A new antimutagen from Mentha cordifolia Opiz

In Vitro Antiviral Activity of Mentha cordifolia Plant Extract in HIV-1 Latently Infected Cells Using an Established Human Cell Line

Emergence of drug resistance demands new therapeutic strategies against the human immunodeficiency virus (HIV). Currently, there is an increasing research focus on targeting gene expression-the crucial step wherein new viruses and new viral strains are amplified. Moreover, natural products are also being considered as potential candidates for new antivirals. We screened the extract obtained from a Philippine medicinal plant, Mentha cordifolia (Mc). In this study, we demonstrated that Mc ammonium sulfate extract has antiretroviral activity against HIV. HIV-1 latently infected cells (OM10.1) were pretreated with Mc extract and activated with TNFα. In treated cells, viral replication was inhibited in both cell culture supernatant and whole cell lysates. The level of viral production, as measured by the viral p24 protein concentration, was very much inhibited under noncytotoxic concentrations to the similar level without addition of TNFα. Luciferase assays, however, showed that Mc does not inhibit the HIV-1 long terminal repeat-driven gene expression. IκBα degradation and p65 nuclear translocation was also not affected as visualized through Western blot and immunofluorescence. These observations demonstrated that Mc possessed an antiviral component against HIV-1 and warrant further work to explore its target of action at a later step of gene expression. Our study introduces a potential source of a lead compound that targets steps in the HIV life cycle.

Antibacterial Activities of Endophytic Fungi Isolated from Mentha cordifolia Leaves and Their Volatile Constituents

A total of 17 endophytic fungal isolates were obtained from the leaves of Mentha cordifolia Opiz (Lamiaceae). Seven isolates were identified to the level of genus by using taxonomically relevant morphological traits. Colletotrichum and Phomopsis species were dominant among these strains. All strains were separated from M. cordifolia leaf for the first time. The ethyl acetate extracts of all endophytic fungi were tested for antibacterial activity against Salmonella typhimurium TISTR1166 and Pseudomonas aeruginosa TISTR781. Most endophytes exhibited antibacterial activity. Ustilago sp. MFLUCC15-1024 presented the highest inhibition zone diameter with a MIC of 31.25 μg/mL against the tested pathogens. The chemical composition of the ethyl acetate extract of this strain was investigated using gas chromatography-mass spectrometry. Twenty-one components were identified. 2-Phenylethanol (38.7%), E-ligustilide (12.4%), α-eudesmol (10.2%), β-vetivone (4.6%), β-ylangene (3.7%) and verbanol (3.4%) were the major components of the extract. The strong antibacterial activity of Ustilago sp. MFLUCC15-1024 ethyl acetate extract may be attributed to the presence of a high concentration of bioactive compounds including phenyl ethyl alcohol, E-ligustilide and α-eudesmol. The results indicate that there is high diversity of endophytic fungi in M. cordifolia leaf, and that Ustilago sp. MFLUCC15-1024 strain could be an excellent resource of natural antibacterial compounds.

Determination of antimutagenic properties of apigenin-7-O-rutinoside, a flavonoid isolated from Mentha longifolia (L.) Huds. ssp. longifolia with yeast DEL assay

Lamiaceae is an important plant family that has been investigated for its medicinal properties due to its large amounts of phenolic acids and flavonoids. Flavonoids have been shown to have antioxidant and antimutagenic activities in different test systems, but their certain mechanisms are still unclear. This study was designed to evaluate the mutagenic and antimutagenic activities of apigenin 7-O-rutinoside, a flavonoid isolated from Mentha longifolia (L.) Huds. ssp. longifolia. The possible antimutagenic potential of apigenin 7-O-rutinoside (A7R) was examined against mutagens ethyl methanesulfonate (EMS) and acridine (AC) in a eukaryotic cell system Saccharomyces cerevisiae RS112. The results showed that A7R has different inhibition rates against EMS and AC-induced mutagenicity. Thus, the properties of A7R are of great pharmacological importance and might be beneficial for reducing the risk of reactive oxygen species-related diseases.

Protective effects of solvent fractions of Mentha spicata (L.) leaves evaluated on 4-nitroquinoline-1-oxide induced chromosome damage and apoptosis in mouse bone marrow cells

Spearmint leaves (Mentha spicata L.) contain high levels of antioxidants that are known to protect against both exogenous and endogenous DNA damage. In this study, the protective effects of the hexane fraction (HF), chloroform fraction (CF) and ethyl acetate fraction (EAF) in an ethanol extract from M. spicata were evaluated against 4-nitroquinoline-1-oxide (4-NQO) induced chromosome damage and apoptosis in bone marrow cells of Swiss albino mice. Two (EAF; 80 and 160 mg/ kg body weight - bw) or three (HF and CF; 80, 160 and 320 mg/ kg bw) doses of solvent fractions or vehicle control (25% DMSO in water) were administered orally for five consecutive days. Upon the sixth day, 4-NQO was injected intraperitoneally. The animals were killed the following day. Other control groups were comprised of animals treated with either the vehicle control or the various doses of solvent fractions, but with no 4-NQO treatment. 4-NQO induced micro-nucleated polychromatic erythrocytes (MnPCEs) in all the test groups. However, pre-treatment of animals with the solvent fractions significantly reduced the 4-NQO-induced MnPCEs as well as the percentage of apoptotic cells. The reduction of both MnPCE and apoptosis was more evident following the pre-treatment of animals with 160 mg/kg bw EAF.

Anti-inflammatory activity of four solvent fractions of ethanol extract of Mentha spicata L. investigated on acute and chronic inflammation induced rats

Anti-inflammatory effects of four solvent fractions of ethanol extract of Mentha spicata were evaluated in acute and chronic inflammation induced in Wistar albino rats. Lipid peroxidation (LPO) and some antioxidants produced during chronic inflammation were quantitated. Hexane (320mg/kg of body weight in 25% DMSO), chloroform (320mg/kg body weight in 25% DMSO), ethyl acetate (160mg/kg body weight in 25% DMSO), aqueous (320mg/kg of body weight in ddH(2)O) fractions, two negative control groups (25% DMSO and ddH(2)O) and two anti-inflammatory drugs (Diclofenac: 25mg/kg of body weight; Indomethacin: 10mg/kg of body weight both in ddH(2)O) were administered by oral intubations to the eight groups of rats consisting six animals, each. In acute study, 1% carrageenan was injected subcutaneously in the sub-plantar region of the right hind paw after 1h of administration of test doses. The increased paw edema was measured at 0.5, 1, 2, 4, 8, 16 and 24h intervals. In the chronic study, the oral administration was carried out for seven consecutive days. On eighth day, four sterile cotton pellets (50mg each) were implanted subcutaneously in the dorsal region of the rats. On the sixteenth day, the rats were sacrificed and the cotton pellets with granulomatous tissue were dissected out and weighed (fresh and dry). Both in chronic and acute inflammation, ethyl acetate (EAF) and aqueous fraction (AF) were effective. EAF is comparable with the positive standards in chronic inflammation. The results indicate that EAF's anti-inflammatory activity is largely due to its ability to modulate in vivo antioxidants.

Natural product isolation

Since the 1990s, interest in natural product research has increased considerably. Following several outstanding developments in the areas of separation methods, spectroscopic techniques, and sensitive bioassays, natural product research has gained new attention for providing novel chemical entities. This updated review deals with sample preparation and purification, recent extraction techniques used for natural product separation, liquid-solid and liquid-liquid isolation techniques, as well as multi-step chromatographic operations. It covers examples of papers published since the NPR review 'Modern separation methods' by Marston and Hostettmann,1 with major emphasis on methods developed and the research undertaken since 2000.

Modulatory effects of Mentha piperita on lung tumor incidence, genotoxicity, and oxidative stress in benzo[a]pyrene-treated Swiss albino mice

Mentha piperita or peppermint is currently used for alleviating nausea, flatulence, and vomiting. In the present investigation, we evaluated the chemopreventive, antigenotoxic, and antioxidative effects of an aqueous extract of Mentha piperita leaves. One-day-old Swiss albino mice were treated with a single subcutaneous injection of 0.5 mg benzo[a]pyrene (BP) and then given either water or a Mentha extract (ME; 1 g/kg body weight) by gavage starting at 3 weeks of age (weaning). The mice were killed at 9 weeks of age and tested for lung tumor incidence (chemoprevention); bone marrow micronucleus and chromosome aberration frequency (antigenotoxicity); and levels of liver and lung sulfhydral groups, superoxide dismutase (SOD) and catalase (CAT) activity, and lipid peroxidation (LPO) (antioxidative properties). The ME treatment resulted in a significant reduction in the number of lung adenomas from an incidence of 67.92% in animals given only BP to 26.31%, an inhibition of 61.26%. Tumor multiplicity was 1.22 in the BP-alone group and 1.15 in the BP + ME group. In addition, compared with the animals in the BP-alone group, ME reduced the frequency of chromosomal aberrations and micronuclei in bone marrow cells and decreased the levels of LPO and increased reduced glutathione content, and SOD and CAT activities in liver as well as lung. The results of this study indicate that ME is chemopreventive and antigenotoxic when given subsequent to an initiating dose of BP in newborn Swiss albino mice. The chemopreventive action and antigenotoxic effects observed in the present study may be due to the antioxidative properties of ME.

Protective effects of Mentha piperita Linn on benzo[a]pyrene-induced lung carcinogenicity and mutagenicity in Swiss albino mice

The chemopreventive and antimutagenic effects of an aqueous extract of Mentha piperita leaves were evaluated by using 9 week medium term model of benzo[a]pyrene (BP)-induced lung tumors. Lung tumors were induced by a single subcutaneous injection in the scapular region with BP in newborn Swiss albino mice (<24 h old). The oral administration of Mentha extract (ME) showed a significant reduction in the number of lung tumors from an incidence of 67.92% in animals given only BP to 26.31%. The inhibition rate was 61.26% in ME treated group with respect to reference group (BP-alone). However, tumor multiplicity was reduced from 0.83 in the BP-alone group to 0.31 in the BP+ME group. Also, ME treatment reduced the frequency of BP-induced chromosomal aberrations and micronuclei in bone marrow cells and decreased the levels of lipoperoxides and increased sulfhydryl groups in liver as well as lung. In cell-free assays, ME showed strong scavenging activity for both the DPPH* and ABTS*+ radicals. ME had an IC50 value of 272 microg/ml in the DPPH* assay. The chemopreventive action and antimutagenic effects observed in the present study is attributed to the antioxidative and radical scavenging properties of ME.

Antimutagenic activity of spearmint

The antimutagenic activity of spearmint (Mentha spicata), a popular food flavoring agent, was studied in the Salmonella assay. Spearmint leaves were brewed in hot water for 5 min at concentrations up to 5% (w/v), and the water extracts were tested against the direct-acting mutagens 4-nitro-1,2-phenylenediamine (NPD) and 2-hydroxyamino-3-methyl-3H-imidazo[4,5-f]quinoline (N-OH-IQ) using Salmonella typhimurium strain TA98. Nontoxic concentrations of spearmint extract inhibited the mutagenic activity of N-OH-IQ in a concentration-dependent fashion, but had no effect against NPD. These experiments by design focused on the water extract consumed commonly as an herbal tea, but chloroform and methanol extracts of spearmint also possessed antimutagenic activity against N-OH-IQ. Water extract of spearmint inhibited the mutagenic activity of the parent compound, 2-amino-3-methyl-3H-imidazo[4,5-f]quinoline (IQ), in the presence of rat liver S9; however, the concentration for 50% inhibition (IC50) against IQ was approximately 10-fold higher than in assays with N-OH-IQ minus S9. At concentrations similar to those used in the Salmonella assays, spearmint extract inhibited two of the major enzymes that play a role in the metabolic activation of IQ, namely, cytochromes P4501A1 and 1A2, based on ethoxyresorufin O-deethylase and methoxyresorufin O-demethylase assays in vitro. In vivo, rats were given spearmint water extract (2%; w/v) as the sole source of drinking fluid before, during, and after 2-week treatment with IQ; colonic aberrant crypt foci were inhibited significantly at 8 weeks (P < 0.05, compared with rats given IQ alone). Collectively, these findings suggest that spearmint tea protects against IQ and possibly other heterocyclic amines through inhibition of carcinogen activation and via direct effects on the activated metabolite(s).