Zingiberene and curcumene in wild tomato

Composition of ginger oil prepared from fresh ginger rhizomes, Zingiber officinale Roscoe (Zingiberaceae) was determined by gas chromatography (GC) and GC-mass spectrometric techniques. The main sesquiterpene hydrocarbons identified were alpha-zingiberene (27-30%), alpha-curcumene (8-9%), beta-sesquiphellandrene (4.8%). and bisabolene (3.2%). The function of zingiberene and curcumene as insecticides, repellents, and insect feeding deterrents has been previously reported. Other plant species having similar constituents might be found. Leaves of six wild tomato accessions of Lycopersicon hirsutum f. glabratum (Mull); three accessions of L. hirsutum f. typicum (Humb & Bonpl.); two accessions of L. pennellii Corr. (D'Arcy); one accession of L. pimpinellifolium; and one commercial tomato L. esculentumm cv. Fabulous were analyzed. Analysis of L. hirsutum f. typicum (Solanaceae) accessions indicated the presence of zingiberene, curcumene, and other lipophilic secondary metabolites in the leaves of two accessions (PI-127826 and PI-127827). An average three month old wild tomato plant of accessions PI-127826 and PI-127827 provided 1.93 and 1.30 kg fresh leaves (averaging about 38,307 and 28,130 cm2 exposed leaf surface area, respectively) and produced 19.3 and 10.1 g of zingiberene and curcumene (PI-127826) and 17.2 and 1.8 g of zingiberene and curcumene (PI-127827), respectively. Leaf extracts of the wild tomato L. hirsutum f. typicum (accessions PI-127826 and PI-127827) can be used as a biorational source of zingiberene and curcumene.     

Antioxidants in Capsicum chinense: Variation among countries of origin

The main objective of this investigation was to evaluate fruits of C. chinense accessions for their concentration of β -carotene, ascorbic acid, and phenols for use as parents in breeding for these phytochemicals. Mature fruits of 63 accessions of C. chinense originally acquired from Belize, Brazil, Colombia, Ecuador, Mexico, Peru, Puerto Rico, and the United States were analyzed for their chemical composition. Fruits of C. chinense accessions PI-152452 (Brazil) and PI-360726 (Ecuador) contained the greatest concentrations of ascorbic acid (1.2 and 1.1 mg g^?1 fresh fruit, respectively), while PI-438648 (Mexico) contained the greatest concentration of total phenols content (349 μ g g^?1 fresh fruit) among the other 63 accessions tested. Accession PI-355817 from Ecuador contained the greatest concentrations of β -carotene (8 mg g^?1fresh fruit). These accessions were identified as potential candidates for mass production of antioxidants with health-promoting properties.     

Antioxidants in hot pepper: variation among accessions

The U.S. Department of Agriculture (USDA) pepper (Capsicum spp.) germplasm collection contains several thousand members or accessions. Many of these species and cultivars have not been analyzed for their concentrations of ascorbic acid, capsaicin, and total phenolic compounds, which are important antioxidants having a number of benefits for human health. The objective of this investigation was to select candidate accessions of hot pepper having high concentrations of ascorbic acid, capsaicin, free sugars, and total phenols for use as parents in breeding for these compounds. Seventeen accessions of pepper from the core Capsicum germplasm collection (four accessions of Capsicum chinense; five accessions of C. baccatum; six accessions of C. annuum; and two of C. frutescens) were field grown and their mature fruits were analyzed for their antioxidant composition. Concentrations of these compounds tended to be higher in C. chinense and C. baccatum, than in C. annuum and C. frutescens. Across all accessions the concentration of total phenols was correlated with ascorbic acid (r = 0.97) and free sugars (r = 0.80). Concentrations of total phenols (1.4, 1.3, and 1.3 mg g-1 fruit) and ascorbic acid (1.6, 1.2, and 1.3 mg g-1 fruit) were significantly greater in PI-633757, PI-387833, and PI-633754, respectively, compared to other accessions analyzed. Total capsaicinoids concentrations were greatest (1.3 mg g-1 fruit) in PI-438622 and lowest (0.002 mg g-1 fruit) in Grif-9320. The great variability within and among Capsicum species for these phytochemicals suggests that these selected accessions may be useful as parents in hybridization programs to produce fruits with value-added traits.     

Natural products: seasonal variation in trichome counts and contents in Lycopersicum hirsutum f. glabratum

Wild tomato leaves possess a pest-resistance mechanism in their glandular trichomes and the exudates they produce. Type IV and VI glandular trichomes on the leaves of five wild tomato accessions of Lycopersicum hirsutum f. glabratum (PI 126449, PI 134417, PI 134418, PI 251304, and LA 407) grown under greenhouse conditions were counted. Major chemical compounds from glandular leaf trichomes of the accessions tested were extracted, purified, and quantified at different periods during the growing seasons by gas chromatography (GC) and mass spectrometry (GC/MS). The toxicity of two methylketones (2-undecanone and 2-tridecanone), the major constituents of the accessions tested, to adults of the sweetpotato whitefly, Bemisia tabaci (Gennadius) and fourth instar larvae of the Colorado potato beetle (CPB), Leptinotarsa decemlineata (Say), was determined using no-choice bioassays. 2-undecanone caused 80% mortality of the fourth instar larvae of the CPB at the highest concentration tested (100 mg 2-undecanone mL(-1) of acetone) while 2-tridecanone caused 72% mortality of whiteflies at 20 mg 2-tridecanone mL(-1) of 65% ethanol. The concentration of 2-undecanone and 2-tridecanone on the leaves of each of the five accessions of L. hirsutum f. glabratum and the mass spectra of 2-undecanone and 2-tridecanone are presented. Overall, the concentration of 2-undecanone on the leaves was significantly higher than 2-tridecanone. Concentration of the two methylketones varied among accessions and sampling season. Plants produced the highest concentration of 2-undecanone during the month of August. On average, each plant of accession PI 251304 provided 354 g fresh leaves (averaging about 52,353 cm2 exposed leaf surface area) and produced 32.5 and 8.7 mg of 2-undecanone and 2-tridecanone, respectively. L. hirsutum f. glabratum accessions may become a valuable source of natural products, which could minimize reliance on synthetic pesticides.