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Neem oil, extracted from the seeds of Azadirachta indica (family Meliaceae), is renowned for its wide range of bioactivities, including insecticidal, antibacterial, antifungal, antiviral, antioxidant, and anti-inflammatory properties. However, its poor water solubility, susceptibility to oxidation, and instability under light and temperature restrict its direct use in pharmaceutical, agricultural, and cosmetic applications. Nanoemulsion technology has emerged as an effective strategy to overcome these challenges by encapsulating neem oil within nanosized droplets (typically 20?200 nm), thereby enhancing its solubility, bioavailability, stability, and controlled release. Neem oil Nanoemulsion (NEs) are generally prepared using high-energy (ultrasonication, high-pressure homogenization) or low-energy (phase inversion, spontaneous emulsification) methods with biocompatible surfactants and co-surfactants. Numerous studies have reported improved larvicidal, pesticidal, and antimicrobial activities of neem oil NEs compared to bulk formulations, owing to increased surface area, better wetting, and deeper penetration into biological membranes. Furthermore, recent advances focus on green surfactants, solid nanoemulsion gels, and polymer-based delivery systems for sustained efficacy and reduced toxicity. This review critically discusses the formulation strategies, characterization techniques, biological applications, and future prospects of neem oil nanoemulsions, highlighting their potential as eco-friendly and multifunctional nanocarriers for sustainable agriculture and biomedicine.
Keywords
Neem oil; Azadirachta indica; Nanoemulsion; Green nanotechnology; Biopesticide; Antimicrobial; Larvicidal activity; Drug delivery; Stability; Controlled release
Introduction
Neem oil contains several bioactive compounds — the most-studied being azadirachtin, nimbin, salannin and other limonoids — that exhibit insect growth regulatory, repellent and antimicrobial effects. However, neem oil is hydrophobic, prone to oxidation and photodegradation, and difficult to apply uniformly in aqueous environments1. Converting neem oil into oil-in-water nanoemulsions (droplet diameters typically <200 nm for many NEs; some reports show ~30–100 nm) overcomes these limitations by increasing surface area, improving spreading/wetting on target surfaces and enhancing penetration and bioavailability of active constituents2. Several studies and reviews have reported markedly improved larvicidal, antimicrobial and pesticidal performance for neem oil nanoemulsions compared to bulk oil preparations 3 Neem (Azadirachta indica A. Juss.), belonging to the family Meliaceae, is one of the most valuable medicinal plants native to the Indian subcontinent. It has been referred to as the “Village Pharmacy” due to its wide range of therapeutic and agricultural applications. Every part of the neem tree—leaves, seeds, bark, flowers, fruits, and roots—contains bioactive compounds with potent antibacterial, antifungal, antiviral, anti-inflammatory, antioxidant, and insecticidal properties4.
Reference
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→ Comprehensive review on neem’s pharmacological properties and traditional uses.
Schmutterer, H. (1995). The Neem Tree: Source of Unique Natural Products for Integrated Pest Management, Medicine, Industry, and Other Purposes. VCH Publishers, Germany.
→ Classic reference on neem’s botanical characteristics and pesticidal activity.
Subapriya, R., & Nagini, S. (2005). Medicinal properties of neem leaves: A review. Current Medicinal Chemistry – Anti-Cancer Agents, 5(2), 149–156.
→ Details on bioactive compounds (azadirachtin, nimbin, salannin) and their pharmacological roles.
Koul, O., Isman, M.B., & Ketkar, C.M. (1990). Properties and uses of neem, Azadirachta indica. Canadian Journal of Botany, 68(1), 1–11.
→ Describes neem phytochemistry and insecticidal mechanisms.
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→ Discusses neem oil composition, applications, and toxicology.
Ghosh, V., Mukherjee, A., & Chandrasekaran, N. (2013). Neem (Azadirachta indica) seed oil nanoemulsion: a potent larvicidal agent against Culex quinquefasciatus. Pest Management Science, 69(8), 1017–1023.
→ Reports enhanced larvicidal activity of neem oil nanoemulsion compared to bulk oil.
→ Fundamental reference on nanoemulsion principles and droplet size range (20–200 nm).
Kumar, A., et al. (2021). Formulation and evaluation of neem oil-based nanoemulsion for enhanced antimicrobial and larvicidal efficacy. Journal of Drug Delivery Science and Technology, 63, 102512.
→ Confirms improved stability and biological efficiency of neem oil in nanoemulsion form.
Sujarwo, W., Keim, A.P., Caneva, G., Toniolo, C., & Nicoletti, M. (2016). Ethnobotanical uses of neem (Azadirachta indica A. Juss.; Meliaceae) in Bali (Indonesia): the tree of 100 uses. Journal of Ethnobiology and Ethnomedicine, 12(1), 12.
→ Covers traditional medicinal and cultural uses of neem.
Okoh, S.O., Asekun, O.T., Familoni, O.B., & Afolayan, A.J. (2016). Composition and antioxidant activities of leaf and seed essential oils of Azadirachta indica (A. Juss). International Journal of Molecular Sciences, 17(3), 441.
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BiomedRes (2022). Toxicity Evaluation of Two Neem Oil Nano-Formulations Using Mice. Biomedres
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Agriscigroup (2025). Effect of Neem Oil-based Nano-emulsion Application on Nematodes. IJASFT. agriscigroup.us
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“Olio di neem – Italian Wikipedia entry (traditional uses)” (2023) – provides background on traditional uses. it.wikipedia.org
“Neem oil – Wikipedia” (2023) – general overview. en.wikipedia.org
“Nimbin (chemical) – Wikipedia” (2023) – details on one of the limonoids. en.wikipedia.org
“Azadirachtin – Wikipedia” (2023) – insecticidal active limonoid. en.wikipedia.org
Rinaldi F., et al. (2022) – again for antioxidant nanoemulsion work. (duplicate reference but supports multiple parts) PMC
“Green Micro- and Nanoemulsions for Managing Parasites, Vectors and Pests” (2023) – review on nanoemulsions in pest/vector management.