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1.
J Agric Food Chem ; 65(46): 10064-10073, 2017 Nov 22.
Article in English | MEDLINE | ID: mdl-29058428

ABSTRACT

This study investigated the effect of germination and fermentation on the composition of carbohydrates in Australian sweet lupin. Specifically, the amount of sugars (sucrose, fructose, and glucose), starch, oligosaccharides (verbascose, stachyose, and raffinose), and dietary fiber were measured in germinated lupin seeds and fermented lupin flour, and compared with those in soy. High performance liquid chromatography coupled with refractive index was employed for quantitation of sugars, starch, and oligosaccharides, and gas chromatography coupled with a flame ionization detector was used for quantitation of simple sugars in total, and soluble, and insoluble dietary fiber. The enzyme activities of α-amylase and α-glucosidase were compared before and after germination or fermentation. The α-amylase activity in germinated lupin increased to  ∼17 nmol/mL/min/0.1 g and in germinated soy∼32; in fermented lupin, the activity increased to ∼52, while in fermented soy it decreased to ∼20. In general, germination or fermentation decreased the oligosaccharide content, and increased the total sugar in samples (p < 0.05). Total oligosaccharides in lupin after uncontrolled germination were reduced by 98% to 6 mg/g, and after controlled germination reduced by 44% to 86 mg/g. Fermentation with yogurt culture lowered the content of total oligosaccharides due to 94% decrease in stachyose. Total oligosaccharides in soy flour prior to fermentation were 180 mg/g and significantly decreased to ∼124 mg/g in fermented soy. Germination did not affect the starch content. There was no significant change in the amounts of total, soluble, and insoluble dietary fiber after germination or fermentation of lupin except for galactose, which was significantly reduced in germinated lupin seeds. Soluble dietary fiber in germinated soy significantly increased. Germination and fermentation are simple and effective techniques to reduce the oligosaccharides while maintaining the composition of dietary fibers.


Subject(s)
Carbohydrates/chemistry , Flour/analysis , Glycine max/chemistry , Lupinus/chemistry , Seeds/growth & development , Australia , Fermentation , Germination , Lupinus/growth & development , Lupinus/metabolism , Lupinus/microbiology , Plant Proteins/analysis , Plant Proteins/metabolism , Seeds/chemistry , Seeds/metabolism , Seeds/microbiology , Glycine max/growth & development , Glycine max/metabolism , Glycine max/microbiology , alpha-Amylases/analysis , alpha-Amylases/metabolism , alpha-Glucosidases/analysis , alpha-Glucosidases/metabolism
2.
J Food Sci ; 82(2): 333-340, 2017 Feb.
Article in English | MEDLINE | ID: mdl-28098940

ABSTRACT

Date (Pheonix dactylifera L.) seeds are a valuable and abundant by-product with various potential food applications. Free polyphenols (FPPs) and bound polyphenols (BPPs) of date seeds from Deglet Nour variety grown in Australia were investigated using high-performance liquid chromatography-mass spectrometry. The FPP fraction contained the following main phenolic compounds per gram of date seed powder; procyanidin B1 (499.8 ± 7.8 µg), procyanidin B2 (288.6 ± 6.1 µg), catechin (167.6 ± 2.1 µg), epicatechin (39.44 ± 0.39 µg), and protocatechuic acid (1.77 ± 0.22 µg). Additionally, one of the 2 A-type dimers was confirmed as procyanidin A2 (24.05 ± 0.12 µg/g). A-type dimers have not been reported before in date seeds. The BPP fraction contained epicatechin (52.59 ± 0.76 µg/g) and procyanidin B2 (294.2 ± 3.7 µg/g), while several peaks exhibiting ESI- m/z of 153 indicated dihydroxybenzoic acid isomers including protocatechuic acid (2.138 ± 0.025 µg/g). These findings contributed to our knowledge of date seed phytochemicals and understanding of their contribution to the reported bioactivities.


Subject(s)
Chromatography, High Pressure Liquid/methods , Mass Spectrometry/methods , Phoeniceae/chemistry , Plant Extracts/chemistry , Polyphenols/chemistry , Seeds/chemistry , Australia
3.
Mol Nutr Food Res ; 61(5)2017 05.
Article in English | MEDLINE | ID: mdl-27981743

ABSTRACT

SCOPE: Whey protein isolate (WPI) contains vitamin B12 and folate. However, the efficacy of WPI as a bioavailable source of these vitamins in the elderly with low vitamin B12 was not previously tested. We investigated the effects of WPI supplementation on vitamin B12 and folate status in blood and measured changes in homocysteine (HCY), methylmalonic acid (MMA), and genome integrity biomarkers in elderly individuals with low vitamin B12 status. The effect of WPI was compared to soy protein isolate (SPI). METHODS AND RESULTS: In this randomized controlled cross-over intervention trial, 56 subclinically vitamin B12 -deficient participants received 50 g WPI or 50 g SPI as a control for 8 wk followed by 16-wk washout phase and then cross-over to alternative supplement for next 8 wk. Consumption of WPI resulted in significant increase in serum active B12 (p < 0.0001) and serum folate (p = 0.0094). MMA, HCY, and nucleoplasmic bridges increased significantly after SPI intake but not after WPI (p = 0.052; p = 0.028; p = 0.0009, respectively). CONCLUSION: Results indicate that WPI consumption improves active B12 and folate status. Unlike SPI, WPI consumption may prevent increase in MMA, HCY, and genome instability in older Australians with low vitamin B12 status.


Subject(s)
Folic Acid/blood , Vitamin B 12 Deficiency/blood , Vitamin B 12 Deficiency/drug therapy , Vitamin B 12/blood , Whey Proteins/pharmacology , Aged , Australia , Cross-Over Studies , DNA Damage/drug effects , Diet , Dietary Supplements , Female , Homocysteine/blood , Humans , Male , Methylmalonic Acid/blood , Middle Aged , Nutrition Assessment
4.
Food Chem ; 148: 92-6, 2014 Apr 01.
Article in English | MEDLINE | ID: mdl-24262531

ABSTRACT

Inflammation is a well-known contributing factor to many age-related chronic diseases. One of the possible strategies to suppress inflammation is the employment of functional foods with anti-inflammatory properties. Edible mushrooms are attracting more and more attention as functional foods since they are rich in bioactive compounds, but their anti-inflammatory properties and the effect of food processing steps on this activity has not been systematically investigated. In the present study, White Button and Honey Brown (both Agaricus bisporus), Shiitake (Lentinus edodes), Enoki (Flammulina velutipes) and Oyster mushroom (Pleurotus ostreatus) preparations were tested for their anti-inflammatory activity in lipopolysaccharide (LPS) and interferon-γ (IFN-γ) activated murine RAW 264.7 macrophages. Potent anti-inflammatory activity (IC50<0.1 mg/ml), measured as inhibition of NO production, could be detected in all raw mushroom preparations, but only raw Oyster (IC50=0.035 mg/ml), Shiitake (IC50=0.047 mg/ml) and Enoki mushrooms (IC50=0.099 mg/ml) showed also potent inhibition of TNF-α production. When the anti-inflammatory activity was followed through two food-processing steps, which involved ultrasonication and heating, a significant portion of the anti-inflammatory activity was lost suggesting that the anti-inflammatory compounds might be susceptible to heating or prone to evaporation.


Subject(s)
Agaricales/chemistry , Anti-Inflammatory Agents/pharmacology , Inflammation/immunology , Interferon-gamma/immunology , Lipopolysaccharides/immunology , Macrophages/drug effects , Macrophages/immunology , Agaricales/classification , Animals , Anti-Inflammatory Agents/chemistry , Mice , Tumor Necrosis Factor-alpha/immunology
5.
Plant Foods Hum Nutr ; 69(1): 30-6, 2014 Mar.
Article in English | MEDLINE | ID: mdl-24202545

ABSTRACT

Eryngium bornmuelleri Nab. (Tusî) is an endemic botanical from the Eastern Anatolia region of Turkey traditionally used for preparation of herbal tea. Within this study, phenolic composition, antioxidant capacities and inhibitory activities towards selected digestive enzymes of E. bornmuelleri leaf were investigated. Sequential extracts, obtained by extraction of plant tissue by ethanol, acetone and water exhibited pronounced antioxidant capacities and in a dose-dependent manner suppressed the metabolic syndrome related enzymes: α-amylase, α-glucosidase and pancreatic lipase. All extracts contained high levels of phenolic compounds. Flavonoid glycosides were the main phytochemicals detected, with rutin as the major compound (70% of total phenolics). Chlorogenic, hydroxybenzoic and caftaric acids as well as traces of caffeic, ferulic and rosmarinic acids were also detected. Correlation analysis indicated that phenolic compounds were the major sources of the enzyme-inhibitory activities. This study suggests that E. bornmuelleri leaf extracts can modulate the metabolism of sugars and fats through inhibition of the relevant digestive enzymes.


Subject(s)
Antioxidants/pharmacology , Enzyme Inhibitors/pharmacology , Eryngium/chemistry , Metabolic Syndrome/enzymology , Phenols/pharmacology , Plant Extracts/pharmacology , Rutin/pharmacology , Antioxidants/analysis , Enzyme Inhibitors/analysis , Glycoside Hydrolase Inhibitors , Humans , Lipase/antagonists & inhibitors , Phenols/analysis , Plant Extracts/chemistry , Plant Leaves/chemistry , Rutin/analysis , Turkey , alpha-Amylases/antagonists & inhibitors
6.
PLoS One ; 8(10): e76362, 2013.
Article in English | MEDLINE | ID: mdl-24204618

ABSTRACT

Vitamin D deficiency is widespread, affecting over 30% of adult Australians, and increasing up to 80% for at-risk groups including the elderly (age>65). The role for Vitamin D in development of the central nervous system is supported by the association between Vitamin D deficiency and incidence of neurological and psychiatric disorders including Alzheimer's disease (AD). A reported positive relationship between Vitamin D status and cognitive performance suggests that restoring Vitamin D status might provide a cognitive benefit to those with Vitamin D deficiency. Mushrooms are a rich source of ergosterol, which can be converted to Vitamin D2 by treatment with UV light, presenting a new and convenient dietary source of Vitamin D2. We hypothesised that Vitamin D2-enriched mushrooms (VDM) could prevent the cognitive and pathological abnormalities associated with dementia. Two month old wild type (B6C3) and AD transgenic (APPSwe/PS1dE9) mice were fed a diet either deficient in Vitamin D2 or a diet which was supplemented with VDM, containing 1±0.2 µg/kg (∼54 IU/kg) vitamin D2, for 7 months. Effects of the dietary intervention on memory were assessed pre- and post-feeding. Brain sections were evaluated for amyloid ß (Aß) plaque loads and inflammation biomarkers using immuno-histochemical methods. Plasma vitamin D metabolites, Aß40, Aß42, calcium, protein and cholesterol were measured using biochemical assays. Compared with mice on the control diet, VDM-fed wild type and AD transgenic mice displayed improved learning and memory, had significantly reduced amyloid plaque load and glial fibrillary acidic protein, and elevated interleukin-10 in the brain. The results suggest that VDM might provide a dietary source of Vitamin D2 and other bioactives for preventing memory-impairment in dementia. This study supports the need for a randomised clinical trial to determine whether or not VDM consumption can benefit cognitive performance in the wider population.


Subject(s)
Agaricus/chemistry , Ergocalciferols/pharmacology , Memory/drug effects , Alzheimer Disease/metabolism , Alzheimer Disease/pathology , Amyloid beta-Peptides/blood , Amyloid beta-Peptides/metabolism , Animal Feed , Animals , Brain/drug effects , Brain/metabolism , Brain/pathology , Calcium/blood , Cholesterol/blood , Cytokines/metabolism , Dietary Supplements , Disease Models, Animal , Ergocalciferols/chemistry , Ergocalciferols/toxicity , Inflammation/metabolism , Inflammation Mediators/metabolism , Liver/drug effects , Liver/metabolism , Male , Maze Learning , Mice , Mice, Transgenic , Plaque, Amyloid , Time Factors , Vitamin D/blood , Vitamin D/metabolism
7.
Nutr Cancer ; 65(5): 746-64, 2013.
Article in English | MEDLINE | ID: mdl-23859043

ABSTRACT

Numerous in vitro studies using solvent or aqueous extracts of raw dietary plant material have demonstrated modulation of colon cancer cell growth and apoptosis and effects on immune and nonimmune pathways of inflammation. We have developed a generic, 3-staged food-compatible process involving heating for conversion of dietary plants into food ingredients and report results on potential colon cancer-regulating properties of processed forms of Bay leaf (Laurus nobilis). In vitro studies demonstrated inhibition of cancer cell growth by processed Bay leaf products in HT-29, HCT-116, Caco-2, and SW-480 human cancer cell lines, which were accompanied by variable levels of elevated apoptosis. Bay leaf also exerted moderate inhibition of cycloxygenase 2 and 5 lipoxygenase enzymatic activity. In addition, these extracts significantly downregulated interferon-γ production in T helper Type 1-stimulated whole blood from healthy donors. Furthermore, size fractionation of the extracts revealed that antiproliferative and proapoptotic activities were associated with low mass (primarily polyphenolics and essential oils) and high mass (primarily proteins including polyphenol oxidase) chemical classes, respectively. Bay leaf exerted in vitro bioactivity that might be relevant to protecting against early events in sporadic colorectal cancer, with potential for further optimization of bioactivity by size-based fractionation.


Subject(s)
Cell Differentiation/drug effects , Colorectal Neoplasms/metabolism , Laurus/chemistry , Antineoplastic Agents, Phytogenic/pharmacology , Antioxidants/pharmacology , Apoptosis/drug effects , Arachidonate 5-Lipoxygenase/metabolism , Caco-2 Cells , Cell Survival/drug effects , Cyclooxygenase 2/metabolism , Enzyme Inhibitors/pharmacology , HCT116 Cells , HT29 Cells , Humans , Interferon-gamma/metabolism , Oils, Volatile/pharmacology , Plant Extracts/pharmacology , Plant Leaves/chemistry , Polyphenols/pharmacology
8.
Int J Med Mushrooms ; 15(3): 233-49, 2013.
Article in English | MEDLINE | ID: mdl-23662612

ABSTRACT

The consumption of mushrooms has been linked with protection against dementia, including Alzheimer's disease (AD), by several biological pathways including inhibiting beta-site APP-cleaving enzyme (BACE1), which is responsible for releasing toxic ß-amyloid peptide in the brain. We have investigated the capacity of several medicinal mushroom species-Auricularia polytricha (wood ear mushroom), Agaricus bisporus (button mushroom), Flammulina velutipes (winter or enoki mushroom), and Lentinus edodes (shiitake mushroom)-in the regulation of BACE1. Mushrooms were subjected to a generic food-compatible processing method to detect process-stable or process-modified products; the effects of processing were interpreted to infer the chemical classes associated with bioactivity. We have shown previously that in addition to enzyme inhibition, in the presence of the BACE1 proenzyme, heteropolymeric species such as heparin can activate BACE1 by modulating access to the catalytic site. We observed both inhibitory and activating components of the various mushrooms. Only BACE1 inhibitory species were detected in unprocessed and processed forms of A. polytricha, whereas the dominant extracted species from A. bisporus, F. velutipes, and L. edodese were activators of BACE1. It is not known whether activating species were masking the presence of inhibitory species in A. bisporus, F. velutipes, and L. edodes. Inhibitory species were attributed to hispidin-derived polyphenols, whereas activating species were attributed to soluble polysaccharides and possibly low-mass Maillard products produced during processing. Larger molecular BACE1-activating species are unlikely to be bioavailable to brain in contrast with possible brain bioavailability of smaller, lipophilic hispidins.


Subject(s)
Amyloid Precursor Protein Secretases/antagonists & inhibitors , Aspartic Acid Endopeptidases/antagonists & inhibitors , Basidiomycota/chemistry , Basidiomycota/metabolism , Flammulina , Hot Temperature , Molecular Structure , Neuroprotective Agents
9.
Food Funct ; 4(4): 592-601, 2013 Apr 25.
Article in English | MEDLINE | ID: mdl-23370542

ABSTRACT

Chemical and sensory characterisation of whole and fractionated myrosinase-free extracts from selected Australian-grown, raw Brassica vegetables (broccoli, cauliflower, Brussels sprouts and red cabbage) was carried out to determine the contribution of key phytochemicals (i.e. glucosinolates, free sugars, phenolics) to the taste profiles of these vegetables. Glucosinolate (GS) and phenolic profiles were determined by liquid chromatography coupled with photodiode array detection and mass spectrometry. Ten glucosinolates (GS) were quantified across the vegetables investigated. Brussels sprouts (186.3 µg g(-1) FW) followed by broccoli (164.1 µg g(-1) FW) were found to contain the most GS. The phenolic profiles of all samples were dominated by hydroxycinnamic acid derivatives. As expected, red cabbage was the only vegetable with a significant anthocyanin signal (574.0 µg g(-1) FW). Red cabbage (26.7 mg g(-1) FW) and cauliflower (18.7 mg g(-1) FW) were found to contain a higher concentration of free sugars than Brussels sprouts (12.6 mg g(-1) FW) and broccoli (10.2 mg g(-1) FW). Descriptive sensory analysis of the whole extracts found sweetness (cauliflower and red cabbage sweeter than broccoli and Brussels sprouts) and bitterness (Brussels sprouts more bitter than others) as the most discriminating attributes. A hydrophilic fraction with sweetness, umami and saltiness as the main attributes was the most taste active fraction across all Brassica whole extracts. Sub-fractionation showed that this fraction was also bitter but the presence of sugars counteracted bitterness. Several components within each extract were found to contribute to the bitterness of whole Brassica extracts. The total and individual GS content alone could not explain the perceived bitterness of these extracts. Phenolics and/or other components are likely to be contributing to the bitterness associated with these vegetables.


Subject(s)
Brassica/chemistry , Plant Extracts/chemistry , Taste , Vegetables/chemistry , Adult , Brassica/classification , Chromatography, High Pressure Liquid , Female , Humans , Male , Mass Spectrometry , Middle Aged
10.
J Sci Food Agric ; 93(4): 846-52, 2013 Mar 15.
Article in English | MEDLINE | ID: mdl-22887449

ABSTRACT

BACKGROUND: Diets high in fruit and vegetables are known to have significant health benefits. This is in part due to the presence of phytochemicals, which possess potential protective health benefits. This study focuses on the ability of strawberries to be bred for higher anthocyanin content. This is a major contributor to the characteristic colour and nutritional value of ripe strawberries, together with phenolic acids, ascorbic acid and total antioxidant capacity. RESULTS: Anthocyanins in five commercial strawberry cultivars and three breeding lines were assessed. This led to the discovery of one breeding line (BL 2006-221) as an exceptional source of anthocyanins (~1 g kg(-1) fresh weight), with approximately double the levels of current commercial cultivars. Temperature was shown to influence anthocyanin extraction, with 40 °C being the best extraction temperature using the accelerated solvent extraction (ASE) method. Hue angle and anthocyanin concentration showed a good correlation (r(2) = 0.69). CONCLUSION: The new breeding line BL 2006-221 has the potential to be used in the development of phytochemically rich strawberry cultivars. Using hue angle as a screening tool for total anthocyanin concentration and extraction of anthocyanins from strawberries by ASE at 40 °C would support such cultivar development.


Subject(s)
Anthocyanins/genetics , Breeding , Fragaria/genetics , Fruit/chemistry , Anthocyanins/analysis , Color , Diet , Fragaria/chemistry , Humans , Nutritive Value , Plant Extracts , Species Specificity
11.
Public Health Nutr ; 15(8): 1474-82, 2012 Aug.
Article in English | MEDLINE | ID: mdl-22230576

ABSTRACT

OBJECTIVE: To investigate the relative importance of specific health knowledge and taste on acceptance of Brassica vegetables (broccoli, red and green cabbages, broccolini, cauliflower, Brussels sprouts). DESIGN: In a sample of adults all reporting medium-high physical activity (as a marker/control of health behaviour) and reporting either low (≤2 portions/d) or high (≥3 portions/d) vegetable intake, half of those with low vegetable consumption (Li group) and half of those with high vegetable consumption (Hi group) received cancer protection information, while the other half did not (Ln and Hn groups), before hedonic (9-point), perceived taste and flavour impact responses (100 mm scales) to samples of six Brassica vegetables were elicited. Additionally, attitudes towards foods for health, pleasure and reward, sociodemographics, intentions to consume the vegetables in the near future and recall of health information were also measured. SUBJECTS: Adult males and females (n 200) aged 18-55 years. SETTING: Central location testing, Adelaide, Australia. RESULTS: Information groups Li and Hi reported specific cancer protection information knowledge, in contrast to Ln and Hn groups (P < 0·000). Information independently influenced responses to (the least liked) Brussels sprouts only. Multivariate regression analysis found sensory perception tended to predict liking and intentions to consume Brassica vegetables. For example, broccoli hedonics (adjusted R 2 = 0·37) were predicted (P < 0·05) by bitterness (ß = -0·38), flavour (ß = 0·31), sweetness (ß = 0·17) and female gender (ß = 0·19) and intentions to consume (adjusted R 2 = 0·20) were predicted (P < 0·05) by bitterness (ß = -0·38), flavour (ß = 0·24), female gender (ß = 0·20) and vegetable intake (ß = 0·14). CONCLUSIONS: Addressing taste dimensions (while retaining healthy compounds) may be more important than promoting health information in order to increase the popularity of Brassica vegetables.


Subject(s)
Choice Behavior , Feeding Behavior , Health Knowledge, Attitudes, Practice , Health Promotion , Taste , Vegetables , Adolescent , Adult , Australia , Brassica , Energy Intake , Female , Food Preferences , Humans , Male , Middle Aged , Motor Activity , Multivariate Analysis , Surveys and Questionnaires , Taste Perception , Young Adult
12.
Nutr Cancer ; 63(7): 1074-84, 2011.
Article in English | MEDLINE | ID: mdl-21875324

ABSTRACT

Kakadu plum (Terminalia ferdinandiana Exell, Combretaceae) and Illawarra plum (Podocarpus elatus Endl., Podocarpaceae) extracts were fractionated, using a bioassay-guided approach and screened for antioxidant activity [oxygen radical absorbance capacity (ORAC) and cellular antioxidant activity (CAA) assays] and antiinflammatory activity (nitrite concentration and prostaglandin E(2) release in lipopolysaccharide (LPS)-activated murine macrophages). Among 8 fractions obtained from KP and 5 fractions obtained from IP, fraction KPF5 from KP exhibited superior activity in all assays, with an ORAC value of 3,776 ± 603 µmol Trolox/g DW and a CAA value of 52.2 ± 8.6 µmol quercetin equivalents/g DW. In addition, KPF5 further demonstrated an upregulation of the Nrf2/Keap1 ratio in Hep G2 cells. KPF5 also inhibited the expression of COX-2 and iNOS in LPS-activated murine macrophages, potentially through the NF-κB, p44/42 mitogen activated protein kinase and Akt pathways. KPF5 also induced apoptosis and DNA damage in HT-29 cells, as determined by the cytokinesis block micronucleus cytome assay.


Subject(s)
Anti-Inflammatory Agents/pharmacology , Antioxidants/pharmacology , Plant Extracts/pharmacology , Polyphenols/pharmacology , Prunus/chemistry , Animals , Anticarcinogenic Agents , Apoptosis/drug effects , Blotting, Western , Cell Line , Cyclooxygenase 2/genetics , Cyclooxygenase 2/metabolism , Dinoprostone/metabolism , HT29 Cells , Hep G2 Cells , Humans , Intracellular Signaling Peptides and Proteins/genetics , Intracellular Signaling Peptides and Proteins/metabolism , Kelch-Like ECH-Associated Protein 1 , Lipopolysaccharides/metabolism , Macrophages/drug effects , Mice , Mitogen-Activated Protein Kinase 3/genetics , Mitogen-Activated Protein Kinase 3/metabolism , NF-E2-Related Factor 2/genetics , NF-E2-Related Factor 2/metabolism , NF-kappa B/metabolism , Nitric Oxide Synthase Type II/genetics , Nitric Oxide Synthase Type II/metabolism , Nitrites/analysis , Proto-Oncogene Proteins c-akt/genetics , Proto-Oncogene Proteins c-akt/metabolism , Quercetin/pharmacology , Signal Transduction , Up-Regulation
13.
Plant Physiol Biochem ; 42(11): 875-82, 2004 Dec.
Article in English | MEDLINE | ID: mdl-15694281

ABSTRACT

Melaleuca alternifolia (Cheel) is an Australia native tree harvested for its monoterpene-rich, essential oil. Monoterpene synthases (E.C. 4.2.3.20) were partially purified from the flush growth of the commercially important, high terpinen-4-ol chemotype of M. alternifolia. The purified fractions produced an acyclic monoterpene, linalool that is not present in the essential oil. To further characterise the monoterpene synthase, a cDNA library was constructed and 500 expressed sequence tags (ESTs) were sequenced to isolate putative terpene synthases. A single clone with similarity to the TspB gene sub-family of angiosperm monoterpene and isoprene synthases was isolated but was truncated at the 5' end. This single clone was used to design a probe for a cDNA library and was applied to isolate a full-length clone. This gene encoded a polypeptide 583 amino acids in length (67 kDa) including a putative transit peptide. Heterologous expression of the gene in Escherichia coli and subsequent assay of the recombinant enzyme did not result in the production of terpinen-4-ol, the major constituent of tea tree oil, or of its precursor sabinene hydrate. Significant quantities of linalool were observed in these assays, and in the assays of monoterpene synthase activity of a native enzyme in vitro, but the racemic nature of the linalool means that it may have a non-enzymatic origin.


Subject(s)
Expressed Sequence Tags , Intramolecular Lyases/metabolism , Melaleuca/enzymology , Monoterpenes/chemistry , Recombinant Proteins/metabolism , Base Sequence , Cloning, Molecular , Escherichia coli/genetics , Gene Library , Intramolecular Lyases/isolation & purification , Melaleuca/genetics , Molecular Sequence Data , Recombinant Proteins/isolation & purification
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