Apoptosis inducing effects of Kuding tea polyphenols in human buccal squamous cell carcinoma cell line BcaCD885

Chemopreventive and Anti-tumor Potential of Natural Products in Oral Cancer

Oral cancer (OC) is a multifactorial disease caused by isolated or combined risk factors related to tobacco, alcohol consumption, and human papillomavirus infection. It is an aggressive pathology with a low five-year survival rate after surgery, chemotherapy, and/or radiotherapy, frequently associated with severe side effects. Drugs with the highest anti-tumor effect are obtained from natural products with diverse biological and molecular activities and potential chemopreventive and anticancer properties. This review summarizes the natural products reported to have the chemopreventive and anti-tumor potential for OC treatment, showing that several of these compounds are promising candidates as chemopreventive agents, and those with the highest anti-tumor potential induce apoptosis and inhibit proliferation and metastasis-related processes. For this reason, natural products have the potential to be important preventive and therapeutic options for OC in the future.

Chemical Composition, Bioactivity and Safety Aspects of Kuding Tea-From Beverage to Herbal Extract

Kuding tea (KT) is a bitter-tasting herbal tea that has been commonly used in traditional Chinese medicine (TCM). The large-leaved Ku-Ding-Cha (Aquifoliaceae) is composed of its representative species Ilex latifolia Thunb and Ilex kudingcha C.J. Tseng. Because of its potential lipid-lowering, body weight-reducing and blood-glucose-lowering properties, KT has increasingly been recognised for its importance over the past several decades. KT is no longer used only as a beverage, and various extraction methods have been applied to obtain aqueous and ethanolic KT extracts (KTE) or their fractions, which could potentially be used as dietary supplements. The major bioactive components of KT are triterpene saponins and polyphenols, but the composition of KT differs substantially between and among the different KT species. This in turn might affect the physiological effects of KT. KT exhibits antiobesity properties, possibly partly by affecting the intestinal microbiota. In addition, KT may mediate putative antioxidative, anti-inflammatory and anticancer activities. However, there is evidence that high KTE supplementation can adversely affect liver metabolism. The physiological relevance of KT in humans remains rather unclear since the potential health benefits of KT and its constituents reviewed here are mainly derived on the basis of in vitro and animal studies.

Comparative Survey of Morphological Variations and Plastid Genome Sequencing Reveals Phylogenetic Divergence between Four Endemic Ilex Species

Holly (Ilex L.), from the monogeneric Aquifoliaceae, is a woody dioecious genus cultivated as pharmaceutical and culinary plants, ornamentals, and industrial materials. With distinctive leaf morphology and growth habitats, but uniform reproductive organs (flowers and fruits), the evolutionary relationships of Ilex remain an enigma. To date, few contrast analyses have been conducted on morphology and molecular patterns in Ilex. Here, the different phenotypic traits of four endemic Ilex species (I. latifolia, I. suaveolens, I. viridis, and I. micrococca) on Mount Huangshan, China, were surveyed through an anatomic assay and DNA image cytometry, showing the unspecified link between the examined morphology and the estimated nuclear genome size. Concurrently, the newly-assembled plastid genomes in four Ilex have lengths ranging from 157,601 bp to 157,857 bp, containing a large single-copy (LSC, 87,020–87,255 bp), a small single-copy (SSC, 18,394–18,434 bp), and a pair of inverted repeats (IRs, 26,065–26,102 bp) regions. The plastid genome annotation suggested the presence of numerable protein-encoding genes (89–95), transfer RNA (tRNA) genes (37–40), and ribosomal RNA (rRNA) genes (8). A comprehensive comparison of plastomes within eight Ilex implicated the conserved features in coding regions, but variability in the junctions of IRs/SSC and the divergent hotspot regions potentially used as the DNA marker. The Ilex topology of phylogenies revealed the incongruence with the traditional taxonomy, whereas it informed a strong association between clades and geographic distribution. Our work herein provided novel insight into the variations in the morphology and phylogeography in Aquifoliaceae. These data contribute to the understanding of genetic diversity and conservation in the medicinal Ilex of Mount Huangshan.

Diplatin, a novel water-soluble platinum complex, inhibits lung cancer growth via augmentation of Fas-mediated apoptosis

Platinum drugs, such as cisplatin (DDP) and carboplatin (CBP), are the main drugs for the treatment of lung cancer, but their practical clinical application is limited by severe toxicity and acquired drug resistance. Our previous study has indicated that diplatin, [2-(4-(diethyl-amino)butyl)malonate-O,O']-[(1R,2R)-cyclohexane-1,2-diamine N,N'] platinum (II) phosphate, a novel water-soluble platinum complex, could overcome DDP-resistant cells and was less toxic than comparable platinum drugs. In the present study, the effects and mechanisms of diplatin were further evaluated for its development as a novel anti-lung cancer platinum drug. Here, we found diplatin down-regulated the viability of H460 and LTEP-A-2 cells in a dose-dependent manner. Nude mice administrated with diplatin (30-120 mg/kg) via tail vein injection dose-dependently inhibited the growth of H460 and LTEP-A-2 xenograft tumors, whose action mainly correlated with the induction of tumor apoptosis. Particularly, the exposure of lung cancer cells or xenograft tumors to diplatin resulted in elevated Fas level, and knockdown of Fas ameliorated diplatin-induced cells apoptosis. Overall, we suggest that diplatin has potent anti-tumor activity, which probably acts through Fas-mediated signaling pathway.

The metabolic change in serum lysoglycerophospholipids intervened by triterpenoid saponins from Kuding tea on hyperlipidemic mice

Triterpenoid saponins from Kuding tea have demonstrated preventive effects on hyperlipidaemia induced by a high-fat diet. Lysoglycerophospholipids (Lyso-GPLs) are known to be associated with proatherogenic conditions such as hyperlipidaemia. In this study, a target profiling strategy based on a multiple reaction monitoring mode was applied for the analysis of Lyso-GPLs. The metabolic changes were evaluated by the qualitative and relative quantitative distribution of six classes of Lyso-GPLs in mouse serum. A total of 153 Lyso-GPL regioisomers, consisting of 85 lysophosphatidylcholines, 15 lysophosphatidic acids, 23 lysophosphatidylethanolamines, 5 lysophosphatidylserines, 19 lysophosphatidylinositols and 6 lysophosphatidylglycerols, were detected and quantified. The results showed decreased trends in the content of total Lyso-GPLs in the serum of hyperlipidemic mice compared with that in normal controls. The content of total Lyso-GPLs significantly increased after treatment with triterpenoid saponins from Kuding tea. Among them, the proportions of most Lyso-GPLs with a higher degree of unsaturation or a longer carbon chain in fatty acyl chains dramatically decreased in hyperlipidemic mice. However, this tendency reversed after the treatment of triterpenoid saponins from Kuding tea. This is the first study regarding a target profiling strategy for the quantitative analysis of six different types of Lyso-GPLs on high-fat diet-induced hyperlipidemic mice intervened by Kuding tea. Those Lyso-GPLs changed significantly may be potential biomarkers for hyperlipidaemia, and involved in the mechanism of the preventive intervention of Kuding tea on Lipid metabolic diseases.

Targeting NF-κB signaling pathway in cancer by dietary polyphenols

Being a transcription factor, NF-κB regulates gene expressions involving cell survival and proliferation, drug resistance, metastasis, and angiogenesis. The activation of NF-κB plays a central role in the development of inflammation and cancer. Thus, the down-regulation of NF-κB may be an exciting target in prevention and treatment of cancer. NF-κB could act as a tumor activator or tumor suppressant decided by the site of action (organ). Polyphenols are widely distributed in plant species, consumption of which have been documented to negatively regulate the NF-κB signaling pathway. They depress the phosphorylation of kinases, inhibit NF-κB translocate into the nucleus as well as interfere interactions between NF-κB and DNA. Through inhibition of NF-κB, polyphenols downregulate inflammatory cascade, induce apoptosis and decrease cell proliferation and metastasis. This review highlights the anticancer effects of polyphenols on the basis of NF-κB signaling pathway regulation.

Protective Effects of Kuding Tea (Ilex kudingcha C. J. Tseng) Polyphenols on UVB-Induced Skin Aging in SKH1 Hairless Mice

In this study, the protective effects of Kuding tea polyphenols (KTPs) on ultraviolet B (UVB)-induced skin injury of SKH1 hairless mice were studied. The ion precipitation method was used for extraction of polyphenols from Kuding tea. High-performance liquid chromatography showed that KTPs contains chlorogenic acid, cryptochlorogenic acid, isochlorogenic acid B, isochlorogenic acid A, and isochlorogenic acid C. SKH1 hairless mice were induced skin aging using 2.0 mW/s intensity of 90 mJ/cm² UV light once a day for seven weeks. The 2.5% and 5% KTPs solution was smeared on 2 cm² of back skin of skin aging mice twice a day. Mouse experiments showed that KTP strongly increased the serum levels of total superoxide dismutase (T-SOD) and catalase (CAT) and reduced those of malondialdehyde, interleukin 6 (IL-6), IL-1β, and tumor necrosis factor alpha (TNF-α) in mice with UVB-induced skin damage. KTP also increased the levels of type 1 collagen (Col I), hydroxyproline, and hyaluronic acid and reduced those of Col III and hydrogen peroxide in the damaged skin tissues of mice. Pathological observations of tissues stained with H & E, Masson’s trichrome, Verhoeff, and toluidine blue showed that KTPs could protect skin cells, collagen, and elastin and decrease the number of mast cells, thus inhibiting skin damage. Quantitative PCR and western blot assays showed that KTP upregulated the mRNA and protein expression of tissue inhibitor of metalloproteinase 1 (TIMP-1), TIMP-2, copper/zinc-SOD, manganese-SOD, CAT, and glutathione peroxidase and downregulated the expression of matrix metalloproteinase 2 (MMP-2) and MMP-9. In addition, the same concentration of KTP had stronger protective effects than vitamin C. The results of this study demonstrate that KTPs have good skin protective effects, as they are able to inhibit UVB-induced skin damage.

Preventive Effect of Lactobacillus fermentum CQPC08 on 4-Nitroquineline-1-Oxide Induced Tongue Cancer in C57BL/6 Mice

Lactobacillus fermentum CQPC08 (LF-CQPC08) is a newly discovered strain of bacteria isolated and identified from traditional pickled vegetables in Sichuan, China. We used 4-nitroquinoline 1-oxide to establish an experimental tongue cancer mouse model to evaluate the preventive effect of LF-CQPC08 on tongue cancer in vivo. Lactobacillus delbruechii subsp. bulgaricus, is a common commercial strain and is used as a positive control to compare the effect with LF-CQPC08. The preventive strength and mechanism of LF-CQPC08 on tongue cancer were determined by measuring the biochemical indicators in mouse serum and tissues. Our results showed LF-CQPC08 inhibits the decline of splenic index, thymus index, percentage of phagocytic macrophages, and phagocytic index effectively. LF-CQPC08 also increased levels of mouse serum granulocyte-colony stimulating factor (G-CSF), granulocyte-macrophage-CSF (GM-CSF), immunoglobulin (Ig)G, IgM levels of serum interleukin (IL)-4, IL-12, tumor necrosis factor-alpha, and interferon-gamma levels, thereby inhibiting the decline in immunity caused by tongue cancer. It also increased the activity levels of superoxide dismutase and glutathione peroxidase and decreased the levels of malondialdehyde in the tissues of the tongue cancer mouse model, thereby suppressing the oxidative stress damage in the tissue caused by tongue cancer. Through quantitative PCR, LF-CQPC08 upregulated the mRNA expression of nuclear factor-erythroid 2 related factor 2 (Nrf2), heme oxygenase-1 (HO-1), glutathione-S-transferases-π (GST-π), and Bcl-2-associated X protein (Bax), and downregulated the mRNA expression of p53, p63, p73, phosphatase and tensin homolog (PTEN), B-cell lymphoma 2 (Bcl-2) and B-cell lymphoma-extra large (Bcl-xL) in the tongue tissues of the tongue cancer mouse. These results indicated that LF-CQPC08 reduced the influence of tongue cancer on the immune system and oxidative balance and improved the immunity and enhanced antioxidant capacity of the mouse model, thereby preventing tongue cancer. LF-CQPC08 could be used as a microbial resource with a preventive effect on tongue cancer.

Preventive Effect of Raw Liubao Tea Polyphenols on Mouse Gastric Injuries Induced by HCl/Ethanol via Anti-Oxidative Stress

Liubao tea is a type of traditional Chinese tea, belonging to the dark teas. This study is a basic research of the contained polyphenols (active substances) and detected preventive effects of polyphenols of raw Liubao tea (PRLT) on mouse gastric injuries induced by HCl/ethanol. High-pressure liquid chromatography was used to analyze the components of PRLT. Furthermore, a mouse gastric injury model was established to observe the preventive effects. PRLT was shown to contain gallic acid, EGC (epigallocatechin), catechin, caffeine, EC (epicatechin), EGCG (epigallocatechin gallate), GCG (gallocatechin gallate), and ECG (epicatechin gallate). The results of the in vivo study indicate that PRLT can inhibit the observed increase of gastric juice volume and decrease of gastric juice pH caused by gastric injury. PRLT can decrease the serum levels of IL-6 (interleukin-6), IL-12 (interleukin-12), TNF-α (tumor necrosis factor-α), and IFN-γ (interferon-γ) in mice with gastric injuries. Moreover, it can also increase the serum levels of SS (somatostatin) and VIP (vasoactive intestinal peptide) and reduce the serum levels of both SP (substance P) and ET-1 (endothelin-1). PRLT was also shown to increase SOD (superoxide dismutase) and GSH (glutathione) levels and decrease MDA (malondialdehyde) level. The detection of mRNA and protein in gastric tissues indicates that PRLT could also up-regulate the expression of Cu/Zn-SOD (copper/zinc superoxide dismutase), Mn-SOD (manganese superoxide dismutase), CAT (catalase), nNOS (neuronal nitric oxide synthase), and eNOS (endothelial nitric oxide synthase) and down-regulate the expression of both iNOS (inducible nitric oxide synthase) and COX-2 (cyclooxygenase-2). Thus, PRLT possess a good preventive effect on gastric injury, which is directly related to the contained active substance. PRLT show good anti-oxidative and preventive effect in gastric injury and offer promising application value.

Lactobacillus plantarum CQPC06 Activity Prevents Dextran Sulfate Sodium-Induced Colitis by Regulating the IL-8 Pathway

Lactobacillus plantarum CQPC06 (LP-CQPC06) is a newly discovered lactic acid bacterial strain. Here, the beneficial effects of this strain on C57BL/6J mice with dextran sulfate sodium-induced colitis were investigated. LP-CQPC06 was more resistant to gastric acid and bile salts than L. delbrueckii subsp. bulgaricus (LB). In the DSS-induced colitis mouse model, LP-CQPC06 treatment decreased the colon weight/length ratio and increased the colon length as compared to untreated mice with DSS-induced colitis. LP-CQPC06 also reduced the serum levels of interleukin 8 (IL-8), IL-1, tumor necrosis factor alpha, and macrophage inflammatory protein-1 alpha, as well as reducing levels of myeloperoxidase (MPO) and nitric oxide (NO) in the colon tissues of mice with DSS-induced colitis. In all cases, the effects of LP-CQPC06 were significantly stronger than those of LB. Quantitative polymerase chain reactions and western blots indicated that LP-CQPC06 increased the mRNA and protein expression levels of neuronal nitric oxide synthase, endothelial nitric oxide synthase, and nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor alpha, while decreasing the expression levels of inducible nitric oxide synthase, nuclear factor kappa-beta, C-X-C motif chemokine receptor 1 (CXCR1), and CXCR2. Thus, L. plantarum CQPC06 had a good protective effect against colitis in a mouse model via the IL-8 pathway. Therefore, L. plantarum CQPC06 might have potential uses as a probiotic for colonic protection.

PRACTICAL APPLICATION

In this study, a newly discovered lactic acid bacteria was investigated. This bacterial strain had a good prophylactic effect against colitis in a mouse model, and might have potential utility as a probiotic.

Polyphenols in Kuding tea help prevent HCl/ethanol-induced gastric injury in mice

We conducted the present study to determine the gastric injury preventive effects of polyphenols in Kuding tea (KTPs) in Kunming (KM) mice through the inhibition of gastric-acid secretion and the protection of the gastric mucosa.

Induction of apoptosis in human glioma cell lines of various grades through the ROS-mediated mitochondrial pathway and caspase activation by Rhaponticum carthamoides transformed root extract

The present study is the first investigation of the inhibitory effect of Rhaponticum carthamoides transformed roots (TR) extract on the proliferation of grade II and III human glioma cells. TR extract showed the cytotoxic effect and inhibited the colony formation of both glioma cell lines in dose-dependent manner. The root extract induced apoptosis by increasing of the reactive oxygen species (about threefold compared to the control cells) leading to a disruption of mitochondrial membrane potential. Additionally, the mRNA levels of the apoptotic factors such as Bax, Tp53, caspase-3, and caspase-9 were observed to increase. These results indicate that the TR extract possesses anticancer activity by inhibiting glioma cell proliferation and inducing apoptotic cell death, and may be used as a promising anticancer agent.

Metabolite of ellagitannins, urolithin A induces autophagy and inhibits metastasis in human sw620 colorectal cancer cells

Autophagy is an evolutionarily conserved pathway in which cytoplasmic contents are degraded and recycled. This study found that submicromolar concentrations of urolithin A, a major polyphenol metabolite, induced autophagy in SW620 colorectal cancer (CRC) cells. Exposure to urolithin A also dose‐dependently decreased cell proliferation, delayed cell migration, and decreased matrix metalloproteinas‐9 (MMP‐9) activity. In addition, inhibition of autophagy by Atg5‐siRNA, caspases by Z‐VAD‐FMK suppressed urolithin A‐stimulated cell death and anti‐metastatic effects. Micromolar urolithin A concentrations induced both autophagy and apoptosis. Urolithin A suppressed cell cycle progression and inhibited DNA synthesis. These results suggest that dietary consumption of urolithin A could induce autophagy and inhibit human CRC cell metastasis. Urolithins may thus contribute to CRC treatment and offer an alternative or adjunct chemotherapeutic agent to combat this disease.

In vitro polyphenol effects on apoptosis: An update of literature data

Polyphenols are secondary plant metabolites which have been studied extensively for their health-promoting properties, and which could also exert pharmacological activities ranging from anti-inflammatory effects, to cytotoxic activity against cancer cells. The main mechanism for programmed cell death is represented by apoptosis, and its dysregulation is involved in the etiopathology of cancer. As such, substances able to induce apoptosis in cancer cells could be used as new anticancer agents. The aim of this paper is to review literature data on the apoptotic effects of polyphenols and the molecular mechanisms through which they induce these effects in cancer cells. In addition, a brief summary of the new delivery forms used to increase the bioavailability, and clinical impact of polyphenols is provided. The studies reported show that many polyphenol rich plant extracts, originating from food and herbal medicine, as well as isolated polyphenols administered individually or in combination, can regulate cell apoptosis primarily through intrinsic and extrinsic mechanisms of action in in vitro conditions. Due to these promising results, the use of polyphenols in the treatment of cancer should therefore be deeply investigated. In particular, because of the low number of clinical trials, further studies are required to evaluate the anticancer activity of polyphenols in in vivo conditions.

Inhibition of human glioma cell proliferation by altered Bax/Bcl-2-p53 expression and apoptosis induction by Rhaponticum carthamoides extracts from transformed and normal roots

OBJECTIVE

The objective of this study was to determine the cytotoxic effect and apoptotic activity of Rhaponticum carthamoides transformed root (TR) and root of soil-grown plant (NR) extracts in a human glioma primary cells. The effect of these root extracts on cell cycle arrest, mitochondrial membrane potential (ΔΨm) and expression levels of apoptosis-related genes (Bcl-2, Bax and p53) were also examined.

METHODS

Cytotoxic activity of root extracts was evaluated by MTT assay. Apoptosis and cell cycle were determined by flow cytometry. Expression levels of apoptosis-related gene were analysed by RT-PCR and Western blotting. ΔΨm was examined by the use of JC-1 reagent.

KEY FINDINGS

Rhaponticum carthamoides root extracts inhibit cell growth and induce apoptosis in a dose-dependent manner in human glioma cells. The root extracts were found to up-regulate the pro-apoptotic Bax protein and down-regulate the anti-apoptotic Bcl-2 protein, consequently increasing the ratios of Bax/Bcl-2 protein levels. Moreover, an increase of the p53 protein level and reduction of ΔΨm in glioma cells were observed after treatment with NR and TR extracts.

CONCLUSION

The results of this study may offer a new insight into the potential anticancer activity of R. carthamoides root extracts.

Chloroplast genome structure in Ilex (Aquifoliaceae)

Aquifoliaceae is the largest family in the campanulid order Aquifoliales. It consists of a single genus, Ilex, the hollies, which is the largest woody dioecious genus in the angiosperms. Most species are in East Asia or South America. The taxonomy and evolutionary history remain unclear due to the lack of a robust species-level phylogeny. We produced the first complete chloroplast genomes in this family, including seven Ilex species, by Illumina sequencing of long-range PCR products and subsequent reference-guided de novo assembly. These genomes have a typical bicyclic structure with a conserved genome arrangement and moderate divergence. The total length is 157,741 bp and there is one large single-copy region (LSC) with 87,109 bp, one small single-copy with 18,436 bp, and a pair of inverted repeat regions (IR) with 52,196 bp. A total of 144 genes were identified, including 96 protein-coding genes, 40 tRNA and 8 rRNA. Thirty-four repetitive sequences were identified in Ilex pubescens, with lengths >14 bp and identity >90%, and 11 divergence hotspot regions that could be targeted for phylogenetic markers. This study will contribute to improved resolution of deep branches of the Ilex phylogeny and facilitate identification of Ilex species.

Inhibition of growth and migration of oral and cervical cancer cells by citrus polyphenol

BACKGROUND/PURPOSE

It has been confirmed that polyphenolic compounds present in food have various pharmaceutical functions. The purpose of this study was to evaluate citrus polyphenol (CP) for dental applications. The culture medium with CP was developed to inhibit the proliferation of oral cancer cells. CP could be used as a supplemental compound for topical application for oral cancer patients.

METHODS

In this study, the metabolic activity and cell toxicity of CP (at concentrations of 1%, 0.1%, and 0.01%) for oral and cervical cancer cells were investigated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide and lactate dehydrogenase assays (n = 6). Furthermore, the effects of CP on motilities of oral and cervical cancer cells were also evaluated using a scratch assay model.

RESULTS

We found that the growth of Ca9-22 and HeLa cells on tissue culture polystyrene was greatly inhibited when 1% CP was added to the medium. In addition, significant differences (p < 0.01) in cytotoxicities of oral and cervical cancer cells were observed after 6 days in the culture medium to which 1% CP was added. Furthermore, using a scratch assay model to evaluate the migratory abilities of oral and cervical cancer cells, it was also found that CP could inhibit the migratory abilities of cancer cells.

CONCLUSION

The results confirmed the feasibility of the topical application of CP as a supplemental compound for inhibition of cancer cell proliferation and migration.

Anticancer Effect of Ursodeoxycholic Acid in Human Oral Squamous Carcinoma HSC-3 Cells through the Caspases

Bear bile was used as a traditional medicine or tonic in East Asia, and ursodeoxycholic acid (UDCA) is the most important compound in bear bile. Further, synthetic UDCA is also used in modern medicine and nutrition; therefore, its further functional effects warrant research, in vitro methods could be used for the fundamental research of its anticancer effects. In this study, the apoptotic effects of UDCA in human oral squamous carcinoma HSC-3 cells through the activation of caspases were observed by the experimental methods of MTT (3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide) assay, DAPI (4’,6-diamidino-2-phenylindole) staining, flow cytometry analysis, RT-PCR (reverse transcription-polymerase chain reaction) assay and Western blot assay after HSC-3 cells were treated by different concentrations of UDCA. With 0 to 400 μg/mL UDCA treatment, UDCA had strong growth inhibitory effects in HSC-3 cells, but had almost no effect in HOK normal oral cells. At concentrations of 100, 200 and 400 μg/mL, UDCA could induce apoptosis compared to untreated control HSC-3 cells. Treatment of 400 μg/mL UDCA could induce more apoptotic cancer cells than 100 and 200 μg/mL treatment; the sub-G1 DNA content of 400 μg/mL UDCA treated cancer cells was 41.3% versus 10.6% (100 μg/mL) and 22.4% (200 μg/mL). After different concentrations of UDCA treatment, the mRNA and protein expressions of caspase-3, caspase-8, caspase-9, Bax, Fas/FasL (Fas ligand), TRAIL (TNF-related apoptosis-inducing ligand), DR4 (death receptor 4) and DR5 (death receptor 5) were increased in HSC-3 cells, and mRNA and protein expressions of Bcl-2 (B-cell lymphoma 2), Bcl-xL (B-cell lymphoma-extra large), XIAP (X-linked inhibitor of apoptosis protein), cIAP-1 (cellular inhibitor of apoptosis 1), cIAP-2 (cellular inhibitor of apoptosis 2) and survival were decreased. Meanwhile, at the highest concentration of 400 μg/mL, caspase-3, caspase-8, caspase-9, Bax, Fas/FasL, TRAIL, DR4, DR5, and IκB-α expression levels were the highest, and Bcl-2, Bcl-xL, XIAP, cIAP-1, cIAP-2, survival, and NF-κB expression levels were the lowest. These results proved that UDCA could induce apoptosis of HSC-3 cancer cells through caspase activation, and the higher concentration of UDCA had stronger effects in vitro. UDCA might be a good nutrient for oral cancer prevention.

Resources and biological activities of natural polyphenols

The oxidative stress imposed by reactive oxygen species (ROS) plays an important role in many chronic and degenerative diseases. As an important category of phytochemicals, phenolic compounds universally exist in plants, and have been considered to have high antioxidant ability and free radical scavenging capacity, with the mechanism of inhibiting the enzymes responsible for ROS production and reducing highly oxidized ROS. Therefore, phenolic compounds have attracted increasing attention as potential agents for preventing and treating many oxidative stress-related diseases, such as cardiovascular diseases, cancer, ageing, diabetes mellitus and neurodegenerative diseases. This review summarizes current knowledge of natural polyphenols, including resource, bioactivities, bioavailability and potential toxicity.