Using essential oils to control vectors, intermediate hosts, and disease-causing microorganisms is a promising approach. The genus Croton in the family Euphorbiaceae is a large genus, with many species containing large amounts of essential oils, however, essential oil studies are limited in terms of the number of Croton species investigated. In this work, the aerial parts of C. hirtus growing wild in Vietnam were collected and analyzed by gas chromatography/mass spectrometry (GC/MS). A total of 141 compounds were identified in C. hirtus essential oil, in which sesquiterpenoids dominated, comprising 95.4%, including the main components β-caryophyllene (32.8%), germacrene D (11.6%), β-elemene (9.1%), α-humulene (8.5%), and caryophyllene oxide (5.0%). The essential oil of C. hirtus showed very strong biological activities against the larvae of four mosquito species with 24 h LC50 values in the range of 15.38–78.27 μg/mL, against Physella acuta adults with a 48 h LC50 value of 10.09 μg/mL, and against ATCC microorganisms with MIC values in the range of 8–16 μg/mL. In order to provide a comparison with previous works, a literature survey on the chemical composition, mosquito larvicidal, molluscicidal, antiparasitic, and antimicrobial activities of essential oils of Croton species was conducted. Seventy-two references (seventy articles and one book) out of a total of two hundred and forty-four references related to the chemical composition and bioactivity of essential oils of Croton species were used for this paper. The essential oils of some Croton species were characterized by their phenylpropanoid compounds. The experimental results of this research and the survey of the literature showed that Croton essential oils have the potential to be used to control mosquito-borne and mollusk-borne diseases, as well as microbial infections. Research on unstudied Croton species is needed to search for species with high essential oil contents and excellent biological activities.

Solanum melongena is a member of Solanum genus that widely cultivated as fruit vegetable in Vietnam. According to Vietnamese traditional medicine, the fruits and whole plants are used to treat toothache, turgescence, pruritus, and haemorrhoids. As part of our project to study the chemical composition and bioactivity of Solanum genus in Vietnam, five flavonoid glycosides including kaempferol-3-O-β-D-glucopyranoside (1), isovitexin (2), kaempferol 3-O-β-D-glucoside-7-O-α-L-rhamnoside (3), kaempferol 3-O-β-D-sophoroside-7-O-α-L-rhamnoside (4), and kaempferol 3-O-β-D-sophoroside (5) were isolated from the methanol extract of the leaves of Solanum melongenagrowing in Thua Thien Hue province, by using various chromatography methods. Their chemical structures were determined by detailed analysis of 1D- and 2D-NMR and HR-ESI-MS data as well as comparison with the literature. Compounds (2) and (5) were isolated from Solanum melongena for the first time while compounds (3) and (4) were the first isolated from the Solanum genus. Besides, compounds 2-4 showed weak anti-inflammatory activities against NO production in RAW 264.7 macrophage line with IC50 values ranging from 54.28 to 91.37 μg/ml.

Solanum torvum Swartz, belonging to the family Solanaceae, a herb known as “Ca dai hoa trang”, “Ca hoang gai”, “Ca nong”, or “Ca du” in Vietnam, is widely distributed in Vietnam. Solanum torvum has been used as folk medicine to treat various illnesses, such as stomachache, cough, fever, toothache, and bee stings. As a part of our research on genus Solanum in Vietnam, three natural compounds including paniculonin A (1), paniculonin B (2), and isorhamnetin-3-O-glucopyranoside (3) were isolated from the water layer of Solanum torvum collected in Thua Thien - Hue. This is the first time compound 3 was isolated from this species.