Herbicidal activity of clove oil and its main constituents eugenol, β-caryophyllene, and α-humulene was studied by measuring their effects on cell membrane integrity in broccoli and common lambsquarters plants at the three- and nine-leaf stage, respectively. Roles of essential oil constituents in the overall phytotoxicity of clove oil, dose-response (10 to 160 mM) relationships of their phytotoxicity, and the effect of light intensity on phytotoxicity of clove oil and eugenol were studied. Most of the phytotoxicity of clove oil (2.5% solution) was due to eugenol, its largest constituent. β-caryophyllene and α-humulene played little or no role. Dose-response relationships showed that at equimolar concentration, eugenol was the most phytotoxic essential oil constituent of the clove oil. On a per unit biomass basis, membrane damage in response to clove oil and eugenol sprays decreased with increasing light intensity. This suggests that efficacy of essential oil in causing plant damage could be affected by light intensity experienced by plants prior to the oil spray.

Plant-based whole foods provide thousands of bioactive metabolites to the human diet that reduce the risk of developing chronic diseases. β-Caryophyllene (CAR) is a common constituent of the essential oil of numerous plants, vegetables, fruits and medicinal herbs, and has been used as a flavouring agent since the 1930 s. Here, we report the antioxidant activity of CAR, its protective effect on liver fibrosis and its inhibitory capacity on hepatic stellate cell (HSC) activation. CAR was tested for the inhibition of lipid peroxidation and as a free radical scavenger. CAR had higher inhibitory capacity on lipid peroxidation than probucol, α-humulene and α-tocopherol. Also, CAR showed high scavenging activities against hydroxyl radical and superoxide anion. The activity of 5-lipoxygenase, an enzyme that actively participates in fibrogenesis, was significantly inhibited by CAR. Carbon tetrachloride-treated rats received CAR at 2, 20 and 200 mg/kg. CAR significantly improved liver structure, and reduced fibrosis and the expression of Col1a1, Tgfb1 and Timp1 genes. Oxidative stress was used to establish a model of HSC activation with overproduction of extracellular matrix proteins. CAR (1 and 10 μm) increased cell viability and significantly reduced the expression of fibrotic marker genes. CAR, a sesquiterpene present in numerous plants and foods, is as a natural antioxidant that reduces carbon tetrachloride-mediated liver fibrosis and inhibits hepatic cell activation.

Investigations were carried out on the origin of osmeterial secretions exuded by fourth instar larvae of Papilio helenus and P. protenor that had been reported to secrete a variety of terpenic compounds. Variations in the chemical composition of the secretion induced by dietary and/or genetic factors were quantitative rather than qualitative in both species. Overall pattern of the chemical constituents was found to be highly species-specific and substantially invariable in a given species. Several sesquiterpene hydrocarbons secreted by the larvae were not present in detectable amounts in the leaves of the host plant, Fagara ailantoides, suggesting that the sesquiterpenes were biosynthesized by these larvae. Deuterium was efficiently incorporated in vivo into sesquiterpene hydrocarbons in the secretion, (E)-β−farnesene, β−caryophyllene, germacrene-A and germacrene-B, by topical application of deuteriumlabelled acetic acid to everted osmeteria, while similar treatment with deuterium oxide resulted in much lower incorporation of deuterium. These results provide evidence for de nova biosynthesis of sesquiterpene hydrocarbons in young Papilio larvae.