivation. With increasing concentration, pinostrobin caused a gradual leakage, also contributing to breakage of the envelope and virus inactivation. Treatment effect of oral pinostrobin in vivo showed that pinostrobin (50mg/kg/dose) possesses definite therapeutical effect in the development of lesion score. In general, the results showed that AFM represents a powerful technique for the investigation of morphology and size of HSV-1 treated by antiviral agents. AFM is applicable to study chemically induced morphological changes at the nanometer level.

Tualang honey induces apoptosis and disrupts the mitochondrial membrane potential of human breast and cervical cancer cell lines

Honey is reported to contain various compounds such as phenols, vitamins and antioxidants. The present study investigates the anticancer potential of Tualang honey (Agromas) (TH) in human breast (MCF-7 and MDA-MB-231) and cervical (HeLa) cancer cell lines; as well as in the normal breast epithelial cell line, MCF-10A. The cells were treated with increasing doses of TH (1-10%) for up to 72 h. Increase in lactate dehydrogenase (LDH) leakage from the cell membranes indicates that TH is cytotoxic to all three cancer cells with effective concentrations (EC(50)) of 2.4-2.8%. TH is however, not cytotoxic to the MCF-10A cells. Reactivity with annexin V fluorescence antibody and propidium iodide as analysed by flow cytometry and fluorescence microscopy shows that apoptosis occurred in these cancer cells. TH also reduced the mitochondrial membrane potential (Δψ(m)) in the cancer cell lines after 24h of treatment. The activation of caspase-3/7 and -9 was observed in all TH-treated cancer cells indicating the involvement of mitochondrial apoptotic pathway. This study shows that TH has significant anticancer activity against human breast and cervical cancer cell lines.

Cytotoxicity of Constituents from Mexican Propolis against a Panel of Six Different Cancer Cell Lines

The cytotoxicity of 39 compounds, including eighteen flavonoids (flavanones, 1–10; flavones, 11–17; flavanol, 18), sixteen phenolic acid derivatives (aromatic acids, 19–24; aldehyde, 25; esters, 26–34) and five glycerides (35–39), isolated from Mexican propolis, were evaluated against a panel of six different cancer cell lines; murine colon 26-L5 carcinoma, murine B16-BL6 melanoma, murine Lewis lung carcinoma, human lung A549 adenocarcinoma, human cervix HeLa adenocarcinoma and human HT-1080 fibrosarcoma. A phenylpropanoid-substituted flavanol, (2 R,3 S)-8-[4-phenylprop-2-en-1-one]-4’,7-dihydroxy-3’,5-dimethoxyflavan-3-ol (18), showed the most potent cytotoxicity against A549 cells (IC50, 6.2 μM) and HT-1080 cells (IC50, 3.9 μM), stronger than those of the clinically used anticancer drug, 5-fluorouracil (IC50, 7.5 μM and 5.4 μM, respectively). Based on the observed results, the structure–activity relationships are discussed.