Clarice Noleto Dias

Eugenia uniflora L. Essential Oil as a Potential Anti-Leishmania Agent: Effects on Leishmania amazonensis and Possible Mechanisms of Action

Eugenia uniflora L. is a member of the Myrtaceae family and is commonly known as Brazilian cherry tree. In this study, we evaluated the chemical composition of Eugenia uniflora L. essential oil (EuEO) by using gas chromatography-mass spectrometry (GC-MS) and assessed its anti-Leishmania activity. We also explored the potential mechanisms of action and cytotoxicity of EuEO. Thirty-two compounds were identified, which constituted 92.65% of the total oil composition. The most abundant components were sesquiterpenes (91.92%), with curzerene (47.3%), γ-elemene (14.25%), and trans-β-elemenone (10.4%) being the major constituents. The bioactivity shown by EuEO against promastigotes (IC50, 3.04 μg·mL−1) and amastigotes (IC50, 1.92 μg·mL−1) suggested significant anti-Leishmania activity. In the cytotoxicity determination, EuEO was 20 times more toxic to amastigotes than to macrophages. Hemolytic activity was 63.22% at the highest concentration tested (400 μg·mL−1); however, there appeared to be no toxicity at 50 μg·mL−1. While the data show that EuEO activity is not mediated by nitric oxide production, they do suggest that macrophage activation may be involved in EuEO anti-Leishmania activity, as evidenced by increases in both the phagocytic capacity and the lysosomal activity. More studies are needed to determine in vivo activity as well as additional mechanisms of the anti-Leishmania activity.

Molluscicidal and leishmanicidal activity of the leaf essential oil of Syzygium cumini (L.) SKEELS from Brazil.

The chemical composition and biological potential of the essential oil extracted from Syzygium cumini leaves collected in Brazil were examined. GC/MS Analyses revealed a high abundance of monoterpenes (87.12%) in the oil. Eleven compounds were identified, with the major components being α‐pinene (31.85%), (Z)‐β‐ocimene (28.98%), and (E)‐β‐ocimene (11.71%). To evaluate the molluscicidal effect of the oil, it was tested against Biomphalaria glabrata and the LC50 obtained was 90 mg/l. The essential oil also showed significant activity against Leishmania amazonensis, with an IC50 value equal to 60 mg/l. In addition, to evaluate its toxicity towards a non‐target organism, the essential oil was tested against Artemia salina and showed a LC50 of 175 mg/l. Thus, the essential oil of S. cumini showed promising activity as a molluscicidal and leishmanicidal agent and might be valuable in combating neglected tropical diseases such as schistosomiasis and leishmaniasis. Further research is being conducted with regard to the purification and isolation of the most active essential‐oil compounds.

Molluscicidal and larvicidal activities and essential oil composition of Cymbopogon winterianus

Abstract Context. Cymbopogon winterianus Jowitt ex Bor (Poaceae), known as citronella grass, is an aromatic herbaceous plant and the essential oil extracted from this grass is used in cosmetics, perfumes, hygiene and cleanliness products worldwide. Objective: This study investigated the composition and molluscicidal and larvicidal activities of the essential oil of C. winterianus cultivated in North Brazil. Materials and methods: The oil was obtained by hydrodistillation, analyzed by gas chromatography (GC) and GC-mass spectrometry and then its molluscicidal and larvicidal activities against snails (Biomphalaria glabrata) and hatched larvae of Artemia salina, respectively, were evaluated at concentrations from 10 to 1000 mg/L. Results: The main constituents of oil were citronellal (26.5%), geraniol (16.2%), elemol (14.5%) and citronellol (7.3%). The molluscicidal test revealed significant lethal concentration (LC) values (LC90 = 97.0 mg/L, LC50 = 54.0 mg/L and LC20 = 22.0 mg/L), indicating the presence of molluscicidal compounds in the oil. In addition, the oil showed moderate larvicidal activity (LC50 = 181.0 mg/L) against the larvae of A. salina, which could justify its use in the aquatic environment without affecting other living organisms. Discussion and conclusion: The results suggest that the oil of C. winterianus could be an effective alternative to control schistosomiasis, with an average margin of safety to other living organisms that coexist with snails.

Chemical Composition and Larvicidal Activity of Essential Oils Extracted from Brazilian Legal Amazon Plants against Aedes aegypti L. (Diptera: Culicidae)

The mosquito Aedes aegypti L. (Diptera: Culicidae) is the major vector of dengue and chikungunya fever. The lack of effective therapies and vaccines for these diseases highlights the need for alternative strategies to control the spread of virus. Therefore, this study investigated the larvicidal potential of essential oils from common plant species obtained from the Chapada das Mesas National Park, Brazil, against third instar A. aegypti larvae. The chemical composition of these oils was determined by gas chromatography coupled to mass spectrometry. The essential oils of Eugenia piauhiensis Vellaff., Myrcia erythroxylon O. Berg, Psidium myrsinites DC., and Siparuna camporum (Tul.) A. DC. were observed to be mainly composed of sesquiterpene hydrocarbons. The essential oil of Lippia gracilis Schauer was composed of oxygenated monoterpenes. Four of the five tested oils were effective against the A. aegypti larvae, with the lethal concentration (LC50) ranging from 230 to 292 mg/L after 24 h of exposure. Overall, this work demonstrated the possibility of developing larvicidal products against A. aegypti by using essential oils from the flora of the Brazilian Legal Amazon. This in turn demonstrates the potential of using natural resources for the control of disease vectors.

Plant Derived Essential Oils Against Aedes aegypti L. and Their Biotechnological Production

Aedes aegyti L. is the main vector of important viruses like Dengue, Yellow, Zika and Chikungunya fevers. In many countries, these diseases are considered as great public health problems due to the serious consequences they can cause such as Guillain-Barre syndrome, neurological disorders and internal hemorrhagic problems, which may lead to death. The transmission of these diseases occurs through the bite of infected female of A. aegypti. According to World Health Organization, the major way to avoid the spread of these diseases is to control the vector by using larvicides and insecticides products. Many efforts have been done to find natural products that can be used to eliminate different phases of the life cycle of this mosquito. Among these, essential oils are recognized as important plant-derived products to control A. aegypti. Essential oils are complex mixture of mono, sesquiterpenes and phenylpropanoids and normally have a nice odor. Several studies have shown the larvicidal and insecticides properties of essential oils in plants belonging to different families. The literature studies indicated that in most of the cases monoterpenes like geraniol and citronellol, and phenylpropanoids; eugenol were the main components of essential oils that can control A. aegypti spread. In vitro studies suggested that composition and production of essential oils could be manipulated by the use of different concentrations and combinations of growth regulators and elicitors.