Quantitation of monoterpenoid compounds with potential medicinal use in biological fluids

Differentiating and apoptotic dose-dependent effects in (-)-alpha-bisabolol-treated human endothelial cells

The effect on angiogenesis of (-)-alpha-bisabolol [(-)-6-methyl-2-(4-methyl-3-cyclohexen-1-yl)-5-hepten-2-ol] (1), a widely distributed plant sesquiterpene alcohol, was investigated for the first time. Human endothelial cells treated with 1 were analyzed for their ability to differentiate and organize in microvessels and for their sensitivity to this compound in terms of cytotoxicity and cell growth inhibition. Within 24 h of the treatment with 5 microM 1, cells underwent massive death. Apoptosis induction was responsible for cytotoxicity triggered by 1 as revealed by the release of cytochrome c from the mitochondria, reduction of the Bcl-2/Bax ratio, and caspase 3 activation. At a lower, non-apoptotic concentration (0.25 microM), 1 showed a differentiating effect resulting in growth inhibition, invasiveness reduction, and tubule stabilization.

Bimolecular and unimolecular contributions to the disparate self-chemical ionizations of alpha-pinene and camphene isomers

The contributions of molecular and fragment ions toward the disparate self-chemical ionization (SCI) of alpha-pinene and camphene isomers were investigated. A kinetic model was constructed to predict the SCI outcomes for these two C(10)H(16) isomers. A major portion of the camphene molecular ions (isolated 500 ms after the 10 ms EI event at 24 eV) unimolecularly dissociated within 200 s of the ionization event. Conversely, under similar experimental conditions, the alpha-pinene molecular ions as well as the major fragment ions of alpha-pinene and camphene showed no unimolecular dissociation. The alpha-pinene and camphene molecular ions yielded product ions through two different reaction mechanisms (direct charge-transfer {CT} and indirect proton transfer {PT}). The isolated terpene fragment ions at m/z 93 and 121 reacted with their respective neutrals to produce [M + H](+). Proton affinity (PA) bracketing experiments, PA additivity schemes, and alkene PA versus adiabatic ionization energy (IE) linear correlation indicated that the PAs of camphene and alpha-pinene were comparable ( approximately 210 +/- 2 kcal x mol(-1)). The observed [M + H](+) SCI terpene ions were mainly the products of various fragment ion reactions.

LC determination of citral in Cymbopogon citratus volatile oil

It was the aim of this study to develop and validate a HPLC method for the quantitative determination of citral in Cymbopogon citratus volatile oil. The HPLC assay was performed using a Spherisorb CN column (250 mm x 4.6 mm, 5 microm), a n-hexane:ethanol (85:15) mobile phase and an UV detector (set at 233 nm). The following parameters were evaluated: linearity, precision, accuracy, specificity, quantification and detection limits. The method showed linearity in the range of 10.0-30.0 microg ml(-1). Precision and accuracy were determined at the concentration of 20 microg ml(-1). The concentration of citral in C. citratus volatile oil obtained with this assay was 75%. The HPLC method developed in this study showed an excellent performance (linearity, precision, accuracy and specificity) and can be applied to assay citral in volatile oil.

Sensitive biomonitoring of monoterpene exposure by gas chromatographic-mass spectrometric measurement of hydroxy terpenes in urine

A gas chromatographic method with mass selective detection was developed which enables the simultaneous determination of the urinary hydroxy terpenes cis-verbenol, alpha-terpineol, myrtenol, carveol, perillyl alcohol and trans-sobrerol. The sample preparation consisted of enzymatic hydrolysis, solid phase extraction (SPE) with RP-C(18) SPE material and clean up with silica gel cartridges. Large volume injection was used and the mass selective detection was done in the single ion modus. Low detection limits in the range of 1.0-4.5 microg/l for the terpene metabolites in urine and mean recoveries of 100% were achieved.