Evaluation of naturally occurring curcuminoids and related compounds against mosquito larvae

The Golden Spice for Life: Turmeric with the Pharmacological Benefits of Curcuminoids Components, Including Curcumin, Bisdemethoxycurcumin, and Demethoxycurcumins

BACKGROUND

Turmeric (Curcuma longa L.), belonging to the Zingiberaceae family, is a perennial rhizomatous plant of tropical and subtropical regions. The three major chemical components responsible for the biological activities of turmeric are curcumin, demethoxycurcumin, and bisdemethoxycurcumin.

METHODS

The literature search included review articles, analytical studies, randomized control experiments, and observations, which have been gathered from various sources, such as Scopus, Google Scholar, PubMed, and ScienceDirect. A review of the literature was carried out using the keywords: turmeric, traditional Chinese medicine, traditional Iranian medicine, traditional Indian medicine, curcumin, curcuminoids, pharmaceutical benefits, turmerone, demethoxycurcumin, and bisdemethoxycurcumin. The main components of the rhizome of the leaf are α-turmerone, β-turmerone, and arturmerone.

RESULTS

The notable health benefits of turmeric are antioxidant activity, gastrointestinal effects, anticancer effects, cardiovascular and antidiabetic effects, antimicrobial activity, photoprotector activity, hepatoprotective and renoprotective effects, and appropriate for the treatment of Alzheimer's disease and inflammatory and edematic disorders.

DISCUSSION

Curcuminoids are phenolic compounds usually used as pigment spices with many health benefits, such as antiviral, antitumour, anti-HIV, anti-inflammatory, antiparasitic, anticancer, and antifungal effects. Curcumin, bisdemethoxycurcumin, and demethoxycurcumin are the major active and stable bioactive constituents of curcuminoids. Curcumin, which is a hydroponic polyphenol, and the main coloring agent in the rhizomes of turmeric, has anti-inflammatory, antioxidant, anti-cancer, and anticarcinogenic activities, as well as beneficial effects for infectious diseases and Alzheimer's disease. Bisdemethoxycurcumin possesses antioxidant, anti-cancer, and anti-metastasis activities. Demethoxycurcumin, which is another major component, has anti-inflammatory, antiproliferative, and anti-cancer activities and is the appropriate candidate for the treatment of Alzheimer's disease.

CONCLUSION

The goal of this review is to highlight the health benefits of turmeric in both traditional and modern pharmaceutical sciences by considering the important roles of curcuminoids and other major chemical constituents of turmeric.

Disruptive Effects of Two Curcuminoids (Demethoxycurcumin and Bisdemethoxycurcumin) on the Larval Development of Drosophila melanogaster

Juvenile hormones (JHs) play a central role in insect development, reproduction, and various physiological functions. Curcuminoids generally exhibit a wide range of biological activities, such as antioxidant, anti-inflammatory, antibacterial, and insecticidal, and they exhibit insect growth inhibitory effects. However, research on insecticidal properties of curcuminoids has been limited. Moreover, to the best of our knowledge, studies on JHs of insects and curcuminoids are lacking. Therefore, this study aimed to identify the substances that act as JH disruptors (JHDs) from edible plants. Demethoxycurcumin (DMC) and bisdemethoxycurcumin (BDMC), two curcuminoids from the turmeric plant Curcuma longa L. inhibited the formation of a methoprene-tolerant (Met)-Taiman (Tai) heterodimer complex in Drosophila melanogaster, as shown through in vitro yeast two-hybrid assays. An artificial diet containing 1% (w/v) DMC or BDMC significantly reduced the number of D. melanogaster larvae in a concentration-dependent manner; larval development was disrupted, preventing the progression of larvae to pupal stages, resulting in an absence of adults. Building on the results obtained in this study on curcuminoids, researchers can use our study as a reference to develop eco-friendly pesticides.

Curcumin and curcumin nanoparticles counteract the biological and managemental stressors in poultry production: An updated review

Antibiotics have the potential to have both direct and indirect detrimental impacts on animal and human health. For instance, antibiotic residues and pathogenic resistance against the drug are very common in poultry because of antibiotics used in their feed. It is necessary to use natural feed additives as effective alternatives instead of synthetic antibiotics. Curcumin, a polyphenol compound one of the natural compounds from the rhizomes of turmeric (Curcuma spp.) and has been suggested to have several therapeutic benefits in the treatment of human diseases. Curcumin exhibited some positive responses such as growth promoter, antioxidant, antibacterial, antiviral, anticoccidial, anti-stress, and immune modulator activities. Curcumin played a pivotal role in regulating the structure of the intestinal microbiome for health promotion and the treatment of intestinal dysbiosis. It is suggested that curcumin alone or a combination with other feed additives could be a dietary strategy to improve poultry health and productivity.

The impact of curcumin on livestock and poultry animal's performance and management of insect pests

Plant-based natural products are alternative to antibiotics that can be employed as growth promoters in livestock and poultry production and attractive alternatives to synthetic chemical insecticides for insect pest management. Curcumin is a natural polyphenol compound from the rhizomes of turmeric (Curcuma spp.) and has been suggested to have a number of therapeutic benefits in the treatment of human diseases. It is also credited for its nutritional and pesticide properties improving livestock and poultry production performances and controlling insect pests. Recent studies reported that curcumin is an excellent feed additive contributing to poultry and livestock animal growth and disease resistance. Also, they detailed the curcumin's growth-inhibiting and insecticidal activity for reducing agricultural insect pests and insect vector-borne human diseases. This review aims to highlight the role of curcumin in increasing the growth and development of poultry and livestock animals and in controlling insect pests. We also discuss the challenges and knowledge gaps concerning curcumin use and commercialization as a feed additive and insect repellent.

Colupulone, colupone and novel deoxycohumulone geranyl analogues as larvicidal agents against Culex pipiens

BACKGROUND

As climate change proceeds, the management of the population of mosquitoes becomes more and more challenging. Insect adulticides and larvicides constitute significant control techniques, with the latter being considered the leading mosquito control method. However, the development of mosquito resistance development and the adverse side effects caused by the extensive use of synthetic insecticides have turned research towards the discovery of environmentally-friendly solutions. Plants and bacteria have historically proven to be a good source of insecticidally active compounds, which may possess novel modes of action to overcome current resistance mechanisms and could also possess favorable human and environmental safety profiles. A previous study demonstrated that the naturally occurring prenylated acyl phloroglucinol deoxycohumulone is a potent larvicidal agent against Culex pipiens. Herein the structural characteristics that improve it are explored by evaluating colupulone and novel geranylated analogues.

RESULTS

Colupulone, a prenylated acyl phloroglucinol isolated from Humulus lupulus, colupone, and novel geranylated acyl phloroglucinol congeners, were synthesized and evaluated against Cx. pipiens larva. Results indicated that selected derivatives exhibited superior potency than deoxycohumulone (LC₅₀ 43.7 mg L^-1 ). Thus, strong activity was observed for colupulone (LC₅₀ 19.7 mg L^-1 ), and some novel geranyl analogues of deoxycohumulone reaching at LC₅₀ 17.1 mg L^-1 , while colupone and similar compounds were almost inactive.

CONCLUSION

The results determined the relationship between the target activity and the chemical structure of the tested compounds, and they revealed significantly improved larvicidal candidates. These results highlight the potential of the acyl phloroglucinol chemistry for further development of mosquito larvicides. © 2022 Society of Chemical Industry.

Molecular insights on ar-turmerone as a structural, functional and pharmacophoric analogue of synthetic mosquito repellent DEET by comprehensive computational assessment

Mosquitoes are vectors for a variety of infectious illnesses, and chemical synthetic insecticides have made it possible to control them effectively. Mosquito repellents are a typical means of keeping mosquitos at bay. Because of its main effectiveness of skin permeability, N,N-Diethyl-meta-toluamide (DEET) is one of the most extensively used mosquito repellents but a dangerous synthetic chemical. DEET was identified about a decade ago to inhibit mosquito's Odorant Binding Protein 1 (OBP1), impairing the mosquito's ability to recognise the host body odour. OBP1 has been identified as a possible target for the development of new mosquito repellents since its discovery. Essential oils from different plants, on the other hand, have been used to repel mosquitos since antiquity. One essential oil from the Curcuma longa (Zingiberales: Zingiberaceae) rhizome display mosquito repellent properties, according to the literature. Furthermore, one of the phytochemicals found in abundance in C. longa essential oil, ar-turmerone, exhibits mosquito repellency as comparable to synthetic DEET. Till date studies on in-silico interaction of natural ar-turmerone with OBP1, which we depict in our current work are scarce. Further, there exist no published reports demonstrating the literary evidence on detailed insights of interaction of DEET with OBP1 along with Molecular Dynamics (MD) simulation studies. We further performed detailed molecular investigations using pharmacophore analysis of ar-turmerone and compared it with DEET, where our findings in the current manuscript unveils for the first time that ar-turmerone is a functional, structural and pharmacophoric analogue of DEET.

Environmentally Safe Photodynamic Control of Aedes aegypti Using Sunlight-Activated Synthetic Curcumin: Photodegradation, Aquatic Ecotoxicity, and Field Trial

This study reports curcumin as an efficient photolarvicide against Aedes aegypti larvae under natural light illumination. Larval mortality and pupal formation were monitored daily for 21 days under simulated field conditions. In a sucrose-containing formulation, a lethal time 50 (LT50) of 3 days was found using curcumin at 4.6 mg L⁻¹. This formulation promoted no larval toxicity in the absence of illumination, and sucrose alone did not induce larval phototoxicity. The photodegradation byproducts (intermediates) of curcumin were determined and the photodegradation mechanisms proposed. Intermediates with m/z 194, 278, and 370 were found and characterized using LC-MS. The ecotoxicity of the byproducts on non-target organisms (Daphnia, fish, and green algae) indicates that the intermediates do not exhibit any destructive potential for aquatic organisms. The results of photodegradation and ecotoxicity suggest that curcumin is environmentally safe for non-target organisms and, therefore, can be considered for population control of Ae. aegypti.

Extending the lore of curcumin as dipteran Butyrylcholine esterase (BChE) inhibitor: A holistic molecular interplay assessment

Since its origin, the emergence of vector-borne infections has taken a toll on incalculable human lives. The use of chemical insecticides is one of the early known methods of vector control and although their use is still a prevalent way to combat insect population sadly the perils of insects related transmission still persists. Most commonly, the existing insecticides face the wrath of getting resisted repeatedly, paying way to develop resilient, efficient, and cost-effective natural insecticides. In this study, computational screening was performed using homology modelling, E-pharmacophore feature mapping, molecular docking, Density Function Theory (DFT) assessment, Molecular mechanics generalized Born surface area (MM-GBSA) based binding free energy calculations and Molecular Dynamics (MD) simulation to identify a potential lead phytochemical out of a manually curated library from published literature. The protein target used under this study is insect Butyrylcholine esterase (BChE). Additionally, in vitro insect (Aedes aegypti) BChE inhibition assay was also performed with the top phytochemical identified from in silico assessments. Our research highlights that curcumin leads to inhibition of enzyme BChE of Ae. aegypti. The identified mode of action of curcumin as an insect BChE inhibitor indicates the possibility of its use as an environment friendly and natural futuristic insecticide.

Revealing the molecular interplay of curcumin as Culex pipiens Acetylcholine esterase 1 (AChE1) inhibitor

Emergence of vector borne diseases has continued to take toll on millions of lives since its inception. The use of insecticides began as vector control strategy in the early 1900's but the menace of insects is still prevalent. Additionally, the inadequate use of organophosphates and carbamates which target acetylcholine esterase (AChE), are known to develop resistance amongst vectors of transmission and are toxic to humans. In this study, extensive computational screening was performed using homology modelling, molecular docking, molecular dynamics (MD) simulation and free energy change calculation, which highlighted curcumin as a lead molecule out of ~ 1700 phytochemicals against Culex pipiens AChE. In vivo larvicidal activity was carried out along with in vivo and in vitro AChE inhibition assay to determine the biochemical efficacy of curcumin. Our study reveals that curcumin induces mortality in Cx. pipiens at an early stage of its life cycle by AChE inhibition. This also underlines the use of curcumin as a coming-age natural product insecticide.

Curcumin Derivatives as Potential Mosquito Larvicidal Agents against Two Mosquito Vectors, Culex pipiens and Aedes albopictus

Vector-borne diseases have appeared or re-emerged in many Southern Europe countries making the transmission of infectious diseases by mosquitoes (vectors) one of the greatest worldwide health threats. Larvicides have been used extensively for the control of Aedes (Stegomyia) albopictus (Skuse, 1895) (Diptera: Culicidae) and Culex pipiens Linnaeus, 1758 (Diptera: Culicidae) mosquitoes in urban and semi-urban environments, causing the increasing resistance of mosquitoes to commercial insecticides. In this study, 27 curcuminoids and monocarbonyl curcumin derivatives were synthesised and evaluated as potential larvicidal agents against Cx. pipiens and Ae. albopictus. Most of the compounds were more effective against larvae of both mosquito species. Four of the tested compounds, curcumin, demethoxycurcumin, curcumin-BF2 complex and a monocarbonyl tetramethoxy curcumin derivative exhibited high activity against both species. In Cx. pipiens the recorded LC50 values were 6.0, 9.4, 5.0 and 32.5 ppm, respectively, whereas in Ae. albopictus they exhibited LC50 values of 9.2, 36.0, 5.5 and 23.6 ppm, respectively. No conclusive structure activity relationship was evident from the results and the variety of descriptors values generated in silico provided some insight to this end.

Larvicidal activity and in silico studies of cinnamic acid derivatives against Aedes aegypti (Diptera: Culicidae)

Cinnamic acid derivatives (CAD's) represent a great alternative in the search for insecticides against Aedes aegypti mosquitoes since they have antimicrobial and insecticide properties. Ae. aegypti is responsible for transmitting Dengue, Chikungunya, and Zika viruses, among other arboviruses associated with morbimortality, especially in developing countries. In view of this, in vitro analyses of n-substituted cinnamic acids and esters were performed upon 4th instar larvae (L4) of Ae. aegypti, as well as, molecular docking studies to propose a potential biological target towards this mosquitoes species. The larvicide assays proved that n-substituted ethyl cinnamates showed a more pronounced activity than their corresponding acids, in which p-chlorocinnamate (3j) presented a LC₅₀ value of 8.3 µg/mL. Thusly, external morphologic alterations (rigid and elongated body, curved bowel, and translucent or darkened anal papillae) of mosquitoes' group exposed to compound 3j, were observed by microscopy. In addition, an analytical method was developed for the quantification of the most promising analog by using high-performance liquid chromatography with UV detection (HPLC-UV). Molecular docking studies suggested that the larvicide action is associated with inhibition of acetylcholinesterase (AChE) enzyme. Therefore, expanding the larvicidal study with the cinnamic acid derivatives against the vector Ae. aegypti is important for finding search for more effective larvicides and with lower toxicity, since they have already shown good larvicidal properties against Ae. aegypti.

Curcumin/d-mannitol as photolarvicide: induced delay in larval development time, changes in sex ratio and reduced longevity of Aedes aegypti

BACKGROUND

Resistant populations of Ae. aegypti have been a major problem in arboviruses epidemic areas, generating a strong demand for novel methods of vector control. In this regard, our group has demonstrated the use of curcumin as an efficient photoactive larvicide to eliminate Ae. aegypti larvae. This work was aimed to evaluate the Ae. aegypti (Rockefeller) development under sublethal conditions, using a curcumin/d-mannitol (DMC) formulation. The photolarvicidal efficacy under semi-field and field conditions (wild populations) was also analyzed, as well as the photobleaching and residual activity of DMC.

RESULTS

A delay in development time when larvae were exposed to sublethal concentrations of DMC was observed, followed by significant changes in sex ratio and reduction in longevity. DMC also presented a low residual activity when compared to usual larvicides, and had a substantial photolarvicidal activity against wild populations in field trials, achieving 71.3% mortality after 48 h.

CONCLUSIONS

Overall, these findings are of great biological importance for the process of enabling the implementation of DMC as a new product in the control of Ae. aegypti larvae, and contributes to the improvement of new plant-based larvicides. © 2021 Society of Chemical Industry.

Environmental safety and mode of action of a novel curcumin-based photolarvicide

Aedes aegypti is the vector of important diseases like dengue, zika, chikungunya, and yellow fever. Vector control is pivotal in combating the spread of these mosquito-borne illnesses. Photoactivable larvicide curcumin obtained from Curcuma longa Linnaeus has shown high potential for Ae. aegypti larvae control. However, the toxicity of this photosensitizer (PS) might jeopardize non-target aquatic organisms. The aim of this study was to evaluate the toxicity of this PS to Daphnia magna and Danio rerio, besides assessing its mode of action through larvae biochemical and histological studies. Three PS formulations were tested: PS in ethanol+DMSO, PS in sucrose, and PS in D-mannitol. The LC₅₀ of PS in ethanol+DMSO to D. rerio was 5.9 mg L^-1, while in D. magna the solvents were extremely toxic, and LC₅₀ was not estimated. The PS formulations in sugars were not toxic to neither of the organisms. Reactive oxygen species (ROS) were generated in D. magna exposed to 50 mg L^-1 of PS in D-mannitol, and D. rerio did not elicit this kind of response. D. magna feeding rates were not affected by the PS in D-mannitol. Concerning Ae. aegypti larvae, there were changes in reduced glutathione and protein levels, while catalase activity remained stable after exposure to PS in D-mannitol and sunlight. Histological changes were observed in larvae exposed to PS in sucrose and D-mannitol, most of them irreversible and deleterious. Our results show the feasibility of this photolarvicide use in Ae. aegypti larvae control and its safety to non-target organisms. These data are crucial to this original vector control approach implementation in public health policies.

Curcumin in formulations against Aedes aegypti: Mode of action, photolarvicidal and ovicidal activity

Combating the Aedes aegypti vector is still the key to control the transmission of many arboviruses, such as Dengue, Zika, and Chikungunya. As few products are efficient for Aedes aegypti control, the search for new strategies have become pivotal., t Substances with photodynamic activity, such as curcumin and their formulations, are strongly encouraged, due to their multi-target mechanism of action. In this study, we evaluated the photolarvicidal and ovicidal activity of curcumin in the presence of sucrose (named SC) and d-mannitol (named DMC). To support the understanding of the larvicidal action of these formulations, Raman micro-spectroscopy was employed. We also studied the morphological changes in Danio rerio (Zebrafish) gills, a non-target organism, and demonstrate that this is an environmentally friendly approach. Both SC and DMC presented a high photo-larvicidal potential. DMC showed the highest larval mortality, with LC_50-24h values between 0.01 and 0.02 mg.L^-1. DMC also significantly decreased egg hatchability, reaching a hatching rate of 10 % at 100 mg.L^-1. The analysis of molecular mechanisms via Raman micro-spectroscopy showed that DMC is highly permeable to the peritrophic membrane of the larva, causing irreversible damage to the simple columnar epithelium of the digestive tube. Histological changes found in the D. rerio gills were of minimal or moderate pathological importance, indicating an adaptive trait rather than detrimental characteristics. These findings indicate that curcumin in sugar formulations is highly efficient, especially DMC, proving it to be a promising and safe alternative to control Aedes mosquitoes. Moreover, Raman micro-spectroscopy demonstrated high potential as an analytical technique to understand the mechanism of action of larvicides.

Design, synthesis, and evaluation of curcumin analogues as potential inhibitors of bacterial sialidase

Sialidases are key virulence factors that remove sialic acid from the host cell surface glycan, unmasking receptors that facilitate bacterial adherence and colonisation. In this study, we developed potential agents for treating bacterial infections caused by Streptococcus pneumoniae Nan A that inhibit bacterial sialidase using Turmeric and curcumin analogues. Design, synthesis, and structure analysis relationship (SAR) studies have been also described. Evaluation of the synthesised derivatives demonstrated that compound 5e was the most potent inhibitor of S. pneumoniae sialidase (IC50 = 0.2 ± 0.1 µM). This compound exhibited a 3.0-fold improvement in inhibitory activity over that of curcumin and displayed competitive inhibition. These results warrant further studies confirming the antipneumococcal activity 5e and indicated that curcumin derivatives could be potentially used to treat sepsis by bacterial infections.

Chemical constituents and biological research on plants in the genus Curcuma

Curcuma, a valuable genus in the family Zingiberaceae, includes approximately 110 species. These plants are native to Southeast Asia and are extensively cultivated in India, China, Sri Lanka, Indonesia, Peru, Australia, and the West Indies. The plants have long been used in folk medicine to treat stomach ailments, stimulate digestion, and protect the digestive organs, including the intestines, stomach, and liver. In recent years, substantial progress has been achieved in investigations regarding the chemical and pharmacological properties, as well as in clinical trials of certain Curcuma species. This review comprehensively summarizes the current knowledge on the chemistry and briefly discusses the biological activities of Curcuma species. A total of 720 compounds, including 102 diphenylalkanoids, 19 phenylpropene derivatives, 529 terpenoids, 15 flavonoids, 7 steroids, 3 alkaloids, and 44 compounds of other types isolated or identified from 32 species, have been phytochemically investigated. The biological activities of plant extracts and pure compounds are classified into 15 groups in detail, with emphasis on anti-inflammatory and antitumor activities.

Alves L, Brocksom TJ, de Oliveira KT. Combining batch and continuous flow setups in the end-to-end synthesis of naturally occurring curcuminoids

A successful end-to-end continuous flow synthesis of pure curcumin (1) and two other natural derivatives present in turmeric is described.

Larvicidal and Biting Deterrent Activity of Essential Oils of Curcuma longa, Ar-turmerone, and Curcuminoids Against Aedes aegypti and Anopheles quadrimaculatus (Culicidae: Diptera)

Essential oils and extract of Curcuma longa, ar-turmerone, and curcuminoids were evaluated for their larvicidal and deterrent activity against mosquitoes. Ar-turmerone and curcuminoids constituted 36.9, 24.9 and 50.6% of rhizome oil, leaf oil, and rhizome extract, respectively. Ar-turmerone was the major compound of the rhizome oil (36.9%) and leaf oil (24.9%). The ethanolic extract had 15.4% ar-turmerone with 6.6% bisdesmethoxycurcumin, 6.1% desmethoxycurcumin, and 22.6% curcumin. In in vitro studies, essential oils of the leaf (biting deterrence index [BDI] = 0.98), rhizome (BDI = 0.98), and rhizome ethanolic extract (BDI = 0.96) at 10 µg/cm(2) showed biting deterrent activity similar to DEET at 25 nmol/cm(2) against Aedes aegypti L. Among the pure compounds, ar-turmerone (BDI = 1.15) showed the biting deterrent activity higher than DEET at 25 nmol/cm(2) whereas the activity of other compounds was lower than DEET. In Anopheles quadrimaculatus Say, only ar-turmerone showed deterrent activity similar to DEET. In dose-response bioassay, ar-turmerone showed significantly higher biting deterrence than DEET at all the dosages. Ar-turmerone, at 15 nmol/cm(2), showed activity similar to DEET at 25 nmol/cm(2) and activity at 5 nmol/cm(2) was similar to DEET at 20 and 15 nmol/cm(2). Leaf essential oil with LC(50) values of 1.8 and 8.9 ppm against larvae of An. quadrimaculatus and Ae. aegypti, respectively, showed highest toxicity followed by rhizome oil and ethanolic extract. Among the pure compounds, ar-turmerone with LC(50) values of 2.8 and 2.5 ppm against larvae of An. quadrimaculatus and Ae. aegypti, respectively, was most toxic followed by bisdesmethoxycurcumin, curcumin, and desmethoxycurcumin.

Curcumin, demethoxycurcumin and bisdemethoxycurcumin differentially inhibit morphine's rewarding effect in rats

RATIONALE

Recent animal studies reported that curcumin, the active constituent of Curcuma longa, has several central actions and may attenuate morphine tolerance.

OBJECTIVES

In the present study, we utilized the intracranial self-stimulation (ICSS) paradigm to examine the effects of the commercially available curcuminoid mixture and each one of its components, individually, on brain stimulation reward and on the reward-facilitating effect of morphine.

METHODS

Male Sprague-Dawley rats were implanted with an electrode into the medial forebrain bundle and trained to respond for electrical stimulation using a rate-frequency paradigm. In the first study, rats were injected with graded doses either of the curcuminoid mixture, or curcumin I, or II, or III. In the second study, we examined whether a low dose of the curcuminoid mixture or each individual curcumin analogue composing it could counteract the reward-facilitating effect of morphine.

RESULTS

At low doses, both the curcuminoid mixture and curcumin I did not affect brain stimulation reward, whereas, higher doses increased ICSS thresholds. Curcumin II and curcumin III did not affect brain stimulation reward at any doses. Subthreshold doses of the curcuminoid mixture and curcumin I inhibited the reward-facilitating effect of morphine.

CONCLUSION

Both the curcuminoid mixture and curcumin I lack hedonic properties and moderate the reward-facilitating effect of morphine. Our data suggest that curcumin interferes with brain reward mechanisms responsible for the expression of the acute reinforcing properties of opioids and provide evidence that curcumin may be a promising adjuvant for attenuating morphine's rewarding effects in patients who are under long-term opioid therapy.

Hyperforin and deoxycohumulone as a larvicidal agent against Culex pipiens (Diptera: Culicidae)

The larvicidal effect of hyperforin (1), a bioactive compound of Hypericum perforatum, and deoxycohumulone (2) (biosynthetic precursor of hyperforin) were evaluated against Culex pipiens (Diptera: Culicidae) for the first time. All the acetate analogues (3-6) of hyperforin (1) and deoxycohumulone (2) were also synthesized and bioassayed to provide information on structural requirements for the tested compounds. Larvicidal results revealed that hyperforin (1) and deoxycohumulone (2) exhibited potent activity with LC50 value of 26.72 and 51.03 mg L(-1), respectively. The monoacetyl-deoxycohumulone (4) displayed lower activity with LC50 value of 135.92 mg L(-1), while all other acetate analogues were inactive at concentrations even as high as 150 mg L(-1), indicating that the free hydroxyl groups are essential for the larvicidal activity. The mortality values were increased, more than 80%, when 10 mg L(-1) piperonyl butoxide were added in hyperforin (1) or deoxycohumulone (2) bioassays. Finally, sub-lethal survival analysis is conducted for three doses of hyperforin (1) and deoxycohumulone (2) and results are discussed.