Guaiol

Abstract: In this paper, we present principal component analysis (PCA) results from a dataset containing 494 cannabis flower samples and 170 concentrate samples analyzed for 31 compounds. A continuum of chemical composition amongst cannabis strains was found instead of distinct chemotypes. Our data shows that some strains are much more reproducible in chemical composition than others. Strains labeled as indica were compared with those labeled as sativa and no evidence was found that these two cultivars are distinctly different chemotypes. PCA of “OG” and “Kush” type strains found that “OG” strains have relatively higher levels of α-terpineol, fenchol, limonene, camphene, terpinolene and linalool where “Kush” samples are characterized mainly by the compounds trans-ocimene, guaiol, β-eudesmol, myrcene and α-pinene. The composition of concentrates and flowers were compared as well. Although the absolute concentration of compounds in concentrates is much higher, the relative composition of compounds between flowers and concentrates is similar.

Abstract: The essential oils of the leaves, stems, rhizomes and roots of the medicinal plant Alpinia galanga from southern India were investigated by GC-FID, GC-MS and olfactometry. In all four samples, mono- and sesquiterpenes as well as (E)-methyl cinnamate could be identified. They are responsible for the characteristic odor as well as for the reported use in (folk) medicine and in food products of A. galanga. The essential oil of A. galanga leaves is rich in 1,8-cineole (28.3%), camphor (15.6%), beta-pinene (5.0%), (E)-methyl cinnamate (4.6%), bornyl acetate (4.3%) and guaiol (3.5%). The stem essential oil contains 1,8-cineole (31.1%), camphor (11.0%), (E)-methyl cinnamate (7.4%), guaiol (4.9%), bornyl acetate (3.6%), beta-pinene (3.3%) and alpha-terpineol (3.3%). 1,8-cineole (28.4%), alpha-fenchyl acetate (18.4%), camphor (7.7%), (E)-methyl cinnamate (4.2%) and guaiol (3.3%) are the main constituents of the rhizome essential oil. The root essential oil contains alpha-fenchyl acetate (40.9%), 1,8-cineole (9.4%), borneol (6.3%), bornyl acetate (5.4%) and elemol (3.1%). In addition, biological and aroma effects of the main and minor compounds of the four essential oils of Alpinia galanga are discussed in terms of their possible use in medicine, cosmetics and foods.

Abstract: Mosquitoes are important vectors of several diseases, and control of these insects is imperative for human health. Insecticides have proven useful in controlling mosquito populations, but insecticide resistance and environmental concerns are increasing. Additionally, emerging and re-emerging microbial infections are problematic. Essential oils have been shown to be promising mosquito larvicidal agents as well as antimicrobial agents. In this work, the essential oils from four species of Myrtaceae (Baeckea frutescens, Callistemon citrinus, Melaleuca leucadendra, and Syzygium nervosum) growing wild in central Vietnam have been obtained by hydrodistillation and analyzed by gas chromatographic techniques. The essential oils have been screened for mosquito larvicidal activity against Aedes aegypti, Aedes albopictus, and Culex quinquefasciatus, and for antimicrobial activity against Enterococcus faecalis, Staphylococcus aureus, and Candida albicans. Callistemon citrinus fruit essential oil, rich in α-pinene (35.1%), 1,8-cineole (32.4%), limonene (8.2%), and α-terpineol (5.8%) showed good larvicidal activity with 24-h LC50 = 17.3 μg/mL against both Ae. aegypti and Cx. quinquefasciatus, and good antibacterial activity against E. faecalis (minimum inhibitory concentration (MIC) = 16 μg/mL) The 48-h larvicidal activities of M. leucadendra leaf essential oil, rich in α-eudesmol (17.6%), guaiol (10.9%), linalool (5.1%), (E)-caryophyllene (7.0%), and bulnesol (3.6%) were particularly notable, with LC50 of 1.4 and 1.8 μg/mL on Ae. aegypti and Cx. quinquefasciatus. Similarly, M. leucadendra bark essential oil, with α-eudesmol (24.1%) and guaiol (11.3%), showed good antibacterial activity against. E. faecalis. Both B. frutescens and C. citrinus leaf essential oils demonstrated anti-Candida activities with MIC values of 16 μg/mL. The results of this investigation suggest that essential oils derived from the Myrtaceae may serve as “green” alternatives for the control of mosquitoes and/or complementary antimicrobial agents.