Larvicidal activity of Tagetes erecta against Aedes aegypti

An efficient process for the extraction of lutein and chemical characterization of other organic volatiles from marigold (Tagetes erecta L.) flower

Marigold (Tagetes erecta L.) petals are the primary industrial source of lutein, which is used as a colouring agent and nutrient supplement to foods. This research extracted marigold petals using different solvents, covering conventional and non-toxic green solvents. The oleoresin, free lutein, and recrystallized lutein yields varied from 8.47-16.67%, 2.56-9.62%, and 1.11-1.61%, respectively. The purity of lutein was achieved up to 92.57% and 97.64% in conventional and newly established green methods, respectively. The present study described an efficient green process to isolate lutein with significantly improved yield (2.56%) and purity (97.33%) over the conventional methods. Based on the results, 2-methyltetrahydrofurancould be a practical green alternative to the traditional toxic solvents for the processing of lutein. Further, the chemical analysis of the essential oil of the residual receptacles obtained after removing petals revealed the presence of important organic volatiles, including piperitone (54.7%) and piperitenone oxide (6.5%), indicating its usefulness for value-addition.

A parasitoid's dilemma between food and host resources: the role of volatiles from nectar-providing marigolds and host-infested plants attracting Aphidius platensis

The use of nectar-producing companion plants in crops is a well-known strategy of conserving natural enemies in biological control. However, the role of floral volatiles in attracting parasitoids and effects on host location via herbivore-induced plant volatiles is poorly known. Here, we examined the role of floral volatiles from marigold (Tagetes erecta), alone or in combination with volatiles from sweet pepper plant (Capsicum annuum), in recruiting Aphidius platensis, an important parasitoid of the green peach aphid Myzus persicae. We also investigated whether marigold floral volatiles are more attractive to the parasitoid than those emitted by sweet pepper plants infested by M. persicae. Olfactometry assays indicated that floral volatiles attracted A. platensis to the marigold plant and are more attractive than sweet pepper plant volatiles. However, volatiles emitted by aphid-infested sweet pepper were as attractive to the parasitoid as those of uninfested or aphid-infested blooming marigold. The composition of volatile blends released by uninfested and aphid-infested plants differed between both blooming marigold and sweet pepper, but the parasitoid did not discriminate aphid-infested from uninfested blooming marigold. Volatile released from blooming marigold and sweet pepper shared several compounds, but that of blooming marigold contained larger amounts of fatty-acid derivatives and a different composition of terpenes. We discuss the potential implications of the aphid parasitoid attraction in a diversified crop management strategy.

Tagetes erecta L. flowers, a medicinal plant traditionally used to promote diuresis, induced diuretic and natriuretic effects in normotensive and hypertensive rats

ETHNOPHARMACOLOGICAL RELEVANCE

Tagetes erecta L., known as marigold, belongs to the Asteraceae family and is mainly found in South America. Despite reports that T. erecta flowers are used in folk medicine to treat cardiovascular and renal diseases, there is no study regarding its diuretic effect.

AIM

This study aimed to evaluate the chemical composition and the diuretic efficacy of the hydroethanolic extract from T. erecta (HETE) in normotensive (NTR) and hypertensive (SHR) rats.

MATERIAL AND METHODS

The HETE was analyzed by liquid chromatography coupled to diode array detector and mass spectrometry (LC-DAD-MS). Female and male NTR and SHR received the treatment with vehicle, HETE (0.01 mg/kg, 0.1 mg/kg, and 1 mg/kg) or hydrochlorothiazide (HCTZ; 5 mg/kg) orally. The urinary parameters were measured at the end of the 8-h experiment.

RESULTS

From HETE, saccharides and triterpenes were the main annotated compounds, such as erythrodiol and β-amyrin. The urine volume was significantly increased in the groups treated with HETE, in both male and female NTR and SHR rats, compared to the respective vehicle-treated groups. Regarding electrolytes elimination, the treatment with HETE did not reveal significant changes in the urine levels of K⁺ or Cl^-, but it showed a natriuretic and Ca²⁺-sparing effects. The HETE beneficial result in reducing Ca²⁺ excretion was confirmed through the protective effect found in front of the urinary calcium oxalate precipitation and crystallization. The combination with HCTZ, a classic diuretic and saluretic medicine, significantly enhanced HETE-induced diuresis, natriuresis, and the Ca²⁺-sparing effect. On the other hand, the K⁺-sparing action was improved in the combination of HETE with amiloride, a standard K⁺-sparing diuretic. In contrast, the combination of HETE with atropine (a non-selective muscarinic receptor antagonist) and indomethacin (an inhibitor of the cyclooxygenase enzyme), promoted an important reduction in urinary volume, but interestingly the natriuretic effect was maintained.

CONCLUSION

This study contributed to the preclinical validation of the diuretic efficacy of T. erecta, highlighting this species as promising for the development of new pharmacological strategies for the management of kidney disorders.

Thiophene-Based Trimers and Their Bioapplications: An Overview

Certainly, the success of polythiophenes is due in the first place to their outstanding electronic properties and superior processability. Nevertheless, there are additional reasons that contribute to arouse the scientific interest around these materials. Among these, the large variety of chemical modifications that is possible to perform on the thiophene ring is a precious aspect. In particular, a turning point was marked by the diffusion of synthetic strategies for the preparation of terthiophenes: the vast richness of approaches today available for the easy customization of these structures allows the finetuning of their chemical, physical, and optical properties. Therefore, terthiophene derivatives have become an extremely versatile class of compounds both for direct application or for the preparation of electronic functional polymers. Moreover, their biocompatibility and ease of functionalization make them appealing for biology and medical research, as it testifies to the blossoming of studies in these fields in which they are involved. It is thus with the willingness to guide the reader through all the possibilities offered by these structures that this review elucidates the synthetic methods and describes the full chemical variety of terthiophenes and their derivatives. In the final part, an in-depth presentation of their numerous bioapplications intends to provide a complete picture of the state of the art.

The Potential of Biologically Active Brazilian Plant Species as a Strategy to Search for Molecular Models for Mosquito Control

Natural products are a valuable source of biologically active compounds and continue to play an important role in modern drug discovery due to their great structural diversity and unique biological properties. Brazilian biodiversity is one of the most extensive in the world and could be an effective source of new chemical entities for drug discovery. Mosquitoes are vectors for the transmission of dengue, Zika, chikungunya, yellow fever, and many other diseases of public health importance. These diseases have a major impact on tropical and subtropical countries, and their incidence has increased dramatically in recent decades, reaching billions of people at risk worldwide. The prevention of these diseases is mainly through vector control, which is becoming more difficult because of the emergence of resistant mosquito populations to the chemical insecticides. Strategies to provide efficient and safe vector control are needed, and secondary metabolites from plant species from the Brazilian biodiversity, especially Cerrado, that are biologically active for mosquito control are herein highlighted. Also, this is a literature revision of targets as insights to promote advances in the task of developing active compounds for vector control. In view of the expansion and occurrence of arboviruses diseases worldwide, scientific reviews on bioactive natural products are important to provide molecular models for vector control and contribute with effective measures to reduce their incidence.

Efficiency of cow dung based vermi-compost on seed germination and plant growth parameters of Tagetes erectus (Marigold)

Vermi-composting is an environmental friendly and economic process to decompose organic waste. The objective of this study was to produce vermi-compost using E isenia fetida and to investigate the impact of vermi-compost (VC) and organic manure (cow dung) on seed germination, seedlings, and growth parameters of Tagetes erecta. Physio-chemical parameters of vermi-compost and organic manure were recorded. A potting experiment was designed, germination medium containing soil, sand, and various concentrations of vermi-composts. The composition of germinating media was: TO (Sand + Soil), TCC (Sand + Soil + Cow dung), 10% VC (Sand + Soil + 0.1 kg VC), 15% VC (Sand + Soil + 0.15 kg VC), 20% VC (Sand + Soil + 0.2 kg VC), 25% VC (Sand + Soil + 0.25 kg VC), 30% VC (Sand + Soil + 0.3 kg VC), and 35% VC (Sand + Soil + 0.35 kg VC). Seed germination, seedling, vegetative plant growth, and flowering parameters were evaluated in different germinating media. Pre and post-physio-chemical parameters of germination media were also recorded to check their stability and quality. Results showed that 20% VC was effective for the early initiation of seed germination (2.0 ± 0.0 days) and all growth parameters of marigold seedlings. The germination percentage at 20% VC was recorded as 87.5 ± 1.40 %. The best vegetative plant growth and flowering parameters of marigold plants were observed with 35% VC after transplantation. Findings showed that vermi-compost is the best-suited germination and growing media, which not only improved the soil health but also promoted seed germination and plant growth. Our study undoubtedly indicates that vermi-compost is a more encouraging and advantageous bio-fertilizer and can be used as a powerful and effective for immediate marigold production.

Larvicidal Activity of Essential Oils Against Aedes aegypti (Diptera: Culicidae)

The Aedes aegypti is responsible for the transmission of arboviruses, which compromise public health. In the search for synthetic product alternatives, essential oils (OEs) have been highlighted by many researchers as natural insecticides. This systematic review (SR) was performed according to PRISMA guidelines (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) and its objective was to evaluate studies addressing OEs with larvicidal properties against Ae. aegypti, through electronic database searches (Pubmed, Science Direct and Scielo), covering an overview of the plant sources OEs, which plant parts were used, the extraction methods, analytical techniques, major and/or secondary constituents with greater percentages, as well as the LC50s responsible for larval mortality. Following study analysis, plants distributed across 32 families, 90 genera and 175 species were identified. The Lamiaceae, Myrtaceae, Piperaceae, Asteraceae, Rutaceae, Euphorbiaceae and Lauraceae families obtained the highest number of species with toxic properties against larvae from this vector. Practically all plant parts were found to be used for OE extraction. Hydrodistillation and steam distillation were the main extraction methods identified, with GC-MS/GC-FID representing the main analytical techniques used to reveal their chemical composition, especially of terpene compounds. In this context, OEs are promising alternatives for the investigation of natural, ecologically correct and biodegradable insecticides with the potential to be used in Ae. aegypti control programs.

A Review of Resistance Mechanisms of Synthetic Insecticides and Botanicals, Phytochemicals, and Essential Oils as Alternative Larvicidal Agents Against Mosquitoes

Mosquitoes are a serious threat to the society, acting as vector to several dreadful diseases. Mosquito management programes profoundly depend on the routine of chemical insecticides that subsequently lead to the expansion of resistance midst the vectors, along with other problems such as environmental pollution, bio magnification, and adversely affecting the quality of public and animal health, worldwide. The worldwide risk of insect vector transmitted diseases, with their associated illness and mortality, emphasizes the need for effective mosquitocides. Hence there is an immediate necessity to develop new eco-friendly pesticides. As a result, numerous investigators have worked on the development of eco-friendly effective mosquitocidal compounds of plant origin. These products have a cumulative advantage of being cost-effective, environmentally benign, biodegradable, and safe to non-target organisms. This review aims at describing the current state of research on behavioral, physiological, and biochemical effects of plant derived compounds with larvicidal effects on mosquitoes. The mode of physiological and biochemical action of known compounds derived from various plant families as well as the potential of plant secondary metabolites, plant extracts, and also the essential oils (EO), as mosquitocidal agents are discussed. This review clearly indicates that the application of vegetal-based compounds as mosquito control proxies can serve as alternative biocontrol methods in mosquito management programes.

Plant-Derived Essential Oils; Their Larvicidal Properties and Potential Application for Control of Mosquito-Borne Diseases

Mosquito-borne diseases are currently considered as important threats to human health in subtropical and tropical regions. Resistance to synthetic larvicides in different species of mosquitoes, as well as environmental pollution, are the most common adverse effects of excessive use of such agents. Plant-derived essential oils (EOs) with various chemical entities have a lower chance of developing resistance. So far, no proper classification based on lethal concentration at 50% (LC₅₀) has been made for the larvicidal activity of EOs against different species of Aedes, Anopheles and Culex mosquitoes. To better understand the problem, a summary of the most common mosquito-borne diseases have been made. Related articles were gathered, and required information such as scientific name, used part(s) of plant, target species and LC₅₀ values were extracted. 411 LC₅₀ values were found about the larvicidal activity of EOs against different species of mosquitoes. Depending on the obtained results in each species, LC₅₀ values were summarized as follows: 24 EOs with LC₅₀ < 10 µg/mL, 149 EOs with LC₅₀ in range of 10- 50 µg/mL, 143 EOs having LC₅₀ within 50- 100 µg/mL and 95 EOs showing LC₅₀ > 100 µg/mL. EOs of Callitris glaucophylla and Piper betle against Ae. aegypti, Tagetes minuta against An. gambiae, and Cananga odorata against Cx. quinquefasciatus and An. dirus having LC₅₀ of ~ 1 µg/mL were potentially comparable to synthetic larvicides. It appears that these plants could be considered as candidates for botanical larvicides.

Tagetes spp. Essential Oils and Other Extracts: Chemical Characterization and Biological Activity

Tagetes (marigold) is native to America, and its cultivation currently extends to other countries in Africa, Asia, and Europe. Many species of this genus, such as T. minuta, T. erecta, T. patula, and T. tenuifolia, are cultivated as ornamental plants and studied for their medicinal properties on the basis of their use in folk medicine. Different parts of the Tagetes species are used as remedies to treat various health problems, including dental, stomach, intestinal, emotional, and nervous disorders, as well as muscular pain, across the world. Furthermore, these plants are studied in the field of agriculture for their fungicidal, bactericidal, and insecticidal activities. The phytochemical composition of the extracts of different Tagetes species parts are reported in this work. These compounds exhibit antioxidant, antiinflammatory, and enzyme inhibitory properties. Cultivation and the factors affecting the chemical composition of Tagetes species are also covered. In the current work, available literature on Tagetes species in traditional medicine, their application as a food preservative, and their antimicrobial activities are reviewed.

High efficacy of (Z)-γ-bisabolene from the essential oil of Galinsoga parviflora (Asteraceae) as larvicide and oviposition deterrent against six mosquito vectors

The eco-friendly management of mosquitoes with novel and effective larvicides and oviposition deterrents is a crucial challenge to prevent outbreaks of mosquito-borne diseases. However, most of the herbal formulations tested in these years showed LC₅₀ values higher of 40 ppm, and significant oviposition deterrent activity only when tested at relatively higher doses (> 50 μg/ml). Herein, we studied the chemical composition of the Galinsoga parviflora essential oil (EO). This plant is an annual herb native to South America naturalized all over the world. We tested the EO larvicidal and oviposition deterrent action on 6 mosquito species. Totally 37 compounds were identified in the EO of G. parviflora by GC and GC-MS analyses. The major constituent was (Z)-γ-bisabolene (38.9%). The G. parviflora EO and (Z)-γ-bisabolene showed acute toxicity on An. stephensi (LC₅₀ = 31.04 and 2.04 μg/ml, respectively), Ae. aegypti (LC₅₀ = 34.22 and 2.26 μg/ml, respectively), Cx. quinquefasciatus (LC₅₀ = 37.10 and 2.47 μg/ml, respectively), An. subpictus (LC₅₀ = 40.97 and 4.09 μg/ml, respectively), Ae. albopictus (LC₅₀ = 45.55 and 4.50 μg/ml, respectively) and Cx. tritaeniorhynchus (LC₅₀ = 49.56 and 4.87 μg/ml, respectively) larvae. Furthermore, the oviposition deterrent potential of the G. parviflora EO and (Z)-γ-bisabolene was studied on six mosquito vectors, showing that 25 μg/ml of (Z)-γ-bisabolene led to an Oviposition Activity Index lower of - 0.79 in all tested mosquito vectors. Overall, all larvicidal LC₅₀ values estimated for (Z)-γ-bisabolene were lower than 5 μg/ml. This result far encompasses current evidences of toxicity reported for the large majority of botanical products currently tested against mosquito young instars, allowing us to propose this compound as an highly effective mosquito larvicide and oviposition deterrent.

Bamboo-Leaf Prickly Ash extract: A potential bio-pesticide against oriental leaf worm, Spodoptera litura (Fabricius) (Lepidoptera: Noctuidae)

Bamboo-Leaf Prickly Ash, Zanthoxylum armatum (Rutaceae) is a versatile and widely distributed plant species in nature. It is an edible plant species, commonly used in daily life for condiments and therapeutic remedies. Besides its bioactive and medicinal properties, different plant parts of the Z. armatum also have insecticidal potential. However, this potential has not been yet determined against many agricultural pests, including leaf worm, Spodoptera litura (Lepidoptera: Noctuidae). In this study, we demonstrated for the first time the contact and oral toxicity and sub-lethal effects (including antifeedent and ovicidal action) of various fractions of pericarp, leaf and seeds of Z. armatum against S. litura. Overall findings revealed that the n-hexane pericarp extract of Z. armatum has strong antifeedent, ovicidal and larvicidal properties against S. litura. Sub-lethal doses of pericarp extract can negatively alter the biology of S. litura. Since n-hexane extract of leaves also has better larvicidal properties, it could also be utilized for the S. litura management during period of unavailability of fruits (or pericarp). Accordingly, the Z. armatum pericarp and leaf extract has tremendous commercial utilization potential for the management of polyphagus pests like S. litura and other related species, which are quite difficult to manage even by chemical pesticides.

Structure-related antifeedant activity of halolactones with a p-menthane system against the lesser mealworm, Alphitobius diaperinus Panzer

BACKGROUND

Feeding deterrent activity of synthetic halogen lactones against larvae and adults of the lesser mealworm, Alphitobius diaperinus Panzer, in laboratory choice and no-choice tests was studied. The compounds were synthesised from racemic and enantiomerically enriched (ee = 91-98%) cis- and trans-piperitols, which were obtained from (±)-piperitone.

RESULTS

Structure-activity relationship studies identified several synthetic halolactones with a very strong feeding deterrent activity. The most active were the enantiomeric chlorolactones with chiral centre configurations (1S,4S,5R,6R) and (1R,4R,5S,6S) and their racemic mixture. The racemic bromo- and iodolactones obtained from cis-piperitol and saturated lactones with a chiral centre configuration (1R,4S,6R) were also very good antifeedants in comparison with piperitone. Most of the studied compounds were better antifeedants against adults than against larvae-among the 21 compounds, only one bromolactone with a chiral centre configuration (1S,4R,5R,6R) was a weaker deterrent for adults.

CONCLUSION

Chemical transformation of the piperitone molecule by the introduction of a lactone function and a halogen atom strongly changed its antifeedant properties against the lesser mealworm. Optimum activity is dependent on the presence of a chlorine atom at C-5 of the cyclohexane ring. The activity of bromo- and iodolactones depended strongly on the chiral centre configuration and the halogen substituent.

Insecticidal activity against Aedes aegypti of m-pentadecadienyl-phenol isolated from Myracrodruon urundeuva seeds

BACKGROUND

Myracrodruon urundeuva Fr. Allemao is a common tree in the Caatinga that has been widely used for various medical purposes. Previous studies showed that the ethanol seed extract of M. urundeuva has potent activity against the larval stage of the dengue vector Aedes aegypti. Given this potential insecticidal activity, bioguided separation steps were performed in order to isolate the active compound(s).

RESULTS

The isolation process resulted in only one active chemical compound, identified by infrared spectroscopy and mass spectrometry as m-pentadecadienyl-phenol. This compound presented potent larvicidal and pupicidal activity (LC50 10.16 and 99.06 µg mL(-1) respectively) and great egg hatching inhibitory activity (IC50 49.79 µg mL(-1)). The mode of action was investigated through observations of behavioural and morphological changes performed in third-instar larvae treated with m-pentadecadienyl-phenol solution after 1, 6, 12, 16 and 20 h of exposure. Some changes were observed as flooding of the tracheal system, alterations in siphonal valves and anal gills and lethargy, probably caused by the strong anticholinesterasic activity reported previously.

CONCLUSION

The compound isolated from M. urundeuva seeds, m-pentadecadienyl-phenol, showed potent activity against immature stages of dengue vector, Ae. aegypti, being considered the main larvicidal principle.