Neem the Wonder Tree: Its Pesticide and Medicinal ApplicationsAbstract The neem tree (Azadirachta indica) and its chemical products have been used for centuries in many facets for human utility—as an agrochemical, pesticide, food, heating source, wood, soil amendment (Agroforestree), and significant healing agent for purportedly over 100 diseases (Neem Foundation). Scientific literature has been surveyed in order to describe the habitat of neem and its main chemicals, in particular, azadirachtin, and explore its most popular applications as a pesticide. In addition, neem frontier studies and medicinal applications (namely, cancer, pregnancy and contraception, skin disorders, dental and oral care, HIV/ AIDS, diabetes, antioxidant, and ulcers) will also be delved into, in this discussion of what is referred to in scientific circles as the “wonder “ plant (Muñoz-Valenzuela 2007). Photo credit: Plants Florida blogspot. Neem the Wonder Tree: Its Pesticide and Medicinal Applications Pamela Paterson Scholarly Paper Masters of Chemical and Life Sciences University of Maryland August 2009 Acknowledgements I would like to gratefully acknowledge the support of two people in the drafting of this paper: • Dr. Bruce Jarvis, for all of his valued assistance with this paper. Only an email away, Dr. Jarvis provided immediate and thoughtful comments that assisted me in formulating my topic and working through the myriad of queries about my paper. Thank you. • To my husband, Robert Long, who has infinite patience and support in the pursuit of my dreams. You are simply the best and all I could ever hope for. Pamela Paterson
[email protected] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Contents Neem the W o n der T r ee: I ts P es ti c i de a n d Medicinal A ppl i c a ti o n s . . . . . 19 Effects on Insects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Neem as a Pesticide . . . . . . . . . . . . . . . . . . . 13 Pesticid e . . . . . . . . HIV/AIDS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 Cancer . . 27 Hu m an Med i c i n e . . . . . . . . . . . . . . . . . . . . . . . . . . . Diabetes . . . . . . . . . . . . . . . . . . . . . . 2009 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Neem Oil Composition . . . . . . . . . . . . . . . . 1 Abstract . . . . . . . . . . . . . . . . . . . Dental and Oral Care . . . . . . . . . . . . . . . . . . . . . . 33 35 37 38 39 40 41 Copyright by Pamela Paterson. . . . . . . . . . . . . . . . . . . Antioxidant . . . . . . . . . . . 11 Extraction and Formulation . . . . . . . . . . . . . . . . . . . . . . . . Pregnancy and Contraception Skin Disorders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Geography and Habitat . . . . 1 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 21 Formulations . . . . . . . . 5 Chem ical Co mp o un ds . . . . . . . . . . . . . 3 A bout Neem . . . . . . . . . . . . . . . . 3 Getting to Know Neem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Azadirachtin . . . 44 Bibliogr aphy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Ulcers . . . . . . . . . . . . . . . . . . . . . . . . 49 2 Copyright by Pamela Paterson. . . . . . 2009 . . . . . . . . 42 Safety and Toxicity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 C onclu sion . . . Even the leaves are a source of food—they are used as fodder in the dry season (AgroForestryTree Database). known as “neem glue”. which is colorless. and malodorous.Getting to Know Neem About Neem Getting to Know Neem Neem is truly a tree with roots firmly embedded in the cultures of its people. 2009 3 . The gum (resin). neem leaf juice applied on skin to treat disorders. The fruit is also a major food source for birds and bats (they eat the pulp. and neem leaves placed in the home to ward away bugs (Muñoz-Valenzuela 2007). Copyright by Pamela Paterson. among others. neem tea drunken as a tonic. Its fruit (about the size of an olive) are eaten raw or cooked. is also a high-protein food additive used in Southeast Asia. not the seed). sticky. For 2000 years in India (Reutemann 2008) neem twigs have been chewed on to clean teeth. and young twigs and flowers are sometimes eaten as vegetables. 4 Copyright by Pamela Paterson. is used locally to make furniture. In addition. and the oil is used as lamp oil throughout India. fungi. 2009 . and insects (AgroForestryTree Database). it enhances the efficiency of nitrogen fertilizers by reducing the rate of nitrification and hampering pests such as nematodes. Its popularity in being used to make furniture is partly due to its insect repellent properties. the tree bark has 12% to 14% tannins. As such it is useful as a dune fixation tree (AgroForestryTree Database). for insects are deterred from coming near the furniture or the items inside. making it an important agent in erosion control because it is virtually drought-resistant. which makes it a good source for tannin chemicals (AgroForestryTree Database).About Neem Neem also has important fuel uses: the wood is used as firewood and to produce excellent-grade charcoal. The wood is also popular for fencing and construction. Farmers in India use neem cake (the residue left after extracting oil from the seeds) as an organic manure and soil amendment. The timber. although it has a rough grain and does not polish well. Neem has a well-developed root system that can extract nutrients from lower soil levels. and Margosa tree (Barceloux 2008).Geography and Habitat Geography and Habitat G e o g r a p h ic Di stri bu ti o n The neem tree is native to India. neem is grown in Florida and California. Sri Lanka. It has since been transplanted to many parts of the world. Myanmar. Indian lilac. and Thailand. Malaysia. leaf form. branching type. 2009 5 . Middle East. The trees themselves are known to have genetic variation in height. Neem populations are heterogenous in all respects. In the United States. Copyright by Pamela Paterson. is also called the Indian neem tree. Indonesia. the Caribbean. and others (AgroForestryTree Database). Senegal. Pakistan. South America. a member of the Meliaceae family (Mahogany family) (AgroForestryTree Database). Latin America. B o t a n ic a l Desc ri pti o n The neem tree (Azadirachta indica). including several countries in Africa. and color (Muñoz-Valenzuela 2007). owing greatly to differences in soil and climate. These foliage proportions provide for shade nearly year-round (AgroForestryTree Database). et al. AgroForestryTree Database) 6 Copyright by Pamela Paterson. 2009 . Figure 1 Neem Tree (E.L. Neem has a large. or even 30 m (AgroForestryTree Database) with limbs of 15 m in length (Barceloux 2008). 2006). Kidiavai.About Neem Height generally ranges from 15 to 25 m (Cseke. round crown of about 10 m (maximum 20 m) in diameter. 2005). When damaged. Figure 2 Neem leaves (Mansha Enterprises). the leaves emit a garlic odor (Schoonhoven. 2009 7 .5 cm wide (Muñoz-Valenzuela 2007) and the leaf blade is glabrous (Barceloux 2008). et al.Geography and Habitat Shiny dark green leaves are pinnately compound (leaflets attached in two rows to the main vein. as in Figure 2). Copyright by Pamela Paterson. The 10 to 12 serrated leaflets on each leaf are 7 cm long by 2. and has one (infrequently.About Neem White flowers are found as inflorescences with joined sepals. 8 Copyright by Pamela Paterson. size. two) seeds (Barceloux 2008). 2009 . about 1 to 2 cm long (resembling an olive (Schoonhoven. 2005)). et al. and oil content and quality are also varied (Muñoz-Valenzuela 2007). composition. weight. kernel proportion. the fruit form. fleshy. The fruit is yellow. Figure 3 Neem Fruit (Mansha Enterprises) Like other characteristics of the tree population. or where there is a hard calcareous or clay pan near the surface (AgroForestryTree Database). Neem can grow within an altitude range of 0 to 1500 m. but is not able to tolerate frost (AgroForestryTree Database). and tolerate conditions to 40°C with a mean annual rainfall of 400 to 1200 mm (AgroForestryTree Database). The young neem. stony.2 to 7. on the other hand. lowland monsoon forest in Indonesia. ranging from mixed forest in India. Copyright by Pamela Paterson. evergreen forest and dry deciduous forest in Africa (AgroForestryTree Database). neem can grow in almost any climate in the lowland tropics. but the optimum pH is 6. and Florida.Geography and Habitat Na t u r a l H a b i tat Except for waterlogged soil. neem can live 150 to 200 years (Neem Foundation). can grow at least for the first few years in areas that are predominantly shaded. The adult neem is able to tolerate some frost. Neem can grow in soils from neutral to alkaline. In an ideal habitat. but requires a significant amount of sunlight. 2009 9 . to more recently the Caribbean. It can also live well on shallow. sandy soils. California. depending on the region and time of year. it does not (AgroForestryTree Database). From the beginning of the flowering stage to the seed falling (after the fruit shrivels away). A mature tree produces 30 to 50 kg fruit annually (Neem Foundation). in Thailand neem produces flowers and fruits year-round—whereas in East Africa. Subsequently. At four or five years old. is 27 weeks (Cseke. as some isolated trees do not set fruit (AgroForestryTree Database). The flowering and fruiting seasons vary. neem can produce flowers and fruit. The ripe yellow fruit is sweet. then develops hard green fruits which are bitter to the taste. or even as much as 50 to 100 kg of fruit per year (Cseke. For example. et al. et al. Johnson et al. but only after 10 to 12 years will it produce economically viable seed quantities (AgroForestryTree Database). Neem may be self-incompatible. 2009 . 2006). 10 Copyright by Pamela Paterson. 2006. with its defined dry and wet seasons.About Neem Re p r o d u c t iv e B io l o g y Neem first produces white fragrant blossoms. It is pollinated by insects such as honeybees. the flesh (pericarp) softens and the fruit changes color to yellow. 1996). Copyright by Pamela Paterson. found in the fruit. et al. including insecticides (Koul. 2004). There are over 300 plant secondary compounds (Koul. seeds. and root bark. 2009 11 . and then spray this suspension over plants (Cseke. et al. Extraction and Formulation Indian farmers are known to grind the kernels or leaves and use water to extract the chemicals. the main ingredient in many commercial products. Most of the active compounds are terpenoids. 2006). 2004). stem. Of most prominence and of most commercial use is the tetranortripernoid azadirachtin (a liminoid) in the seed kernels. twigs. et al.Extraction and Formulation Chemical Compounds Neem is chemically rich. Neem oil is yellowish in color. et al. malodorous. Neem Oil Composition Neem oil extract. If needing to be stored for the long term or transported a far distance. ethanol is most often used as the solvent because limonoids are very soluble in alcohols. azadirachtin can be extracted and sold as a concentrate (Cseke. 2006). Some additives such as the antioxidants sesame oil or paraaminobenzoic acid (natural pesticides from Chrysanthemum spp. Neem seeds are about 45% oil (AgroForestryTree Database). These aqueous extracts can then be applied directly to the crop either with or without a wetting agent. 2009 . The seeds are crushed and then soaked in alcohol either at that time or after extracting the oil component with hexane. and has an unpleasant taste due to the sulfur compounds (Barceloux 2008). et al.) protect the liminoids from ultraviolet damage (Cseke. which is the fatty acid-extract of neem tree seeds. and provide the major source of neem 12 Copyright by Pamela Paterson. 2006). is the most widely used product of the neem tree.Chemical Compounds For commercial-scale extraction and concentration of azadirachtin. Azadirachtin chemicals (Cseke, et al. 2006). Should a neem tree produce 50 to 100 kg of fruit it can yield approximately 10 kg of neem oil per year (Cseke, et al. 2006). Neem oil primarily consists of glycerides of oleic and stearic acids, at 50% and 20%, respectively (Gokhale, et al. 2009). Neem oil also contains at least 35 pharmacologically active compounds and a number of other compounds such as flavonoids and sulfur compounds, at varying concentrations (Cseke, et al. 2006; Barceloux 2008). Of these pharmacologically active compounds, the azadirachtins are the most bioactive and popular commercially. In addition to the azadirachtins, the other major liminoids are the salannins and nimbins. Compounds from these groups comprise at least 80% of the neem seed extract by weight (Isman, 1997). Azadirachtin Azadirachtin, found only in Azadirachta sp. (Capinera 2008), is a complex tetranortriterpenoid liminoid from the neem seeds. Of all of the liminoids in neem, azadirachtin and its about 25 natural ana- Copyright by Pamela Paterson, 2009 13 Chemical Compounds logues (Devakumar and Kumar 2008) are the most biologically active. Of these, azadirachtin-A (Aza A) is the most plentiful and biologically active one (Cseke, et al. 2006) and it is generally Aza A that is used for commercial insecticides (Barceloux 2008). Aza A is about 80% of the azadirachtin found in neem, while up to 15% of the azadirachtin may be Aza B (3-tigloylazadirachtol) (Devakumar and Kumar 2008). Figure 4 Azadirachtin A, C35H44O16 (Newfoundland Forestry Service, 2002) 14 Copyright by Pamela Paterson, 2009 Azadirachtin Figure 5 Azadirachtin B, C33H42O14 (Newfoundland Forestry Service, 2002) Neem seeds have 4 to 6 g/kg of azadirachtin, depending on the ecotype of the tree and local conditions (Mordue (Luntz) et al. 2000). Of the triterpenoids isolated from neem, azadirachtin is the most oxygenated, and one of the most polar (Johnson et al. 1996). It has 16 stereogenic centers, 7 of which are quaternary. The water solubility is negligible, at 50 ug/mL, which has been a limiting factor in its use as a biopesticide or in herbal medicine in natural form (Liu et al. 2005). Copyright by Pamela Paterson, 2009 15 Liminoids have as a precursor the 4. it tends toward instability in acids and bases.8-trimethyl-17-furanyl steroid skeleton. and through oxidative degradation four carbons are lost from the side chain. Azadirachtin is believed to be biosynthesized from the steroid precursor tirucallol (Dewick 2001). Until that point. et al. et al. and this consideration must be taken into account when choosing a suitable solvent and developing formulations. as shown in Figure 6. While azadirachtin was first isolated in 1968. each of these subfragments had their own insecticidal effects (Collinge. the two subfragments decalin and hydroxy furan were synthesized. 2008). Its synthesis in the laboratory would elude scientists for 20 subsequent years. Interestingly. its structure was not determined conclusively until 1987 (Ishaaya. 2007).4.Chemical Compounds Because azadirachtin has acid and base sensitive functional groups. 16 Copyright by Pamela Paterson. 2009 . Another factor in its instability is that azadirachtin is UV-labile due to its many double bonds (Free Patents Online). Azadirachtin Figure 6 Two subfragments of azadirachtin: decalin (left) and hydroxy furan (Collinge. et al. Steve Ley and colleagues (40 PhD students over 20 years) finally synthesized azadirachtin in a process involving a Claisen rearrangement for the formation of a C8-C14 bond and radical cycli- Copyright by Pamela Paterson. 2009 17 . 2008) In 2007. 2008). 2007. 2009) 18 Copyright by Pamela Paterson. 2009 . Devakumar and Kumar. Figure 7 Claisen rearrangement in Ley’s synthesis of azadirachtin (Carreira. In the synthesis. decalin was derived from azadirachtin in its natural form (Veitch.Chemical Compounds zation to form the bridged ring system. Refer to Figure 7. et al. which causes ulcerative dermatitis and “significant losses to fisheries and fish culture” (Harikrishnan and Balasundaram. By far. neem has been suggested as an effective infertility agent in controlling populations of rodents. and is known as the Copyright by Pamela Paterson. 2007). It has also been shown to be effective in controlling foodborne pathogens. such as rats (Morovati et al. 2008). et al. the most widespread use of neem has been as an insecticide.Neem as a Pesticide Pesticide Neem as a Pesticide Neem has impressive and far-reaching pesticide properties. 2007). 2009 19 . having been cited as effective against the pathogen Aeromonas hydrophila in goldfish. Recently. Azadirachtin is the predominant biologically active chemical in most insect-based bioassays (Ishaaya. 2008). Neem even has a potential application in the fisheries industry. making it a potential agent against food spoilage bacteria (Hoque et al. and ants). Siphonaptera (fleas). and Thysanoptera (thrips) (AgroForestryTree Database). 2004). Lepidoptera (moths and butterflies). 2007). Heteroptera (true bugs). Dictyoptera (cockroaches and mantids). In fact. even though there are 20 Copyright by Pamela Paterson. Isoptera (termites). postulated because of co-evolutionary origins of the neem tree and locust to Burma (Mordue (Luntz) et al. These antifeedant effects were first discovered in 1952 by Heinrich Schmutterer who found that desert locusts (Schistocerca gregaria. 2000). Forscal) did not eat the neem tree (Koul. S. wasps.Pesticide “most potent insect antifeedant discovered to date” (Ishaaya. with the few exceptions of serious pests such as the scale insect Aonidiella orientalis and the tea mosquito bug Helopeltis antonii. Azadirachtin is active in nearly 550 insect species (Anuradha and Annadurai. Orthoptera (grasshoppers. leaf hoppers. neem has few serious pests. katydids). et al. et al. mostly in orders Coleoptera (beetles and weevils). Homoptera (aphids. 2008). 2009 . Diptera (flies). Neem possesses potency towards insects without having many serious pests of its own. gregaria had a very high sensitivity to azadirachtin. Tapinanthus spp). bark. 2009 21 . Cseke. 2004) TABLE 1. interferes with other chemoreceptors for taste perception. 2000. in which azadirachtin is bioactive. Mordue (Luntz) et al. Some others pests include shoot borers. fungus (Psuedocercospora subsesessilis). Effects on Insects Insects. 2006). mistletoes (Dendrophtoe falcate. Azadirachtin inhibits peristalsis. Microtermes. and leaves. shoots. may be affected in a multitude of ways. et al. inhibits midgut cell replacement. Koul. Effects / Target Primary antifeedancy Target: Mouthpart & other chemoreceptors Secondary antifeedancy Target: Gut Copyright by Pamela Paterson. Summary of Azadirachtin Effects on Insects Mode of Action Azadirachtin activates deterrent cells in chemoreceptors. and bacteria (Pseudomonas azadirachtae) (AgroForestryTree Database. and blocks firing of “sugar” receptor cells that are integral in stimulating feeding.Effects on Insects over 35 known pests that feed on its sap. reduces enzyme production as food moves through gut. These combined effects result in death by anorexia. and reduces feeding. as shown in Table 1: (Anuradha and Annadurai 2008. et al. roots. gregaria testes. the binding of azadirachtin to S. and abnormal and delayed molts.Pesticide TABLE 1. azadirachtin binds to the axoneme (cell cytoskeletal element) of the tails of developing sperm in the testes follicles. Summary of Azadirachtin Effects on Insects Mode of Action Azadirachtin as an ecdysone agonist causes alterations to ecdysteroid and Juvenile Hormone (JH) titers by blocking the release of morphogenetic peptides from the brain. Azadirachtin disrupts the JH titers and ovarian ecdysteroid production. leading to a reduction in the number of viable eggs and live progeny. 2009 . gregaria sperm tails is essentially irreversible. there was “major cytogenetic effects” on spermatogenesis when injected in the 5th instar. causing reduced growth. Effects / Target Insect growth regulation Target: Cuticle Sterility / Reproduction Target: Reproductive organs 22 Copyright by Pamela Paterson. More specifically. increased mortality. In desert locus S. In a dose-dependent manner. Azadirachtin affects the formation of spermatozoa. such as in the wing discs of developing larvae. the primary target of azadirachtin in vivo and in silico is actin. in the Mexican bean beetle. azadirachtin caused “massive tissue degeneration” where there should be active cell division. thus possibly having a useful role in reducing insect resistance. Epilachna varivestis. Protein synthesis inhibition also reduces the levels of detoxification enzymes in insects. Azadirachtin blocks digestive enzyme production in the gut. and testes. which is down-regulated. the fat body. Copyright by Pamela Paterson. Summary of Azadirachtin Effects on Insects Mode of Action Azadirachtin blocks cell division in meiosis and mitosis. Azadirachtin adversely affects rapidly dividing cells and causes cell cycle arrest by not allowing the correct microtubule orientation during spindle assembly in the axonemes. ovary.Effects on Insects TABLE 1. In the fruit fly Drosophila melanogaster (Dipteran). For example. 2009 23 . and inhibits protein synthesis in various tissues. Effects / Target Cellular processes Target: Dividing cells Target: Muscles Target: Cell synthetic machinery Azadirachtin causes a loss of muscle tone. As shown in Table 2. 2000). sanguinipes has no co-evolutionary pattern with neem and therefore has no chemoreceptors that respond negatively to it (Mordue (Luntz) et al. gregaria is very sensitive to azadirachtin and will not feed on it. M. but with antifeedancy there was a tremendous amount of variation depending on insect order and species in the orders (Mordue (Luntz) et al. 24 Copyright by Pamela Paterson. to the insensitive Melanoplus sanguinipes (Fab. 2000).Pesticide Azadirachtin caused toxic insect growth regulatory (IGR) effects in all species tested. Lepidoptera are highly sensitive to azadirachtin. 2009 .) (North American Plains grasshopper). S. 2007). Note that within Orthoptera there is a wide range of sensitivity. et al. from an ED50 of 0. with some species being “behaviorally quite indifferent” to it (Ishaaya.001 to more than 1000 ppm—for example. Sensitivity of Insects to Azadirachtin as Antifeedant ED50 (ppm) < 0. and this could be an issue in particular for areas at high risk for malaria.87 ppm) (Gunasekaran. but even among species within the same order (Mordue (Luntz) et al.001 . et al.500 0. and can be a “very useful” component of an integrated Copyright by Pamela Paterson.> 1000 Order Lepidoptera Coleoptera Hemiptera Hymenoptera Orthoptera Not only does the efficacy of neem vary among orders.500 100 .50 100 . When the concentrated azadirachtin product NeemAzal®-T/S was tested for larvicidal activity on three mosquito species. Aedes aegypti (8.001 . the LC50 results varied tremendously as follows: Anopheles stephensi (1. Nonetheless. Nor is neem as powerful as synthetic agents such as permethrin and DEET (when probing/biting rates on shaved-belly rabbits were counted). 2000). neem by most accounts offers a promising future as a mosquito repellent (Vatandoost and Hanafi-Bojd 2008).Effects on Insects TABLE 2. 2009 25 .92 ppm).500 100 . and Culex quinquefasciatus (15.42 ppm). 2003). and predatory mites. lady beetles. such as spiders. for in the case of Harmonia axyridis Pallas. a beetle which feeds on the North American soybean aphid Aphis glycines Matsumura. 2009 . negligible for bees. Neem has little if any effect on beneficial pests. however. 2008). especially when compared to synthetic insecticides (Gianotti. and high for fish. Figure 8 shows the level of toxicity of azadirachtin insecticidal products—there is none for birds. as well as delayed development (Kraiss and Cullen 2008). axyridis instar survival to adulthood. neem formulations containing azadirachtin reduced H. This is not a universal truth.Pesticide approach against malaria transmission because of its efficacy. et al. and safety. low cost. nor does it affect levels of honey bee pollinations or worker bees (Hall and Menn 1999). Figure 8 Toxicity of azadirachtin insecticidal products (University of Delaware) 26 Copyright by Pamela Paterson. local availability. parasitic wasps. there is no “magic bullet”. 2009 27 . Formulations With respect to the “best” formulation of neem chemicals for a pesticide. the natural proportions of chemicals in neem are generally known to be more effective than azadirachtin alone. deacetylnimbin. Interestingly. it is the least toxic toward humans and does not require any signal word in labelling. nimbin. Copyright by Pamela Paterson. but do require a label of caution (University of Delaware. caution. Adding other neem liminoids—such as nimbandiol. Environmental Protection Agency. warning. azadirachtin used in combination with other herbal compounds provides even better efficacy. Dermal LD50 values are also low. and 6-acetylnimbandiol—to azadirachtin insecticides have been shown to improve efficacy (Hall and Menn 1999). and none).S.Formulations According to the U. deacetylsalannin. its oral LD50 values are so low that out of the four toxicity categories for severities of product labelling (danger. EPA). and in many cases. .)) and leafhopper (jassid) Amrasca biguttulla (Ishida) (Dhingra. cedar oil (Cedrus deodara Roxh). 28 Copyright by Pamela Paterson. for the whitefly (Bemisia tabaci (Genn. and neem oil (Azadirachta indica A. the efficacy increased from 4 to 10 fold for the LC50. the combination of Lawsonia inermis seed powder (Henna). 2009 . when neem oil cakes and karanja (Pongamia glabra) oil cake were used in combination against three mosquito species (Culex quinquefasciatus (say). S. The natural instability of azadirachtin (refer to "Azadirachtin" on page 13) that causes it to need frequent reapplication as an insecticide. et al. as was shown with tetrahydroazadirachtin-A (THA) when it was sprayed on okra crops Abelmoschus esculentus (L. 2008). and 2 to 6 fold for the LC95 over individual applications (Shanmugasundaram. et al. as a molluscide. And. 2008).) Moench. Aedes aegypti (L.) and Anopheles stephensi (L.)). Juss) was more toxic than individual applications of those and several other natural products against Lymnaea acuminate and Indoplanorbis exustus (snails) (Singh and Singh 2001).Pesticide For example. may be solved by synthesizing stable derivatives of azadirachtin. Neemix®-Soydex® was 92%. Copyright by Pamela Paterson. many commercial insecticides are being marketed worldwide. Neemix® has been used in the U. 1999). As with the formulations of neem products. and Neemix®-Joint Venture® was 91% (Hall and Menn 1999). for food crops (Hall and Menn. Against first instar nymphs Trialeurodes vaporariorum (greenhouse whitefly) on tomato. Since 1993. 2009 29 .Formulations It has also been suggested that the use of adjuvants would increase the effectiveness of neem-based insecticides. results among adjuvants vary. Despite the considerations involved in azadirachtin and other neem chemicals. Neemix® solutions in combination with adjuvants that contained vegetable or mineral oil (Joint Venture® and Soydex®) facilitated the highest mortality. The mortality for Neemix® alone was 33%. Neemix® and Bioneem® were comparable in efficacy to organophosphate pesticides (Watson and Preedy 2008). it has limited motility from leaf to leaf—adjuvants increase the motility. Although azadirachtin will move across the leaf cuticle.S. and can harm beneficial pests. 30 Copyright by Pamela Paterson. Considering that organic synthetic insecticides are more dangerous. 2009 . are not readily biodegradable (Peshin and Dhawan 2009).Pesticide Since neem does not kill adult insects. leave toxic residues in food. neem offers a sound alternative in these respects. neem-based insecticides tend to be used with other strategies like adulticides (to kill adult insects) or beneficial pests (Hall and Menn 1999). and in particular. 2009 31 . leaves (Subapriya et al. Copyright by Pamela Paterson. roots.000 years (Reutemann 2008). 2005) to treat more than 100 diseases (Neem Foundation). seeds. In traditional medicine. bark. fruits.Formulations Human Medicine Neem has been used as a medicinal agent for more than 2. all parts of the neem tree are used—flowers. the modes of action for neem chemicals in human medicinal applications are not as well understood nor described in published studies.Human Medicine Even in Western medicine. Subapriya et al. and includes (AgroForestryTree Database. Boeke et al. Talwar et al. 2004. 1997. Liu et al. Unlike the modes of action for pesticide applications. 2006. the list of reported medicinal benefits in published studies is extensive. Medicinal Applications of Neem antimalarial antimicrobial antimutagenic antioxidant antiparasitic antiperiodic antiperiodontic antipurgative antirheumatic antiseptic antituberculosis antiulcer antiviral antiworm boils blood detoxifier diuretic eye diseases immunomodulatory pimples skin diseases spermicidal abortifacient antibacterial anticarcinogenic anticlotting antifertility antifungal antihepatic antihyperglycemic anti-inflammatory anti-implantation antileprosy Despite this evidence. The information that 32 Copyright by Pamela Paterson. 2009 . et al. 2005. 2005): TABLE 3. Cseke. to date no neem-based health products have been approved for internal use in the United States. cancer may result. The triterpenoid nimbolide showed antigrowth activity of moderate to very strong in human colon carcinoma HT-29 cells (Roy et al.Cancer follows reflects these deficiencies. The protein-folding machinery of Hsp90 is responsible for folding client proteins into their biologically active form. • Another neem tetranortriterpenoid. and the proteins chaperoned by Hsp90 are called client proteins. Hsp90 is becoming a leading therapeutic target of interest in cancer research. and breast. 2006). It is known as a chaperone protein. possesses anticancer properties as an Hsp90 (heat shock protein 90) inhibitor. When mutations or abnormal expression of these client proteins occur. colon. and is presented primarily to illustrate the voluminous amount of research conducted about neem chemicals and their potential use in Western medicine. Cancer A number of neem chemicals have been shown to be active in several cancer studies. 2006). including prostate. 2009 33 . • Neem extract induces apoptosis of prostate cancer cells (PC-3) (Kumar et al. gedunin. As Copyright by Pamela Paterson. Human Medicine Hsp90 maintains the function of these cancer promoting. it is a worthy target to inhibit because it results in apoptosis in the cells of these client proteins. • A neem leaf preparation (NLP) was also shown to induce apoptosis in tumor cells—not directly. 2009 . 2008. performed the best (Brandt et al. Gedunin does not bind competitively versus ATP. or oncogenic. The antibodies produced by BTAANLP immunization induced cytotoxicity in MCF-7 cells (human breast adenocarcinoma cell line) that expressed BTAA. The natural gedunin. 2007). BTAA by itself is not very immunogenic. The proteins are degraded and tumor progression is inhibited. Infinity Pharmaceuticals). client proteins. so potentially the future may yield 34 Copyright by Pamela Paterson. which in turn caused anti-proliferative activity in tumor cells as well as induced apoptosis via the release of cytotoxic cytokines (Bose et al. but its exact mechanism of action is unknown. but through stimulating human peripheral blood mononuclear cells (PBMC). NLP was shown to enhance the breast tumor associated antigen (BTAA). • In mice and rats. as opposed to the 19 semisynthetic derivatives of gedunin. 2 micromolar of nimbolide.Pregnancy and Contraception an NLP-enhanced BTAA vaccine. Praneem (licensed to Panacea Biotec. thus making it potentially useful in anticancer therapy (Roy et al. 2007). Survival data of the mice and rats was not reported. and B16 (mouse melanoma). THP1 (human acute monocytic leukemia). It is not known which compounds in NLP are responsible for the activity (Mandal-Ghosh et al. Pregnancy and Contraception While there are no neem pregnancy and contraception products available in the United States. Nimbolide at varying doses caused cell cycle disruption and significantly damaged DNA profiles. HL-60 (human promyelocytic leukemia). India) is a poly- Copyright by Pamela Paterson. 2007). in India one product is currently in clinical trials. Apoptosis resulted with “remarkable lethality” for 60% of cells at 1. 2009 35 . • The triterpenoid nimbolide from neem flowers was shown to restrict cancer cell proliferation in cancer cell lines U937 (human leukemic monocyte lymphoma). 2009 . Despite these positive results. In vitro. 1994). Garg et al. 2008. 1996). without any permanent effects. it does not appear that any such product is yet available commercially. 36 Copyright by Pamela Paterson. Because it is selective and does not damage normal cells. Other studies also reported that neem has pregnancy and contraceptive properties: • Neem oil has antifertility. and abortifacient properties. Fraction isolated from neem oil. anti-implantation. • Neem and seed extracts administered orally at the beginning of the post-implantation stage resulted in pregnancy termination in rodents and primates. NIM-76 selectively kills all human sperm in less than 20 seconds at a concentration of 25 mg/mL. and was an effective vaginal contraceptive. The mechanism of action is not fully understood (Talwar et al. had spermicidal properties without the abortifacient properties. NIM-76.Human Medicine herbal vaginal tablet that has proven to be effective in immobilizing sperm (Joshi et al. NIM-76 is said to be a “highly desirable potential vaginal contraceptive agent” (Sharma et al. 1997). 2009 37 . even after only 10 minutes of exposure time. • A new formulation of neem shampoo (identified as Type AP30) has proven to be “highly effective against all stages of head lice” for 66 children (4-15 years old) with significant head lice infestations. only a second retreatment was needed for most children to remain lice-free. neem was used to treat scabies in 814 people—97% of them were cured within 3 to 15 days of application. The percentages of effectiveness ranged from 86% to 97% after a single application of the shampoo. except for a couple living in squalor conditions and one with very fatty hair. Copyright by Pamela Paterson. No adverse effects were observed (Abdel-Ghaffar and Semmler 2007).Skin Disorders Skin Disorders Neem can treat many skin disorders. including scabies and lice: • In a paste combination with Curcuma longa (turmeric). and no adverse reactions were observed (Charles and Charles 1992). primary dental caries) (Vanka et al. • When saliva-conditioned hydroxyapatite (a bone salt that strengthens the matrix of teeth and bone) was pre-treated with neem extract (from bark sticks) there was major inhibition in some Streptococcus colonization on tooth surfaces (Wolinsky et al. Streptococcus mitis. As mango is also known to inhibit other microorganisms that cause dental caries (Streptococcus mutans. 38 Copyright by Pamela Paterson. 1996). 2007). 2009 . neem inhibited Streptococcus mutans (bacterium causing tooth decay) and reversed incipient carious lesions (that is.Human Medicine Dental and Oral Care Neem also has benefits in dental and oral care by inhibiting bacteria that causes tooth decay: • In preliminary findings. 2001). and Streptococcus sanguis). chewing both mango and neem tree sticks would provide even further benefit (Prashant et al. Streptococcus salivarius. the number of HIV/AIDS pathologies decreased from the 120 baseline to 5.HIV/AIDS • A neem-extract dental gel significantly reduced plaque and bacteria (Streptococcus mutans and Lactobacilli species were tested) over the control group that used commercially available mouthwash containing the germicide chlorhexidine gluconate (0. IRAB is recommended as part of an HIV/AIDS drug treatment program (Mbah et al. 2004). 2007). hemoglobin concentration (24%). and lymphocyte differential count (24%). a 12-week oral administration of acetonewater neem leaf extract (IRAB) had a “significant” influence in vivo on CD4 cells (which HIV reduces) without any adverse effects in the patients. 50 were completely laboratory-test compliant. which is a major increase. Of the 60 patients who completed treatment. Copyright by Pamela Paterson. and significant increases were experienced in body weight (12%). HIV/AIDS In HIV/AIDS patients. 2009 39 . The mean levels of CD4 cells increased by 159% in 50 patients.2% w/v) (Pai et al. or a tulsi-neem leaf powder mixture. Reduction of Diabetic Symptoms Group 2 Neem 32% 40% 44% 16% 33% Group 3 Tulsi-Neem 27% 20% 29% 17% 40% Highest %a N N N T TN Symptom Polyuria Sweating Burning feet Itching Polydypsia Group 1 Tulsi 19% 33% 43% 20% 35% 40 Copyright by Pamela Paterson. 2009 . tulsi alone provided the most significant reduction only for itching. polyphagia. polyphagia (excessive hunger) and fatigue. and burning feet. and less commonly sweating. The tulsi-neem combination provided the most relief for polydypsia. Neem provided the most relief for polyuria. and headaches. 2009): TABLE 4. polyuria (increased frequency of urination). itching. fatigue. burning feet. As shown in Table 4. Ninety participants in three groups were given tulsi (Ocimum sanctum). Diabetic symptoms were significantly reduced in all groups—commonly polydypsia (excessive thirst). and headaches (Kochhar. sweating.Human Medicine Diabetes Neem reduced diabetic symptoms in non-insulin dependent diabetics. et al. neem leaf powder. Reduction of Diabetic Symptoms Group 2 Neem 35% 18% 38% Group 3 Tulsi-Neem 40% 25% 40% Highest %a TN TN TN Symptom Polyphagia Fatigue Headaches Group 1 Tulsi 21% 13% 27% a. 2009 41 . 2005).6% for flower. 2009). T=tulsi. and TN=tulsi-neem mixture Overall.0% and 50. while the tulsi-neem mixture provided the most relief for diabetic symptoms. malondialdehyde (MDA). et al. respectively. N=neem. An indicator of oxidative stress. neem alone was also very effective. prompting the recommendation to use neem as a vegetable bitter tonic to promote good health (Sithisarn et al. It was recommended that tulsi and neem leaves be ingested by diabetic patients to reduce symptoms (Kochhar. Antioxidant Extracts from young flowers and leaves have strong antioxidant potential. was reduced by 46. Copyright by Pamela Paterson.and leaf-based extracts.Antioxidant TABLE 4. recurrent generalized seizures (that may lead to coma or cardio-pulmonary arrest (Barceloux 2008)). the duodenal ulcers were nearly fully healed.Human Medicine Ulcers Neem bark extract reduced human gastric acid hypersecretion. tachypnea (abnormally fast breathing). 2004). and gastroesophageal and gastroduodenal ulcers. The symptoms of poisoning are vomiting. Toxicity values of azadirachtin insecticidal products in Figure 8 on page 26 more or less support this assertion. especially in infants and young children. can cause toxic encephalopathy. 2009 . As with any bioactive compound. drowsiness. leucocytosis. Safety and Toxicity The Neem Foundation reports that neem does not have any negative health effects for humans because it is gentle. azadirachtin still needs to be treated with care because poisonings have been reported. Margosa oil. and meta- 42 Copyright by Pamela Paterson. After 10 weeks. after 6 weeks one case of esophageal ulcer and gastric ulcer were fully healed (Bandyopadhyay et al. which is a neem seed extract. more peroxisomes. In a case involving an adult. but recovered within a week in the hospital (Barceloux 2008). fatty metamorphosis of liver. Neem oil is not approved by FDA for internal human use. 1990). she became ill with ventricular fibrillation and cardiac arrest. but an estimated safe daily dose of azadirachtin is 15 mg/kg body weight (Barceloux 2008). post-mortem autopsies of children who died after ingesting margosa oil showed swelling of hepatocytes. 2009 43 . Copyright by Pamela Paterson. Fatalities and neurological deficits occur but are not common (Lai et al. depletion of glycogen. and significantly more smooth endoplasmic reticulum (indicating increased detoxification activity) (Barceloux 2008).Safety and Toxicity bolic acidosis. Treatment is primarily supportive and directed toward controlling convulsions. a woman who drank 1L of neem leaf extract. In addition. mitochondrial pyknosis (cell degeneration). et al. 2009 .Conclusion Conclusion Unquestionably. market. has tremendous potential. the barriers to neem becoming produced widespread commercially 44 Copyright by Pamela Paterson. and have only since the early 1990s been approved for pesticide use (Ishaaya.000-yearold track record in traditional usage (Reutemann 2008). and a plethora of health products on the Internet including neem oil promoted as both a female and male contraceptive (Neem Products). 2007). 2007). Even after several pesticide products on the U. neem from natural sources has failed to be used as a good lead in the production of synthetic insecticides at this point (Ishaaya. neembased products have not reached the consumer shelves in the United States for any internal medicinal applications. Despite a 2. In the past. It has outstanding pesticide properties and in many human medicinal studies. et al. neem is a useful and beneficial plant in a number of ways.S. absence of standardization for formulated products). To further illustrate this point. 1997). standardization and quality control (neem kernels without known azadirachtin content. comparing neem-based insecticides is “difficult. and formulation adjuvants. The products were registered based on the azadirachtin content. and registration issues (regulatory approval for the compound mixtures in neem extracts and cost) (Isman. if not impossible” (Hall and Menn 1999). formulation solvents. As a result of India’s efforts.Safety and Toxicity included limited supply of the natural resource. there is an increasing number of companies registering neem insecticides in many parts of the world (Hall and Menn 1999). such as differences in oil quality. acute toxicity and chemical testing were required for all products. In 1993. the government of India created a registration process for neem-based insecticides to correct quality issues. because of the varying extraction processes. In addition. The same obstructions have been encountered when comparing neem studies for the purposes of this paper. 2009 45 . Copyright by Pamela Paterson. it would conceivably be problematic to formulate an insecticide that knowingly does otherwise. Boosting formulations with such compounds as cyclodextrins increases the water solubility of azadirachtin. depending on the cyclodextrin. The water solubility of azadirachtin is negligible.Conclusion Even with standardized oil content. at 50 ug/mL. meaning that the efficacy of neem varies even among basic species of mosquitos. and show promise as indicated through related patents (Liu et al. training and education would need to be a component of the integrated management approach to pests so that users know the best method and timing of applications. Strategies such as these are useful in future formulations. from a range of 1. has been a limiting factor in its use as a biopesticide or in herbal medicine. partly because of the “temperamental” nature of the insect targeting. When other natural compounds in combination with neem compounds have boosted the insecticide efficacy significantly. 2005). 2009 . since azadirachtin biodegrades quickly by sunlight (Capinera 2008). 46 Copyright by Pamela Paterson. In addition.5 mg/mL. effective formulations are complex to develop.3 to 3. There is said to be over 90 patents issued worldwide (Benny 2005) to companies for inventions of products from neem. et al. 1997). Traditional users of neem claim that some of these patents are invalid—they have been known in traditional medicine for 2000 years (Cseke. registering a new active ingredient can start at more than $250. In 2000. not uncommon to new applications of bio products. The relatively low market share of botanical pesticides versus the multimillion dollar regulatory costs causes an insurmountable hurdle for many botanical pesticides to reach the commercial market. citing that it was already in use in India in a traditional way (Benny 2005). 2006). Supporters of botanical pesticides suggest that the registration requirement needs to be modified for environmentally safe botanical pesticides (Isman.Safety and Toxicity And.000 and possibly exceed $2 million. In the United States. 2009 47 . botanicals tend to be complex mixtures (unlike synthetic chemicals). Copyright by Pamela Paterson. Grace for a neem tree fungicide. Moreover. Yet another hurdle is the waned interest in natural insecticides compared to genetically modified plants (Rai and Carpinella 2006).R. the European Patent Office revoked a patent from USDA and W. making the registration process even more difficult. there are patent issues. 48 Copyright by Pamela Paterson.Conclusion The place of neem in traditional medicine has been established for centuries. Despite this impressive history. 2009 . and markers point in a positive direction for its future in terms of proven applications and increased acceptance by the scientific community. Neem is the wonder tree it is purported to be. it has many hurdles yet to overcome to gain widespread acceptance in Western society for its medicinal applications. Copyright by Pamela Paterson. Sarkar D. Alink GM. 2008. Rietjens IM.Safety and Toxicity Bibliography Abdel-Ghaffar F. J Ethnopharmacol. 95(11). John Wiley & Sons. Annadurai RS. 2009. 2004. Debnath P. 2007. Benny J. Inc. D. van Huis A. 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