African Mint

Scientific Name(s): Ocimum canum Sims., also known as Ocimum americanum L. Family: Lamiaceae.

Common Name(s): African mint , American basil , Asian basil , hairy basil

Uses

The plant species has been examined for its activity against soil phytopathagens and as a mosquito repellant to prevent malaria and dengue fever. It has also been evaluated for its anti-inflammatory and chemotherapeutic activity and for use in diabetes.

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Dosing

Numerous dosage forms (ie, tablets, pellets, granules) are available commercially. Because limited clinical data are available, the manufacturer's suggested dosage guidelines should be followed.

Contraindications

Avoid use if hypersensitivity to any of the chemical components of O. canum exists.

Pregnancy/Lactation

Information regarding safety and efficacy in pregnancy and lactation is lacking.

Interactions

None well documented.

Adverse Reactions

A 12-week clinical trial documented abdominal discomfort, flatulence, and constipation in patients consuming 15 g of O. canum seeds daily.

Toxicology

None well documented. The constituent of O. canum , estragole, is carcinogenic.

Botany

The Lamiaceae family contains approximately 220 genera and nearly 4,000 species worldwide. 1 , 2 Numerous members of the family contain biologically active essential oils. O. canum is a semiperennial plant species found in Africa and Asia, but not native to North America. 3 The plant grows 30 to 40 cm high and branches out from its base. It has angled stems and oval pubescent leaves. Its long flower spikes are pale to intense pink. The mature calyx is about 4 mm in diameter. 2

History

The plant is used medicinally in Africa to treat conjunctivitis, malaria, and headache. 2 It also has been used to manage diabetes mellitus in Ghana 4 and as an analgesic and rubefacient in other parts of Africa. 5 Ethnopharmacology studies document its use in treating dysuria in Iran. 1 The essential oils of the plant species have been used mainly as an antipyretic and for treating respiratory diseases on the eastern coast of Africa. 6 The aerial plant parts or the leaves and flowers have been used with other spices for culinary purposes. 2

The essential leaf and flower oils have been used as flavoring in foods, chewing gums, sweets, teas, soft drinks, energy drinks, and milk products. The oils are also used in cosmetics, shampoos, soaps, shower gels, body lotions, and toothpastes. 2

Chemistry

O. canum essential oils from various origins occur as several physiological forms or chemotypes. 1 , 2 , 3 , 7 Most chemotypes have 2 major flavonoids, the most common being nevadensin and salvigenin. 3 , 8 Depending on geographical location, 2 other examples include species with methyl cinnamate-rich oils from Central Africa, Comoro Island, India, São Tomé, Aruba, and Nigeria. A citral type from East Africa and India, as well as a linalool-type from Rwanda, India, and Israel are documented. An eugenol type has additionally been described from samples in the United States and Nigeria. A camphor-type from India, Somali, and Zimbabwe has been described. Further documentation is available on the chemotypes. 7 , 8 , 9 , 10 , 11

The seeds of O. americanum contain a high content of mucilage and have been studied as a disintegrant in tablet formulations. 12

Uses and Pharmacology

Anti-inflammatory, chemotherapeutic, and blood glucose-lowering activity is documented in the scientific literature. However, most research examines the plant's use against vector-borne diseases and as an insect repellent in agricultural soils.

Anti-inflammatory activity

Anti-inflammatory activity may be associated with the essential oils and linolenic acid content, which can block both the cyclooxygenase and lipoxygenase pathways of arachidonate metabolism. 13 , 14

Animal data

O. americanum inhibited carrageenan, prostaglandin E2, leukotriene, and arachidonic acid-induced paw edema. 13

Chemotherapeutic activity
In vitro data

The oil from O. canum leaves, but not flowers, was active against gram-positive versus gram-negative bacteria. 11 , 15 , 16 The essential oils were also toxic against ringworm fungi. 17

Diabetes

The antidiabetic activity of O. canum may be associated with its polysaccharide content.

Animal data

Studies in mice found insulin release to be dose responsive with increasing concentrations of O. canum extract ( P < 0.05). Glucose-stimulated insulin release peaked with a dose of O. canum 0.03 mg/mL. The extract also decreased weight gain, lowered fasting glucose levels in obese diabetic mice, and facilitated glucose-induced insulin release from pancreatic β-islet cells in a concentration-dependent manner. 5 A similar study of O. canum concluded with decreasing serum total cholesterol and low-density lipoprotein cholesterol, and increasing high-density lipoprotein cholesterol. 4

Other pharmacological activity
Cholesterol

One 12–week clinical study of 30 hypercholesterolemic patients in Thailand examined the clinical outcome of nutrition counseling with O. canum seed supplementation on serum lipid levels. During the supplementation period, patients consumed 15 g of O. canum seeds daily. The results documented no additional benefit of O. canum supplementation to nutrition counseling on serum levels for total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and triacylglycerols. 18

Vector-borne diseases

The plant has been examined for its activity against soil phytopathogens and as a mosquito repellant to prevent malaria and dengue fever. Ethnobotanical studies document selective fungitoxicity of the essential oils against soil phytopathogens. The oils were not phytotoxic. In general, the plant is used in various parts of Africa to protect agricultural crops from insect damage. 19 , 20 , 21 , 22

When O. americanum potted plants were placed inside experimental huts, the entry of malaria vector mosquitoes decreased by nearly 40% compared with the use of a nonfragrant native grass. 23 Ethnobotanical surveys also document that O. americanum is one of the most commonly used repellent plants in various villages and communities in Africa. 24 , 25 Malaria vector mosquitoes were repelled for up to 8 hours when the oils of O. americanum were combined with turmeric, citronella grass, and 5% vanillin. 26

The essential oils of O. americanum (LC 50 67 ppm) were also effective against the major vector of dengue fever, Aedes aegypti L., in a study completed in Brazil. 27

Dosage

Numerous dosage forms (ie, tablets, pellets, granules) are available commercially. Because limited clinical data are available, the manufacturer's suggested dosage guidelines should be followed.

Pregnancy/Lactation

Information regarding safety and efficacy in pregnancy and lactation is lacking.

Interactions

None well documented.

Adverse Reactions

A 12-week clinical trial documented abdominal discomfort, flatulence, and constipation in patients consuming 15 g of O. canum seeds daily.

Toxicology

None well documented. The O. canum constituent, estragole, is carcinogenic. 28

Bibliography

1. Naghibi F , Mosaddegh M , Motamed SM , Ghorbani A . Labiatae family in folk medicine in Iran: from ethnobotany to pharmacology . Iran J Pharmaceutical Res . 2005 ; 2 : 63-79 .
2. Ngassoum MB , Ousmaila H , Ngamo LT , Maponmetsem PM , Jirovetz L , Buchbauer G . Aroma compounds of essential oils of two varieties of the spice plant Ocimum canum Sims from northern Cameroon . J Food Compost Anal . 2004 ; 17 ( 2 ): 197-204 .
3. Vieira RF , Grayer RJ , Paton AJ . Chemical profiling of Ocimum americanum using external flavonoids . Phytochemistry . 2003 ; 63 ( 5 ): 555-567 .
4. Nyarko AK , Asare-Anane H , Ofosuhene M , Addy ME , Teye K , Addo P . Aqueous extract of Ocimum canum decreases levels of fasting blood glucose and free radicals and increases antiatherogenic lipid levels in mice . Vascul Pharmacol . 2002 ; 39 ( 6 ): 273-279 .
5. Nyarko AK , Asare-Anane H , Ofosuhene M , Addy ME . Extract of Ocimum canum lowers blood glucose and facilitates insulin release by isolated pancreatic β-islet cells . Phytomedicine . 2002 ; 9 ( 4 ): 346-351 .
6. Martins AP , Salgueiro LR , Vila R , et al. Composition of the essential oils of Ocimum canum , O. gratissimum and O. minimum . Planta Med . 1999 ; 65 ( 2 ): 187-189 .
7. Grayer RJ , Vieira RF , Price AM , Kite GC , Simon JE , Paton AJ . Characterization of cultivars within species of Ocimum by exudate flavonoid profiles . Biochem Syst Ecol . 2004 ; 32 ( 10 ): 901-913 .
8. Grayer RJ , Veitch NC , Kite GC , Price AM , Kokubun T . Distribution of 8-oxygenated leaf-surface flavones in the genus Ocimum . Phytochemistry . 2001 ; 56 ( 6 ): 559-567 .
9. Grayer RJ , Kite GC , Veitch NC , et al. Leaf flavonoid glycosides as chemosystematic characters in Ocimum . Biochem Syst Ecol . 2002 ; 30 ( 4 ): 327-342 .
10. Xaasan CC , Cabdulraxmaan AD , Passannanti S , Piozzi F , Schmid JP . Constituents of the essential oil of Ocimum canum . J Nat Prod . 1981 ; 44 ( 6 ): 752-753 .
11. Bassole IH , Nebie R , Savadogo A , Ouattara CT , Barro N , Traore SA . Composition and antimicrobial activities of the leaf and flower essential oils of Lippia chevalieri and Ocimum canum from Burkina Faso . Afr J Biotechnol . 2005 ; 4 ( 10 ): 1156-1160 .
12. Patel DM , Prajapati DG , Patel NM . Seed mucilage from Ocimum americanum Linn. as disintegrant in tablets: Separation and evaluation . Indian J Pharm Sci . 2007 ; 69 : 431-435 .
13. Singh S . Comparative evaluation of antiinflammatory potential of fixed oil of different species of Ocimum and its possible mechanism of action . Indian J Exp Biol . 1998 ; 36 ( 10 ): 1028-1031 .
14. Setty AR , Sigal LH . Herbal medications commonly used in the practice of rheumatology: mechanisms of action, efficacy, and side effects . Semin Arthritis Rheum . 2005 ; 34 ( 6 ): 773-784 .
15. Cimanga K , Kambu K , Tona L , et al. Correlation between chemical composition and antibacterial activity of essential oils of some aromatic medicinal plants growing in the Democratic Republic of Congo . J Ethnopharmacol . 2002 ; 79 ( 2 ): 213-220 .
16. Tajo A , Thoppil J . Antimicrobial activities of Ocimum americanum L. essential oil . Indian J Pharm Sci . 1999 ; 61 ( 6 ): 377-378 .
17. Yadav P , Dubey NK . Screening of some essential oils against ringworm fungi . Indian J Pharm Sci . 1994 ; 56 ( 6 ): 227-230 .
18. Kangsadalampai O , Meksawan K , Buranaprapruk N . Ocimum canum seed supplementation did not influence serum lipid levels in hypercholesterolemic patients . Nutr Res . 2007 ; 27 ( 4 ): 206-211 .
19. Khanom F , Kayahara H , Tadasa K . Tyrosinase inhibitory activity of Bangladeshi indigenous medicinal plants . Biosci Biotechnol Biochem . 2000 ; 64 ( 9 ): 1967-1969 .
20. Belmain SR , Neal GE , Ray DE , Golob P . Insecticidal and vertebrate toxicity associated with ethnobotanicals used as post-harvest protectants in Ghana . Food Chem Toxicol . 2001 ; 39 ( 3 ): 287-291 .
21. Pandey VN , Dubey NK . Antifungal potential of leaves and essential oils from higher plants against soil phytopathogens . Soil Biol Biochem . 1994 ; 26 ( 10 ): 1417-1421 .
22. Lehman AD , Dunkel FV , Klein RA , et al. Insect management products from Malian traditional medicine—establishing systematic criteria for their identification . J Ethnopharmacol . 2007 ; 110 ( 2 ): 235-249 .
23. Seyoum A , Kabiru EW , Lwande W , Killeen GF , Hassanali A , Knols BG . Repellency of live potted plants against Anopheles gambiae from human baits in semi-field experimental huts . Am J Trop Med Hyg . 2002 ; 67 ( 2 ): 191-195 .
24. Pålsson K , Jaenson TG . Plant products used as mosquito repellents in Guinea Bissau, West Africa . Acta Trop . 1999 ; 72 ( 1 ): 39-52 .
25. Seyoum A , Pålsson K , Kung'a S , et al. Traditional use of mosquito-repellent plants in western Kenya and their evaluation in semi-field experimental huts against Anopheles gambiae : ethnobotanical studies and application by thermal expulsion and direct burning . Trans R Soc Trop Med Hyg . 2002 ; 96 ( 3 ): 225-231 .
26. Tawatsin A , Wratten SD , Scott RR , Thavara U , Techadamrongsin Y . Repellency of volatile oils from plants against three mosquito vectors . J Vector Ecol . 2001 ; 26 ( 1 ): 76-82 .
27. Cavalcanti ES , Morais SM , Lima MA , Santana EW . Larvicidal activity of essential oils from Brazilian plants against Aedes aegypti L . Mem Inst Oswaldo Cruz . 2004 ; 99 ( 5 ): 541-544 .
28. De Vincenzi M , Silano M , Maialetti F , Scazzocchio B . Constituents of aromatic plants: II. Estragole . Fitoterapia . 2000 ; 71 ( 6 ): 725-729 .

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