Essential oil from leaves of Eugenia calycina Cambes: Natural larvicidal against Aedes aegypti

Essential oil of Eugenia stictopetala Mart. ex DC. has antioxidant, antibacterial, and gastrointestinal protective effect

This work aimed to investigate the chemical composition, antioxidant capacity, antibacterial activity, and intestinal and gastric protective effects, in addition to the acute toxicity of the essential oil of E. stictopetala (EOEs). (E)-caryophyllene (18.01%), β-pinene (8.84%), and (E)-nerolidol (8.24%), were the components found in higher content in the essential oil. The EOEs showed antioxidant capacity with IC50 values ranging from 220.28 to 283.67 μg/mL, in addition to presenting antibacterial activity against Escherichia coli, Enterobacter aerogenes, Vibrio cholerae, Salmonella enterica, and Listeria monocytogenes. The essential oil showed a gastroprotective effect, with a reduction in the levels of TNF-α, IL-1β, and IL-6, having multiple pharmacological mechanisms of action. An antidiarrheal effect of EOEs was observed in the castor oil-induced diarrheal model, with reduced intestinal motility. Our findings demonstrate that essential oil can be beneficial in pharmaceutical and therapeutic applications for treating gastrointestinal diseases.

Effectiveness of repellent from patchouli (Pogestemon cablin) varieties of Southeast Sulawesi against Aedes aegypti

BACKGROUND OBJECTIVES

The incidence of Dengue Hemorrhagic Fever (DHF) continues to increase over time in the world, including Indonesia. One of the prevention efforts against dengue virus transmission is to avoid vector mosquito bites by the use of repellants. Using repellents can reduce exposure to mosquito bites that may cause infection with the dengue virus. This study aimed to determine the effectiveness of repellent lotion composed of patchouli batik extract (Pogostemon cablin) from Southeast Sulawesi varieties against Aedes aegypti mosquitoes.

METHODS

The research subjects were Aedes aegypti adult mosquitoes. The research consisted of three stages. The first stage was a phytochemical test (qualitative method), the second stage was the analysis of patchouli essential oil (GC-MS method) and the third stage was a test of the effectiveness of lotions made from patchouli extract in lotion preparations against Aedes aegypti.

RESULTS

The results of the effectiveness test of patchouli leaf repellent (Pogestemon cablin) lotion preparations were as follows: for a concentration of 2.5%, protective power 81.5%; concentration 5%, protection power 83.67%; concentration 7.5%, protection power 88.64 %; the concentration of 10%, protection power 90.44%, and the concentration of 12.5% had protection power 90.89%. Probit analysis and linear regression showed the value of ProbitLc 50 was 6.631.

INTERPRETATION CONCLUSION

The results of the effectiveness test of Pogestemon cablin repellent lotion preparations with the most effective concentrations were 10% and 12.5%. The results of ANOVA test indicated there was no difference in the average value of the protection power in patchouli leaves.

Chemical Composition, Larvicidal and Molluscicidal Activity of Essential Oils of Six Guava Cultivars Grown in Vietnam

Diseases transmitted by mosquitoes and snails cause a large burden of disease in less developed countries, especially those with low-income levels. An approach to control vectors and intermediate hosts based on readily available essential oils, which are friendly to the environment and human health, may be an effective solution for disease control. Guava is a fruit tree grown on a large scale in many countries in the tropics, an area heavily affected by tropical diseases transmitted by mosquitoes and snails. Previous studies have reported that the extracted essential oils of guava cultivars have high yields, possess different chemotypes, and exhibit toxicity to different insect species. Therefore, this study was carried out with the aim of studying the chemical composition and pesticide activities of six cultivars of guava grown on a large scale in Vietnam. The essential oils were extracted by hydrodistillation using a Clevenger-type apparatus for 6 h. The components of the essential oils were determined using gas-chromatography-mass-spectrometry (GC-MS) analysis. Test methods for pesticide activities were performed in accordance with WHO guidelines and modifications. Essential oil samples from Vietnam fell into two composition-based clusters, one of (E)-β-caryophyllene and the other of limonene/(E)-β-caryophyllene. The essential oils PG03 and PG05 show promise as environmentally friendly pesticides when used to control Aedes mosquito larvae with values of 24 h LC50-aegypti of 0.96 and 0.40 µg/mL while 24 h LC50-albopictus of 0.50 and 0.42 µg/mL. These two essential oils showed selective toxicity against Aedes mosquito larvae and were safe against the non-target organism Anisops bouvieri. Other essential oils may be considered as molluscicides against Physa acuta (48 h LC50 of 4.10 to 5.00 µg/mL) and Indoplanorbis exustus (48 h LC50 of 3.85 to 7.71 µg/mL) and with less toxicity to A. bouvieri.

Old Meets New: Mass Spectrometry-Based Untargeted Metabolomics Reveals Unusual Larvicidal Nitropropanoyl Glycosides from the Leaves of Heteropterys umbellata

The Aedes aegypti (Diptera: Culicidae) mosquito is the vector of several arboviruses in tropical and subtropical areas of the globe, and synthetic pesticides remain the most widely used combat strategy. This study describes the investigation of secondary metabolites with larvicidal activity from the Malpighiaceae taxon using a metabolomic and bioactivity-based approach. The workflow initially consisted of a larvicidal screening of 394 extracts from the leaves of 197 Malpighiaceae samples, which were extracted using solvents of different polarity, leading to the selection of Heteropterys umbellata for the identification of active compounds. By employing untargeted mass spectrometry-based metabolomics and multivariate analyses (PCA and PLS-DA), it was possible to determine that the metabolic profiles of different plant organs and collection sites differed significantly. A bioguided approach led to the isolation of isochlorogenic acid A (1) and the nitropropanoyl glucosides karakin (2) and 1,2,3,6-tetrakis-O-[3-nitropropanoyl]-beta-glucopyranose (3). These nitro compounds exhibited larvicidal activity, possibly potentialized by synergistic effects of their isomers in chromatographic fractions. Additionally, targeted quantification of the isolated compounds in different extracts corroborated the untargeted results from the statistical analyses. These results support a metabolomic-guided approach in combination with classical phytochemical techniques to search for natural larvicidal compounds for arboviral vector control.

Chemistry and Bioactivity of Croton Essential Oils: Literature Survey and Croton hirtus from Vietnam

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.

Essential oil from the leaves of Eugenia pohliana DC. (Myrtaceae) alleviate nociception and acute inflammation in mice

Eugenia pohliana DC.(Myrtaceae) is used in folk medicine by communities in Brazil. However, there are no reports on its biological activity. This is the first study to identify the components of E. pohliana essential oil (EpEO) and evaluate their antinociceptive and anti-inflammatory activities in an in vivo model at doses of 25, 50, and 100 mg/kg. The essential oil (EO) was obtained by hydrodistillation, and the analysis was performed by gas chromatography coupled with mass spectrometry. Antinociceptive activity was evaluated by writhing tests, tail movement, and formalin (neurogenic and inflammatory pain); naloxone was used to determine the nociception mechanism. Anti-inflammatory activity was assessed by oedema and peritonitis tests. We found that (E)-β-caryophyllene (BCP) (15.56%), δ-cadinene (11.24%) and α-cadinol (10.89%) were the major components. In the writhing test, there was a decrease in writing by 42.95-70.70%, in the tail movement, an increase in latency time by 69.12-86.63%, and in the formalin test, there was a reduction in pain neurogenic by 29.54-61.74%, and inflammatory pain by 37.42-64.87%. The antinociceptive effect of EpEO occurs through the activation of opioid receptors. In addition, a reduction in inflammation by 74.93‒81.41% was observed in the paw edema test and inhibition of the influx of leukocytes by 51.86‒70.38% and neutrophils by 37.74‒54.72% in the peritonitis test. It was concluded that EpEO has antinociceptive effect by the opioid pathway, as shown by the inhibitory effect of naloxone, and anti-inflammatory actions, and that its use does not cause hemolytic damage or behavioral change.

Larvicidal activity and Histopathological changes of Cinnamomum burmannii, Syzygium aromaticum extracts and their combination on Culex pipiens

In order to develop an eco-friendly botanical larvicide alternative to the synthetic larvicides, extracts were prepared from the Cinnamomum burmannii (C.B.) and Syzygium aromaticum (S.A.) with hexane using a sonicator. The extracts were evaluated for larvicidal activity individually and in combination against the Culex pipiens larvae. The LC₅₀ value of C.B. and the S.A. hexane extracts tested individually were 184.2 and 363.7 µg/mL against Cx. pipiens respectively. All the combinations of the extract of C.B. and S.A. showed synergistic factors higher than one. Among the different ratios of extracts, the SA25%: CB75% extract was found to be more toxic than the other combinations (LC₅₀:125.7 µg/mL). Midgut cells treated with S.A. 25%: C.B. 75% extract showed severe morphological alterations such as degradation of microvilli; degeneration of epithelial cells, and peritrophic membrane; loss of nuclei, irregular and damage of microvilli. The extract has a promising larvicidal potential against Cx. pipiens, However, the extract was toxic against HUVEC cells, as evident from MTT and cell morphology. Further investigation is required to assess the toxicity of the extract on aquatic animals.

Insecticidal effects of a novel polyherbal formulation (HF7) against Culex pipiens L. (Diptera: Culicidae)

Plant secondary metabolites represent the most efficient and convenient method to control and overcome environmental pollution and insecticidal resistance. This study explored the mosquitocidal activity of the combined extract of seven plants, (HF7) extracted using a Soxhlet extractor against Culex pipiens under laboratory conditions. Exposure of the 3rd instars of Cx. pipiens to HF7 hexane extract resulted in LC₅₀:114.5 μg/mL and LC₉₀:117.0 μg/mL values after 24 h. The ovicidal activities of hexane extract against Cx. pipiens eggs were 21.6%, 48.3%, and 71.6% at 187.5, 93.7, and 46.88 μg/mL, respectively. HF7-treated larvae showed the formation of irregular blebbing of epithelial cells toward the lumen and sloughing into the gut lumen. HF7 extract resulted in 100% adulticidal mortality at the concentration of 3.7 mg/test tube after 30 min of exposure. The IC₅₀ of HF7 extract was 97.03 µg/ml against larvae, at which nuclear and morphological changes were observed. The spectroscopy spectrum of HF7 hexane extract disclosed the presence of 57 different secondary metabolites, among which the dominant compound was eugenol (32.3%). HF7 hexane extract could serve as a botanical insecticide for controlling Cx. pipiens and potentially other mosquito species.