Cytoprotective and pro-apoptotic activities of native Australian herbs polyphenolic-rich extracts
Highlights
► Cellular protective activities of polyphenolic-rich extracts from native herbs are identified. ► The extracts induced apoptosis of cancer cells without affecting proliferation of normal cells. ► No direct DNA damage in HT-29 cells occurred as a result of exposure to extracts.
Introduction
Oxidative stress is the result of a homeostatic imbalance between the generation of reactive oxygen and nitrogen species (RONS) and a decrease in either free radical scavenging or the mechanisms used to repair oxidised macromolecules. This may lead to cellular dysfunction and eventual cell death following damage to various cell targets such as DNA, lipids and proteins (Liu & Finley, 2005). Such molecular damage events have been linked to many chronic diseases including cancer (Klaunig & Kamendulis, 2004) cardiovascular disease, diabetes and inflammatory diseases such as inflammatory bowel disease (Eberhardt and Jeffery, 2006, Evans et al., 2004, Halliwell, 2007). Overwhelming epidemiological evidence strongly correlates the regular consumption of fruits and vegetables with a lower incidence of certain chronic diseases including cardiovascular disease and cancer. This part is thought to be attributed to the cellular protective abilities of naturally occurring antioxidants, which are able to efficiently scavenge RONS, thereby potentially reducing risk of the onset of oxidative stress related diseases (Babich, Schuck, Weisburg, & Zuckerbraun, 2011). Beside the damaging effects on DNA and other cellular molecules, it has been suggested that RONS suppress apoptosis, promote proliferation, invasiveness and metastasis (and possibly angiogenesis), which are the subsequent steps in cancer development and progression (Halliwell, 2007).
Apoptosis, also known as programmed cell death, is a key pathway for normal cellular development and homeostasis. The process can be triggered by a wide variety of physiological and pathological stimuli (Elmore, 2007), associated with morphological changes such as cell shrinkage, membrane blebbing, chromatin condensation, nuclear fragmentation (Hengardner, 2000). Caspases are a family of cysteine proteases that play a key role in the apoptotic process and are highly conserved during development and aging. Caspase-3, the effector caspase in apoptosis, represents a convergence point for two different caspase-dependent apoptotic pathways: the mitochondrial (intrinsic) pathway and the death receptor (extrinsic) pathway. The direct activation of such executioner caspases is thought to be an anticancer strategy which may prove beneficial in treating many cancers in which procaspase-3 concentrations are elevated (Putt et al., 2006).
Selected polyphenols such as quercetin (Kim et al., 2010) and crude extracts of fruits such as strawberry and plum (Ramos, Alia, Bravo, & Goya, 2005) present in the human diet have been shown to be effective in the suppression of the proliferation of HT-29 and HepG2 cancer cells, involving the induction of apoptosis. Epigallocatechin-3-gallate (EGCG) isolated from green tea induced-apoptosis in human prostate carcinoma LNCaP cells, shifting the balance between pro- and anti-apoptotic proteins in favour of apoptosis (Hastak et al., 2003). EGCG has also been found to inhibit cellular proliferation of human laryngeal epidermoid carcinoma Hep2 cells through a p53-mediated mitochondrial pathway which is a caspase-independent pathway (Lee et al., 2010).
Australia has been isolated for thousands of years and thus the local plants have developed in isolation to suit the often harsh natural conditions. The native Australian flora is among the most diverse in the world due to the wide range of different environments and plant communities. Commercially grown native Australian herbs and spices contain high levels of phenolic compounds, especially flavonoids, phenolic acids, and tannins (Konczak et al., 2010, Sakulnarmrat and Konczak, 2012). Commercial production of these herbs has been initiated in 1990’s and currently in Australia they are available in supermarkets and specialty shops, are used in seasoning and in preparation of main meals. Additionally, due to their unique flavour they are included into herbal infusions. The endemic Tasmannia pepper, due to its pungency, is used in cooking and as an additive in processed foods, e.g. cheese. As the production and the consumption of these herbs steadily increases there is a need to understand their effect on human health. The present study focused on the evaluation of potential health-enhancing properties of purified polyphenol-rich extracts obtained from three major commercially grown herbs: Tasmannia pepper leaf, anise myrtle and lemon myrtle. Previous studies reported high antioxidant capacities of polyphenolic-rich extracts obtained from these herbs and their dose-dependent inhibitory activities towards the isolated enzymes: α-glucosidase, pancreatic lipase and angiotensin I-converting enzyme (Sakulnarmrat & Konczak, 2012). Within this study potential cellular-protective and pro-apoptotic activities against human cancer cell lines, especially associated with the digestion system, were investigated. DNA damage events, cytostasis and cytotoxicity of these native Australian herbs polyphenols were assessed by the cytokinesis block micronucleus cytome (CBMNCyt) assay (Fenech, 2007).
Section snippets
Plant material
Commercial samples of dry Tasmannia pepper leaf (Tasmannia lanceolata R. Br., Winteracea) were obtained from the Diemen Pepper Company (Tasmania, Australia). Commercial samples of anise myrtle (Syzygium anisatum (Vickery, Craven & Biffen, Myrtaceae) and lemon myrtle (Backhousia citriodora F. Muell, Myrtaceae) were obtained from Australian Rainforest Products (New South Wales, Australia). Bay leaf (Laurus nobilis L., Lauraceae) from Hoyts Food Industries Pty Ltd., Moorabbin, Victoria, Australia)
Cellular protective activities of polyphenolic-rich extracts from native Australian herbs
Purified polyphenolic-rich extracts comprising of chlorogenic acid, p-coumaric acid and quercetin/derivatives (Tasmannia pepper leaf, TPL), and ellagitannins coupled with myricetin, quercetin and hesperetin [anise myrtle (AM) and lemon myrtle (LM)], exhibited high antioxidant capacity, as evaluated in reagent-based antioxidant assays, and inhibitory activity towards isolated enzymes relevant to metabolic syndrome (Sakulnarmrat & Konczak, 2012). Within this study potential cellular protective
Conclusions
Polyphenolic-rich extracts obtained from native Australian herbs exhibited cellular-protective activities against H2O2 induced cell death and antioxidant activity within a life cell. All herb extracts significantly reduced the proliferation frequency of cancer cells. The flow cytometry analysis suggested an induction of apoptosis in cell populations treated with herb extracts. The CBMN cytome assay confirmed this observation. The occurrence of apoptotic cells occurred simultaneously with an
Acknowledgements
This project was supported by the Rural Industries Research and Development Corporation (RIRDC), Australia. The Ph.D. scholarship to Karunrat Sakulnarmrat by Rajamangala University of Technology Isan (RMUTI), Thailand is gratefully acknowledged.
References (35)
- et al.
Quercetin protects human hepatoma HepG2 against oxidative stress induced by tert-butyl hydroperoxide
Toxicology and Applied Pharmacology
(2006) - et al.
Oxidative DNA damage and disease: Induction, repair and significance
Mutation Research
(2004) - et al.
Protective effects of green tea polyphenols on human HepG2 cells against oxidative damage of fenofibrate
Free Radical Biology & Medicine
(2003) - et al.
Antioxidant capacity and phenolic compounds in commercially grown native Australian herbs and spices
Food Chemistry
(2010) - et al.
EGCG induces apoptosis in human laryngeal epidermoid carcinoma Hep2 cells via mitochondria with the release of apoptosis-inducing factor and endonuclease G
Cancer Letters
(2010) - et al.
Polyphenols: Food sources and bioavailability
American Journal of Clinical Nutrition
(2004) - et al.
Composition of native Australian herbs polyphenolic-rich fractions and in vitro inhibitory activities against key enzymes relevant to metabolic syndrome
Food Chemistry
(2012) - et al.
Water-soluble polymeric polyphenols from cinnamon inhibit proliferation and alter cell cycle distribution patterns of hematologic tumor cell lines
Cancer Letters
(2005) - et al.
Esculetin-induced protection of human hepatoma HepG2 cells against hydrogen peroxide is associated with the Nrf2-dependent induction of the NAD(P)H: Quinone oxidoreductase 1 gene
Toxicology and Applied Pharmacology
(2011) - et al.
Antioxidant and cytoprotective activities of native Australian fruit polyphenols
Food Research International
(2011)
Protection by the flavonoid myricetin, quercetin and rutin against hydrogen peroxide-induced DNA damage in Caco-2 and Hep G2 cells
Nutrition and Cancer
Research strategies in the study of the pro-oxidant nature of polyphenol nutraceuticals
Journal of Toxicology
Clove (Syzygium aromaticum L.), a potential chemopreventive agent for lung cancer
Carciogenesis
An increased micromucleus frequency in peripheral blood lymphocytes predicts the risk of cancer in humans
Carcinogenesis
When dietary antioxidants perturb the thiol redox
Journal of the Science of Food and Agriculture
Apoptosis: A review of programmed cell death
Toxicologic Pathology
Cytokinesis-block micronucleus cytome assay
Nature Protocols
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