Azadirachtin, a neem biopesticide: subchronic toxicity assessment in rats

The Effect of Monensin vs. Neem, and Moringa Extracts on Nutrient Digestibility, Growth Performance, Methane, and Blood Profile of Merino Lambs

Plant secondary compounds are potential rumen modifiers that can improve nutrient utilization in ruminant animals. This study evaluated the effect of Moringa (Moringa oleifera) and Neem (Azadirachta indica) leaf extracts on nutrient digestibility, growth performance, and enteric methane production in South African Mutton Merino lambs. Forty 4-month-old ram lambs with a mean body weight of 35 ± 2.2 kg were blocked by weight and from each block, lambs were randomly allocated into one of the following treatments: (i) diet only (fed a total mixed ration TMR-negative control), (ii) Monensin (fed TMR containing Monensin sodium, 15 mg/kg DM), (iii) Moringa (fed TMR, drenched with Moringa extract 50 mg/kg feed DM intake), and (iv) Neem (fed TMR, drenched with Neem extract 50 mg/kg DM intake). Extracts were administered via oral drenching at a concentration determined based on the previous week's feed intake. There were no differences in dry matter intake, average daily gain, feed conversion efficiency, digestibility, and nitrogen retention across the treatments. However, the extracts tended to reduce methane emitted both in g/head/day (p < 0.08) and g/ kg dry matter intake (p < 0.07). Extracts did not influence any of the blood metabolites in the ram lambs. Although the benefits of utilizing these medicinal plants as rumen modifiers under prolonged feeding conditions is justified, further evaluation is recommended to test Moringa and Neem leaf extracts at higher inclusion levels. Our research group is currently exploring a variety of phytogenic tools for the identification and standardization of key bioactive compounds linked to methane inhibition, in these leaf extracts.

Deciphering the key pathway for triterpenoid biosynthesis in Azadirachta indica A. Juss.: a comprehensive review of omics studies in nature's pharmacy

Since ancient times, Azadirachta indica, or Neem, has been a well-known species of plant that produces a broad range of bioactive terpenoid chemicals that are involved in a variety of biological functions. Understanding the molecular mechanisms that are responsible for the biosynthesis and control of terpenoid synthesis is majorly dependent on successfully identifying the genes that are involved in their production. This review provides an overview of the recent developments concerning the identification of genes in A. indica that are responsible for the production of terpenoids. Numerous candidate genes encoding enzymes that are involved in the terpenoid biosynthesis pathway have been found through the use of transcriptomic and genomic techniques. These candidate genes include those that are responsible for the precursor synthesis, cyclization, and modification of terpenoid molecules. In addition, cutting-edge omics technologies, such as metabolomics and proteomics, have helped to shed light on the intricate regulatory networks that govern terpenoid biosynthesis. These networks are responsible for the production of terpenoids. The identification and characterization of genes involved in terpenoid biosynthesis in A. indica presents potential opportunities for genetic engineering and metabolic engineering strategies targeted at boosting terpenoid production as well as discovering novel bioactive chemicals.

Acute and sub-acute toxicity evaluation of dihydro-p-coumaric acid isolated from leaves of Tithonia diversifolia Hemsl. A. Gray in BALB/c mice

In present study, the acute and sub-acute toxicities of Dihydro-p-coumaric acid isolated from the leaves of Tithonia diversifolia (Hemsl.) A. Gray was studied for safety issues in mammals. For acute toxicity tests, isolated compound was administered orally in both male and female BALB/c mice at the doses of 200, 800, and 1,600 mg/kg body weight for 7 days. In sub-acute toxicity study 50 and 500 mg/kg bw of the compound was orally administered for 14 days. Toxicity induced behavioural changes, haematological parameters, biochemical markers and histopathological sections were studied after Dihydro-p-coumaric acid administration. The vital organs like heart, kidney, uterus and testis revealed no adverse effects at doses of upto 1,600 mg/kg bw and 500 mg/kg bw. Slight hepatotoxicity was however demonstrated by ALT and AST assay but histopathological section did not concur as much. The study demonstrated insignificant difference in the percentage of feed intake, water intake, weight gain, haematological parameters and histopathological changes, with no toxicity signs and mortality. Dihydro-p-coumaric acid can be regarded as safe in both acute and sub-acute toxicity assay in both sexes. This indicates Dihydro-p-coumaric acid as a viable alternative to synthetic pesticides.

Acaricidal Properties of Four Neem Seed Extracts (Azadirachta indica) on the Camel Tick Hyalomma dromedarii (Acari: Ixodidae)

Tick infestation remains one of the major health problems that affect the productivity and comfort of camels. The control of ticks mainly relies on using chemical acaracides. Limited information is available on the potential benefits and activity of various neem extracts on Hyalomma ticks. The present study investigated the acaricidal activity of neem seed extracts at different concentrations against developmental stages of the camel tick Hyalomma dromedarii in comparison to Butox and diazinon. The acaricidal activity of three extracts, namely, hexane extract (HE), methyl chloride extract (MCE), and methanol extract (ME), of neem seeds (Azadirachta indica) were tested at varying concentrations of 5, 10, 15, and 20% on engorged H. dromedarii female ticks at days 1, 3, 5, 7, 12, 16, 20, 28, 37, and 43 after treatment (DPT). Interestingly, results of applying different neem seed extracts to engorged H. dromedarii female ticks showed that the most effective extract was hexane at concentration 20%, causing 100% mortality at 1st day post-application, while methanol extract at 20% and dichloromethane extract at 20% caused the death of all ticks at 28th day posttreatment as compared to Butox® 5.0 and Diazinon-60, which resulted in mortality of all ticks at 3 and 5 DPT, respectively. In addition, no mortality was reported with the application of aqueous extract (AE), which served as the control group. Furthermore, the neem hexane extract exhibited high efficacy against reproductive performance of female ticks, whereas no fertility or oviposition was reported at all of their concentrations. Additionally, no hatchability occurred using all neem extracts, except the aqueous extract, which showing no effect. In the present study, larvae responded more rapidly to the plant extracts, whereas mortality of all larvae was recorded at 24 h after treatment with 5% hexane. Taken together, this study pointed out that the acaricidal effect of hexane extract of neem seeds was more effective and could be economically used for controlling H. dromedarii ticks.

The anti-cancer properties of neem (Azadirachta indica) through its antioxidant activity in the liver: its pharmaceutics and toxic dosage forms. A literature review

OBJECTIVES

The neem (Azadirachta indica) have been used in herbal medicine for the treatment of multiple diseases, particularly cancer. The mechanism of anti-cancer properties of neem are far from clear. However, it is well accepted that anti-cancer effects of neem is mediated via its hepatic anti-oxidant activity. In the present review, we are going to classify in vitro and in vivo studies about anti-cancer activity of neem via its hepatic anti-oxidant activity. We also summarize its active ingredients and some therapeutic and toxic dosage forms.

METHODS

A systematic search in the literature was performed in PubMed, Scopus, Embase, Cochrane Library, Web of Science, as well as Google Scholar pre-print database using all available MeSH terms for neem, A. indica, anti-cancer, anti-tumor, carcinogen, liver, antioxidant activity, neem ingredients, and glutathione. Electronic database searches combined and duplicates were removed.

RESULTS

The neem plant have been used in herbal medicine for the treatment of various diseases, particularly cancer. The mechanisms of anti-cancer effects of neem are far from clear. Cancerous cells growth can induce imbalance the oxidant and anti-oxidant activity in various organs particularly in the liver. Therefore, it seems that neem have anti-cancer effects via restore of the antioxidant disturbances close to the control ones in the liver. Additionally, administration of neem extract can induce oncostatic potential via several mechanism including; suppression of the NF-κβ pathway, increased expression of tumor suppressor (such as p53 and pTEN), decreased expression of oncogenes (such as c-Myc), and increased apoptosis in cancerous cells. The median lethal dose (LD50) value for extracts of neem was higher than 2,500 mg/kg.

CONCLUSIONS

It is suggested that neem plays pivotal role in the prevention and treatment of cancer via its hepatic antioxidant activity. Indeed, application of neem extract can decreased tumor growth via restore of the antioxidant disturbances close to the control ones in the liver.

Fresh-Cut Mangoes: How to Increase Shelf Life by Using Neem Oil Edible Coating

The mango is the most widely cultivated tropical fruit. Fresh-cut mango is very useful, but it is very perishable. The purpose of this study was to highlight the effects of neem oil on fresh-cut mango fruits kept for 9 days at 4 ± 1 °C and 80 ± 5% relative humidity. The neem plant (Azadirachta indica) has numerous antioxidant and antibacterial properties. Despite this, very few studies have been carried out on neem oil added to edible coatings (EC) to retard ripening processes. Two formulations were tested: EC1 (hydroxypropyl methylcellulose + CaCl2) and EC2 (hydroxypropyl methylcellulose + CaCl2 + neem oil), both compared with an untreated sample (control). Physicochemical, microbial, proximate and sensory analyses were carried out. Neem oil reduced loss of firmness and colour, while hydroxypropyl methylcellulose and CaCl2 reduced normal cell degradation (weight loss and soluble solids content). Microbiological investigation showed that the EC2 inhibited the development of the main spoilage bacteria during the entire storage period, prolonging the preservation of fresh-cut fruits. The sensory analysis showed a rapid degradation after 5 d in the control sample, while the EC2 was the best.

Aspergillus flavus induced oxidative stress and immunosuppressive activity in Spodoptera litura as well as safety for mammals

BACKGROUND

In the last few decades, considerable attention has been paid to entomopathogenic fungi as biocontrol agents, however little is known about their mode of action and safety. This study aimed to investigate the toxicity of Aspergillus flavus in insect Spodoptera litura by analyzing the effect of fungal extract on antioxidant and cellular immune defense. In antioxidant defense, the lipid peroxidation (Malondialdehyde content) and antioxidant enzymes activities (Catalase, Ascorbate peroxidase, Superoxide dismutase) were examined. In cellular immune defense, effect of A. flavus extract was analyzed on haemocytes using Scanning Electron Microscopy (SEM). Furthermore, mammalian toxicity was analyzed with respect to DNA damage induced in treated rat relative to control by comet assay using different tissues of rat (blood, liver, and kidney).

RESULTS

Ethyl acetate extract of A. flavus was administrated to the larvae of S.litura using artificial diet method having concentration 1340.84 μg/ml (LC50 of fungus). The effect was observed using haemolymph of insect larvae for different time intervals (24, 48, 72 and 96). In particular, Malondialdehyde content and antioxidant enzymes activities were found to be significantly (p ≤ 0.05) increased in treated larvae as compared to control. A. flavus ethyl acetate extract also exhibit negative impact on haemocytes having major role in cellular immune defense. Various deformities were observed in different haemocytes like cytoplasmic leakage and surface abnormalities etc. Genotoxicity on rat was assessed using different tissues of rat (blood, liver, and kidney) by comet assay. Non-significant effect of A. flavus extract was found in all the tissues (blood, liver, and kidney).

CONCLUSIONS

Overall the study provides important information regarding the oxidative stress causing potential and immunosuppressant nature of A. flavus against S. litura and its non toxicity to mammals (rat), mammals (rat), suggesting it an environment friendly pest management agent.

Angiogenic and anti-inflammatory properties of azadirachtin A improve random skin flap survival in rats

Random skin flaps are widely used to repair tissue defects. However, the distal flap regions are prone to ischemic necrosis, limiting clinical applications. Azadirachtin A, a fruit extract from the neem, improves tissue blood supply and metabolism, reduces cell swelling, promotes tissue healing, and prevents venous thrombosis. We explored whether it enhances random skin flap survival. Fifty-four Sprague-Dawley rats were divided into control, low-dose, and high-dose Azadirachtin A-treated groups using a random number table. We used an improved version of the McFarlane technique to create flaps. On day 2, superoxide dismutase and malondialdehyde levels were measured. Tissue slices prepared on day 7 were stained with hematoxylin and eosin. The expression levels of vascular endothelial growth factor (VEGF), toll-like receptor 4 (TLR4), nuclear factor kappa-B (NF-kB), interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) were immunohistochemically assayed. Microcirculatory blood flow was measured via laser Doppler blood flowmetry. Flap angiography was performed using the lead-oxide gelatin injection technique. And the azadirachtin A groups exhibited a greater mean flap survival area, an improved mean blood vessel density, a greater blood flow, and higher superoxide dismutase and VEGF levels, especially at the high dose. Azadirachtin A markedly reduced the levels of TNF-α, IL-6, IL-1β, TLR4, and NF-kB. These findings suggest that azadirachtin A promotes random skin flap survival by improving the blood supply, reducing tissue inflammation, and inhibiting flap ischemia reperfusion injury.

Green Micro- and Nanoemulsions for Managing Parasites, Vectors and Pests

The management of parasites, insect pests and vectors requests development of novel, effective and eco-friendly tools. The development of resistance towards many drugs and pesticides pushed scientists to look for novel bioactive compounds endowed with multiple modes of action, and with no risk to human health and environment. Several natural products are used as alternative/complementary approaches to manage parasites, insect pests and vectors due to their high efficacy and often limited non-target toxicity. Their encapsulation into nanosystems helps overcome some hurdles related to their physicochemical properties, for instance limited stability and handling, enhancing the overall efficacy. Among different nanosystems, micro- and nanoemulsions are easy-to-use systems in terms of preparation and industrial scale-up. Different reports support their efficacy against parasites of medical importance, including Leishmania, Plasmodium and Trypanosoma as well as agricultural and stored product insect pests and vectors of human diseases, such as Aedes and Culex mosquitoes. Overall, micro- and nanoemulsions are valid options for developing promising eco-friendly tools in pest and vector management, pending proper field validation. Future research on the improvement of technical aspects as well as chronic toxicity experiments on non-target species is needed.

Assessment of azadirachtin-A, a neem tetranortritarpinoid, on rat spermatozoa during in vitro capacitation

BACKGROUND

The exploration of the biological assessment of technical azadirachtin, a tetranortritarpinoid from the neem seed kernel, was reviewed. The present study was, therefore, designed to evaluate the dose-dependent in vitro effects of azadirachtin-A, particularly on the functional studies and determination of molecular events, which are critical in the process of sperm capacitation.

METHODS

To assess the effects of the azadirachtin-A on the functional studies, sperm capacitation, the total sperm adenosine triphosphate levels, acrosome reaction (AR), the sperm-egg interaction and the determination of molecular events like cyclic adenosine-3',5'-monophosphate and calcium levels, the appropriate volumes of the sperm suspension were added to the medium to a final concentration of 1×106 sperm/mL and incubated in a humidified atmosphere of 5% CO2 in air at 37°C. The increasing quantities 0.5-2.0 mM/mL and the equivalent volumes of 50% dimethyl sulfoxide were added to the control dishes prior to the addition of spermatozoa and then observed at various time-points for motility and other analyses.

RESULTS

Results revealed the dose- and time-dependent decrease in the functional consequence of capacitation, i.e. the percentage of motile spermatozoa, motility score and sperm motility index, levels of molecular events in spermatozoa, followed by declined spontaneous AR leading to lesser binding of the cauda epididymal sperm to the Zona pellucida.

CONCLUSIONS

The findings confirm the inhibition of rat sperm motility by blocking some biochemical pathways like energy utilization. They also demonstrate that sperm capacitation is associated with the decrease in AR and that the levels of molecular events in spermatozoa can guide us towards the development of a new male contraceptive constituent.

Chemistry, bioactivities, extraction and analysis of azadirachtin: State-of-the-art

Azadirachta indica A. Juss. (Neem) is an Indian tree recognized for its activity as pesticide, as well as several pharmacological properties. Among the various compounds already isolated and studied from Neem tree, azadirachtin (AZA) was identified as the main bioactive compound. Azadirachtin can be found at different parts of the Neem plant but assumes its maximum concentration at the seed level. This compound features a quite complex chemical structure, which justifies the 20-plus-year difficulty to identify the synthetic pathway that subsequently permitted to carry out its artificial synthesis. Azadirachtin is widely used as a basis for production of biopesticides; nevertheless, other properties have been recognized for this substance, among which the anticancer and antimalarial activity stand out. The methods available for azadirachtin extraction are diverse, including solid-liquid extraction and extraction with solvents at high or low temperatures. Alcohol based solvents are associated with higher extraction yields and are therefore preferred for the isolation of azadirachtin from plant parts. Clean-up of the extracts is generally required for further purification. The highest azadirachtin levels have been obtained from Neem seeds but concentration values present a large variation between batches. Therefore, in addition to extraction procedures, it is essential to establish routine methods for azadirachtin identification and quantification. Chromatography-based techniques are preferably selected for detection and quantification of azadirachtin in plant matrices. Overall, this process will guarantee a future reproducible, safe and effective use of the extracts in formulations for commercial applications.

Cross-Linking Chitosan into Hydroxypropylmethylcellulose for the Preparation of Neem Oil Coating for Postharvest Storage of Pitaya (Stenocereus pruinosus)

The market trend for pitaya is increasing, although the preservation of the quality of this fruit after the harvest is challenging due to microbial decay, dehydration, and oxidation. In this work, the application of antimicrobial chitosan-based coatings achieved successful postharvest preservation of pitaya (Stenocereus pruinosus) during storage at 10 ± 2 °C with a relative humidity of 80 ± 5%. The solution of cross-linked chitosan with hydroxypropylmethylcellulose with entrapped Neem oil (16 g·L^-1) displayed the best postharvest fruit characteristics. The reduction of physiological weight loss and fungal contamination, with an increased redness index and release of azadirachtin from the microencapsulated oil, resulted in up to a 15 day shelf life for this fruit. This postharvest procedure has the potential to increase commercial exploitation of fresh pitaya, owing to its good taste and high content of antioxidants.

Non-target toxicity of novel insecticides

Humans have used insecticides since ancient times. The spectrum and potency of available insecticidal substances has greatly expanded since the industrial revolution, resulting in widespread use and unforeseen levels of synthetic chemicals in the environment. Concerns about the toxic effects of these new chemicals on non-target species became public soon after their appearance, which eventually led to the restrictions of use. At the same time, new, more environmentally-friendly insecticides have been developed, based on naturally occurring chemicals, such as pyrethroids (derivatives of pyrethrin), neonicotinoids (derivatives of nicotine), and insecticides based on the neem tree vegetable oil (Azadirachta indica), predominantly azadirachtin. Although these new substances are more selective toward pest insects, they can still target other organisms. Neonicotinoids, for example, have been implicated in the decline of the bee population worldwide. This review summarises recent literature published on non-target toxicity of neonicotinoids, pyrethroids, and neem-based insecticidal substances, with a special emphasis on neonicotinoid toxicity in honeybees. We also touch upon the effects of pesticide combinations and documented human exposure to these substances.

Safety of Natural Insecticides: Toxic Effects on Experimental Animals

Long-term application and extensive use of synthetic insecticides have resulted in accumulating their residues in food, milk, water, and soil and cause adverse health effects to human and ecosystems. Therefore, application of natural insecticides in agriculture and public health sectors has been increased as alternative to synthetic insecticides. The question here is, are all natural insecticides safe. Therefore, the review presented here focuses on the safety of natural insecticides. Natural insecticides contain chemical, mineral, and biological materials and some products are available commercially, e.g., pyrethrum, neem, spinosad, rotenone, abamectin, Bacillus thuringiensis (Bt), garlic, cinnamon, pepper, and essential oil products. It can induce hepatotoxicity, renal toxicity, hematotoxicity, reproductive toxicity, neurotoxicity, and oxidative stress. It can induce mutagenicity, genotoxicity, and carcinogenicity in mammals. Some natural insecticides and active compounds from essential oils are classified in categories Ib (Highly hazardous) to U (unlikely toxic). Therefore, the selectivity and safety of natural insecticides not absolute and some natural compounds are toxic and induce adverse effects to experimental animals. In concussion, all natural insecticides are not safe and the term "natural" does not mean that compounds are safe. In this respect, the term "natural" is not synonymous with "organic" and not all-natural insecticide products are acceptable in organic farmers.

Antifilarial activity of azadirachtin fuelled through reactive oxygen species induced apoptosis: a thorough molecular study on Setaria cervi

Efficacious therapeutic strategies against lymphatic filariasis are always sought after. However, natural products are a promising resource for developing effective antifilarial agents. Azadirachtin, a significant tetranortriterpenoid phytocompound found in Azadirachta indica, was evaluated in vitro for antifilarial potential against the filarial parasite Setaria cervi. Dye exclusion and MTT assay confirmed the antifilarial potential of azadirachtin against S. cervi with a median lethal dose (LC50) of 6.28 μg/ml for microfilariae (mf), and 9.55 μg/ml for adult parasites. Morphological aberrations were prominent in the histological sections of the azadirachtin-exposed parasites. Moreover, alterations in the reactive oxygen species (ROS) parameters in treated parasites were evident. Induction of apoptosis in treated parasites was confirmed by DNA laddering, acridine orange (AO)/ethidium bromide (EtBr) double staining and in situ DNA fragmentation. The downregulation of anti-apoptotic CED-9 and upregulation of proapoptotic EGL-1, CED-4 and CED-3 at both the transcription and translation levels confirmed apoptosis execution at the molecular level. Changes in the gene expressions of nuc-1, cps-6 and crn-1 further clarified the molecular cause of DNA degradation. Furthermore, azadirachtin was found to be non-toxic in both in vitro and in vivo toxicity analyses. Therefore, the experimental evidence detailed the pharmacological effectiveness of azadirachtin as a possible therapeutic agent against filariasis.

A comprehensive review of phytochemical profile, bioactives for pharmaceuticals, and pharmacological attributes of Azadirachta indica

Azadirachta indica L. is a multipurpose medicinal tree of family Meliaceae. It occurs in tropical and semitropical regions of the world. Different parts of this miraculous tree are used to treat pyrexia, headache, ulcer, respiratory disorders, cancer, diabetes, leprosy, malaria, dengue, chicken pox, and dermal complications. The tree is popular for its pharmacological attributes such as hypolipidemic, antifertility, microbicidal, antidiabetic, anti-inflammatory, hepatoprotective, antipyretic, hypoglycemic, insecticidal, nematicidal, antiulcer, antioxidant, neuroprotective, cardioprotective, and antileishmaniasis properties. A. indica is also rich in various phytochemicals for pharmaceuticals such as alkaloids, steroids, flavonoids, terpenoids, fatty acids, and carbohydrates. The fungicidal potential of the tree is due to the presence of azadirachtin and nimbin. Herein, we have compiled a comprehensive review of phytochemical profile, pharmacological attributes, and therapeutic prospective of this multipurpose tree.

In vitro and ex vivo activity of an Azadirachta indica A.Juss. seed kernel extract on early sporogonic development of Plasmodium in comparison with azadirachtin A, its most abundant constituent

BACKGROUND

NeemAzal^® (NA) is a quantified extract from seed kernels of neem, Azadirachta indica A.Juss. (Meliaceae), with a wide spectrum of biological properties, classically ascribed to its limonoid content. NA contains several azadirachtins (A to L), azadirachtin A (AzaA) being its main constituent. AzaA has been shown to inhibit microgamete formation of the rodent malaria parasite Plasmodium berghei, and NA was found to completely inhibit the transmission of Plasmodium berghei to Anopheles stephensi mosquitoes when administered to gametocytemic mice at a corresponding AzaA dose of 50mg/kg before exposure to mosquitoes.

PURPOSE

The present study was aimed at i) assessing the pharmacodynamics and duration of action of NA and AzaA against P. berghei exflagellation in systemic circulation in mice and ii) elucidating the transmission blocking activity (TBA) of the main NA constituents.

STUDY DESIGN

The NA and AzaA pharmacodynamics on exflagellation were assessed through ex vivo exflagellation assays, while TBA of NA constituents was evaluated through in vitro ookinete development assay.

METHODS

Pharmacodynamics experiments: Peripheral blood from P. berghei infected BALB/c mice with circulating mature gametocytes, were treated i.p. with 50mg/kg and 100mg/kg pure AzaA and with NeemAzal^® (Trifolio-M GmbH) at the corresponding AzaA concentrations. The effect magnitude and duration of action of compounds was estimated by counting exflagellation centers, formed by microgametocytes in process of releasing flagellated gametes, at various time points after treatment in ex vivo exflagellation tests. Ookinete Development Assay: The direct effects of NeemAzal^® and AzaA on ookinete development were measured by fluorescence microscopy after incubation of gametocytemic blood with various concentrations of test substances in microplates for 24h.

RESULTS

The exflagellation tests revealed an half-life of NA anti-plasmodial compounds of up to 7h at a NA dose corresponding to 100mg/kg equivalent dose of AzaA. The ookinete development assay showed an increased activity of NA against early sporogonic stages compared to that of AzaA. The IC₅₀ value determined for NA was 6.8µg/ml (CI₉₅: 5.95-7.86), about half of the AzaA IC₅₀ (12.4µg/ml; CI₉₅: 11.0-14.04).

CONCLUSION

The stronger activity of NA, when compared to AzaA, could not be explained by an additive or synergistic effect by other azadirachtins (B, D and I) present in NA. In fact, the addition of these compounds at 50µM concentration to AzaA did not evidence any decrease of the IC₅₀ against early sporogonic stages to that obtained with AzaA alone. It is likely that other non-limonoid compounds present in NA may contribute to AzaA activity and enhanced pharmacodynamics against exflagellation both in vitro and in vivo.

Transcriptional profiling induced by pesticides employed in organic agriculture in a wild population of Chironomus riparius under laboratory conditions

Copper (Cu) and azadirachtin (AZA-A+B) are pesticides allowed in organic agriculture whose environmental risk and toxicity for aquatic wildlife is only partially known. Reverse Transcription Polymerase Chain Reaction was used to assess the molecular effect of acute and short-term exposure (3, 24h) of Cu (0.01, 0.05, 1, 10, 25mgl(-1)) and AZA-A+B (0.2, 0.3, 0.4, 0.5, 1mgl(-1)) on the expression of five candidate genes (hsp70, hsc70, hsp40, hsp10 and cyP450) in a non-target species, Chironomus riparius. Fourth-instar larvae were collected from a mountain stream polluted by agricultural land run-off. All genes were responsive to both pesticides but each gene had a specific response to the different experimental concentrations and exposure times. A few similarities in transcriptional profiling were observed, such as a linear concentration-dependent response of hsp70 after 24h of exposure (at ≥1mgl(-1) of Cu and ≥0.2mgl(-1) of AZA-A+B) and an up-regulation regardless of the concentration of hsc70 after 24h of exposure (at ≥0mgl(-1) of Cu and ≥0.2mgl(-1) of AZA-A+B and the up-regulation of hsp70 after 3h of exposure at ~LC50 (Cu-LC50=26.1±2.5mgl(-1), AZA-A+B-LC50=1.1±0.2mgl(-1)). According to the results, hsp40, hsp10 and cyP450 may be defined as pesticide-dependent (i.e., hsp40 and hsp10 seemed to responded mainly to AZA-A+B and cyP450 to Cu), while hsc70 as time-dependent regardless of the pesticide (i.e., hsc70 responded only after 24h of treatment with Cu and AZA-A+B). This study gives new insights on the potential role of the C. riparius's hsps and cyP450 genes as sensitive biomarkers for freshwater monitoring.

Neemazal ® as a possible alternative control tool for malaria and African trypanosomiasis?

BACKGROUND

Research efforts to identify possible alternative control tools for malaria and African trypanosomiasis are needed. One promising approach relies on the use of traditional plant remedies with insecticidal activities.

METHODS

In this study, we assessed the effect of blood treated with different doses of NeemAzal ® (NA, neem seed extract) on mosquitoes (Anopheles coluzzii) and tsetse flies (Glossina palpalis gambiensis) (i) avidity to feed on the treated blood, (ii) longevity, and (iii) behavioural responses to human and calf odours in dual-choice tests. We also gauged NeemAzal ® toxicity in mice.

RESULTS

In An. coluzzii, the ingestion of NA in bloodmeals offered by membrane feeding resulted in (i) primary antifeedancy; (ii) decreased longevity; and (iii) reduced response to host odours. In G. palpalis gambiensis, NA caused (i) a knock-down effect; (ii) decreased or increased longevity depending on the dose; and (iii) reduced response to host stimuli. In both cases, NA did not affect the anthropophilic rate of activated insects. Overall, the most significant effects were observed with NA treated bloodmeals at a dose of 2000 μg/ml for mosquitoes and 50 μg/ml for tsetse flies. Although no mortality in mice was observed after 14 days of follow-up at oral doses of 3.8, 5.6, 8.4 and 12.7 g/kg, behavioural alterations were noticed at doses above 8 g/kg.

CONCLUSION

This study revealed promising activity of NA on A. coluzzii and G. palpalis gambiensis but additional research is needed to assess field efficacy of neem products to be possibly integrated in vector control programmes.

Therapeutics Role of Azadirachta indica (Neem) and Their Active Constituents in Diseases Prevention and Treatment

Neem (Azadirachta indica) is a member of the Meliaceae family and its role as health-promoting effect is attributed because it is rich source of antioxidant. It has been widely used in Chinese, Ayurvedic, and Unani medicines worldwide especially in Indian Subcontinent in the treatment and prevention of various diseases. Earlier finding confirmed that neem and its constituents play role in the scavenging of free radical generation and prevention of disease pathogenesis. The studies based on animal model established that neem and its chief constituents play pivotal role in anticancer management through the modulation of various molecular pathways including p53, pTEN, NF-κB, PI3K/Akt, Bcl-2, and VEGF. It is considered as safe medicinal plants and modulates the numerous biological processes without any adverse effect. In this review, I summarize the role of Azadirachta indica in the prevention and treatment of diseases via the regulation of various biological and physiological pathways.

Ectoparasites of medical and veterinary importance: drug resistance and the need for alternative control methods

OBJECTIVES

Despite multiple attempts at eradication, many ectoparasites of humans and domestic livestock remain a persistent problem in the modern world. For many years, a range of pesticide drugs including organophosphates, organochlorides and synthetic pyrethroids provided effective control of these parasites; but intensive use of these drugs has led to the evolution of resistance in many target species. This paper aims to review the effectiveness of current control methods and discuss potential alternatives for the long term sustainable control of ectoparasites.

KEY FINDINGS

Important medical ectoparasites such as scabies mites, head lice and bed bugs present a significant public health problem, and so adequate control methods are essential. Ectoparasites of domestic livestock and farmed fish (for example sheep scab mites, poultry mites and sea lice) are also of concern given the increasing strain on the world's food supply. These parasites have become resistant to several classes of pesticide, making control very difficult. Recently, an increasing amount of research has focussed on alternative control methods such as insect growth regulators, biological control using essential oils or fungi, as well as vaccine development against some ectoparasites of medical and veterinary importance.

SUMMARY

Drug resistance is prevalent in all of the ectoparasites discussed in this review. A wide variety of alternative control methods have been identified, however further research is necessary in order for these to be used to successfully control ectoparasitic diseases in the future.

Mammalian safety of Decaleside II in the laboratory mouse

Decaleside II, a novel trisaccharide isolated from the edible roots of Decalepis hamiltonii, belongs to a new class of natural insecticides. We have evaluated the mammalian safety of Decaleside II in the laboratory mouse. Our results on acute and sub acute toxicity study suggest that Decaleside II is not toxic to the laboratory mice as there were no symptoms of toxicity or mortality up to 2400 mg/kg bw. Haematological profile was unaltered and serum profiles of enzymes were not significantly affected. The lack of toxicity of Decaleside is attributed to the 1,4 α linkage of the sugars which are easily hydrolyzed by the digestive enzymes such as glucosidases. The selective toxicity to insects and mammalian safety of Decaleside II makes them highly suitable for use as novel grain protectants of natural origin.

Hepatoprotective activity of the neem-based constituent azadirachtin-A in carbon tetrachloride intoxicated Wistar rats

The aim of this study was to investigate the hepatoprotective role of azadirachtin-A in carbon tetrachloride (CCl4) induced hepatotoxicity in rats. The group allotment for the animals used in the hepatoprotective study included a vehicle treatment group, CCl4 (1 mL · (kg body mass)(-1)) treatment group, silymarin (100 μg · (kg body mass)(-1) · day(-1)) + CCl4 treatment group, and groups treated with different doses of azadirachtin-A (100 or 200 μg · (kg body mass)(-1) · day(-1)) + CCl4. On the 9th day, blood was obtained for measuring the biochemical parameters, and liver tissue was obtained for pathological examination. The acute toxicity test with azadirachtin-A (500, 1000, or 2000 μg · (kg body mass)(-1)) indicated no mortality after 14 days of treatment; further, there was no change in behavior, food consumption, or organ mass. However with the higher dose, some hematological parameters showed changes. Hepatoprotective studies revealed that the CCl4 treatment group exhibited a decrease in total protein and albumin levels, whereas a significant increase in BUN, AST, ALT, and ALP levels were noticed compared with the vehicle-treated control, indicating that there was liver damage caused by CCl4. Histology and ultrastructure study confirmed that pretreatment with azadirachtin-A dose-dependently reduced hepatocellular necrosis and, therefore, protected the liver against toxicity caused by CCl4. The results from this study indicate that pretreatment with azadirachtin-A at the higher dose levels, moderately restores the rat liver to normal. This study confirms that azadirachtin-A possesses greater hepatoprotective action; however, the effective concentration needs to be determined.

Azadirachta indica treatment on the congenital malformations of fetuses from rats

ETHNOPHARMACOLOGICAL RELEVANCE

Azadirachta indica A. Juss, popularly known as neem, presents medicinal and insecticide properties. However, the repercussions of the neem maternal treatment on fetal development should be investigated. Thus, the aim of this study was to evaluated the effects of Azadirachta indica (neem) on the frequency of congenital malformations in fetuses from rats.

MATERIALS AND METHODS

Pregnant rats were randomly distributed into three experimental groups: NT=non-treated; TOil=treated with neem seed oil (1.2 mL/day); TAP=treated with active principle of Azadirachta indica (azadirachtin-1.0 mg/mL/day). The neem oil (1.2 mL/day) or azadirachtin (1.0 mg/mL/day) treatments were orally administered throughout pregnancy. Blood samples were collected on days 0, 7, 14 and 20 of pregnancy. Oral glucose test tolerance (OGTT) was performed at day 17 of pregnancy for estimation of total area under the curve (AUC). At term, the fetuses were collected and external and internal (visceral and skeletal) malformations were analyzed.

RESULTS

The data showed that the dams treated with neem seed oil and Azadirachtin had no significant change in glucose levels and AUC. It was also verified that neem oil treatment contributed to increase the frequency of malformation/variation, in particular the visceral in their fetuses, while neither significant result was observed in TAP group.

CONCLUSION

In conclusion, neem seed oil treatment administered during pregnancy caused abnormalities in rat fetuses, showing teratogenic effect but the Azadirachtin (active principle) presented no impairment in the fetuses.

Toxicity of a plant based mosquito repellent/killer

The mission to make humans less attractive to mosquitoes has fuelled decades of scientific research on mosquito behaviour and control. The search for the perfect topical insect repellent/killer continues. This analysis was conducted to review and explore the scientific information on toxicity produced by the ingredients/contents of a herbal product. In this process of systemic review the following methodology was applied. By doing a MEDLINE search with key words of selected plants, plant based insect repellents/killers pertinent articles published in journals and authentic books were reviewed. The World Wide Web and the Extension Toxicity Network database (IPCS-ITOX) were also searched for toxicology data and other pertinent information. Repellents do not all share a single mode of action and surprisingly little is known about how repellents act on their target insects. Moreover, different mosquito species may react differently to the same repellent. After analysis of available data and information on the ingredient, of the product in relation to medicinal uses, acute and chronic toxicity of the selected medicinal plants, it can be concluded that the ingredients included in the herbal product can be used as active agents against mosquitoes. If the product which contains the powder of the above said plants is applied with care and safety, it is suitable fo use as a mosquito repellent/killer.

Tick prevention at a crossroad: new and renewed solutions

Ticks have major economic impact through diseases they transmit, direct losses due to their detrimental effect and the efforts invested in prevention measures directed against them. Chemical acaricides represent the main line of anti-tick defense in both humans and domestic animals, but increasing concerns regarding development of acaricide resistance, especially in the cattle tick Rhipicephalus microplus, and environmental safety issues indicate the need for other, less aggressive but equally efficient methods. This paper aims to evaluate the potential, the scientific and economical limitations and future research directions regarding different alternative methods of tick control and their use in integrated pest management, with a separate reference to the pet industry. New research data in each field is presented and the economical aspects for each approach are individually emphasized.

Analytical study of azadirachtin and 3-tigloylazadirachtol residues in foliage and phloem of hardwood tree species by liquid chromatography-electrospray mass spectrometry

A rapid and sensitive LC-ESI-MS method has been developed and validated for the quantitation of azadirachtin and 3-tigloylazadirachtol in deciduous tree matrices. The method involves automated extraction and simultaneous cleanup using an accelerated solvent technique with the matrix dispersed in solid phase over a layer of primary-secondary amine silica. The limits of quantification were 0.02 mg/kg for all matrices with the exception of Norway maple foliage (0.05 mg/kg). Validation at three levels (0.02, 0.1, and 1 mg/kg), demonstrated satisfactory recoveries (71-103%) with relative standard deviation <20%. Two in-source fragment ions were used for confirmation at levels above 0.1 mg/kg. Over a period of several months, quality control analyses showed the technique to be robust and effective in tracking the fate of these natural botanical insecticides following systemic injection into various tree species for control of invasive insect pest species such as the emerald ash borer and Asian longhorned beetle.

Effect of azadirachtin of neemix-4.5 on SWR/J mice

Inbred normal SWR/J male and female mice, 8-10 weeks old and weighing 22.55-26.72 g, were used throughout the study. A total of 100 males and 100 females were used and were divided into 20 groups, 10 animals in each group. Azadirachtin of neemix-4.5, a commercial botanical pesticide derived from the neem tree, orally administered to male and female SWR/J mice at a dose level 9.0 mg/kg (1/10 LD50) for different treatment periods (2, 4, 6, 8 or 11.5 weeks) has produced signs of toxicity, mortality and changes in body and tissue weights of both sexes at almost all treated periods used in the present study. Moreover the oral administration of this dose level for 11.5 weeks has also resulted in some histopathological changes in the livers, kidneys and testes of treated animals compared with the control group, and the degree of these changes ranged from mild to severe in these organs of treated males. However, conflicting results have been reported concerning the toxicity of azadirachtin in mammalian species using different formulations of neem-based pesticides. It appears, therefore, that the toxicity produced by neemix-4.5 in the present study may be due to factors other than azadirachtin in this formulation.

Azadirachtin, a scientific gold mine

Azadirachtin is a highly interesting compound both for its chemical structure, which required 18 years to solve, and its synthesis, which required another 22 years, and for its biological properties as a feeding deterrent for many insects and a growth disruptant for most insects and many other arthropods. Its mode of action, structure-activity relationships, and its biosynthesis still require much research. A valuable natural pesticide, it has very low toxicity for vertebrates, and yet it has still not achieved a prominent place among pesticides and in many countries it is not yet licensed for use. An attempt is made to understand its failure to capture a larger market, 40 years after its discovery.

Timely awareness and prevention of emerging chemical and biochemical risks in foods: proposal for a strategy based on experience with recent cases

A number of recent food safety incidents have involved chemical substances, while various activities aim at the early identification of emerging chemical risks. This review considers recent cases of chemical and biochemical risks, as a basis for recommendations for awareness and prevention of similar risks at an early stage. These cases include examples of unapproved genetically modified food crops, intoxications with botanical products containing unintentionally admixed toxic herbs, residues of unapproved antibiotics and contaminants in farmed aquaculture species such as shrimp and salmon; and adverse effects of chemical and biological pesticides of natural origin. Besides case-specific recommendations for mitigation of future incidents of the same nature, general inferences and recommendations are made. It is recommended, for example, to establish databases for contaminants potentially present within products. Pro-active reconnaissance can facilitate the identification of products potentially contaminated with hazardous substances. In international trade, prevention and early identification of hazards are aided by management systems for product quality and safety, rigorous legislation, and inspections of consignments destined for export. Cooperation with the private sector and foreign authorities may be required to achieve these goals. While food and feed safety are viewed from the European perspective, the outcomes also apply to other regions.

Identification of a putative azadirachtin-binding complex from Drosophila Kc167 cells

Cell-proliferation in Drosophila Kc167 cells was inhibited by 50% when cell cultures contained 1.7 x 10(-7) M azadirachtin for 48 h (a tertranortriterpenoid from the neem tree Azadirachta indica). Drosophila Kc167 cells exhibited direct nuclear damage within 6-h exposure to azadirachtin (5 x 10(-7) M and above) or within 24 h when lower concentrations were used (1 x 10(-9) M). Fractionation of an extract of Drosophila Kc167 cells combined with ligand overlay technique resulted in the identification of a putative azadirachtin binding complex. Identification of the members of this complex by Peptide Mass Fingerprinting (PMF) and N-terminal sequencing identified heat shock protein 60 (hsp60) as one of its components.

Lack of toxic effect of technical azadirachtin during postnatal development of rats

Azadirachtin, a biopesticide has been evaluated for its possible toxic effects during postnatal development of rats over two generations. Rats were fed 100, 500 and 1000ppm technical azadirachtin through diet which is equivalent to 5, 25 and 50mg/kg body weight of rats. Technical azadirachtin has not produced any adverse effects on reproductive function and data were comparable to control animals over two generations. There were no toxicological effect in parent rats as evidenced by clinical signs of toxicity, enzymatic parameters like AST, ALT, ALP, S. bilirubin, S. cholesterol, total protein and histopathology of liver, brain, kidney and testes/ovary. The litters of F(1B) and F(2B) generations were devoid of any morphological, visceral and teratological changes. The percent cumulative loss and growth index of pups were also comparable to respective controls in successive growth period of 0, 4, 7, 14 and 21 days in two generations. There were no major malformations in fetuses while some insignificant minor skeletal variations like missing 5th sternebrae and bipartite thoracic centre found were not compound or dose related. No significant pathomorphological changes were observed in liver, kidney, brain and gonads of F(2B) pups. In conclusion rats fed technical azadirachtin showed no evidence of cumulative effects on postnatal development and reproductive performance over two generations. Absence of any major adverse reproductive effects in adults as well as in 21 days old pups of F(2B) generation suggest the safe use of technical azadirachtin as a biopesticide.

Safety evaluation of neem (Azadirachta indica) derived pesticides

The neem tree, Azadirachta indica, provides many useful compounds that are used as pesticides and could be applied to protect stored seeds against insects. However in addition to possible beneficial health effects, such as blood sugar lowering properties, anti-parasitic, anti-inflammatory, anti-ulcer and hepatoprotective effects, also toxic effects are described. In this study we present a review of the toxicological data from human and animal studies with oral administration of different neem-based preparations. The non-aqueous extracts appear to be the most toxic neem-based products, with an estimated safe dose (ESD) of 0.002 and 12.5 microg/kg bw/day. Less toxic are the unprocessed materials seed oil and the aqueous extracts (ESD 0.26 and 0.3 mg/kg bw/day, 2 microl/kg bw/day respectively). Most of the pure compounds show a relatively low toxicity (ESD azadirachtin 15 mg/kg bw/day). For all preparations, reversible effect on reproduction of both male and female mammals seem to be the most important toxic effects upon sub-acute or chronic exposure. From the available data, safety assessments for the various neem-derived preparations were made and the outcomes are compared to the ingestion of residues on food treated with neem preparations as insecticides. This leads to the conclusion that, if applied with care, use of neem derived pesticides as an insecticide should not be discouraged.

Neem-An Omnipotent Plant: A Retrospection

Neem (Azadirachta indica A. Juss.) has universally been accepted as a wonder tree because of its diverse utility. Multidirectional therapeutic uses of neem have been known in India since the Vedic times. Besides its therapeutic efficacies, neem has already established its potential as a source of naturally occurring insecticide, pesticide and agrochemicals. Safe and economically cheaper uses of different parts of neem in the treatment of various diseases and in agriculture are discussed in this article. It further deals with the active chemical constituents of various neem formulations. Commercially available neem products are also mentioned along with their respective applications. Furthermore, evaluation of safety aspects of different parts of neem and neem compounds along with commercial formulations are also taken into consideration. Systematic scientific knowledge on neem reported so far is thus very useful for the wider interests of the world community.

Assessment of embryo/fetotoxicity and teratogenicity of azadirachtin in rats

To evaluate the potential effect of exposure to azadirachtin technical 12% throughout major organogenesis, rats were fed orally with 500, 1000 and 1500 mg/kg/day azadirachtin on gestation days 6-15 and examined for evidence of embryo/fetotoxicity and teratogenic effects. Technical azadirachtin at different doses did not produce any significant adverse effects in reproductive parameters. Significant embryo/fetotoxic effects were not observed at tested dose levels as evidenced by total number of implantations, post-implantation loss and fetal weight. There were no major malformations, while some minor variants found in high doses were not compound or dose related. The absence of anomalies in fetal gross, visceral morphology and skeleton suggests that technical azadirachtin is not teratogenic in rats at the doses tested.