Antiproliferative Effects of Apple Peel Extract Against Cancer Cells

The potential chemo-preventive roles of Malus domestica against the risk of colorectal cancer: A suggestive insight into clinical application

Biologically active compounds in fruit-derived ingredients, particularly phytochemicals, have significant potential to modulate and mitigate many pathological processes in the development of disease conditions, including cancer. Colorectal cancer (CRC) remains a major public health issue. Nonetheless, prevention is an important step in lowering the rate of mortality from this cancer. Currently, the link between apple consumption and improved health is becoming remarkably evident and is reported to be beneficial for human health. Phytochemicals, such as flavonoids and other polyphenol compounds extensively available in apple fruits, have well-known positive effects on health outcomes and the potential to combat and prevent the development of CRC, including antioxidant, anti-proliferative, and anti-carcinogenic effects. This review describes the bioactive compounds derived from apple fruits, particularly the polyphenols and flavonoids, their proposed mechanisms responsible for their bioactive properties and health-promoting attributes that could provide potential chemo-preventive effects against the risk of CRC development. The conclusion of the review provides insights into the potential effects of apple-derived bioactive compounds and proposes the need for more clinical studies in large trials for future strategies regarding the valuable effects of apple phytochemicals, which might be therapeutic candidates in the campaign against CRC.

Empire Apple (Malus domestica) Juice, Pomace, and Pulp Modulate Intestinal Functionality, Morphology, and Bacterial Populations In Vivo (Gallus gallus)

Approximately $20 billion of apple sales are generated annually in the United States. With an estimated 5 million tons produced yearly in the U.S. within the last decade, apple consumption is considered ubiquitous. Apples are comprised of bioactive constituents such as phytochemicals and prebiotics that may potentiate intestinal health and the gut microbiome. This study aimed to evaluate the effects of Empire apple juice, pomace, and pulp soluble extracts on intestinal functionality, morphology, and the microbiome in vivo (Gallus gallus). There were five treatment groups: non-injected (NI); 18 MΩ H2O (H2O); 6% apple juice (AJ); 6% apple pomace (APo); 6% apple pulp (APu). The eggs were treated by intra-amniotic administration of the samples on day 17 of incubation. After hatching, the blood, tissue, and cecum samples were collected for further analyses—including duodenal histomorphology, hepatic and duodenal mRNA expression, and cecal bacterial populations. Crypt depth was significantly (p < 0.5) shortest in AJ when compared to APo and APu. APo and APu soluble extracts significantly improved villi surface area compared to NI and H2O control groups. The highest count of Paneth cells per crypt was observed in APo as compared to all groups. In addition, the expression of brush border membrane micronutrient metabolism and functional proteins varied between treatments. Lastly, Lactobacillus cecal microbial populations increased significantly in the AJ group, while AJ, APu, and APu increased the abundance of Clostridium (p < 0.5). Ultimately, these results indicate the potential of Empire apple pomace to improve host intestinal health and the gut microbiome.

PPAR-γ Partial Agonists in Disease-Fate Decision with Special Reference to Cancer

Peroxisome proliferator-activated receptor-γ (PPAR-γ) has emerged as one of the most extensively studied transcription factors since its discovery in 1990, highlighting its importance in the etiology and treatment of numerous diseases involving various types of cancer, type 2 diabetes mellitus, autoimmune, dermatological and cardiovascular disorders. Ligands are regarded as the key determinant for the tissue-specific activation of PPAR-γ. However, the mechanism governing this process is merely a contradictory debate which is yet to be systematically researched. Either these receptors get weakly activated by endogenous or natural ligands or leads to a direct over-activation process by synthetic ligands, serving as complete full agonists. Therefore, fine-tuning on the action of PPAR-γ and more subtle modulation can be a rewarding approach which might open new avenues for the treatment of several diseases. In the recent era, researchers have sought to develop safer partial PPAR-γ agonists in order to dodge the toxicity induced by full agonists, akin to a balanced activation. With a particular reference to cancer, this review concentrates on the therapeutic role of partial agonists, especially in cancer treatment. Additionally, a timely examination of their efficacy on various other disease-fate decisions has been also discussed.

Onco-Preventive and Chemo-Protective Effects of Apple Bioactive Compounds

Cancer is one of the leading causes of death globally. Epidemiological studies have strongly linked a diet high in fruits to a lower incidence of cancer. Furthermore, extensive research shows that secondary plant metabolites known as phytochemicals, which are commonly found in fruits, have onco-preventive and chemo-protective effects. Apple is a commonly consumed fruit worldwide that is available all year round and is a rich source of phytochemicals. In this review, we summarize the association of apple consumption with cancer incidence based on findings from epidemiological and cohort studies. We further provide a comprehensive review of the main phytochemical patterns observed in apples and their bioavailability after consumption. Finally, we report on the latest findings from in vitro and in vivo studies highlighting some of the key molecular mechanisms targeted by apple phytochemicals in relation to inhibiting multiple 'hallmarks of cancer' that are important in the progression of cancer.

Zinc oxide nanoparticles enhance expression of maspin in human breast cancer cells

Toxic and apoptotic impacts of zinc oxide nanoparticle (ZNP) on different cancer cells have been reported. Maspin (a mammary serine protease inhibitor) as a tumor suppressor gene can inhibit tumor growth and metastasis. The expression of maspin is modulated by p53, Bcl-2 family genes, and estrogen receptor α (ER-α). This study aimed to assess the ZNP effects on maspin expression in MCF-7 cells (a breast cancer cell). Experimental groups (ZNP5, ZNP10, and ZNP20) received 5, 10, and 20 μM/mL ZNP for 48 h, respectively. 17-β-estradiol (E2) was used to evaluate the role of ER-α in the anticancer impact of ZNP. Cell viability, Annexin V, migration assay, gene expression, and western blotting methods were applied to evaluate ZNP effects on the MCF-7 cells. ZNP at the concentrations of 10 and 20 μM/mL could significantly decrease the viability and migration rate, and significantly increase apoptosis percentage in the MCF-7 cells. ZNP significantly enhanced mRNA expression and protein level of maspin in MCF-7 cells in a concentration-dependent way. ZNP concentration-dependently elevated mRNA expression and protein level of p53 and Bax while reduced the expression of Bcl-2 and ER-α. E2 promoted cancer cell growth by enhancing survival and migration rates. E2 treatment reduced mRNA expression and protein level of maspin and p53, and elevated Bcl-2 expression. ZNP considerably changed these events induced by E2 in the MCF-7 cells. It is concluded that the maspin overexpression is one of the toxic mechanisms of the ZNP on the ER-α-positive breast cancer cells, and can suppress the migration of these cells.

Antioxidant, antimicrobial, and antiproliferative activity-based comparative study of peel and flesh polyphenols from Actinidia chinensis

Background

Kiwifruit (Actinidia chinensis) peel has been always considered as useless because of the harsh taste. To promote the full utilization of kiwifruit resources it is essential to explore the nutritional benefits of kiwifruit peel.

Objective

Our studies explored the difference in polyphenolic composition and biological activity including antioxidant, antimicrobial, and antiproliferative activity of the flesh and peel of kiwifruit.

Design

Antioxidant activity of the extracted polyphenols of the peel and flesh of A. chinensis was checked by 2,2-diphenyl-1-picrylhydrazyl, 2,2’-azino-bis3-ethylbenzothiazoline-6-sulphonic acid (ABTS), hydroxyl ion reduction, and ion chelating ability. Antibacterial activity against Escherichia coli, Listeria monocytogenes, and Staphylococcus aureus and antiproliferative activity against HepG2 was tested in a dose- and time-dependent manner. Liquid chromatography/mass spectrometry (LC/MS) chromatogram of the peel and flesh further differentiated the phenolic acid profile.

Results

The pericarp of kiwifruit was found to be more abundant in polyphenols and flavonoids than the flesh, with contents of 12.8 mg/g and 2.7 mg/g, respectively. LC/MS analysis revealed that the catachin, quercetin and epigallocatechin content (the main polyphenols in kiwifruit) in the peel was significantly higher than in the flesh (P < 0.05). The antioxidant and antibacterial activity of the peel was significantly higher when compared to the flesh. Moreover, the proliferation of HepG2 cells was time- and dose-dependently inhibited by kiwifruit polyphenols, with IC₅₀ values of 170 μg/mL and 291 μg/mL for peel and flesh polyphenols after 72 h of treatment time, respectively.

Conclusion

Kiwifruit peel, with higher content of phenolics and flavonoids, exerts more potent antioxidant, antibacterial, and anticancer activity than the flesh. Our study provides scientific evidence for the development of kiwifruit, especially peel-based, novel natural products with excellent bioactivity.

Antiproliferative Effects of Pancratium Maritimum Extracts on Normal and Cancerous Cells

BACKGROUND

Plants are an important natural source of compounds used in cancer therapy. Pancratium maritimum contains potential anti-cancer agents such as alkaloids. In this study, we investigated the anti-proliferative effects of P. maritimum extracts on MDA-MB-231 human epithelial adenocarcinoma cell line and on normal lymphocytes in vitro.

METHODS

Leaves, flowers, roots, and bulbs of P. maritimum were collected and their contents were extracted and diluted to different concentrations that were applied on MDA-MB-231 cells and normal human lymphocytes cell in vitro for different intervals. Cells viability, proliferation, cell cycle distribution, apoptosis, and growth were evaluated by flow cytometry and microscopy. Parametric unpaired t-test was used to compare effects of plant extracts on treated cell cultures with untreated control cell cultures. IC₅₀ was also calculated.

RESULTS

P. maritimum extract had profound effects on MDA-MB-321 cells. It inhibited cell proliferation in a dose- and time-dependent manner. The IC₅₀ values were 0.039, 0.035, and 0.026 mg/ml after 48, 72, and 96 hours of treatment with 0.1 mg/ml concentration of bulb extract, respectively. Those values were 0.051 and 0.03 mg/ml after 72 and 96 hours for root extract, respectively, and 0.048 mg/ml after 96 hours for flower extract. There were no significant effects of P. maritimum bulb extracts on normal lymphocytes proliferation.

CONCLUSION

P. maritimum extract has anti-proliferative effects on MDA-MB-231 cell line in vitro. The effects imply the involvement of mechanisms that inhibits cell growth and arresting cells at S and G₂/M phases. Cyclin B1, Bcl-2, and Ki67 expression was also affected.

The apple polyphenol phloretin inhibits breast cancer cell migration and proliferation via inhibition of signals by type 2 glucose transporter

Human triple-negative breast cancer (TNBC) is the most aggressive and poorly understood subclass of breast cancer. Glucose transporters (GLUTs) are required for glucose uptake in malignant cancer cells and are ideal targets for cancer therapy. To determine whether the inhibition of GLUTs could be used in TNBC cell therapy, the apple polyphenol phloretin (Ph) was used as a specific antagonist of GLUT2 protein function in human TNBC cells. Interestingly, we found that Ph (10–150 μM, for 24 h) inhibited cell growth and arrested the cell cycle in MDA-MB-231 cells in a p53 mutant-dependent manner, which was confirmed by pre-treatment of the cells with a p53-specific dominant-negative expression vector. We also found that Ph treatment (10–150 μM, for 24 h) significantly decreased the migratory activity of the MDA-MB-231 cells through the inhibition of paxillin/FAK, Src, and alpha smooth muscle actin (α-sMA) and through the activation of E-cadherin. Furthermore, the anti-tumorigenic effect of Ph (10, 50 mg/kg or DMSO twice a week for six weeks) was demonstrated in vivo using BALB/c nude mice bearing MDA-MB-231 tumor xenografts. A decrease in N-cadherin, vimentin and an increase in p53, p21 and E-cadherin were detected in the tumor tissues. In conclusion, inhibition of GLUT2 by the apple polyphenol Ph could potentially suppress TNBC tumor cell growth and metastasis.

Naturally occurring compounds acting as potent anti-metastatic agents and their suppressing effects on Hedgehog and WNT/β-catenin signalling pathways

Despite numerous remarkable achievements in the field of anti-cancer therapy, tumour relapse and metastasis still remain major obstacles in improvement of overall cancer survival, which may be at least partially owing to epithelial-mesenchymal transition (EMT). Multiple signalling pathways have been identified in EMT; however, it appears that the role of the Hedgehog and WNT/β-catenin pathways are more prominent than others. These are well-known preserved intracellular regulatory pathways of different cellular functions including proliferation, survival, adhesion and differentiation. Over the last few decades, several naturally occurring compounds have been identified to significantly obstruct several intermediates in Hedgehog and WNT/β-catenin signalling, eventually resulting in suppression of signal transduction. This article highlights the current state of knowledge associated with Hedgehog and WNT/β-catenin, their involvement in metastasis through EMT processes and introduction of the most potent naturally occurring agents with capability of suppressing them, eventually overcoming tumour relapse, invasion and metastasis.

Apple polyphenol extract improves insulin sensitivity in vitro and in vivo in animal models of insulin resistance

BACKGROUND

Apple polyphenols could represent a novel nutritional approach in the management and control of blood glucose, especially in type 2 diabetics. The aim of this study was to test the therapeutic potential of an apple polyphenol extract (APE) in an insulin-resistant rat model and to determine the molecular basis of insulin sensitivity action in skeletal muscle cells.

METHODS

Acute effect of APE on the postprandial hyperglycemic response was assayed in 15 week old obese Zucker rats (OZR), by using a meal tolerance test (MTT). The ability of APE to improve whole peripheral insulin sensitivity was also assayed in a chronic study by using the euglycemic-hyperinsulinemic clamp technique. To elucidate the molecular mechanisms, rat L6 myotubes were used. Glucose uptake was measured by using 2-[3H]-Deoxy-Glucose (2-DG) and specific inhibitors, as well as phosphorylation status of key kinases, were used to determine the implicated signaling pathway.

RESULTS

In vivo study showed that nutritional intervention with APE induced an increase of insulin sensitivity with an increase of glucose infusion rate (GIR) of 45 %. Additionally, in vitro results showed a synergistic effect between APE and insulin as well as increased glucose uptake through GLUT4 translocation in muscle cells. This translocation was mediated by phosphatydil inositol 3-kinase (PI3K) and peroxisome proliferator-activated receptor-gamma (PPARγ) signaling pathways.

CONCLUSIONS

As a whole, this study describes the mechanisms involved in the insulin sensitizing effect of APE, which could be considered a promising ingredient for inclusion in nutritional products focused on the management of chronic diseases such as diabetes.

Protective effects of Egyptian cloudy apple juice and apple peel extract on lipid peroxidation, antioxidant enzymes and inflammatory status in diabetic rat pancreas

Background

Apples possess rich content of varied polyphenolic compounds showing a variety of biological activities that may ascribe to worthy effects against some chronic diseases. The present study was designed to assess the protective effects of the cloudy apple juice (CAJ) and apple peel extract (APE) of Egyptian Anna apple on the complications in experimental diabetes.

Materials and methods

Four groups were studied. Diabetes was induced by a single dose of streptozotocin (STZ) to only three groups of albino Wistar rats. Two of the diabetic groups received either CAJ or APE for 21 days. At the end of the study, lipid profile parameters were measured in serum while lipid peroxidation (LPO) level, antioxidant enzyme activities and inflammatory markers were evaluated in pancreas tissue samples. The gas chromatography–mass spectrometry (GC-MS) analysis of phenolic compounds found in CAJ and APE was carried out. Moreover, total phenolic content of CAJ and APE were measured.

Results

The significant increase of blood glucose level, serum total cholesterol (TC), triglycerides (TG), low- density lipoprotein cholesterol (LDL-C), and very low-density lipoprotein (VLDL) levels, in addition to tissue malondialdehyde (MDA), nuclear factor kappa B (NF-kB), tumor necrosis factor α (TNF-α), interleukin 6 (IL-6), interleukin 8 (IL-8) levels, but a significant decrease in high-density lipoprotein cholesterol (HDL-C), and the activity of pancreatic antioxidant enzymes were the remarkably parameters observed in diabetic control rats. Dissimilarly, oral supplementation of 15 ml/kg CAJ and 1 g/kg APE for 21 days resulted in a significant decrease in fasting blood glucose, serum TC, TG, LDL-C, VLDL-C and tissue MDA, NF-kB, TNF-α, IL-6, IL-8 levels coupled with a significant elevation of HDL-C and antioxidant enzymes’ activity when compared with diabetic control animals.

Conclusions

The results indicate that Egyptian CAJ and APE supplementation may have protective effects against deleterious complications of diabetes mellitus.

Application of an Optimized HPLC Method for the Detection of Various Phenolic Compounds in Apples from Lithuanian Cultivars

A specific analytical procedure including sample preparation and HPLC analysis was developed and validated for the detection of phenolic compounds in the samples of different apples from popular Lithuanian cultivars “Aldas,” “Auksis,” “Ligol,” and “Šampion.” The conditions for phenol extraction were optimized: the solvent of the extraction was 70% (v/v) ethanol, and the extraction was performed in an ultrasound bath for 20 min at the temperature of 40°C. The HPLC mobile phase consisted of 2% (v/v) acetic acid in water and 100% (v/v) acetonitrile. Using the HPLC technique, 11 analytes were identified, and their specificity was confirmed: procyanidin B1, (+)-catechin, chlorogenic acid, procyanidin B2, (−)-epicatechin, rutin, hyperoside, isoquercitrin, avicularin, quercitrin, and phloridzin. Chlorogenic acid was the major component in “Aldas,” “Auksis,” and “Ligol” and procyanidin B2 in “Šampion.” Hyperoside and avicularin were the dominant compounds of all the identified quercetin derivatives in “Aldas” and “Auksis;” hyperoside in “Šampion;” and quercitrin in “Ligol.” The total content of phenolic compounds varied from 1641.0 ± 47.9 μg/g (cv. “Ligol”) to 4291.3 ± 154.2 μg/g (cv. “Aldas”).

Dietary patterns and breast cancer risk in the California Teachers Study cohort

BACKGROUND

Evidence that diet is associated with breast cancer risk is inconsistent. Most studies have examined risks associated with specific foods and nutrients, rather than measures of overall diet.

OBJECTIVE

This study aimed to evaluate dietary patterns and their relation to breast cancer risk in a large cohort of women.

DESIGN

Data from 91,779 women in the California Teachers Study cohort were analyzed, including data from 4140 women with a diagnosis of invasive breast cancer made between 1995 and 2009. Five predominant dietary patterns were identified by using principal components factor analysis: a plant-based diet, high in fruit and vegetables; a high-protein, high-fat diet, high in meats, eggs, fried foods, and high-fat condiments; a high-carbohydrate diet, high in convenience foods, pasta, and bread products; an ethnic diet, high in legumes, soy-based foods, rice, and dark-green leafy vegetables; and a salad and wine diet, high in lettuce, fish, wine, low-fat salad dressing, and coffee and tea.

RESULTS

The plant-based pattern was associated with a reduction in breast cancer risk (RR: 0.85; 95% CI: 0.76, 0.95 for the highest compared with the lowest consumption quintile; P-trend = 0.003); risk reduction was greater for estrogen receptor-negative progesterone receptor-negative (ER-PR-) tumors (RR: 0.66; 95% CI: 0.48, 0.91; P-trend = 0.03). The salad and wine pattern was associated with an increased risk of estrogen receptor-positive progesterone receptor-positive tumors (RR: 1.29; 95% CI: 1.12, 1.49); this effect was only slightly attenuated after adjustment for alcohol consumption.

CONCLUSION

The finding that greater consumption of a plant-based dietary pattern is associated with a reduced breast cancer risk, particularly for ER-PR- tumors, offers a potential avenue for prevention.

Callose and cellulose synthase gene expression analysis from the tight cluster to the full bloom stage and during early fruit development in Malus × domestica

Apple (Malus × domestica) is an economically important temperate fruit-bearing crop which belongs to the family of Rosaceae and its pomaceous fruit is one of the most commonly cultivated. Several studies have demonstrated that the cell wall plays a pivotal role during flower and fruit development. It takes active part in pollen tube growth and contributes to determine the fruit firmness trait through the action of cell wall-related enzymes (i.e. polygalacturonase and pectinmethylesterase). We have investigated the expression of callose and cellulose synthase genes during flowering from tight cluster to anthesis and during early fruit development in domesticated apple. We also link the changes observed in gene expression to the profile of soluble non-structural carbohydrates at different developmental stages of flowers/fruitlets and to the qualitative results linked to wall polysaccharides' composition obtained through near-infrared spectroscopy. This work represents an important addition to the study of tree physiology with respect to the analysis of the expression of callose and cellulose synthase genes during flower and early fruit development in domesticated apple.

Role of maspin in cancer

Maspin (mammary serine protease inhibitor), is a member of the serine protease inhibitor/non-inhibitor superfamily. Its expression is down-regulated in breast, prostate, gastric and melanoma cancers but over-expressed in pancreatic, gallbladder, colorectal, and thyroid cancers suggesting that maspin may play different activities in different cell types. However, maspin expression seems to be correlated with better prognosis in prostate, bladder, lung, gastric, colorectal, head and neck, thyroid and melanoma cancer. In breast and ovarian cancer maspin significance is associated with its subcellular localization: nucleus maspin expression correlates with a good prognosis, whilst in pancreatic cancer it predicts a poor prognosis. Since tumor metastasis requires the detachment and invasion of tumor cells through the basement membrane and stroma, a selectively increased adhesion by the presence of maspin may contribute to the inhibition of tumor metastasis. Furthermore the different position of maspin inside the cell or its epigenetic modifications may explain the different behavior of the expression of maspin between tumors. The expression of maspin might be useful as a prognostic and possibly predictive factor for patients with particular types of cancer and data can guide physicians in selecting therapy. Its expression in circulating tumor cells especially in breast cancer, could be also useful in clinical practice along with other factors, such as age, comorbidities, blood examinations in order to select the best therapy to be carried out. Focusing on the malignancies in which maspin showed a positive prognostic value, therapeutic approaches studied so far aimed to re-activate a dormant tumor suppressor gene by designed transcription factors, to hit the system that inhibits the expression of maspin, to identify natural substances that can determine the activation and the expression of maspin or possible “molecules binds” to introduce maspin in cancer cell and gene therapy capable of up-regulating the maspin in an attempt to reduce primarily the risk of metastasis.

Further studies in these directions are necessary to better define the therapeutic implication of maspin.

Apple can act as anti-aging on yeast cells

In recent years, epidemiological and biochemical studies have shown that eating apples is associated with reduction of occurrence of cancer, degenerative, and cardiovascular diseases. This association is often attributed to the presence of antioxidants such as ascorbic acid (vitamin C) and polyphenols. The substances that hinder the presence of free radicals are also able to protect cells from aging. In our laboratory we used yeast, a unicellular eukaryotic organism, to determine in vivo efficacy of entire apples and their components, such as flesh, skin and polyphenolic fraction, to influence aging and oxidative stress. Our results indicate that all the apple components increase lifespan, with the best result given by the whole fruit, indicating a cooperative role of all apple components.

Modulation of angiogenesis by dietary phytoconstituents in the prevention and intervention of breast cancer

Breast cancer is the leading cause of cancer-related deaths for women in the United States and the rest of the world. About 8% of women develop breast cancer during the course of their lives. Dietary habits are closely associated with both the risk and progression of breast cancer. Dietary agents have accumulated increasing importance with regards to the prevention and treatment of breast cancer. One such manner by which these compounds can target breast cancer development and progression is through interference with the angiogenic pathways. Angiogenesis is an intricate process that involves the development of new capillaries from previously existing blood vessels. Disruption of this pathway, therefore, provides a novel and effective avenue for therapeutic intervention of breast cancer. Various phytochemicals found in the diet kill breast cancer cells in vitro and prevent as well as suppress breast cancer progression in various preclinical animal models. This review examines the value of dietary phytoconstituents in the prevention and treatment of breast cancer through modulation of the intricate and complex process of angiogenesis. In addition, the potential benefits, challenges, and future directions of research on anti-angiogenic dietary phytochemicals in the prevention and intervention of breast cancer are also addressed.