Inhibitory effects of 1'-acetoxychavicol acetate on N-Nitrosobis(2-oxopropyl)-amine-induced initiation of cholangiocarcinogenesis in Syrian hamsters

Pharmacological Effects of 1'-Acetoxychavicol Acetate, a Major Constituent in the Rhizomes of Alpinia galanga and Alpinia conchigera

1'-Acetoxychavicol acetate (ACA) is found in the rhizomes or seeds of Alpinia galanga and Alpinia conchigera, which are used as traditional spices in cooking and traditional medicines in Southeast Asia. ACA possesses numerous medicinal properties. Those include anticancer, antiobesity, antiallergy, antimicrobial, antidiabetic, gastroprotective, and anti-inflammatory activities. ACA is also observed to exhibit antidementia activity. Recent studies have demonstrated that combining ACA with other substances results in synergistic anticancer effects. The structural factors that regulate the activity of ACA include (1) the acetyl group at position 1', (2) the acetyl group at position 4, and (3) the unsaturated double bond between positions 2' and 3'. ACA induces the activation of AMP-activated protein kinase (AMPK), which regulates the signal transduction pathways, and has an important role in the prevention of diseases, including cancer, obesity, hyperlipidemia, diabetes, and neurodegenerative disorders. Such findings suggest that AMPK has a central role in different pharmacological functions of ACA, and ACA is useful for the prevention of life-threatening diseases. However, more studies should be performed to evaluate the clinical effects of ACA and to better understand its potential.

Modifying Effects of 1'-Acetoxychavicol Acetate (ACA) and the Novel Synthetic Retinoids Re-80, Am-580 and Am-55P in a Two-Stage Carcinogenesis Model in Female Rats

Effects of dietary administration of 1'-acetoxychavicol acetate (ACA) and the novel synthetic retinoids 4-[1-hydroxy-3-oxo-3-(5,6,7,8-tetrahydro-3-hydroxy-5,5,8,8-tetramethyl-2-naphthalenyl)-1-propenyl]benzoic acid (Re-80); 4-[(5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-2-naphthalenyl)carboxamido]benzoic acid (Am-580); and 6-[(3,5-di-tert-butylphenyl) carbamoyl]nicotinic acid (Am-55P) were examined using a two-stage rat carcinogenesis model. A total of 190 female SD rats was treated sequentially with 1,2-dimethylhydrazine (DMH, s.c.); 7,12-dimethylbenz(a)anthracene (DMBA, i.g.); and 2,2'-dihydroxy-di- n-propylnitrosamine (DHPN, in the drinking water) during the first three weeks (DDD-initiation), and an additional 60 rats received the vehicle alone (non-initiation). One week after the completion of the initiation period, they were divided into nine groups and administrated Re-80 (at dose levels of 1.0 or 0.4 ppm), Am-580 (20 or 4 ppm), Am-55P (20 ppm), ACA (100 ppm), all- trans-retinoic acid (10 or 2 ppm) or no supplement in the diet for 33 weeks, until survivors were euthanatized at week 37 weeks. After DDD-initiation, all- trans-retinoic acid at the high dose delayed the development of mammary tumors. The multiplicity of colon tumors in the group fed Am-55P and the incidences of nephroblastomas with ACA or Am-580 were decreased as compared with the control values, but the other chemicals had no modifying effects on tumor development in any organs. Thus, among ACA and the novel synthetic retinoids tested, only Am-55P showed a weak inhibitory effect on a neoplasm of general interest under the present experimental conditions.

An extract of pomegranate fruit and galangal rhizome increases the numbers of motile sperm: a prospective, randomised, controlled, double-blinded trial

Pomegranate fruit (Punica granatum) and galangal (Alpinia galanga) have separately been shown to stimulate spermatogenesis and to increase sperm counts and motility in rodents. Within traditional medicine, pomegranate fruit has long been used to increase fertility, however studies on the effect on spermatogenesis in humans have never been published. With this study we investigated whether oral intake of tablets containing standardised amounts of extract of pomegranate fruit and powder of greater galangal rhizome (Punalpin) would increase the total number of motile spermatozoa. The study was designed as a prospective, randomized, controlled, double-blinded trial. Enrolment was based on the mean total number of motile spermatozoa of two ejaculates. The participants delivered an ejaculate after 4–8 days of tablet intake and two ejaculates just before they stopped taking the tablets. Seventy adult men with a semen quality not meeting the standards for commercial application at Nordic Cryobank, but without azoospermia, were included in the study. Participants were randomized to take tablets containing extract of pomegranate fruit (standardised with respect to punicalagin A+B, punicalin and ellagic acid) and freeze-dried rhizome of greater galangal (standardised with respect to 1′S-1′-acetoxychavicol acetate) or placebo on a daily basis for three months. Sixty-six participants completed the intervention (active treatment: n = 34; placebo: n = 32). After the intervention the total number of motile spermatozoa was increased in participants treated with plant extracts compared with the placebo group (p = 0.026). After three months of active treatment, the average total number of motile sperm increased by 62% (from 23.4 to 37.8 millions), while for the placebo group, the number of motile sperm increased by 20%. Sperm morphology was not affected by the treatment. Our findings may help subfertile men to gain an improved amount of motile ejaculated sperm by taking tablets containing preparations of pomegranate fruit extract and rhizome of greater galangal.

A Mainstay of Functional Food Science in Japan—History, Present Status, and Future Outlook

The development of food science in the near future probably depends on the advance in functional food science, the concept of which was proposed first in Japan nearly 15 years ago. The new science has been internationally distributed and accepted as conceptually being beyond nutrition. In Japan, however, it traced a unique path of progress in the form of a product-driven rather than concept-driven science. Actually, a number of substances and products with potential for disease risk reduction rather than simply for health maintenance have been investigated for their body-modulating functions. Some of them have been applied in practice to the industrialization of functional foods in terms of "foods for specified health uses" legally defined by new legislation. A variety of sophisticated methods have been introduced as well, including the so-called "XYZ" evaluation system, database construction for assessment of the function, and even the DNA microarray technique. The Ministry of Agriculture, Forestry, and Fisheries (MAFF) and the Ministry of Health and Welfare (MHW) also commenced their scientific as well as political activity, with its spread to industries which almost simultaneously began to vigorously investigate functional food products for enlargement of the food market. With all of this as a background, the Japan Liaison of the International Union of Food Science and Technology (IUFoST) hold a function food science symposium on behalf of related scientific bodies including the Japan Section of the International Life Science Institute (ILSI). This paper is an overview compiled from 12 presentations made in the symposium, with the aim of internationally publicizing the activity of functional food science in Japan.

MicroRNAs contribute to the anticancer effect of 1'-acetoxychavicol acetate in human head and neck squamous cell carcinoma cell line HN4

1'-Acetoxychavicol acetate (ACA), extracted from rhizomes of tropical ginger, possesses antitumor properties against a wide variety of malignancies. MicroRNAs have been found to act as oncogenes and as tumor suppressor genes in the development of cancer. The purpose of this study was to investigate the miRNA involved in the molecular mechanisms of ACA action on tumor inhibition. It was found that ACA significantly inhibited the growth of human head and neck squamous cell carcinoma cell line HN4 and induced cell apoptosis. Further studies indicated that ACA downregulated the expression of miR-23a in HN4 cells. Transfection with anti-miR-23a inhibited the proliferation of HN4 cells and induced cell apoptosis. In addition, phosphatase and tensin homolog deleted on chromosome 10 (PTEN) was confirmed to be the target of miR-23a. Taken together, our findings suggest that ACA might have anticancer effects against human head and neck cancer through downregulation of miR-23a, which can repress tumor suppressor PTEN.

1'-acetoxychavicol acetate inhibits adipogenesis in 3T3-L1 adipocytes and in high fat-fed rats

Alpinia galanga and Languas galanga, which are plants belonging to the ginger family, are frequently used for cooking, especially in Thai and Indonesian cuisine. The compound 1'-acetoxychavicol acetate (ACA), which is naturally obtained from the rhizomes and seeds of these gingers, has antioxidant and anti-inflammatory properties. We investigated the anti-obesity effects of ACA in 3T3-L1 adipocytes and in high fat diet (HFD)-induced rat models of obesity. ACA caused a significant decrease in the activity of GPDH in 3T3-L1 adipocytes without eliciting cell cytotoxicity, and it inhibited cellular lipid accumulation through the down-regulation of transcription factors such as PPARγ and C/EBPα. ACA also induced a dose-dependent phosphorylation of AMP-activated protein kinase (AMPK). In the animal model, rats fed an HFD containing 0.05% ACA gained less weight than rats fed an HFD alone. The visceral fat mass in rats fed an HFD containing 0.05% ACA tended to be lower than that in rats fed an HFD alone. Furthermore, a histological examination of livers from rats fed an HFD showed steatohepatitis. However, rats fed an HFD containing 0.05% ACA showed no histopathological changes in the liver tissue. Our results show that ACA exerts anti-obesity activities both in vitro and in vivo and suggests that ACA may have a novel preventive activity against obesity and possibly other metabolic diseases.

AMPK synergizes with the combined treatment of 1'-acetoxychavicol acetate and sodium butyrate to upregulate phase II detoxifying enzyme activities

SCOPE

Phase II enzymes play important roles in detoxifying xenobiotics. We previously reported that both 1'-acetoxychavicol acetate (ACA) and sodium butyrate individually increased phase II enzyme activities. Here, we determined the combined action of ACA and sodium butyrate on phase II enzyme activities in intestinal epithelial cells (IEC 6).

METHODS AND RESULTS

ACA and sodium butyrate synergistically increased phase II enzyme activities. Protein levels of intranuclear transcription factor NF-E2-related factor 2 (Nrf2) were increased by ACA or sodium butyrate treatment, but treatment with both did not produce a synergistic effect. Intranuclear p53 protein levels were increased by ACA but decreased by sodium butyrate alone or combined treatment with ACA and sodium butyrate. In contrast, p53 acetylation was promoted by sodium butyrate and the ACA and sodium butyrate combination. Inhibition of AMPK activity decreased phase II enzyme activities that were upregulated by treatment with ACA plus sodium butyrate or other phytochemicals, including kaempferol, quercetin, and epigallocatechin-3-gallate. Combined treatment with ACA and sodium butyrate increased phosphorylated AMPK levels.

CONCLUSION

These results suggest that ACA and sodium butyrate synergistically contribute to xenobiotics metabolism. The combined ACA and sodium butyrate treatment synergistically upregulated phase II enzyme activities through AMPK activation and p53 acetylation.

1'-Acetoxychavicol acetate enhances the phase II enzyme activities via the increase in intranuclear Nrf2 level and cytosolic p21 level

(1'S)-acetoxychavicol acetate ((S)-ACA) exhibits chemopreventive effects on chemically induced tumor formation. It has been shown that ACA inhibited the development of azoxymethane-induced colon carcinogenesis through its suppression of cell proliferation in the colonic mucosa and its induction of glutathione S-transferase and quinone oxidoreductase 1 in vivo. In this study, we investigated how ACA induced these enzymes by using rat intestine epithelial cells (IEC6) in vitro. ACA induced glutathione S-transferase (GST) and NAD (P)H: quinone oxidoreductase 1 (NQO1) activities, increased intracellular glutathione (GSH) level, and upregulated intranuclear Nrf2 and cytosolic p21. It suggested that activation of phase II enzymes via Nrf2 associated with p21 is one of possible mechanisms of ACA to prevent advance of carcinogenesis.

Establishment of a mammary carcinoma cell line from Syrian hamsters treated with N-methyl-N-nitrosourea

Clearly new breast cancer models are necessary in developing novel therapies. To address this challenge, we examined mammary tumor formation in the Syrian hamster using the chemical carcinogen N-methyl-N-nitrosourea (MNU). A single 50mg/kg intraperitoneal dose of MNU resulted in a 60% incidence of premalignant mammary lesions, and a 20% incidence of mammary adenocarcinomas. Two cell lines, HMAM4A and HMAM4B, were derived from one of the primary mammary tumors induced by MNU. The morphology of the primary tumor was similar to a high-grade poorly differentiated adenocarcinoma in human breast cancer. The primary tumor stained positively for both HER-2/neu and pancytokeratin, and negatively for both cytokeratin 5/6 and p63. When the HMAM4B cell line was implanted subcutaneously into syngeneic female hamsters, tumors grew at a take rate of 50%. A tumor derived from HMAM4B cells implanted into a syngeneic hamster was further propagated in vitro as a stable cell line HMAM5. The HMAM5 cells grew in female syngeneic hamsters with a 70% take rate of tumor formation. These cells proliferate in vitro, form colonies in soft agar, and are aneuploid with a modal chromosomal number of 74 (the normal chromosome number for Syrian hamster is 44). To determine responsiveness to the estrogen receptor (ER), a cell proliferation assay was examined using increasing concentrations of tamoxifen. Both HMAM5 and human MCF-7 (ER positive) cells showed a similar decrease at 24h. However, MDA-MB-231 (ER negative) cells were relatively insensitive to any decrease in proliferation from tamoxifen treatment. These results suggest that the HMAM5 cell line was likely derived from a luminal B subtype of mammary tumor. These results also represent characterization of the first mammary tumor cell line available from the Syrian hamster. The HMAM5 cell line is likely to be useful as an immunocompetent model for human breast cancer in developing novel therapies.

Comparison of glutathione reductase activity and the intracellular glutathione reducing effects of 13 derivatives of 1'-acetoxychavicol acetate in Ehrlich ascites tumor cells

In a previous study, we showed that (1'S)-acetoxychavicol acetate ((S)-ACA) caused a rapid decrease in glutathione (GSH) levels less than 15 min after exposure. (S)-ACA-induced cell death was reversed by the addition of N-acetylcysteine. In the current study, we investigated the inhibitory activities of 13 derivatives of (S)-ACA on tumor cell viability, intracellular GSH level and GR activity. Correlations were found among a decrease in cell viability, intracellular GSH levels and the activity of GR in Ehrlich ascites tumor cells treated with the various ACA analogues. A test of the 13 derivatives revealed that the structural factors regulating activity were as follows: (1) the para or 1'-position of acetoxyl group (or other acyl group) was essential, (2) the presence of a C2'-C3' double or triple bond was essential, and (3) the S configuration of the 1'-acetoxyl group was preferable.

(1'S)-Acetoxychavicol acetate and its enantiomer inhibit tumor cells proliferation via different mechanisms

Elucidation of the mechanisms underlying potential anticancer drugs continues and unraveling these mechanisms would not only provide a conceptual framework for drug design but also promote use of natural products for chemotherapy. The biological effects of (1'S)-acetoxychavicol acetate ((S)-ACA) have been widely investigated. However, in most cases, a natural product or synthetic racemic compound was used in the study. In this study, we prepared (S)-ACA and its enantiomer (R)-ACA by a lipase-catalyzed esterification method and sought to determine the mechanisms of action of (S)-ACA and (R)-ACA in the growth inhibitory effect in Ehrlich ascites tumor cells (EATC). (S)-ACA caused an accumulation of tumor cells in the G1 phase of the cell cycle, which was accompanied by a decrease in phosphorylated retinoblastoma protein (Rb), an increase in Rb and a decrease in the phosphorylation of p27kip1. However, (R)-ACA caused an accumulation of tumor cells in the G2 phase of the cell cycle, an increase in hyperphosphorylated Rb and an increase in the phosphorylation of p27kip1. The results obtained in the present study demonstrate for the first time, to the best of our knowledge, that both (S)-ACA and (R)-ACA caused the inhibition of tumor cells growth but the inhibition was caused via different mechanisms.

Cellular thiol status-dependent inhibition of tumor cell growth via modulation of p27kip1 translocation and retinoblastoma protein phosphorylation by 1′-acetoxychavicol acetate

1'-Acetoxychavicol acetate (ACA) has been shown to inhibit tumor cell growth, but there is limited information on its effects on cell signaling and the cell cycle control pathway. In this study, we sought to determine how ACA alters cell cycle and its related control factors in its growth inhibitory effect in Ehrlich ascites tumor cells (EATC). ACA caused an accumulation of cells in the G1 phase and an inhibition of DNA synthesis, which were reversed by supplementation with N-acetylcysteine (NAC) or glutathione ethyl ester (GEE). Furthermore, ACA decreased hyperphosphorylated Rb levels and increased hypophosphorylated Rb levels. NAC and GEE also abolished the decease in Rb phosphorylation by ACA. As Rb phosphorylation is regulated by G1 cyclin dependent kinase and CDK inhibitor p27(kip1), which is an important regulator of the mammalian cell cycle, we estimated the amount of p27(kip1) levels by western blotting. Treatment with ACA had virtually no effect on the amount of p27(kip1) levels, but caused a decrease in phosphorylated p27(kip1) and an increase in unphosphorylated p27(kip1) as well as an increase in the nuclear localization of p27(kip1). These events were abolished in the presence of NAC or GEE. These results suggest that in EATC, cell growth inhibition elicited by ACA involves decreases in Rb and p27(kip1) phosphorylation and an increase in nuclear localization of p27(kip1), and these events are dependent on the cellular thiol status.

1'S-1'-acetoxychavicol acetate isolated from Alpinia galanga inhibits human immunodeficiency virus type 1 replication by blocking Rev transport

AIDS remains a major global health concern. Despite a number of therapeutic advancements, there is still an urgent need to develop a new class of therapy for human immunodeficiency virus (HIV). Here, it was shown that 1'S-1'-acetoxychavicol acetate (ACA), a small molecular compound isolated from the rhizomes of Alpinia galanga, inhibited Rev transport at a low concentration by binding to chromosomal region maintenance 1 and accumulating full-length HIV-1 RNA in the nucleus, resulting in a block in HIV-1 replication in peripheral blood mononuclear cells. Additionally, ACA and didanosine acted synergistically to inhibit HIV-1 replication. Thus, ACA may represent a novel treatment for HIV-1 infection, especially in combination with other anti-HIV drugs.

Inhibitory effect of meloxicam, a cyclooxygenase-2 inhibitor, on N-nitrosobis (2-oxopropyl) amine induced biliary carcinogenesis in Syrian hamsters

Pancreaticobiliary maljunction (PBM) is a high risk factor in biliary tract carcinoma. The chemopreventive action of a cyclooxygenase (COX)-2 inhibitor (meloxicam) on N-nitrosobis (2-oxopropyl) amine (BOP)-induced gallbladder cancer in hamster PBM models was investigated. In 7-week-old female Syrian golden hamsters, the extrahepatic bile duct at the distal end of the common duct was ligated and cholecystoduodenostomy was performed (group I). In group II, the same surgery was performed and from week 4 after surgery, 10 mg/kg of BOP was injected subcutaneously once a week with a 1-week interval. In group III, in addition to the measures employed in group II, 5 mg/kg/day of meloxicam was administered once a day, every weekday. Pathological findings in the gallbladder in week 20 after surgery were as follows. In group I, proper epithelium (PE) was predominant and there was no cancer. In group II, PE was predominant, but there was also hyperplasia and atypical epithelium (AE) recognized in 8 of 11 cases (72.7%); the area of AE was more extensive than that in group I. Carcinoma in situ (CIS) was recognized in 4 of 11 cases (36.4%) in group II. Group III showed the same pathological findings as group I. However, compared with group II, the incidence of AE decreased to 27.3% and no cancerous lesion was observed. In week 20 after surgery, the proliferative cell nuclear antigen labeling index in group III was statistically significantly lower than in group II (P = 0.045). No statistically significant differences were noted among the groups in terms of apoptosis labeling index in week 20 after surgery. In conclusion, it was confirmed that meloxicam suppresses carcinogenesis in hamster PBM models and its mechanism may be based on the suppression of cell growth.

Protective effect of fluvastatin, an HMG-CoA reductase inhibitor, on the formation of 8-oxo-2'-deoxyguanosine in the nuclear DNA of hamster pancreas after a single administration of N-nitrosobis(2-oxopropyl)amine

We examined whether fluvastatin (FV), a 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor, has antioxidant activity against oxidative DNA damage to hamster pancreas induced by a chemical carcinogen, N-nitrosobis(2-oxopropyl)amine (BOP). Female Syrian golden hamsters were treated with FV by gastric intubation 30 min before BOP administration. Control animals were intubated with saline. Animals were injected subcutaneously with BOP (20 mg/kg body weight) or saline, and sacrificed 1 and 4 h later. The contents of 8-oxo-2'-deoxyguanosine (8-oxodG) in the nuclear DNA and thiobarbituric acid-reacting substances (TBARS) were measured in the pancreas and liver of hamsters. Treatment with more than 0.22 mg/kg body weight FV significantly inhibited the increase in 8-oxodG content induced by BOP treatment. The TBARS contents in pancreas changed similarly by intubation of FV. In the liver, the contents of 8-oxodG and TBARS were not affected by a single administration of BOP. The protective effect of FV was stronger than those of pravastatin and other antioxidants such as Trolox, ascorbic acid and green tea catechin. These results suggest that FV inhibits oxidative damage to DNA and lipids caused by reactive oxygen species formed through the metabolism of chemical carcinogens.

Effects of selected food factors with chemopreventive properties on combined lipopolysaccharide- and interferon-gamma-induced IkappaB degradation in RAW264.7 macrophages

Degradation of IkappaB (IkappaB) is a key step for nuclear factor-kappaB (NF-kappaB)-induced transcription of certain proinflammatory genes, including inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX)-2. We selected seven chemopreventive agents and examined their effects on combined lipopolysaccharide- and interferon-gamma-induced IkappaB degradation in RAW264.7 murine macrophages. IkappaB degradation was notably suppressed by 1'-acetoxychavicol acetate (ACA), zerumbone (ZER), and benzylisothiocyanate (BITC), however, not by auraptene (AUR), while the suppressive potencies of nobiletin (NOB), genistein (GEN), and resveratrol (RES) were low, but significant. These results suggest that ACA, ZER, and BITC suppress iNOS/COX-2 gene expression mainly by attenuating IkappaB degradation, while other chemopreventive agents use alternative pathway(s) to suppress the expression of proinflammatory genes.

Involvement of protein tyrosine phosphorylation and reduction of cellular sulfhydryl groups in cell death induced by 1' -acetoxychavicol acetate in Ehrlich ascites tumor cells

Elucidation of the mechanisms underlying potential anticancer drugs continues and unraveling these mechanisms would not only provide a conceptual framework for drug design but also promote use of natural products for chemotherapy. To further evaluate the efficacy of the anticancer activity of 1'-acetoxychavicol acetate (ACA), this study investigates the underlying mechanisms by which ACA induces death of Ehrlich ascites tumor cells. ACA treatment induced loss of cell viability, and Western blotting analysis revealed that the compound stimulated tyrosine phosphorylation of several proteins with 27 and 70 kDa proteins being regulated in both dose- and time-dependent manner prior to loss of viability. Protein tyrosine kinase inhibitor herbimycin A moderately protected cells from ACA-induced toxicity. In addition, cellular glutathione and protein sulfydryl groups were also significantly reduced both dose- and time-dependently during evidence of cell death. Replenishing thiol levels by antioxidant, N-acetylcysteine (NAC), an excellent supplier of glutathione and precursor of glutathione, substantially recovered the viability loss, but the recovery being time-dependent, as late addition of NAC (at least 30 min after ACA addition to cultures) was, however, ineffective. Addition of NAC to ACA treated cultures also abolished tyrosine phosphorylation of the 27 kDa protein. These results, at least partly, identify cellular sulfhydryl groups and protein tyrosine phosphorylation as targets of ACA cytotoxicity in tumor cells.