Antimutagenic and antitumor activities of a water-soluble fraction of soursop (syn Graviola, Annona muricata L.) fruit pulp

Soursop (Annona muricata) is a tropical tree whose decoction derived from bark, root, seed, or leaf has been used for medicinal uses. In addition, the fruit itself is considered a food, and the juice is utilized to treat heart and liver diseases. The aim of this study was to determine the phenolic content. In addition, a water-soluble fraction of the soursop fruit pulp (WSSP) was examined for the following properties: antioxidant, mutagenic, and antimutagenicity. UV-visible spectrophotometry determined total phenolic content by the Folin-Ciocalteu method to be 11.22 ± 0.6 mg of gallic acid equivalent per gram dried extract, and free-radical scavenging activity by the 2,2'-diphenyl-1-picryl-hydrazyl (DPPH•) showed an EC50 of 1032 µg/ml. In the Salmonella/microsome assay, no marked mutagenicity was induced following WSSP treatment, and a chemopreventive capacity was observed in the antimutagenic assay. The cytotoxicity assays were carried out using the water-soluble tetrazolium salt and lactate dehydrogenase (LDH) assays demonstrated that WSSP induced significant cytotoxicity in MCF-7 and Caco-2 cells, indicating greater effectiveness of cytotoxic action by destroying cell membrane integrity. Data suggest that WSSP may exert beneficial effects as a DNA chemopreventive and antitumor agent.

In vitro chemopreventive and cytotoxic effects of Amazon mosses Leucobryum martianum (Hornsch.) and Leucobryum laevifolium (Broth) extracts

Several bioactive compounds, such as polyphenols, demonstrate low toxicity and prominent effects on cancer cells with antioxidant, anti-inflammatory, and antitumor activities. Such compounds can be found in Amazon mosses Leucobryum martianum (Hornsch.) Hampe ex Müll. Hal. (Hornsch.) and Leucobryum laevifolium (Broth). Antimutagenic assay with Salmonella enterica serovar Typhimurium and cytotoxicity with different eukaryotic cell lines were carried out to screen aqueous, hydroalcoholic, and ethanolic extracts of those Amazon mosses for anticancer potential. The results indicate the capacity of all extracts of both mosses to exert chemopreventive effects against 4-nitroquinoline-N-oxide (4NQO) and 2-aminoanthracene (2-AA), which are direct or indirect mutagens. In particular, the ethanolic and aqueous extract from L. martianum. The ethanolic extract from L. martianum induces significant cytotoxicity by mitochondrial metabolism and cell membrane disruption pathways to tumor or non-tumor cells. The aqueous extract from L. martianum showed a mainly cytotoxic response in the HepG2 cells, a human liver carcinoma, reaching ~90% cytotoxicity. The same extract did not induce significant damage to normal liver cells (F C3H cells) by membrane interaction pathway. The selective cytotoxicity in the aqueous extract of L. martianum makes it a candidate against liver cancer. Further studies, including in vivo models, are necessary to validate the efficacy and safety of the aqueous extract of L. martianum.

RED RICE BRAN EXTRACT SUPPRESSES COLON CANCER CELLS VIA APOPTOSIS INDUCTION/CELL CYCLE ARREST AND EXERTS ANTIMUTAGENIC ACTIVITY

BACKGROUND

Red rice bran extract (RRBE) contains many biologically active substances exerting antioxidant and anti-inflammatory effects.

AIM

To evaluate the anticancer potential of RRBE in human colon cancer cells and its mutagenic/antimutagenic effects on nonmalignant cells.

MATERIALS AND METHODS

The cytotoxic effect of RRBE was determined by trypan blue exclusion in HCT116, HT29 cell lines and a non-cancerous HEK293 cell line, and its antiproliferative effect using MTS and colony formation assay. The apoptosis induction was evaluated using ELISA, and the apoptotic rate and cell cycle progression were assessed by flow cytometry. The mutagenic/ antimutagenic potential of RRBE was analyzed by micronucleus assay in the V79 cell line.

RESULTS

RRBE caused a dose-dependent reduction of cell viability in colon cancer cells and showed a limited cytotoxicity against HEK293 cells. The treatment with RRBE suppressed proliferation of HCT116 and HT29 cells and induced apoptosis as evidenced by the increased DNA fragmentation and the apoptotic cell counts. Furthermore, RRBE treatment significantly increased the number of cells at the G2/M phase triggering the arrest of the cell cycle in colon cancer cells. Interestingly, RRBE did not increase the micronucleus frequency in V79 cells but reduced the micronucleus formation caused by mitomycin C.

CONCLUSION

RRBE effectively suppressed proliferation, induced apoptosis, and caused a cell cycle arrest in human colon cancer cells while being non-mutagenic and exerting antimutagenic effects in vitro.

Bioefficacy of Nga-Mon (Perilla frutescens) Fresh and Dry Leaf: Assessment of Antioxidant, Antimutagenicity, and Anti-Inflammatory Potential

Perilla leaves are known to be a rich source of polyphenols, which have been shown to exhibit various biological effects. This study aimed to compare the bioefficacies and bioactivities of fresh (PLE_f) and dry (PLE_d) Thai perilla (Nga-mon) leaf extracts. Phytochemical analysis indicated that both PLE_f and PLE_d were abundant in rosmarinic acid and bioactive phenolic compounds. PLE_d, which had higher levels of rosmarinic acid but lower levels of ferulic acid and luteolin than PLE_f, exhibited greater effectiveness in a free radical scavenging assay. Furthermore, both extracts were found to suppress intracellular ROS generation and exhibit antimutagenic activity against food-borne carcinogens in S. typhimurium. They also attenuated lipopolysaccharide-induced inflammation in RAW 264.7 cells by inhibiting the expression of nitric oxide, iNOS, COX-2, TNF-α, IL-1β, and IL-6 through the suppression of NF-κB activation and translocation. However, PLE_f exhibited a higher ability to suppress cellular ROS production and higher antimutagenic and anti-inflammatory activities than PLE_d, which can be attributed to its combination of phytochemical components. Overall, PLE_f and PLE_d have the potential to serve as natural bioactive antioxidant, antimutagenic, and anti-inflammatory agents to achieve potential health benefits.

Pistacia lentiscus L. fruits showed promising antimutagenic and antigenotoxic activity using both in-vitro and in-vivo test systems

Pistacia lentiscus L. is one of the most popular medicinal plants attributed to its beneficial properties on human health. However, few toxicogenetic studies have been carried out. Therefore, the aim of this study was to examine the potential genotoxic/antigenotoxic and mutagenic/antimutagenic properties of oil, ethyl acetate and ethanolic extracts of P. lentiscus L. fruits using in vitro the Ames and Umu assays, as well as in vivo micronucleus (MN) test. Extracts did not exert any significant mutagenic/genotoxic effects but provided protection against standard mutagenic and genotoxic agents including 2 nitrofluorene (2-NF) at 2.5 and 5 µg/ml; sodium azide at 5 and 10 µg/ml; 3-methylcholanthrene (3-MC) at 25 and 50 μg/ml; cyclophosphamide (CP) at 50 and 100 μg/ml; 4-nitroquinoline 1-oxide (4-NQO) at 0.05 µg/ml and 2-amino-anthracene (AA) at 0.2 µg/ml. Further, cytotoxicity and selectivity were examined on human hepatocarcinoma (HepG2), and MCF-7 breast cancer cell lines as well as a human normal-like fibroblast cell line (TelCOFS02MA) using MTT assay. Among all extracts, PF1 (ethanolic) showed the most significant selectivity index (SI) (HepG2:11.98; MCF7:4.83), which led to further investigations using an animal model. Oral administration of PF1 (125-1000 mg/kg b.w.) significantly decreased the number of micronucleated cells in CP -initiated (50 mg/kg b.w.) mice, while the number of micronucleated reticulocytes (MNRET), micronucleated polychromatic erythrocytes (MNPCE) or mitotic index (MI) were not markedly affected. Further, PF1 significantly enhanced catalase (CAT) and superoxide dismutase (SOD) activities in the livers and kidneys of these animals. The obtained results indicated the beneficial properties of P. lentiscus L. fruits for use in therapy against harmful effects of genotoxic and mutagenic agents. However, while promising it should be noted that the obtained results are preliminary and need to be confirmed prior to therapeutic use.

Antimutagenic, Cytoprotective and Antioxidant Properties of Ficus deltoidea Aqueous Extract In Vitro

Ficus deltoidea var. deltoidea is used as traditional medicine for diabetes, inflammation, and nociception. However, the antimutagenic potential and cytoprotective effects of this plant remain unknown. In this study, the mutagenic and antimutagenic activities of F. deltoidea aqueous extract (FDD) on both Salmonella typhimurium TA 98 and TA 100 strains were assessed using Salmonella mutagenicity assay (Ames test). Then, the cytoprotective potential of FDD on menadione-induced oxidative stress was determined in a V79 mouse lung fibroblast cell line. The ferric-reducing antioxidant power (FRAP) assay was conducted to evaluate FDD antioxidant capacity. Results showed that FDD (up to 50 mg/mL) did not exhibit a mutagenic effect on either TA 98 or TA 100 strains. Notably, FDD decreased the revertant colony count induced by 2-aminoanthracene in both strains in the presence of metabolic activation (p < 0.05). Additionally, pretreatment of FDD (50 and 100 µg/mL) demonstrated remarkable protection against menadione-induced oxidative stress in V79 cells significantly by decreasing superoxide anion level (p < 0.05). FDD at all concentrations tested (12.5–100 µg/mL) exhibited antioxidant power, suggesting the cytoprotective effect of FDD could be partly attributed to its antioxidant properties. This report highlights that F. deltoidea may provide a chemopreventive effect on mutagenic and oxidative stress inducers.

Antimutagenic, Antiproliferative and Antioxidant Properties of Sea Grape Leaf Extract Fractions (Coccoloba uvifera L.)

BACKGROUND

Cancer is a disease characterized by the invasion and uncontrolled growth of cells. One of the best ways to minimize the harmful effects of mutagens is through the use of natural antimutagens. In this regard, the search for new antimutagens that act in the chemoprevention could represent a promising field in this area. <p >Objective: In this study biological potential of 11 fractions from Coccoloba uvifera L. leaf hexane extract was evaluated by several in vitro tests.

METHODS

Leaves were lyophilized and hexane extraction was performed. The extract was fractionated by column chromatography with hexane, ethyl acetate, and methanol. The antimutagenic (Ames test), antiproliferative (MTT test), and antioxidant capacity (DPPH, ABTS, and ferrous ion chelation) of the fractions were evaluated.

RESULTS

Fractions 4, 6, 8, and 9 have antimutagenic activity (against sodium azide in strain TA100), fraction 11 showed antiproliferative capacity (IC50 of 24 ± 9 μg/mL in cells of HCT 116). The fractions with the highest activity were analyzed by HPLC-MS and lupeol, acacetin, and β-sitosterol were identified.

CONCLUSION

This study demonstrates, for the first time, the bioactivity of C. uvifera leaf as a new source of high biological value compounds (HBVC), which can be of interest to the food and pharmaceutical industries.

The Chemical and Biological Profiles of Leaves from Commercial Blueberry Varieties

Blueberries have seen an ascending production line boosted by World Health Organization (WHO) approvals for their contributions to a healthy diet and the evidence that they act against different diseases. This increase resulted in significant amounts of discarded leaves, which could be a valuable source of bioactive compounds. In the present study, ultrasound-assisted extraction technology was used to determine and compare the chemical and biological profiles of leaves from six commercial blueberry (Vaccinium corymbosum L.) varieties. Feruloylquinic acid was the major compound identified, ranging from 19.23 ± 0.18 mg/g (at the lowest level, registered in the Spartan variety) to 49.62 ± 0.41 mg/g (at the highest level, registered in the Nelson variety). Rutin was the second major compound identified, for which Toro, Nelson, and Elliot leaves registered the highest values, with 35.77 ± 0.19 mg/g, 32.50 ± 0.20 mg/g, and 31.53 ± 0.1 mg/g, respectively. Even though analogous polyphenols were detected in the six cultivars, their concentrations and amounts were different. The leaf extracts of the cultivars Toro, Elliot, and Nelson appear to be good sources of antioxidants, registering high percentage inhibitions of DPPH radicals, of 70.41%, 68.42%, and 58.69%, respectively. The blueberry leaf extracts had a strong antibacterial activity and a low antifungal capacity, and a low-to-moderate antimutagenic capacity towards Salmonella typhimurium TA98 and TA100 strains, with Toro leaf being the best candidate. All of these biological activities indicate health-related benefits, recommending them as suitable candidates for medical and pharmaceutical applications. The present paper adds significant knowledge to the field of blueberry leaves via chemical and biological profiles, supporting the ultrasound-assisted extraction technique as a useful and green method to provide alternative sources of bioactive compounds.

Antioxidant Phytoconstituents From Onosma bracteata Wall. (Boraginaceae) Ameliorate the CCl4 Induced Hepatic Damage: In Vivo Study in Male Wistar Rats

Onosma bracteata Wall. (Boraginaceae) is a highly valuable medicinal herb that is used for the treatment of fever, bronchitis, asthma, rheumatism, stomach irritation, and other inflammatory disorders. The present study aims to explore the hepatoprotective potential of ethanolic extract (Obeth) from O. bracteata aerial parts against carbon tetrachloride (CCl₄) which causes hepatic damage in the male Wistar rats. Obeth showed effective radical quenching activity with an EC₅₀ of 115.14 and 199.33 µg/mL in superoxide radical scavenging and lipid peroxidation analyses respectively along with plasmid DNA protective potential in plasmid nicking assay. The Obeth modulated mutagenicity of 2 Aminofluorine (2AF) in the pre-incubation mode of investigation (EC₅₀ 10.48 µg/0.1 mL/plate) in TA100 strain of Salmonella typhimurium. In in vivo studies, pretreatment of Obeth (50, 100, and 200 mg/kg) had the potential to normalize the biochemical markers aggravated by CCl₄ (1mL/kg b.wt.) including liver antioxidative enzymes. Histopathological analysis also revealed the restoration of CCl₄-induced liver histopathological alterations. Immunohistochemical studies showed that the treatment of Obeth downregulated the expression levels of p53 and cyclin D in hepatocytes. and downregulation in the Western blotting analysis revealed the downregulation of p-NF-kB, COX-2, and p53. HPLC data analysis showed the supremacy of major compounds namely, catechin, kaempferol, epicatechin, and Onosmin A in Obeth. The present investigation establishes the hepatoprotective and chemopreventive potential of O. bracteata against CCl₄-induced hepatotoxicity via antioxidant defense system and modulation of the expression of proteins associated with the process of carcinogenesis in hepatic cells.

Myricitrin from Combretum lanceolatum Exhibits Inhibitory Effect on DNA-Topoisomerase Type IIα and Protective Effect Against In Vivo Doxorubicin-Induced Mutagenicity

Flavonoids-compounds abundant in balanced daily diets-have been extensively investigated for biological activity. The pronounced antiproliferative effects of flavonoids have prompted studies to elucidate their mode of action against tumor cells. The anticancer properties of myricetin, a 3',4',5'-tri-hydroxylated flavonol, have been confirmed for a number of neoplasms, but myricitrin, its 3-O-rhamnoside derivative found in fruits and other parts of edible plants, has been scarcely investigated as a chemopreventive agent. This study evaluated the antiproliferative potential of myricitrin obtained from Combretum lanceolatum (Combretaceae) against MCF7 (breast), PC-3 (prostate), HT-29 (colon), 786-0 (kidney), and HL-60 (acute promyelocytic leukemia) cancer cell lines, using the sulforhodamine B and tetrazolium salt assays. Myricitrin proved most effective in inhibiting growth of HL-60 cells (GI₅₀ = 53.4 μmol·L^-1), yet showed weak antiproliferative activity against other cell lines. Possible cytotoxic mechanisms involving inhibition of topoisomerases I and IIα by myricitrin were also evaluated, revealing inhibitory activity only against topoisomerase IIα. The results suggested that topoisomerase IIα inhibition is the probable mechanism responsible for the antiproliferative activity of myricitrin. In vivo mutagenicity by myricitrin and its possible antimutagenic effect on doxorubicin-induced DNA damage were also investigated by performing the somatic mutation and recombination test (SMART) on Drosophila melanogaster. Myricitrin proved nonmutagenic to the offspring of standard (ST) and high-bioactivation (HB) crosses, while cotreatments with doxorubicin revealed the antimutagenic properties of myricitrin, even under conditions of high metabolic activation.

Chemical Composition and Biological Activities of the Nord-West Romanian Wild Bilberry (Vaccinium myrtillus L.) and Lingonberry (Vaccinium vitis-idaea L.) Leaves

This study was performed to evaluate and compare the in vitro antioxidant, antimicrobial, and antimutagenic activities, and the polyphenolic content of the Nord-West Romanian wild bilberry (Vaccinium myrtillus L.) and lingonberry (Vaccinium vitis-idaea L.) leaves from three different natural habitats (Smida, Turda, Borsa). In the case of both species, the flavanols level was higher in Smida habitat (altitude 1100 m), whereas quercetin derivates were more abundant in Borsa habitat (altitude 850 m). The bilberry leaf extracts contained in the highest amounts the feruloylquinic acid (59.65 ± 0.44 mg/g for Borsa habitat) and rutin (49.83 ± 0.63 mg/g for Borsa habitat), and showed relevant 2,2-diphenyl-1-picrylhydrazyl (DPPH) antioxidant activity (271.65 mM Trolox/100 g plant material for Borsa habitat, 262.77 mM Trolox/100 g plant material for Smida habitat, and 320.83 mM Trolox/100 g plant material for Turda habitat), for all the three extracts. Gallocatechin was the dominant flavanol in lingonberry species, with the highest amount being registered for Smida habitat (46.81 ± 0.3 mg/g), revealing a DPPH antioxidant activity of 251.49 mM Trolox/100 g plant material. The results obtained in the antimicrobial tests showed that the best inhibitory effect among bilberry species was attributed to the Turda (altitude 436 m) and Smida locations, against both Gram-positive and Gram-negative bacterial strains. For lingonberry, the differences in habitat did not influence the antibacterial effect, but the antifungal effect, only in the case of Candida zeylanoides. A strong antimutagenic effect was registered by the bilberry leaves toward Salmonella typhimurium TA100. Our study may be able to provide a better understanding of the correlation between natural habitat conditions and the accumulation of secondary metabolites and their related bioactivities in studied leaves.

Correlation between Antioxidant/Antimutagenic and Antiproliferative Activity of Some Phytochemicals

BACKGROUND

Chemotherapeutic drugs have high toxicity associated with undesirable side-effects. Now, natural products are the most important anti-cancer agents because of their low toxicity and potential effectiveness.

METHODS

The half maximal inhibitory concentration (IC50) of amygdalin, naringenin and ellagic acid against breast, colon, and liver cell lines was estimated. The antimutagenic, free radical-, superoxide radical-, and hydroxyl radical- scavenging activities of these phytochemicals were measured. The expression of p53, bid, bax, bcl2, and caspases 9, 3, and 7 was measured by quantitative real-time polymerase chain reaction (qRT-PCR) in breast and liver cells. In addition, the active Caspase 3 protein was estimated in liver cells.

RESULTS

Ellagic acid showed the highest antioxidant and antiproliferative activities. Amygdalin and naringenin with low and moderate antioxidant profiles showed a corresponding low and moderate cytotoxicity against cancer cell lines, respectively. Naringenin and ellagic acid had a significant antimutagenic activity which was detected by the Salmonella test. Ellagic acid offered a much better antimutagenic activity than naringenin. The apoptotic pathway evoked by ellagic acid in HepG2 and MCF-7 cells was investigated. The results showed that a caspase-dependent and a caspase-independent apoptosis occurred in MCF-7 and HepG2, respectively.

CONCLUSION

The antimutagenic/antioxidant properties are well correlated with the antiproliferative activity of the phytochemicals investigated. This study proved that some easy, quick and cheap assays could predict the antiproliferative activity of many nutraceuticals. Finally, this platform could help in the discovery of new anticancer agents where hundreds of compounds are investigated in the pipeline of drug discovery.

Genistein and Ascorbic Acid Reduce Oxidative Stress-Derived DNA Damage Induced by the Antileishmanial Meglumine Antimoniate

Meglumine antimoniate (Glucantime) is a pentavalent antimonial used to treat leishmaniasis, despite its acknowledged toxic effects, such as its ability to cause oxidative damage to lipids and proteins. Recently, our group demonstrated that meglumine antimoniate causes oxidative stress-derived DNA damage. Knowing that antioxidants modulate reactive oxygen species, we evaluated the capacity of genistein and ascorbic acid for preventing genotoxicity caused by meglumine antimoniate. For that, mice (n = 5/group) received genistein (via gavage) in doses of 5, 10, and 20 mg/kg for three consecutive days. After this period, they were treated with 810 mg/kg meglumine antimoniate via intraperitoneal (i.p.) route. Furthermore, mice (n = 5/group) simultaneously received ascorbic acid (i.p.) in doses of 30, 60, and 120 mg/kg and 810 mg/kg meglumine antimoniate. We also conducted post- and pretreatment assays, in which animals received ascorbic acid (60 mg/kg) 24 h prior to or after receiving meglumine antimoniate. Genomic instability and mutagenicity were analyzed through conventional comet assay and enzymatic assay using formamide pyrimidine DNA glycosylase (Fpg) enzyme, as well as the micronucleus test, respectively. Meglumine antimoniate induced an increase in the DNA damage after digestion with Fpg, reinforcing its mutagenic potential by oxidizing DNA bases, which was prevented by genistein. Similarly, ascorbic acid was capable of reducing mutagenic effects in simultaneous treatment as well as in posttreatment. Therefore, our results demonstrate that both compounds are efficient in preventing mutations in mammalian cells treated with meglumine antimoniate.

Antimutagenic constituents from Monanthotaxis caffra (Sond.) Verdc

OBJECTIVES

Monanthotaxis caffra (Sond.) Verdc. (Annonaceae) has been reported to possess antitumoural properties. Preliminary screening showed that the crude methanolic leaf extract had strong antimutagenic effects against aflatoxin B₁ -induced mutagenicity. The aim of this study was to isolate and evaluate the antimutagenic properties of the active constituents from M. caffra.

METHODS

Different chromatographic, spectroscopic and spectrometric techniques were used for the isolation and identification of the antimutagenic constituents. The antimutagenic effect of the extract and compounds was evaluated using Ames, Vitotox and Comet assays.

KEY FINDINGS

Bioassay-guided fractionation of the methanolic leaf extract yielded two antimutagenic compounds identified as (+)-crotepoxide and 5,6-diacetoxy1-benzoyloxymethyl-1,3-cyclohexadiene. Crotepoxide had strong antimutagenicity in the Vitotox assay with an IC₅₀ value of 131 μg/ml. 5,6-Diacetoxy-1-benzoyloxymethyl-1,3-cyclohexadiene showed strong antimutagenic activity in the Ames assay with an IC₅₀ value of 348.9 μg/plate and no antimutagenic activity in the Vitotox test. Furthermore, the compound was able to inhibit, block or prevent biotransformation of aflatoxin B₁ by repressing the proteins involved in transcription.

CONCLUSIONS

Crotepoxide and 5,6-diacetoxy-1-benzoyloxymethyl-1,3-cyclohexadiene have the potential to mitigate the risks arising from consumption of aflatoxin B₁ -contaminated food and feed.

Podophyllum hexandrum ameliorates endosulfan-induced genotoxicity and mutagenicity in freshwater cyprinid fish crucian carp

CONTEXT

Medicinal plants continue to act as a repository for novel drug leads with novel mechanisms of action. Podophyllum hexandrum Royale (Berberideceae) treats diverse conditions in folk medicine.

OBJECTIVE

The antimutagenic potential of P. hexandrum was evaluated against endosulfan-induced clastogenicity in a piscine model by cytogenetic endpoints.

MATERIALS AND METHODS

Podophyllum hexandrum rhizomes were subjected to successive solvent extraction. Fish were exposed to hexane, chloroform, ethyl acetate, methanol and aqueous extracts (15 mg/L each) of plant and endosulfan (0.05 mg/L) alone followed by their combination for antimutagenicity estimates. Chromosomal aberrations (CA) were made from kidney cells and micronuclei (MN) slides from peripheral blood erythrocytes at 48, 72 and 96 h. Antioxidant activity was analyzed by the DPPH assay. Phytochemical analyses were carried out using chromatographic and spectroscopic techniques.

RESULTS

Endosulfan induced significant (p < .05) MN, authenticated by scanning electron microscopy, and CA in a time-dependent manner. However, methanol and ethyl acetate extracts revealed ameliorating effects. The column eluted methanolic fraction-2 (ME-F2) showed highest reduction profile of 83 and 84% in CA and MN, followed in its extent (73 and 72%) by ethyl acetate fraction-4 (EE-F4). ME-F2 and EE-F4 showed three and six major peaks when analyzed by GC-MS. To explore possible mechanism of action, ME-F2 showed potent antioxidant potential and strong correlation (R²=.900) with antimutagenic activity, whereas EE-F4 seemed to act through a different mechanism.

DISCUSSION AND CONCLUSION

This study confirms the antimutagenic potential of the subject plant with the identification of some novel compounds, justifying their use in folk medicine, and their corresponding benefit to mankind.

Functional constituents of wild and cultivated Goji (L. barbarum L.) leaves: phytochemical characterization, biological profile, and computational studies

Goji (Lycium barbarum L.) leaves are emphasized as a functional tea or as dietary supplements. The phenolic compound profile, antioxidant, enzyme inhibitory, antimicrobial, and antimutagenic activities of leaf extracts from two selected cultivars in comparison with wild-growing plants have been evaluated. HPLC-DAD/ESI-ToF-MS analysis revealed the presence of phenolic acids and flavonoids with chlorogenic acid and rutin being the dominant compounds in the cultivated plants, whereas rutin and kaempeferol-3-O-rutinoside for wild growing ones. In particular, cv. Erma contained the highest amount of chlorogenic acid and showed a strong tyrosinase-inhibitory effect. Staphylococcus aureus, Listeria monocytogenes, and Penicillium funiculosum were the most sensitive strains when exposed to extracts from cultivated plants. Antimutagenic activity was evaluated by Ames' test. The tested extracts provided high protection against mutagenicity induced by 2-anthramine (2-AA) to Salmonella typhimurium strains TA 98 and TA 100 (max. inhibition (%) 88% and 74.2%, respectively). Overall, Goji leaves are a rich source of bioactive compounds with functional properties that need further risk/benefit evaluation when used in foods or health-promoting formulations.

Mutagenicity of cigarette butt waste in the bacterial reverse mutation assay: The protective effects of β-caryophyllene and β-caryophyllene oxide

Cigarette filters pose a serious litter and toxic waste disposal problem, because of their not biodegradability and to the leaching of toxins in the environment. Therefore, cigarette butts need to be manipulated as special waste, with potential risks to human health and environment. In the present study, the genotoxic potential of a methanol extract from commonly discharged cigarette butts (CBE) was evaluated in the bacterial reverse mutation assay on Salmonella typhimurium TA98 and TA100 and Escherichia coli WP2uvrA strains, both in the absence and presence of the S9 exogenous metabolic activator. Furthermore, the ability of the natural sesquiterpenes β-caryophyllene (CRY) and β-caryophyllene oxide (CRYO) to inhibit the mutagenicity of CBE was studied as a possible preventive strategy. In order to identify the potential antimutagenic mechanisms, three different protocols (pretreatment, cotreatment, and posttreatment) were applied. CBE showed to increase the number of revertant colonies in all the strains tested in presence of S9, so resulting mutagenic. In the antimutagenicity assay, both CRY and CRYO significantly reduced the revertant colonies induced by CBE, although with different potency and specificity. For both sesquiterpenes, the antimutagenicity was strong in all experimental conditions, except for the cotreatment of CRY with CBE in WP2uvrA, which produced a moderate inhibition. Both desmutagenic and bioantimutagenic mechanisms seem to be involved in the antimutagenicity of the test substances. Taking into account the potential genotoxicity of cigarette butts, CRY and CRYO appear as possible further candidates as environmental decontaminants against this hazardous waste. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1319-1328, 2016.

In vitro mutagenic, antimutagenic, and antioxidant activities evaluation and biotransformation of some bioactive 4-substituted 1-(2-methoxyphenyl)piperazine derivatives

In vitro mutagenic, antimutagenic, and antioxidant potency evaluation and biotransformation of six novel 4-substituted 1-(2-methoxyphenyl)piperazine derivatives demonstrating antidepressant-like activity were investigated. Mutagenic and antimutagenic properties were assessed using the Ames test; free radical scavenging activity was evaluated with 2,2-diphenyl-1-picrylhydrazyl radical scavenging assay and biotransformation was performed with liver microsomes. It was found that all tested compounds are not mutagenic in bacterial strains TA100 and TA1535 and exhibit antimutagenic effects in the Ames test. Noteworthy, compounds possessing propyl linker between phenoxyl and N-(2-methoxyphenyl)piperazine displayed more pronounced antimutagenic properties than derivatives with ethoxyethyl linker. Additionally, compounds 2 and 6 in vitro biotransformation showed that primarily their hydroxylated or O-dealkylated metabolites are formed. Some of the compounds exhibited intrinsic clearance values lower than those reported previously for antidepressant imipramine. To sum up, the results of the present study might represent a valuable step in designing and planning future studies with piperazine derivatives.

Sisymbrium Officinale (L.) Scop. and its Polyphenolic Fractions Inhibit the Mutagenicity of Tert-Butylhydroperoxide in Escherichia Coli WP2uvrAR Strain

One Sisymbrium officinale (L.) Scop. aqueous dry extract (SOE) and its polyphenolic fractions (Fb, Fc, Fd and Fe) were evaluated for their ability to inhibit the oxidative mutagenicity of tert-butylhydroperoxide in the Ames test. The possible involvement of desmutagenic and/or bioantimutagenic mechanisms was evaluated by applying a three-time based protocol (pre-treatment, co-treatment and post-treatment). Furthermore, some protective antioxidant mechanisms were investigated. The total polyphenol and flavonol amount was also determined, and the fingerprint was outlined by high-performance thin-layer chromatography and densitometry. SOE, Fb and Fe exhibited strong antimutagenicity against tert-butylhydroperoxide in all treatment protocols, this suggesting the involvement of both desmutagenic and bioantimutagenic mechanisms. These samples also showed antioxidant properties, including neutralization of the superoxide anion, lipid peroxidation inhibition and chelation and reduction of iron. Fb and Fe were rich in polyphenols and flavonols, so suggesting a possible role of these compounds in the antimutagenicity. Taking into account that oxidative stress is responsible for the damage of various environmental toxicants, particularly tobacco smoke, present results can support the traditional use of hedge mustard by smokers to restore the vocal cord function affected by the oxidative damage and suggest a possible application of SOE and its fractions as food supplements. Copyright © 2016 John Wiley & Sons, Ltd.

"Granny Smith" Displaying Strong Antimutagenicity in Models Including Human Lymphoblast TK6(+/-) Cell Line

Potential prophylactic attributes in terms of antimutagenicity, antioxidant, and radioprotective properties were evaluated for 8 common apple cultivars namely "Fuji," "Golden Delicious," "Granny Smith," "Ambri Kashmiri," "Kinnaur," "Red Delicious," "Royal Gala," and "Shimla," where cultivar based significant variation was observed. Cv. "Granny Smith" displayed significantly higher and broad spectrum antimutagenicity in Escherichia coli rpoB based rifampicin resistance (Rif(R) ) assay, whereas, "Ambri Kashmiri," "Royal Gala," and "Shimla" showed lower antimutagenicity. Cultivars "Ambri Kashmiri," "Kinnaur," and "Red Delicious" exhibited strong antioxidant activity than cv. "Granny Smith" as assayed by radical scavenging, reducing potential and radioprotective property assays. The antioxidant and radioprotective properties were found to be better correlated than antimutagenicity. Suppression of error-prone DNA repair pathway (such as E. coli SOS response) was found to be one of the possible mechanisms contributing to its antimutagenicity. Phenolic extract of "Granny Smithˮ showing higher antimutagenicity was HPLC purified and the bioactive fraction (tR 35.4 min) contributing maximally (∼80%) to the observed antimutagenicity was identified as procyanidin dimer (PD) by ESI-MS/MS. The above observed antimutagenicity in bacterial assay system was well reproduced in Thymidine Kinase Mutation (TKM) assay performed using human lymphoblast cell line (TK6(+/-) ) cell line making the findings more prophylactically relevant.

Assessment of antimutagenic action of Celtis glabrata Steven ex Planch. (Cannabaceae) extracts against base pair exchange and frame shift mutations on Salmonella typhimurium TA98 and TA100 strains by Ames test

CONTEXT

Celtis glabrata is used in Turkey for the treatment of various health disorders.

OBJECTIVE

The acetone, chloroform, ethanol, and methanol extracts of C. glabrata leaf, fruit, and seed were investigated to evaluate their antimutagenic activities.

MATERIAL AND METHODS

The antimutagenicity of these extracts was determined by Ames test against mutagens (4-nitro-O-phenylenediamine, 2-aminofluorene (2-AF), and sodium azide (SA)). The extracts were used at concentrations between 5 and 0.005 mg/plate.

RESULTS

The ethanol extracts of leaves exhibited strong antimutagenicity (70%) against 2-AF with S9 at 5 mg/plate on TA98. But methanol (61%, 53%) and acetone (53%, 52%) also revealed strong inhibition rates at concentrations of ≥ 0.5 mg/plate. Among the extracts, the highest activity (96%) was obtained from acetone extract against SA without S9, followed by chloroform extract (91%) at a dose of 5 mg/plate on TA100 with S9. Ethanol (without S9) and chloroform (with S9) extracts showed strong antimutagenicity at all doses. Exception of chloroform and acetone (without S9), all fruit extracts (with/without S9) manifested strong antimutagenicity at doses of ≥ 0.5 mg/plate on TA98 strain. Ethanol extracts revealed 68% inhibition against 2-AF on TA98. Acetone and ethanol extracts manifested 84% and 82% inhibition against SA on TA100, respectively. All the extracts of seeds revealed strong inhibition against 2-AF at ≥ 0.5 mg/plate doses on TA98, but acetone extract showed excellent antimutagenicity (94%). Moreover, the chloroform (74, 73, 63, 54%), acetone (74, 72, 70, 65%) and methanol (74, 67, 63, 61%) extracts of seeds revealed strong antimutagenic activity on TA100 against SA with S9.

DISCUSSION AND CONCLUSION

This plant may be natural source of antimutagenic agents.

Two antigenotoxic chalcone glycosides from Mentha longifolia subsp. longifolia

CONTEXT

Mentha L. (Labiatae) species (mint) with their flavoring properties have been used in food industries for centuries. Besides they have a great importance in drug development and medicinal applications due to various bioactive compounds of several members of the genus.

OBJECTIVE

The aim of this study was to isolate bioactive compounds with antimutagenic potential by bio-guided fractionation and determine their structures by spectroscopic methods.

MATERIALS AND METHODS

The structural elucidation of the isolated compounds was done based on spectroscopic methods, including MALDI-MS, UV, IR, and 2D NMR experiments, and the bio-guided fractionation process was done by using the Ames/Salmonella test system. Henceforth, solely genotoxic and antigenotoxic potential of the new compounds were also confirmed up to 2 µM/plate by using the same test system.

RESULTS

Two new chalcone glycosides: (βR)-β,3,2',6'-tetrahydroxy-4-methoxy-4'-O-rutinosyldihydrochalcone and (βR)-β,4,2',6'-tetrahydroxy-4'-O-rutinosyldihydrochalcone, were isolated from Mentha longifolia (L.) Hudson subsp. longifolia, together with known six flavonoid glycosides and one phenolic acid: apigenin-7-O-glucoside, luteolin-7-O-glucoside, apigenin-7-O-rutinoside, luteolin-7-O-rutinoside, apigenin-7-O-glucuronide, luteolin-7-O-glucuronide, rosmarinic acid. According to the antimutagenicity results, both new test compounds significantly inhibited the mutagenic activity of 9-aminoacridine in a dose-dependent manner at the tested concentrations from 0.8 to 2 µM/plate. (βR)-β,4,2',6'-Tetrahydroxy-4'-O-rutinosyldihydrochalcone showed the maximum inhibition rate as 75.94% at 2 µM/plate concentration.

CONCLUSIONS

This is the first report that two new chalcone glycosides were isolated from Mentha longifolia subsp. longifolia and their antimutagenic potentials by using mutant bacterial tester strains. In conclusion, the two new chalcone glycosides showed a significant antigenotoxic effect on 9-aminoacridine-induced mutagenesis at tested concentrations.

bark in the micronucleus assay

The aim of this study was to evaluate the mutagenicity (clastogenicity/aneugenicity) of a glycolic extract of Ziziphus joazeiro bark (GEZJ) by the micronucleus assay in mice bone marrow. Antimutagenic activity was also assessed using treatments associated with GEZJ and doxorubicin (DXR). Mice were evaluated 24–48 h after exposure to positive (N-nitroso-N-ethylurea, NEU - 50 mg.kg⁻¹ and DXR - 5 mg.kg⁻¹) and negative (150 mM NaCl) controls, as well as treatment with GEZJ (0.5–2 g.kg⁻¹), GEZJ (2 g.kg⁻¹) + NEU and GEZJ (2 g.kg⁻¹) + DXR. There were no significant differences in the frequencies of micronucleated polychromatic erythrocytes in mice treated with GEJZ and GEJZ + DXR compared to the negative controls, indicating that GEZJ was not mutagenic. Analysis of the polychromatic:normochromatic erythrocyte ratio revealed significant differences in the responses to doses of 0.5 g.kg⁻¹ and 1–2 g.kg⁻¹ and the positive control (NEU). These results indicated no systemic toxicity and moderate toxicity at lower and higher doses of GEZJ. The lack of mutagenicity and systemic toxicity in the antimutagenic assays, especially for treatment with GEZJ + DXR, suggested that phytochemical compounds in Z. joazeiro bark attenuated DXR-induced mutagenicity and the moderate systemic toxicity of a high dose of Z. joazeiro bark (2 g.kg⁻¹). Further studies on the genotoxicity of Z. joazeiro extracts are necessary to establish the possible health risk in humans and to determine the potential as a chemopreventive agent for therapeutic use.

Evaluation of the biological activity of novel monocationic fluoroaryl-2,2'-bichalcophenes and their analogues

A series of bichalcophene fluorobenzamidines 5a–e was synthesized from the corresponding mononitriles 4a–e via a direct reaction with lithium bis(trimethylsilyl)amide LiN(TMS)₂ followed by de-protection with ethanolic HCl (gas). Bichalcophene fluorobenzonitriles 4a–e were prepared adopting a Stille coupling reaction between the bromo compounds 3a–c and 2-(tri-n-butylstannyl)furan or analogues. As an approach to drug discovery, the structure–antimutagenicity relationship of novel fluoroarylbichalcophenes was examined using the Ames Salmonella/microsomal assay. At nontoxic concentrations (10 and 20 μM), all derivatives alone or in combination with sodium azide (NaN₃; 2 μg/plate) or benzo[a]pyrene (B[a]P; 20 μM) in the presence of S9 mix were not mutagenic. The fluoroaryl derivatives significantly reduced the NaN₃-induced and B[a]P-induced mutagenicity under pre-exposure and co-exposure conditions. The recorded antimutagenic activity of fluoroaryl derivatives varied depending on the kind of mutagen and the exposure regimen. Monocationic fluoroarylbichalcophenes were superior to the corresponding mononitriles in reducing B[a]P-induced mutagenicity. Nevertheless, mononitriles were more active against NaN₃, especially at low concentrations and under pre-exposure treatments. The antimutagenic activity was congruent with a high antioxidant activity that could promote the DNA repair system. The fluorine substitution changed the antimutagenic signature of bichalcophenes. Some of these compounds could be selected for further anticancer studies.

In vivo evaluation of the antimutagenic and antigenotoxic effects of β-glucan extracted from Saccharomyces cerevisiae in acute treatment with multiple doses

Ample evidence suggests that cancer is triggered by mutagenic damage and diets or supplements capable of reducing such incidences can be related to the prevention of neoplasy development or to an improvement in life quality of patients who undergo chemotherapy. This research aimed to evaluate the antimutagenic and antigenotoxic activity of β-glucan. We set up 8 experimental groups: control (Group 1), cyclophosphamide (Group 2), Groups 3–5 to assess the effect of β-glucan administration, and Groups 6–8 to evaluate the association between cyclophosphamide and β-glucan. The intraperitonial concentrations of β-glucan used were 100, 150 and 200 mg/kg. Micronucleus and comet assays showed that within the first week of treatment β-glucan presented a damage reduction rate between 100–62.04% and 94.34–59.52% for mutagenic and genotoxic damages, respectively. This activity decreased as the treatment was extended. During the sixth week of treatment antimutagenicity rates were reduced to 59.51–39.83% and antigenotoxicity was not effective. This leads to the conclusion that the efficacy of β-glucan in preventing DNA damage is limited when treatment is extended, and that its use as a chemotherapeutic adjuvant need to be better clarified.

Antimutagenic activity and preventive effect of black tea on buccal mucosa cancer

A black tea product was evaluated for anti-mutagenic and in vivo anticancer effects. At concentrations of 1.25 and 2.5 mg/plate, black tea exhibited anti-mutagenicity with N-methyl-N′-nitro-N-nitrosoguanidine (MNNG) in the Salmonella typhimurium TA100 strain. A Kunming (KM) mouse buccal mucosa cancer model was established by injecting mice with U14 squamous cell carcinoma cells. Following injection, the wound at the injection site was smeared with black tea. It was observed that the tumor volumes for the groups treated with different concentrations of black tea were smaller than the control groups. The sections of buccal mucosa cancer tissue showed that cancer development in the black tea groups was weaker compared with that in the control group. Similar results were observed in the lesion section of the cervical lymph. Using reverse transcription polymerase chain reaction (RT-PCR), the black tea groups demonstrated an increase in Bcl-2-associated X protein (Bax) and a decrease in B cell lymphoma-2 (Bcl-2) expression, compared with the control groups. The results demonstrated that black tea had an improved antimutagenic effect and in vivo buccal mucosa cancer preventive activity compared with the untreated control in mice.

Antimutagenic and antioxidant activity of novel 4-substituted phenyl-2,2'-bichalcophenes and aza-analogs

Evaluation of the potential antimutagenic activities of new compounds by Ames assay has been of great interest for the development of novel therapeutics for many diseases including cancer. Ten novel bichalcophenes with in vitro and in vivo broad spectrum activities against various microbial strains were investigated throughout the present study for their cytotoxic, antioxidant, and antimutagenic potential in a Salmonella reverse mutation assay system against sodium azide (NaN(3)) and benzo[a]pyrene (B[a]P). At nontoxic concentrations, all bichalcophenes alone or in combination with NaN(3) (1 μg/plate) or B[a]P (20 μM) with S9 mix were not mutagenic. The bichalcophenes significantly reduced NaN(3)- and B[a]P-induced mutagenicity under pre-exposure and co-exposure conditions in a concentration-independent manner. However, the antimutagenic activity of bichalcophenes against B[a]P varied depending on the exposure regimen, being more effective under pre-exposure conditions. The antimutagenic activity was correlated with a high antioxidant activity that could promote the DNA repair system. Bichalcophenes are least likely to interfere with the microsomal bioactivation of B[a]P. Monocationic bichalcophenes were superior to the corresponding mononitriles as antimutagenic agents against both mutagens investigated, possibly due to the higher nucleophilic centers they have which could bind and protect the bacterial DNA. Three monocationic compounds were shown to have a strong anticancer activity against the 58 cell line. Based on the results of the present investigation, monocationic compounds (1, 4, and 5B) will be selected for further time consuming and costly chemoprevention studies in animal models.

Determination of genotoxic and antigenotoxic properties of essential oil from Ferula orientalis L. using Ames/Salmonella and E. coli WP2 bacterial test systems

The essential oils having many application fields such as medicine, flavoring, cosmetics are natural products obtained from aromatic plants. As the natural products of Ferula species have a wide range of use in folk medicine, this study was planned to evaluate the mutagenic and antimutagenic activities of essential oils of leaves and flowers of Ferula orientalis grown in Erzurum, through the bacterial reverse mutation assay. Furthermore, the chemical compositions of essential oils isolated by the hyrodistillation method were analysed by gas chromatography (GC) and gas chromatography-mass spectroscopy (GC-MS), as their biological activities were connected to their contents. According to our results, any tested essential oil at any used concentration on Salmonella typhimurium TA1535 and TA1537 strains and in Escherichia coli WP2 uvrA strain showed no mutagenic activity. However, the tested materials at different concentrations showed antimutagenic activities against the used mutagens. The inhibition rates ranged against sodium azide (NaN3) on S. typhimurium TA1535 from 29% to 36%, against 9-aminoacridine (9-AA) on S. typhimurium TA1537 from 40% to 68% and against N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) on E. coli WP2 uvrA from 23% to 52%, respectively. Also, it is revealed by GC and GC/MS analysis of the essential oils isolated from the leaves and flowers, respectively. The major compounds in these oils were determined as α-cadinol, δ-cadinene and germacrene D-4-ol. The results of this study indicate that as the essential oils of F. orientalis have many constituents, they show no mutagenic activity but significant antimutagenic activity, and these materials can be safely used in medicinal applications after further investigations.

Antimutagenicity and antiproliferative studies of lipidic extracts from white shrimp (Litopenaeus vannamei)

An organic extract from fresh shrimp (Litopenaeus vannamei) was studied for antimutagenic and antiproliferative properties using Salmonella typhimurium tester strains TA98 and TA100 with metabolic activation (S9) and a cancer cell line (B-cell lymphoma), respectively. Shrimp extract was sequentially fractionated by thin layer chromatography (TLC) and each fraction was tested for antimutagenic and antiproliferative activities. Crude organic extracts obtained from shrimp reduced the number of revertants caused by aflatoxina B₁, showing a dose-response type of relationship. Sequential TLC fractionation of the active extracts produced several antimutagenic and/or antiproliferative fractions. These results suggested that the lipid fraction of the tested species contained compounds with chemoprotective properties that reduce the mutagenicity of AFB₁ and proliferation of a cancer cell line.

(Rhizophoraceae), using in vivo and in vitro test systems

An aqueous extract of Rhizophora mangle L. bark is used as raw material in pottery making in the State of Espirito Santo, Brazil. This extract presents large quantities of tannins, compounds possessing antioxidant properties. Tannin antioxidant activity, as a plant chemical defense mechanism in the process of stabilizing free radicals, has been an incentive to studies on anti-mutagenicity. The present work aimed to evaluate possible antimutagenic activity of a R. mangle aqueous extract, using the Allium cepa test-system and micronuclear (MN) assay with blockage of cytokinesis in Chinese hamster ovary cells (CHO-K1). The Allium cepa test-system indicated antimutagenic activity against the damage induced by the mutagenic agent methyl methanesulfonate. A reduction in both MN cell frequency and chromosome breaks occurred in both the pre and post-treatment protocols. The MN testing of CHO-K1 cells revealed anti-mutagenic activity of the R. mangle extract against methyl methanesulfonate and doxorubicin in pre, simultaneous and post-treatment protocols. These results suggest the presence of phyto-constituents in the extract presenting demutagenic and bio-antimutagenic activities. Since the chemical constitution of Rhizophora mangle species presents elevated tannin content, it is highly probable that these compounds are the antimutagenic promoters themselves.

Effects of nine active ingredients in Chinese herbal medicine sho-saiko-to on 2-(2-furyl)-3-(5-nitro-2-furyl)acrylamide mutagenicity

The antimutagenic effects of nine active compounds in the Chinese herbal medicine "sho-saiko-to" on mutagenesis induced by a direct-acting mutagen, 2-(2-furyl)-3-(5-nitro-2-furyl)acrylamide (AF-2) were investigated in Salmonella typhimurium, strain TA100. The active compounds examined were classified into two major groups, saponins and flavonoids, the former comprising glycyrrhizin, saikosaponins a, c, and d, and ginsenosides Rb1 and Rg1, and the latter, baicalin, baicalein and wogonin. Saikosaponin a and ginsenoside Rb1 were found to reduce the mutagenicity of AF-2 significantly when applied post-AF-2-treatment in the Salmonella mutagenicity assay. Ginsenoside Rb1 also decreased the mutagenic activity of AF-2 in a simultaneous treatment protocol. The results indicate that saikosaponin a and ginsenoside Rb1 may enhance DNA repair, and ginsenoside Rb1 may also have the ability to inactivate the mutagenic activity of AF-2 directly. On the other hand, saikosaponin d and baicalin showed a slight enhancing effect. None of the compounds, except baicalein, showed any toxic effect on the test strain. These findings may be useful for the development of chemopreventive agents.

Isolation of A Slightly Water-soluble Antimutagenic Compound from Products of the Glucose-Tryptophan Maillard-Reaction

The glucose-tryptophan Maillard-reaction products (GT MRPs) were prepared by refluxing D-glucose and L-tryptophan at 100°C and pH 11.0 for 10 h and fractionated into six fractions by membrane filters with various ranges of molecular weight (MW). The greatest inhibitory activity of six fractions against the mutagenicity of 2-Amino-3-methylimidazo(4,5-f)quinoline (IQ) was observed in the fraction of MW 30,000 to 50,000 (for Salmonella typhimurium TA98), or MW 30,000 to 50,000 and MW above 100,000 (for TA100) at the dose 0.5 mg/plate. The mutagenicity of 4-nitroquinoline-N-oxide (direct mutagen) was enhanced by some fractions of GT MRPs. The fraction of MW 30,000 to 50,000 was further separated by Sephadex G-100 into three subfractions; the subfraction GT10-G2 showed the greatest antimutagenic activity against IQ. The mean MW of subfraction GTl0-G2 estimated from the elution profile of a calibration kit was about MW 37,000. The slightly water-soluble compound (GTl0-G2-P) collected from the solution of GTl0-G2 by precipitation and centrifugation exhibited a greater antimutagenic activity than the supernatant. The GTl0-G2-P inhibited 28.9 and 32.0% mutagenicity of IQ towards S. typhimurium TA98 and TA100, respectively, at the dose 0.1 mg/plate. Antimutagenic substances, mutagens and mutagen-enhancing substances coexist in GT MRPs, whereas the activity of each factor varied with the dose.