Denys J. Charles

Effects of osmotic stress on the essential oil content and composition of peppermint

Abstract The essential oil content and composition of hydroponically-grown peppermint ( Mentha x piperita L.) plants (29- and 36-day-old cuttings) were each affected by growth solution potential (ψ s ) and duration of exposure to mild and moderate osmotic stress. After one week of treatment, the essential oil content of leaves increased from 44.0 to 61.1 ul μl g −1 leaf dry wt as ψ s decreased from −0.05 to −0.6 MPa, and no differences in shoot biomass, leaf area, or total oil production by leaves were evident in plants grown at these treatment levels. The same levels of ψ s applied for two weeks resulted in larger differences in plant growth and leaf oil content. When plants were subjected to increasing levels of osmotic stress, leaf essential oil content increased linearly from 44.0 to 70.8 μl g −1 dry wt, but shoot biomass and leaf area each decreased exponentially. Total essential oil yield of plants subjected to two weeks of treatment was significantly reduced as stress increased. The major constituents of essential oil, menthone and menthol, together accounted for ca 80% of the total monoterpenes, and this proportion was unaffected by treatment. Few consistent trends in oil composition among stress treatments were evident, although the relative proportion of sesquiterpenes increased with osmotic stress.

Water Stress-Induced Alterations in Essential Oil Content and Composition of Sweet Basil

ABSTRACT Mild and moderate plant water stress increased sweet basil leaf essential oil content and altered oil composition. After 21 d of plant water deficit, the oil content of leaves increased from 3.1 to 6.2 μl.g1 leaf dry wt. as xylem water potential (ψ) decreased from −0.30 to −1.12 MPa. Significant decreases in leaf dry weight and stem dry weight were observed as plant water deficit increased. Only leaf area from plants subjected to a mild water deficit (-0.68 MPa) was not significantly reduced compared to the control, non-stressed plants. Water stress altered the oil composition (both as a relative percentage of total oil and μl.g1 leaf dry weight). Linalool and methyl chavicol increased as water stress increased, while the relative proportion of sesquiterpenes decreased.

Characterization of the Essential Oil of Artemisia annua L.

ABSTRACT A germplasm collection of Artemisia annua L. consisting of 13 accessions was field grown. The essential oil, which was obtained from dry leaves and flowers by hydrodistillation was analyzed by GC and GC/MS for essential oil composition. The oil content of leaves ranged from 0.84% to 1.51% (volume/dry weight) with individual plants as high as 2.35%. Thirty-two constituents were identified in the oil of the leaves and flowers, and the greatest concentration of oil was found in fully mature leaves (47% total oil/plant), the middle third portion of the foliage. The major components of the oil include: artemisia ketone (35.6%) and 1,8-cineole (28.1%) in the leaves of early summer harvested plants, artemisia ketone (26.8%) and camphor (20.5%) in leaves of fall harvested plants, and artemisia ketone (56%) and camphor (10.5%) in flowers of fall harvested plants. Certain accessions which were rich in specific constituents (as % of essential oil) were identified, e.g., artemisia ketone (68.5%), camphor (27...

Purification and characterization of acetyl-CoA carboxylase from developing soybean seeds☆

Abstract Acetyl-CoA carboxylase from two lines of soybean ( Glycine max ) seeds has been purified to apparent homogeneity. The procedure included affinity chromatography of the enzyme on avidin-monomer-Sepharose 4B. The enzyme from both lines showed a single band on polyacrylamide gel electrophoresis. On sodium dodecyl sulphatepolyacrylamide gel electrophoresis, the enzyme from experimental line 9686 showed a single protein band having the M , 240 000. The enzyme from the commercial line Wayne, however, showed three protein bands having the M , s 240 000, 65 000 and 58 000, respectively. High concentrations of the enzyme were required for stability as well as the presence of dithiothreitol, glycerol and Triton X-100. The enzyme was active over a wide pH range, with an optimum at 8.2 for 9686 and 7.5 for Wayne. The enzyme from both 9686 and Wayne showed absolute specificity for acetyl-CoA as a substrate and this could not be replaced by propionyl-CoA, butyryl-CoA, hexanoyl-CoA or S-methylerotonyl-CoA. At the optimum pH the apparent K m values for the substrates were: bicarbonate, 1.13 mM; acetyl-CoA, 0.32 mM; ATP, 0.46 mM for the Wayne carboxylase and bicarbonate, 1.56 mM; acetyl-CoA, 0.17 mM; ATP, 0.14 mM for the 9686 enzyme. Citrate, at higher concentrations, was strongly inhibitory. Both ADP and AMP inhibited the enzyme from 9686 and Wayne. The enzyme from both 9686 and Wayne did not appear to be highly regulated by cellular metabolites.

A New Geraniol Chemotype of Ocimum gratissimum L.

ABSTRACT The essential oils which were obtained from the leaves, flowers and stems of Ocimum gratissimum in concentrations of 1.34%, 1.49% and 0.14% respectively, were examined by GC/MS. Fifteen constituents in the essential oil were identified with geraniol (83.7–88.8%) as the major constituent. Other major components included γ-muurolene (1.58–3.88%), β-caryophyllene (1.2–2.29%), neral (1.35–3.82%) and limonene (0.74–1.91%). Essential oil composition was similar among plant parts. Eugenol and thymol reported as the major constituent of Nigerian and Indian oil could not be detected in this oil. This is the first report of a geraniol-rich essential oil from O. gratissimum.

Characterization of acetyl-CoA carboxylase in the seed of two soybean genotypes☆

Abstract Changes in the activity of acetyl-CoA carboxylase was followed during the formation of two lines of soybean ( Glycine max .) seeds. The acetyl-CoA carboxylase activity expressed as units/seed was found to be higher in the experimental variety 9686 than in the cultivar, Wayne. The maximum activity in 9686 was around 40 days after flowering (DAF), while in Wayne it was around 30 DAF. The enzyme was active over a wide pH range, with an optimum at 8.2 for 9686 and 7.5 for Wayne. Citrate below 3 mM bad no effect on 9686 enzyme, but higher concentrations were inhibitory. In Wayne, an increase in citrate up to 5 mM slightly stimulated the enzyme but higher concentrations were strongly inhibitory. Mn 2+ could not replace Mg 2+ as an essential activator of the carboxylase in both Wayne and 9686. A differential regulation of acetyl-CoA carboxylase in the two lines of soybean is suggested.

Volatile leaf oil of the curry plant [Helichrysum italicum (Roth) G. Don subsp. italicum] and dwarf curry plant [subsp. microphyllum (Willd.) Nyman] in the North American herb trade

Abstract The essential oil of the leaves and stems of Helichrysum italicum (Roth) G. Don subsp. italicum, examined by GC/MS, is dominated by neryl acetate (16.60±2.01%) and γ-curcumene (15.98±1.44%). The essential oil of the leaves and stems of H. italicum subsp. microphyllum (Willd.) Nyman is dominated by neryl acetate (38.60±15.11%), linalool (17.28±7.75%), nerol (14.55±8.71%), and limonene (10.73±4.56%).

Purification and characterization of a phenylalanine ammonia-lyase from Ocimum basilicum

Abstract A new phenylalanine ammonia-lyase (PAL) was purified from leaves of Ocimum basilicum L. (chemotype, methyl cinnamate). Separation techniques applied icluded anion exchange chromatography and preparative electroelution from a non-denaturing polyacrylamide gel. A 180-fold purification was obtained. The native enzyme was a homotetramer of Mr 152 000–153 000; the intact subunit Mr was ca 38 000. The enzyme catalysed the conversion of l -phenylalanine -d 8 into trans-cinnamic acid-d7, as determined by GC-mass spectral analysis of silylated reaction products. The purified native enzyme had Km and Vmax values of 329 μM and 11.43 μmol min−1 mg−1 protein, respectively, for l -phenylalanine and was competitively inhibited by 2-aminoindan-2-phosphonic acid, trans-cinnamic acid and trans-methyl cinnamate with Ki values of 19 nM and 57 and 130 μM, respectively. Comparing the Ki values between trans-cinnamic acid and trans-methyl cinnamate for l -phenylalanine indicated that the regulation of PAL is not only related to the mechanism of feedback inhibition in the biosynthesis of trans-methyl cinnamate.

The Essential Oil of Alpinia galanga Willd.

ABSTRACT Twelve compounds have been characterized by GC and GC/MS in oil obtained from the rhizome and leaves of Alpinia galanga Willd. The major compound is myrcene (94.51%, rhizome; 52.34%, leaves).

Differentiating Organic from Conventional Peppermints Using Chromatographic and Flow Injection Mass Spectrometric (FIMS) Fingerprints

High-performance liquid chromatography (HPLC) and flow injection mass spectrometric (FIMS) fingerprinting techniques were tested for their potential in differentiating organic and conventional peppermint samples. Ten organic and ten conventional peppermint samples were examined using HPLC-UV and FIMS methods. Principal component analysis (PCA) showed that both HPLC and FIMS fingerprints could determine the difference in the commercial organic and conventional peppermints. FIMS fingerprinting provided a rapid test to differentiate organic and conventional peppermints in 1 min of analysis and has potential for high-throughput applications. On the other hand, HPLC fingerprints provide more information about the chemical composition of the samples, but take a longer time to differentiate organic and conventional peppermint samples.