Terpene

About: Terpene is a research topic. Over the lifetime, 2208 publications have been published within this topic receiving 51480 citations. The topic is also known as: terpenes.

Terpenes, Phenylpropanoids, Sulfur and Other Essential Oil Constituents as Inhibitors of Cholinesterases.

Abstract: Essential oils constituents are a diverse family of low molecular weight organic compounds with comprehensive biological activity. According to their chemical structure, these active compounds can be divided into four major groups: terpenes, terpenoids, phenylpropenes, and "others". In addition, they may contain diverse functional groups according to which they can be classified as hydrocarbons (monoterpenes, sesquiterpenes, and aliphatic hydrocarbons); oxygenated compounds (monoterpene and sesquiterpene alcohols, aldehydes, ketones, esters, and other oxygenated compounds); and sulfur and/or nitrogen containing compounds (thioesters, sulfides, isothiocyanates, nitriles, and others). Compounds that act as cholinesterase inhibitors still represent the only pharmacological treatment of Alzheimer´s disease. Numerous in vitro studies showed that some compounds, found in essential oils, have a promising cholinesterase inhibitory activity, such as α-pinene, δ-3-carene, 1,8-cineole, carvacrol, thymohydroquinone, α- and β-asarone, anethole, etc. This review summarizes the most relevant research published to date on essential oil constituents and their acetylcholinesterase/butyrylcholinesterase inhibitory potential as well as their structure related activity, synergistic and antagonistic effects.

Understanding Synergistic Toxicity of Terpenes as Insecticides: Contribution of Metabolic Detoxification in Musca domestica.

Abstract: Essential oils, which are mixtures of terpenes, frequently show stronger insecticide activity, i.e., lower lethal dose 50 (LC50), than their most abundant terpenes. Synergy between terpenes provides a plausible explanation, but its demonstration has been elusive. In the present work, we look for an alternative explanation, by considering the influence of insect metabolic detoxification. Basically, we propose a model (metabolic model, MM) in which the LC50 of the major terpene in a mixture is expected to include a fraction that is detoxified by the insect, whereas a minor terpene would act unimpeded, showing a lower LC50 than when acting alone. In order to test this idea, we analyzed the effects of inhibiting the cytochrome P450 detoxification system with piperonyl butoxide (PBO), on the lethal concentration of terpenes as fumigants against Musca domestica. We found that, within a group of 10 terpenes [linalool, citronellal, (R)-α-pinene, 1,8-cineole, γ-terpinene, limonene, α-terpinene, (S)-β-pinene, thymol and (R)-pulegone], seven showed the LC50PBO (the lethal concentration for PBO-treated flies) between 1.7 and 12.4 times lower than the corresponding LC50 when P450 was not inhibited. Only in one case, that of (R)-pulegone, was the LC50PBO greater than the LC50, while two terpenes [(S)-β-pinene and thymol] showed no changes in toxicity. The increased activity of most terpenes (particularly linalool and citronellal) in PBO-treated flies supports our hypothesis that normally the LC50 includes a fraction of inactive compound, due to detoxification. Having previously determined that M. domestica preferentially oxidizes the most abundant terpene in a mixture, while terpenes in smaller proportions are poorly or not detoxified by the P450 system, we assessed whether the toxicity of minority terpenes in a mixture is similar to their activity under P450 inhibition. We chose suitable binary combinations in such a way that one terpene (in greater proportion) should be the target of P450 while the other (in smaller proportion) should intoxicate the fly with LC50PBO or similar. Combinations of 1,8-cineole-citronellal, 1,8-cineole-linalool, linalool-citronellal, (R)-pulegone-linalool, (R)-pulegone-1,8-cineole and (R)-pulegone-citronellal were assayed against M. domestica, and the LC50 of each mixture was determined and compared to values predicted by MM (considering the LC50PBO for minor component) or by the classical approach (LC50 for both components). The MM showed the best fit to the data, suggesting additive rather than synergistic effects, except for the combination of (R)-pulegone-citronellal that was clearly synergistic. Thus, the experimental data indicate that the insect preferentially oxidizes the major component in a mixture, while the terpene in lesser proportion acts as a toxicant, with higher toxicity than when it was assayed alone. These findings contribute to a deeper understanding of the higher toxicity of essential oils compared to their component terpenes and provide important information for the design of effective insecticides based on essential oils or terpenes.

Inhibition of the decrease of volatile esters and terpenes during storage of a white wine and a model wine medium by glutathione and N‐acetylcysteine

Abstract: Summary Glutathione and N-acetylcysteine, each at 20 mg L−1, were tested as inhibitors of the decrease of volatile esters and terpenes during storage of Debina white wine. Moreover, the inhibition of the decrease of isoamyl acetate, ethyl hexanoate and linalool in a model wine medium by glutathione and N-acetylcysteine, each at 0–20 mg L−1, was also tested. Several volatiles, such as isoamyl acetate, ethyl hexanoate, ethyl octanoate, ethyl decanoate and linalool, decreased during wine storage. Glutathione or N-acetylcysteine significantly restricted the decrease of these volatiles. In the model medium, each thiol inhibited the decrease of the three volatiles in a dose-dependent manner. N-acetylcysteine inhibited the decrease of all three volatiles at 2.5 mg L−1 while glutathione at 2.5 or 5.0 mg L−1. The present results indicate that glutathione and N-acetylcysteine may be taken into account as potent inhibitors of the disappearance of aromatic esters and terpenes in wines.