Essential oils are promising as environmentally friendly and safe sources of pesticides for human use. Furthermore, they are also of interest as aromatherapeutic agents in the treatment of Alzheimer’s disease, and inhibition of the enzyme acetylcholinesterase (AChE) has been evaluated as an important mechanism. The essential oils of some species in the genera Callicarpa, Premna, Vitex and Karomia of the family Lamiaceae were evaluated for inhibition of electric eel AChE using the Ellman method. The essential oils of Callicarpa candicans showed promising activity, with IC₅₀ values between 45.67 and 58.38 μg/mL. The essential oils of Callicarpa sinuata, Callicarpa petelotii, Callicarpa nudiflora, Callicarpa erioclona and Vitex ajugifolia showed good activity with IC₅₀ values between 28.71 and 54.69 μg/mL. The essential oils Vitex trifolia subsp. trifolia and Callicarpa rubella showed modest activity, with IC₅₀ values of 81.34 and 89.38, respectively. trans-Carveol showed an IC₅₀ value of 102.88 µg/mL. Molecular docking and molecular dynamics simulation were performed on the major components of the studied essential oils to investigate the possible mechanisms of action of potential inhibitors. The results obtained suggest that these essential oils may be used to control mosquito vectors that transmit pathogenic viruses or to support the treatment of Alzheimer’s disease.

Objective/Background: The essential oils (EOs) of Curcuma species contain various volatile compounds with bioactivity. However, the phytochemical profile of Curcuma thorelii and the antimicrobial activities of Curcuma rhabdota, and Curcuma petiolata have received limited attention. This study aims to characterize and compare the major compounds and the antimicrobial activities of EOs extracted from the rhizomes of C. rhabdota, C. thorelii, and C. petiolata collected in Vietnam . Methods: EOs were obtained by hydrodistillation of the rhizomes of three Curcuma species. The chemical profiles were determined using gas chromatography-mass spectrometry (GC-MS). The antimicrobial activities against bacteria and a pathogenic fungus were determined through the broth dilution method. Results: The volatile profiles of C. rhabdota, C. thorelii, and C. petiolata EOs included 63 (97.1%), 47 (98.0%), and 50 (95.6%) compounds, respectively. The major compound in the EO of C. rhabdota rhizomes was 3-carene (16.6%), followed by camphene (9.8%), α-copaene (7.4%), γ-terpinene (7.3%), camphor (5.9%), and β-curcumene (5.7%). The predominant compounds of the EO extracted from C. thorelii rhizome were xanthorrhizol (40.7%), β-curcumene (20.7%), and α-curcumene (8.9%), while camphene (17.0%), ( E)- β-elemenone (16.8%), (E)-β-farnesene (13.6%), germacrone (8.9%), 1,8-cineole (7.2%), and camphor (6.0%) were the most abundant components in C. petiolata rhizomes. Except for Pseudomonas aeruginosa, which was less susceptible to the EOs with a minimum inhibitory concentration (MIC) value of 128 μg/mL, the three oil samples exhibited potent antimicrobial activities against all investigated strains with MIC values in the range of 2-32 μg/mL. Especially, the EO of C. thorelii rhizomes showed intense activity against Enterococcus faecalis, Staphylococcus aureus, Bacillus cereus, Escherichia coli, and Candida albicans with a MIC value of 2 µg/mL. Conclusion: The results showed the chemical variability of EOs from three Curcuma species and the prepared EO samples showed potent antimicrobial activities against several microbial strains, indicating a high potential application as a food preservative and in the pharmaceutical industry.

The genus Kaempferia (Zingiberaceae) is well-known for its diverse phytochemical constituents and characteristic essential oil. Kaempferia champasakensis was firstly described in 2008 by Chayan Picheansoonthon and Supachai Koonterm in Champasak province of Southern Laos. To date, little is known about phytochemical components and pharmacological activities of the plant. In the present study, the extraction of essential oil from K. champasakensis leaves as well as Gas Chromatography - Mass Spectrometry (GC/MS) profile were investigated. The major components in essential oil extracted from K. champasakensis leaves were determined as β-caryophyllene (16.07%), β-elemenone (14.53%), β-pinene (13.80%), germacrone (9.85%), myrcene (9.46%) and diisooctyl phthalate (8.62%). This is the first report on chemical constituents of essential oil extracted from the leaves of K. champasakensis.

The ginger family (Zingiberaceae) is one of the most diverse and abundant families in the plant kingdom in terms of number of species. In terms of chemistry, this is a family of plants containing much essential oil with mainly monoterpene and sesquiterpene derivatives, which has been widely used in medicine, food, and flavor industries. In our series of studies on ginger family plants, the two new species including Wurfbainia schmidtii (K. Schum.) Škorničk. & A.D. Poulsen and Zingiber atroporphyreus Škorničk. & Q.B. Nguyen has been investigated for the first time. This study aimed to identify the chemical compositions of essential oils extracted from the rhizomes and leaves of these two species using gas chromatography-mass spectrometry (GC/MS) analysis and evaluate their hypoglycemic effects through the α -glucosidase and α -amylase inhibitory assays. In terms of chemical composition, in general, the main compounds appearing in the essential oils of both leaves and rhizomes of each species are similar but they are differences in the percentage of the main components, for example, 1,8-cineole is a main component in leaves whereas fenchyl acetate is the main one in rhizomes of W. schmidtii . Several distinctive compounds, in comparison with other members in the genus Zingiber, namely β -pinene, α -pinene, β -elemene, and sabinene, were found in the essential oil of Z. atroporphyreus . Regarding hypoglycemic effects, the essential oils from the two species tested possessed weak α -glucosidase and α -amylase inhibitory effects. For the first time, this study was designed to investigate the chemical composition as well as the hypoglycemic effect of essential oils distilled from the rhizomes and leaves of two species W. schmidtii and Z. atroporphyreus have been reported, serving as a premise for further systematic research on their phytochemistry and pharmacological effects being conducted.