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Dual production of biofuels and chemicals can increase the economic value of lignocellulosic bioenergy feedstocks. We compared the bioenergy potential of several essential oil (EO) crops with switchgrass ( Panicum virgatum L.), a crop chosen to benchmark biomass and lignocellulosic biofuel production. The EO crops of interest were peppermint ( Mentha × piperita L.), "Scotch" spearmint ( Mentha × gracilis Sole), Japanese cornmint ( Mentha canadensis L.), and sweet sagewort ( Artemisia annua L.). We also assessed each crop for EO production in a marginal production environment in Wyoming, USA, with irrigation and nitrogen (N) rates using a split-plot experimental design. Oil content ranged from 0.31 to 0.4% for Japanese cornmint, 0.23 to 0.26% for peppermint, 0.38 to 0.5% for spearmint, and the overall mean of sweet sagewort was 0.34%. Oil yields ranged from (in kg ha-1) 34 to 165 in Japanese cornmint, 25 to 108 in peppermint, 29.3 to 126 in spearmint, and 39.7 in sweet sagewort. EO production, but not composition, was sensitive to N fertilization. The alternative bioenergy crops and switchgrass produced similar amounts of ethanol from bench-scale simultaneous saccharification and fermentation assays. Value-added incomes from the EO proceeds were estimated to be between $1055 and $5132 ha-1 from peppermint, $1309 and $5580 ha-1 from spearmint, $510 and $2460 ha-1 from Japanese cornmint, and $3613 ha-1 from sweet sagewort under Wyoming growth conditions. The advantage of the proposed crops over traditional lignocellulosic species is the production of high-value natural products in addition to lignocellulosic biofuel production.

Natural antioxidants have drawn growing interest for use in animal feed and the food industry. In the current study, essential oils (EOs) obtained from hydrodistillation of three mentha species, including Mentha piperita (peppermint), Mentha spicata (native spearmint) and Mentha gracilis (Scotch spearmint), harvested in the Midwest region in the United States, were analyzed for their chemical composition using gas chromatography-mass spectrometry, and their antioxidant properties were assessed through chemical assays, in vitro cell culture modeling and in Caenorhabditis elegans (C. elegans). The activity of ferric iron reduction and free-radical scavenging capacity were assessed through chemical-based assays, including the reducing power assay, 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay, and Trolox equivalent antioxidant capacity assay (TEAC). Subsequently, the capacity of EOs to mitigate lipid peroxidation was analyzed at various doses using fresh liver homogenates from pigs. A porcine jejunum epithelial cell line (IPEC-J2) was employed as in vitro model to study the cellular antioxidant activity of the mint EOs. Finally, the effectiveness of mint EOs to alleviate acute systemic oxidative damage were evaluated in vivo using C. elegans. Data were analyzed by the MIXED procedure of SAS. Contrast statement was performed to assess linear or quadratic effects of mint EOs given at various doses. All three EOs are mostly composed of monoterpenes and their derivatives (76&ndash, 90%), but differed in the major compounds, which are menthol and menthone (50%) in peppermint EO and carvone (70%) in spearmint EOs. Three mint EOs demonstrated prominent radical scavenging and Fe3+ reducing activity in chemical-based assays. In comparison with native and Scotch spearmint EOs, peppermint EO had the lowest (p &lt, 0.05) half maximal effective concentration (EC50) in DPPH and TEAC assays and higher efficacy in the reducing power assay. All three EOs exhibited equivalent activity in mitigation of chemical-induced lipid peroxidation in liver tissues in a dose-dependent manner (linear, p &lt, 0.001). The maximal cellular antioxidant activity (CAA) was observed at 5 &micro, g/mL for peppermint, and 100 &micro, g/mL for native and Scotch spearmint EOs. The addition of 25 &micro, g/mL of both spearmint EOs increased (p &lt, 0.05) cellular concentrations of glutathione in H2O2-treated IPEC-J2 cells, suggesting enhanced endogenous antioxidant defense. Supplementation of 100 &micro, g/mL of peppermint or Scotch spearmint EO significantly increased (p &lt, 0.05) the survival rate of C. elegans in response to H2O2-induced oxidative stress. The protective effect is comparable to that of supplementation of 10 &micro, g/mL of ascorbic acid. However native spearmint EO failed to reduce the death rate within the same supplementation dose (10&ndash, 200 &mu, g/mL).

Distillation waste water is a byproduct from steam distillation of aromatic crops, and is currently discharged into streams and rivers. We evaluated distillation waste water (extract) from 15 essential oil crops plus three plant hormones (methyl jasmonate, MJ; gibberellic acid, GA3; and salicylic acid, SA) as foliar spray for Scotch spearmint ( Mentha × gracilis Sole). GA3 and Achillea millefolium extract decreased essential oil content. Hypericum perforatum extract increased α-pinene, whereas SA decreased it. H. perforatum extract increased β-pinene and sabinene concentrations relative to hormones but was not different from the control. H. perforatum also increased l -limonene, while SA and GA3 decreased myrcene and MJ and SA decreased l -limonene. Application of MJ and SA increased l -carvone concentration relative to the control and most other treatments. The sulfur concentration in plant extracts was positively correlated to β-caryophyllene. None of the residual distillation waters showed significant antimicrobial or antimalarial activity. The distillation waste water from essential oil crops may serve as a modifier for Scotch spearmint essential oil.

A determinação de substratos alternativos viáveis para a produção de mudas de plantas medicinais é de grande relevância, pois o aproveitamento de resíduos de atividades agrícolas representa alternativa para problemas ambientais e sociais. Os experimentos foram realizados em ambiente protegido e a campo, na Universidade Tecnológica Federal do Paraná, Campus Dois Vizinhos, com o objetivo de avaliar substratos orgânicos para produção de mudas de hortelã para cultivo a campo. O delineamento experimental foi blocos casualizados, com três repetições, em esquema fatorial, sendo avaliados quatro substratos [esterco bovino + vermiculita + areia (1:1:1), esterco bovino + areia + solo (1:1:1), solo + vermiculita + cama-de-aviário (1:1:1) e substrato organo-mineral Plantmax® HA] e duas espécies de menta (Mentha gracilis e Mentha x villosa). Foram analisadas a altura da plantas e o número de folhas aos 07, 14 e 21 dias após o transplantio, índice de mortalidade, massa fresca e seca da parte aérea e das raízes. Não houve interação entre as espécies de menta e substratos para as variáveis analisadas. O substrato organo-mineral Plantmax® apresentou os melhores resultados para o número de folhas (8,44), altura (8,46 cm), produção de massa fresca (1,56 g planta-1), seca (0,23 g planta-1) e 100% de pegamento de mudas a campo o que para o produtor de menta é de grande interesse. Com base nos resultados obtidos, pode-se concluir que para a produção de mudas de Mentha gracilis e Mentha villosa o substrato Plantmax® HA é o mais recomendado.

Peppermint ( Mentha × piperita L.) and spearmints ('Scotch' spearmint, M. × gracilis Sole, and 'Native' spearmint, Mentha spicata L.) are widely grown essential oil crops in more northern latitudes; however, there is limited information on how harvest time and drying influence peppermint and spearmint yield, oil composition, and bioactivity, when grown south of the 41st parallel. In this 2-year study, the effects of harvest time and drying on the yield, oil composition, and bioactivity of peppermint ('Black Mitcham' and 'B90-9'), 'Scotch' spearmint, and 'Native' spearmint were evaluated. Peppermint oil from the dried material had higher menthol and eucalyptol concentrations. Menthone in both peppermint cultivars decreased from harvest 1 (late June) to harvest 5 (late August) or 6 (early September), whereas menthol increased. (-)-Carvone in spearmints accumulated early, before flowering, allowing for early harvest. Oil yields from the dried spearmint biomass reached the maximum at harvest 3 (mid-July). The essential oil compositions of the four mint genotypes were similar to that of 11 commercially available oils, suggesting that these genotypes can be grown in the hot, humid environment of the southeastern United States. The antioxidant activities (ORAC(oil) values) of the essential oils were 4372, 1713, 1107, and 471 μmol of TE L(-1) for 'Scotch' spearmint, 'Native' spearmint, peppermint, and Japanese cornmint ( Mentha canadensis ), respectively. The oils of the four mint genotypes did not affect ruminal fermentation in vivo, and did not exhibit antimicrobial, antileishmanial, or antimalarial activity at levels that would warrant bioassay-directed fractionation in a drug-discovery screening program. Specifically, the oils did not show greater than 50% growth inhibition against Leishmania donovani , Plasmodium falciparum clones D6 and W2, Candida albicans , Escherichia coli , Pseudomonas aeruginosa , Cryptococcus neoformans , Mycobacterium intracellulare , or Aspergillus fumigates at 50 μg mL(-1).

The effect of different cytokinins on in vitro adventitious shoot regeneration from internodal explants of Menthaxgracilis Sole (scoth spearmint) was investigated. Murashige and Skoog (MS) medium containing 100 mg l−1 myo-inositol, 0.4 mg l−1 thiamine-HCl, 2.0% (w/v) sucrose, 10% (v/v) coconut water and supplemented with 4.5 μM thidiazuron (TDZ) was effective in inducing adventitious shoot formation from callus. The greatest percentage of explants with shoots (85%) with the highest mean number of shoots per explant (29) was obtained with explants from the 1st and the 2nd internodes from 2-wk-old stock plants growing on a medium containing MS basal salts, 2% sucrose, 100 mg l−1 myo-inositol, 0.4 mg l−1 thiamine-HCl, at TDZ 4.5 μM and 10% (v/v) coconut water and solidified with 0.2% (w/v) phytagel. The regenerated shoots rooted on a medium containing MS basal salts, 100 mg l−1 myo-inositol, 0.4 mg l−1 thiamine-HCl, 2.0% sucrose, and 0.054 μM naphthalene acetic acid (NAA). Micropropagated plantlets were transplanted into soil and acclimated to greenhouse conditions. This is the first report describing adventitious shoot regeneration of scotch spearmint.

Corky ringspot disease (CRS) of potato is caused by tobacco rattle virus (TRV). The virus is transmitted by the stubby root nematode (Paratrichodorus allius) in the Pacific Northwest potato-producing regions. Alfalfa (Medicago sativa L.) and Scotch spearmint (Mentha cardiaca Baker) rarely serve as hosts for TRV. Therefore,P. allius reared on these plants for 1 to 3 months are cleansed of TRV in greenhouse trials. However, weeds in alfalfa and Scotch spearmint rotation crops may serve as hosts for the virus. In greenhouse trials, hairy nightshade (Solanum sarrachoides), prickly lettuce (Lactuca serriola), henbit (Lamium amplexicaule) and, green foxtail (Setaria viridis) grown alone were found to be suitable hosts ofP. allius, whereas Powell amaranth (Amaranthus powellii) was not. ViruliferousP. allius added to hairy nightshade, prickly lettuce, henbit, green foxtail, or Powell amaranth in mixtures with alfalfa and/or Scotch spearmint occasionally remained viruliferous over a 3-to 4-month period, whereasP. allius maintained on weed-free alfalfa or Scotch spearmint became virus-free after 1 to 2 months. Potato grown in soil containingP. allius that had been maintained on weed-alfalfa or weed-Scotch spearmint mixtures for 3 to 4 months exhibited slight to severe CRS symptoms on new tubers, whereas potato following weed-free Scotch spearmint or alfalfa were free from CRS symptoms. Severe CRS symptoms on potato tubers were only observed when potatoes were grown in soil containingP. allius that were maintained on hairy nightshade or hairy nightshade mixtures with alfalfa or Scotch spearmint. These preliminary data suggest that the presence of weeds that serve as hosts of both TRV and P.allius may nullify the positive effects of growing alfalfa or Scotch spearmint for CRS control. Targeted control efforts of known weed hosts may be required to successfully eliminate CRS from fields using alfalfa and Scotch spearmint rotational crops.

Seventeen mint accessions representing the three species grown for commercial oil production in the United States were characterized using randomly amplified polymorphic DNA (RAPD) analysis. The RAPD profiles readily identified the different Mentha species; calculation of genetic distance, based on the number of shared bands, indicated that M. spicata L. is more closely related to M. × gracilis than to M. × piperita. The RAPD profiles also distinguished among eight peppermint accessions of different geographical origin. However, only limited polymorphism was observed among the most widely grown peppermint and Scotch spearmint cultivars. These results indicate a potential lack of genetic diversity in mint cultivars grown for oil in the United States.

Peppermint and spearmint clones derived from cobalt 60 gamma irradiation and peppermint seed fertile clones and hybrids were evaluated for resistance to Verticillium dahliae in inoculation tests in the greenhouse. Mutant and fertile clones and hybrids varied significantly for wilt resistance. One peppermint mutant clone, three peppermint hybrids, and four peppermint fertile clones had low but varying wilt-severity values. Native spearmint and mutant lines derived from native spearmint had high levels of resistance. The wilt-severity scale used to assess disease levels was correlated with the number of CFU of V. dahliae from inoculated stems.

The acidic volatile components in Midwest Scotch spearmint oil (Mentha gracilis Sole) were investigated by means of GC, GC/MS and other analytical techniques. A total of 46 acidic components (35 carboxylic acids and 11 phenols) were identified from the oil. Among them, three carboxylic acids peculiar to spear mint oil, cis-2-pentylcyclopropane-1-carboxylic acid, 3-isopropenylpentane-1,5-dioic acid, and 3-isopropenyl-6-oxoheptanoic acid were newly assigned by spectral data and by synthesis. The absolute configuration of one of the compounds was determined to be (IS, 2R)-(+)-enantiomer by an enantioselective multidimensional GC. The quantitative comparison of the major acidic components in the other three types of spearmint oil, in two types of peppermint oil, and in cornmint oil were discussed.

Regeneration from leaf disks and petioles was studied using orange mint (Mentha citrata Ehrh.), peppermint (Mentha piperita L. cv. Black Mitcham), native spearmint (Mentha spicata L.), and Scotch spearmint (Mentha gracilis Sole cv. Baker). Significantly higher regeneration and lower in vitro contamination rates were observed using petioles of stock plants grown in a controlled environmental chamber or maintained in vitro than using tissue from stock plants in a greenhouse. Regeneration from peppermint petioles was significantly higher on medium containing N6-(2-isopentyl) adenine (2iP) as compared with medium containing benzyladenine or zeatin. Regeneration from y-irradiated mint petioles was inconsistent with doses of 0.27 to 5.4 krad. Microcuttings of mint regener-ants grew significantly taller and produced significantly more roots in Redi-EarthR or a mixture of Redi-EarthR and vermiculite (1:1, v:v) as compared with vermiculite alone.

The effect of row spacings (45, 60 and 75 cm) and various amounts of nitrogen fertilizer (0,100,200 and 300 kg N/ha) on plant growth, essential oil production and composition of Scotch spearmint was studied in the field during 1987 and 1988 in Lucknow, India. Nitrogen application increased plant height and leaf area index while decreased leaf-stem ratio and oil concentration, irrespective of row spacings. The green herbage and oil yields increased significantly up to an application of 200 kg N/ha at 45 or 60 cm row spacing as against up to 300 kg N/ha at 75 cm row spacing. The higher N application at 75 cm row spacing, however, did not increase oil yield compared to application of 200 kg N/ha at 60 cm row spacing. Row spacing influenced various response functions and optimum N rate. At optimum N, response per kg N, net return per kg N and benefit-cost ratio were highest at 60 cm row spacing. Oil concentration and composition in green herb were related to leaf area index and N concentration in the...

A radiation-induced mutant of Scotch spearmint (Mentha × gracilis) was shown to produce an essential oil containing principally C3-oxygenated p-menthane monoterpenes that are typical of peppermint, instead of the C6-oxygenated monoterpene family characteristic of spearmint. In vitro measurement of all of the enzymes responsible for the production of both the C3-oxygenated and C6-oxygenated families of monoterpenes from the common precursor (−)-limonene indicated that a virtually identical complement of enzymes was present in wild type and mutant, with the exception of the microsomal, cytochrome P-450-dependent (−)-limonene hydroxylase; the C6-hydroxylase producing (−)-trans-carveol in the wild type had been replaced by a C3-hydroxylase producing (−)-trans-isopiperitenol in the mutant. Additionally, the mutant, but not the wild type, could carry out the cytochrome P-450-dependent epoxidation of the α,β-unsaturated bond of the ketones formed via C3-hydroxylation. Although present in the wild type, the enzymes of the C3-pathway that convert trans-isopiperitenol to menthol isomers are synthetically inactive because of the absence of the key C3-oxygenated intermediate generated by hydroxylation of limonene. These results, which clarify the origins of the C3- and C6-oxygenation patterns, also allow correction of a number of earlier biogenetic proposals for the formation of monoterpenes in Mentha.

Essential oils were eamined in nine clones of Mentha arvensis, four clones of M. spicata, and 20 clones of M. gracilis. An F1 hybrid of M. arvensis M. spicata, selected on the basis of morphology and chromosome number, was matched with one clone of M. Gracilis. Genes for the inheritance of limonene, 1,8-cineole, linalool, isomenthone, carvone, and piperitenone oide were identified in one clone of M. arvensis and two clones of M. spicata. The range of essential oil compounds detected indicates that no one character can be used to identify M. gracilis, but the critical compounds of the oil of M. gracilis can be derived from crosses of M. arvensis M. spicata.