Department of Pharmacognosy, Jayawantrao Sawant College of Pharmacy and Research, Hadapsar, Pune.
Herbal drugs, also known as botanical drugs or phytomedicines, utilize various plant parts such as seeds, berries, roots, leaves, wood, and flowers for medicinal and remedial purposes. These herbal formulations are commonly used for treating chronic conditions like cancer, diabetes, and asthma, and are recognized for their supplementary, nutritive, and cosmetic benefits. Mosquitoes, including species such as Anopheles, Aedes, and Culex, are vectors for several serious diseases, including malaria, dengue fever, and encephalitis. The rising prevalence of mosquito-borne diseases, with over one million reported cases by 2018, underscores the urgency of effective mosquito control. While synthetic chemical repellents are widely used to prevent mosquito bites, their hazardous chemical components pose significant health risks to humans and the environment. As an alternative, herbal-based repellents, such as those derived from Vitex nigundo (Nirgundi), have demonstrated efficacy in repelling mosquitoes and reducing reliance on harmful chemicals. This review explores the potential of herbal medicines, particularly Vitex nigundo, in mosquito repellent formulations and their role in integrated vector control strategies, emphasizing their safety and effectiveness in comparison to conventional chemical repellents.
Herbal drug, also called as botanical drug or phytomedicine, refers to the use of tree parts similar as seeds, berries, roots, leaves, wood or flower for medicinal and remedial purposes [1,2]. Herbal medicine is a medicine intended to be used for complaint treatment, forestalment, safety of humans in the day-to-day life. Frequently the use of herbal drugs is more current in cases with habitual conditions similar as cancer, diabetes, asthma. Herbal phrasings are lozenge form conforming of specified one or further sauces or do condiment in specified amounts to give specific supplementary, nutritive, cosmetics benefits [3].
Mosquito are one of the most disturbing and blood stinking organisms that disturbs Homo sapiens [4] Mosquito species included in the rubrics Anopheles, Aedes and Culex are vectors for the colourful complaint pathogens like malaria, dengue fever, myiasis, unheroic fever, encephalitis etc. The rate increased to one million as of 2018, according to the American Association of Mosquito control. High fever and chills are its symptoms. [5,6,7] A mosquito repellent is a substance applied to skin, apparel, or other surfaces which repels mosquitoes from landing on that surface. It’s a substance that’s synthesized in such a manner so that it makes the surface unwelcome and monstrous to mosquitoes so as to reduce the mortal mosquito contact. Mosquito repellents repel insects but don’t kill them. Thus, they aren’t technically germicides nor fungicides. [8] We now that mosquitoes are veritably dangerous and the commercially available mosquito repellents contain certain dangerous chemical constituents, which are potent carcinogens and are extremely dangerous for the humans and terrain as well. Herb-based metabolites have been shown to be an effective mosquito control volition to synthetic germicides or when used in confluence with other fungicides as part of an integrated vector control strategy [9]. Vitex nigundo (Nirgundi) is one of veritably useful herb in Indian System of medicine. [10] In southern India, leaves of Vitex negundo are burned to repel mosquitoes from houses. [11]
Insect repellent:
An insect repellent is a chemical or natural substance that makes the area within 4 centimetres of human skin unpleasant for insects, thereby discouraging them from coming into contact with or biting the person. [12] There are three primary reasons to use insect repellents: 1) the emergence of new threats to human health from arthropod-borne infectious diseases, including those introduced from other regions; 2) the rise of new, effective insect vectors that spread diseases; and 3) the lack of vaccines to prevent most arthropod-borne diseases, with exceptions like the yellow fever vaccine in South America and Africa, the Japanese encephalitis vaccine in Southeast Asia, and some regional tick-borne virus vaccines in Eastern Europe. The first chemical insect repellents were dialkyl phthalates (dibutyl and dimethyl phthalate), discovered in 1929; indalone, introduced in 1937; and Rutgers 612, introduced in 1939. [13] Today, DEET is available globally in various forms, including aerosols, creams, lotions, sprays, gels, sticks, and wipes, with concentrations ranging from 5% to 100%. Most products contain DEET concentrations between 30% and 40%, and research shows that the insect-repellent effect plateaus once the DEET concentration exceeds 50%. [14] Early plant-based insect repellents included smoke from burning tar or cooking fires, as well as various plants and flowers like chrysanthemum, geranium, and lantana. These were hung around homes, porches, or rubbed on the skin. Plant oils, such as citronella, clove, geranium, mint, nutmeg, pennyroyal, and soybean, also repelled insects for short periods, but their high volatility limited their effectiveness when burned or applied topically. [15] With few exceptions, there are no vaccines to prevent mosquito- and tick-borne diseases. Therefore, the primary ways to prevent disease transmission are through arthropod avoidance, insect repellents, and insecticides. The most effective approach is to use a combination of topical insect repellents like DEET or picaridin with clothing treated with synthetic pyrethroids, which act as insecticides. This combination offers better and longer-lasting protection against mosquitoes and ticks. In cases of exposure to ticks, biting midges, sandflies, or blackflies, repellents containing IR3535, picaridin, or PMD provide better protection than DEET alone.
Types of repellent:
Mosquito repellents are classified in different ways. Based on their origin, they can be either chemical or herbal repellents. They can also be categorized by their mode of action. Repellent insecticides are designed to repel insects and pests without killing them. On the other hand, contact insecticides are chemicals that contain neurotoxins, which affect the nervous systems of mosquitoes and insects, causing them to lose consciousness upon contact. [16]
Need of Herbal mosquito repellent:
Although DEET-containing products are widely used, studies by researchers like Tenenbein and data from poison control centers have identified only a small number of cases involving dermatitis, allergic reactions, and neurological and cardiovascular toxicities, such as seizures, following the application, ingestion, or excessive use of DEET on both children and adults.[18,19,20] Other reported health issues include encephalopathy, tremors, slurred speech, behavioural changes, coma, and in some cases, death.[18,21,22]
Figure. 3: Types of Mosquito repellents [17]
Plant based repellent:
Natural products have proven to be a valuable source of therapeutic molecules, offering greater structural diversity on a larger scale than synthetic compounds. Historically, they have been important for discovering bioactive substances and will continue to play a significant role in the development of new medications. [23] For generations, plant-based repellents have been used as a protective strategy against various Anopheles species in traditional practices. This knowledge of traditional plant repellents is a valuable resource for developing new natural alternatives to chemical repellents. Research from around the world has shown that plant extracts and essential oils are effective in repelling malaria vectors. The aim of this systematic review was to assess the efficacy of plant-based insect repellents against Anopheles mosquitoes. Essential oils and extracts from some plants could be used to create environmentally friendly repellents for Anopheles species. Plant oils, which are relatively safe, affordable, and widely accessible in many parts of the world, could eventually provide viable alternatives to synthetic repellents. [24] Essential oils from plants such as lavender, camphor, catnip, geranium, jasmine, broad-leaved eucalyptus, orange, lemongrass, lemon-scented eucalyptus, amyris, narrow-leaved eucalyptus, carotin, cedarwood, chamomile, cinnamon, juniper, cajeput, soybean, rosemary, niaouli, and olive have shown promising repellent properties.
Advantages of herbal mosquito repellent: [25]
Characteristics of herbal mosquito repellent: [26]
Benefits of herbal mosquito repellent: [27]
One of the main advantages of using a natural mosquito repellent is that it contains no harmful chemicals. Unlike synthetic repellents that have DEET (N, N-Diethyl-3-methyl benzamide), a common chemical, natural options are safe and can be used in spaces like your child's room without concern.
Using essential oils as a herbal mosquito repellent is beneficial for your skin. Not only will it keep mosquitoes and other insects away, but it will also nourish and care for your skin. In contrast, many commercial repellents can cause skin allergies or respiratory issues.
Purchasing an herbal mosquito repellent shows your compassion for animals, as these products are produced without harming any animals. They are entirely vegan and cruelty-free.
Natural mosquito repellents are not only cruelty-free but also environmentally friendly. They do not emit harmful smoke or carbon that could negatively impact the greenhouse effect, helping protect our planet.
A great benefit of herbal mosquito repellents is that they can also serve as room fresheners. Many of the recommended remedies not only keep mosquitoes away but also add a pleasant fragrance to your home.
In addition to mosquitoes, herbal repellents can help keep other pests like ants, flies, spiders, and even lizards at bay. Essentially, a natural mosquito repellent works as an all-purpose insect repellent for your home.
One of the key benefits of using a natural mosquito killer in your home is the peace of mind it provides. Since it is free from chemicals, you can be confident that it won’t harm you. Additionally, it leaves behind a pleasant scent and is environmentally friendly. All of these benefits contribute to a sense of relaxation when using a herbal solution to keep mosquitoes at bay.
Opting for a natural mosquito repellent ensures that your children are safe from harmful chemicals. Many commercial repellents contain DEET, which can negatively impact the respiratory health of young children.
Similarly, using organic mosquito repellents is safe for pregnant women. Exposure to toxic chemicals found in some conventional mosquito repellents could lead to respiratory issues or birth defects in the foetus.
A significant advantage of natural mosquito control methods is that most of the necessary ingredients are easily found at home. These remedies are not only accessible but also far more affordable than expensive commercial mosquito products.
Vitex negundo
Vitex negundo, commonly known as "nirgundi," is a herb native to India and belongs to the Verbenaceae family. The term "nirgundi" in Sanskrit refers to any plant or substance that protects the body from illness. The Nirgundi plant is a large, aromatic shrub that can reach a height of 4.5–5.5 meters, or occasionally a smaller, slender tree. It features quadrangular, densely white-tomentose branchlets with thin, gray-yellow bark, and 3–5 leaflets. The lanceolate leaflets are 5–10 × 1.6–2.3 cm in size, with one smaller lateral leaflet, and all are nearly glabrous. The leaves are green on the upper surface and silvery on the underside. The bluish-purple flowers turn black when ripe, while the plant’s cylindrical, long, woody roots appear tortuous and grey-brown. Nigundi oil, an aromatic volatile oil, is extracted from the leaves of the Vitex negundo plant, also called the three- or five-leaf chaste tree. Castor oil, known as "Erande" in some regions, is a vegetable oil obtained by pressing the seeds of Ricinus communis. Vitex negundo Linn. essential oil is used for treating various ailments such as rheumatoid arthritis, gonorrhoea, bronchitis, leukoderma, eye diseases, toothache, inflammation, and skin ulcers. Additionally, it serves as a tonic, emmenagogue, lactagogue, vermifuge, antimicrobial, antipyretic, and antihistaminic. [28] The essential oil yield from 200 grams of dried powder of Vitex negundo is 0.35%, while from 200 grams of dried powder of Lantana camara it is 0.50%. Essential oils have been utilized by humans since ancient times for various therapeutic purposes, both externally and internally. They are documented in pharmacopoeias, traditional medicine systems, and folk medicine. These oils are known for their therapeutic actions, such as acting as local stimulants, carminatives, diuretics, mild antiseptics, and local irritants. In addition to medicinal uses, they are employed as spices, flavoring agents, in confections, beverages, pharmaceuticals, cosmetics, and the perfumery industry. Historically, essential oils have been used to treat infections and diseases worldwide for centuries. Essential oils from different plant species exhibit ovicidal, larvicidal, and repellent properties against various insect species and are considered environmentally friendly pesticides. Volatile compounds, particularly essential oils, have been shown to possess strong antifungal, antibacterial, insecticidal, and nematocidal properties. [29]
Varied uses of Vitex negundo
Vitex negundo has a wide range of uses. It serves as a hedge, ornamental plant, growth enhancer in agriculture, manure, pesticide, medicine, food, food preservative, household insect repellent, and plays a role in wasteland reclamation and erosion control. Additionally, it is used in basketry, witchcraft, totems, water divination, and for constructing grain storage structures. Dry leaf powder, either alone or combined with dhoop smoke, is effective in repelling mosquitoes. [30]
Nirgundi has a pungent, bitter, and astringent taste, with a hot post-digestive effect and a hot potency. It helps balance vata and kapha doshas, but aggravates pitta dosha. The plant has light and dry characteristics. For an insecticide to be effective according to Ayurveda, it must possess specific properties. Plants with pungent (katu), bitter (teekta), and astringent (kasaya) tastes; katu in vipaka (transformed taste), ushna (hot) in veerya; penetrating (teeksna) quality; and hot potency are antagonistic to the kapha dosha and have insecticidal and anti-worm effects [31]. All parts of the Vitex plant, from root to fruit, contain a variety of phytochemical secondary metabolites, which give the plant a broad range of medicinal applications. It is noteworthy that a single plant species is used in traditional and folk medicine to treat a wide array of health conditions, some of which have been experimentally confirmed. Therefore, Vitex is highly regarded as a versatile medicinal plant and is often referred to in Indian tradition as "sarvaroganivarini" – the cure for all ailments. [32]
Plant Profile:
Taxonomic Classification
Kingdom-Plantae
Subkingdom-Tracheobionta
Super Division-Spermatophyta
Division-Magnoliophyta
Class-Magnoliopsida
Sub Class-Asteridae
Order-Lamiales
Family-Verbenaceae
Genus-Vitex
Species-negundo
Chemical Constituents:
Flavonoids, volatile oil, triterpenes, diterpenes, sesquiterpenes, lignan, flavones, glycosides, iridoid glycosides, and stilbene derivatives are only a few of the numerous chemical components found in plants. Every portion of the plant has these chemical components.
Parts used: root, leaves, flowers, fruits, bark.
Figure no. 1 Nirgundi leaves
Figure no. 2 Nirgundi Plant
Pharmacological Actions Of Nirgundi: [33,34,35]
The herbal plant Vitex negundo Linn. Shows the following pharmacological actions:
1. Anti-inflammatory
2. Immuno stimulant
3. Mosquito repellent activity
4. Anti convulsant
5. Anti-oxidant
6. Antibacterial
7. Anti-fungal
8. Anti-diabetic
9. Anti-arthritic
10. Anti-allergic
11. Hepato protective
12. Analgesic
13. Anti-hyperpigmentation
14. Anti-androgenic
15. Insecticidal and pesticidal
16. Anti-pyretic
17. Anti-microbial
18. Nephro protective
19. Anti-HIV activity
20. Astringent activity
21. Anxiolytic activity
Vitex negundo as mosquito repellent
The Vitex species contains a variety of active compounds, including lauric acid, palmitic acid, stearic acid, oleic acid, and linoleic acid. Its fatty acid methyl ester (FAME) extracts demonstrated larvicidal effects against early fourth-instar larvae of Culex quinquefasciatus, with an LC50 value of 18.64 ppm for V. negundo [36]. The hexane extract from the leaves of V. negundo shows promise as an environmentally friendly method for controlling Aedes subpictus and Culex tritaeniorhynchus due to its mosquito larvicidal properties [37]. The essential oils of V. negundo from six states in the North Central Geopolitical Zone exhibited mosquito repellent activity against Aedes gambiae, with efficacy varying based on composition. Among the states, oils from Niger, Kwara Plateau, and Nasarawa showed significant repellency, with an ED50 ranging from 0.14% to 0.08% v/v. Common terpenes in the oils across all six states included ?-phellandrene, sabinene, ?-pinene, p-cymene, and myrcene, while ?-pinene, linalool, cis-sabinene hydrate, citronellal, verbenone, and bornyl acetate were found in all oils. The compounds linalool, ?-pinene, verbenone, ?-pinene, myrcene, and citronellal exhibited strong binding affinity to odorant binding proteins (OBPs), with ?-pinene, citronellal, linalool, and myrcene inhibiting interactions through hydrophobic interactions at the binding pocket. The LE, LLE, FQ, and LELP values fell within expected ranges, confirming the ligands as potential OBP-binding mosquito repellents. Several compounds, including linalool, cis-sabinene hydrate, citronellal, sabinene, verbenone, ?-terpinene, bornyl acetate, ?-pinene, and ?-phellandrene, displayed low ecotoxicological risks. ?-pinene, linalool, and myrcene, according to ADME/tox and docking studies, are promising candidates for developing environmentally friendly mosquito repellents. When tested in repellent assays, commercial standards of ?-pinene, linalool, and myrcene were effective, and a mixture of these compounds showed comparable activity to DEET, indicating potential synergistic effects. Docking studies suggest that these ligands bind to OBPs and may inhibit olfactory receptors (ORs), leading to disorientation and confusion in Aedes gambiae. [38] Vitex negundo, commonly known as nirgundi, is a highly valuable herb due to its numerous medicinal benefits and has been used for centuries. It possesses properties such as anti-allergic, anti-inflammatory, antibacterial, analgesic, central nervous system depressant, antifungal, wormicidal, and venom-neutralizing effects against snake bites. The herb's effectiveness is further supported by the identification and isolation of key chemical components, especially flavonoids, found in various parts of the plant, including the leaves, flowers, bark, seeds, and roots. Promoting the cultivation of this plant for its therapeutic potential is crucial for fostering a healthier future society. Extensive research, including extraction methods, preliminary testing, phytochemical analysis, physicochemical evaluations, and chromatography standardization, has confirmed the broad spectrum of biological activities exhibited by Vitex negundo. [27] Several species of mosquitoes from the genera Anopheles, Culex, and Aedes serve as vectors for various diseases such as Dengue fever, Malaria, Yellow fever, Japanese Encephalitis, and other infections. Mosquitoes are responsible for transmitting diseases to over 700 million people, with more than one million deaths reported annually worldwide. Consequently, mosquito control is a significant public health issue globally. Commercial mosquito repellents typically contain synthetic chemicals that can be toxic, causing skin or eye irritation, coughing, asthma, and other adverse effects, making their prolonged use, especially among children, the elderly, and pregnant women, undesirable. Currently, repellents are available in different forms, such as coils, cones, and vaporizers. Herbal mosquito repellents are often more effective than synthetic alternatives due to their non-toxic and eco-friendly properties. Following the discovery of DDT, mosquito control largely relied on synthetic organic insecticides. However, concerns over toxicity and increasing insect resistance highlight the need for the development of safer and more effective insecticides and repellents (Mirospecos et al., 2010). In addition to citronella, a variety of other plant extracts have been used as insect repellents to protect against mosquitoes. Understanding the mechanisms by which these natural alternatives prevent human-mosquito contact is crucial for improving personal protection methods. With the increasing issue of insecticide resistance in key vector species, there is continued pressure on the scientific community to create new and better vector control strategies. Combining different approaches is an effective way to harness the benefits of various tools, and essential oils represent a promising area of research. [39] The essential oils of V. trifolia and V. negundo exhibited notable larvicidal effects against the third instar stages of Aedes aegypti. The study conducted by author also revealed significant larvicidal activity of Vitex trifolia against Culex quinquefasciatus larvae. [40]
There is a need to explore plant-based, safe mosquito repellent ingredients and create a herbal mosquito repellent cone that offers a convenient and side-effect-free solution for users.
CONCLUSION
Studies have demonstrated that herbal mosquito repellent cones possess excellent mosquitocidal and repellent properties. These herbal repellents are proven to effectively keep mosquitoes away while also having a positive impact on human health, without any harmful side effects. In contrast, chemical mosquito repellents can cause adverse health effects and pose risks to human well-being. Therefore, herbal mosquito repellents provide a safer and more natural alternative to conventional chemical options. Their use offers not only protection against mosquito-borne diseases but also a reliable, non-toxic solution for those seeking effective mosquito control.
Recent studies on herbal mosquito repellents have yielded promising results, demonstrating their effective repellent action against mosquitoes. the use of these herbal products has been linked to positive health benefits, with no reported negative side effects. As a result, there is increasing interest in using herbal repellents as a safer alternative to chemical ones. Given their proven effectiveness and positive impact on human health, herbal repellents present a promising solution for individuals seeking protection from mosquito-borne diseases without the risks associated with synthetic chemicals.
Vitex negundo (Nirgundi) is recognized for its diverse applications, with ongoing research exploring its various uses. However, its potential as a mosquito repellent remains underexplored. There is a significant need for further investigation into its repellent properties to develop a more effective and natural alternative to chemical-based mosquito repellents
REFERENCES
Riya Pophale*, Kirtee Belsare, Review Natural Protection Redefined: Nirgundi as a Safe Herbal Mosquito Repellent , Int. J. of Pharm. Sci., 2024, Vol 2, Issue 12, 2897-2907. https://doi.org/10.5281/zenodo.14544034
10.5281/zenodo.14544034
