American basil
StarOcimum americanum
Synonyms: Ocimum canum var. integrifolium, Ocimum hispidulum, Ocimum dinteri, Becium obovatum var. glabrior, Ocimum fruticulosum, Ocimum thymoides, Ocimum incanescens, Ocimum stamineum, Ocimum dichotomum, Ocimum serpyllifolium var. glabrius, Ocimum fluminense, Ocimum brachiatum, Ocimum canum
Western Herbalism Properties
Traditional Uses
Ocimum americanum is widely used in Ayurvedic and Siddha medicine and in African and Southeast Asian folk traditions: in Tamil Nadu a decoction of the leaves treats constipation, dysentery, diarrhoea and haemorrhoids, while Swahili-speaking peoples of East Africa use it for stomach complaints and to lower blood pressure, and the mucilaginous seeds and aromatic leaves are taken for coughs, colds and digestive upset (Venkatesan et al., 2023).
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Botanical Description
Ocimum americanum, known as American basil or hoary basil, is an aromatic annual herb of the mint family (Lamiaceae) despite its common name native to Africa and tropical Asia and now pantropical in cultivation and as a naturalized weed. It is a much-branched plant typically reaching about 0.3–0.6 m tall, with quadrangular stems and opposite, ovate to lanceolate leaves that are softly hairy, grey-green, and strongly scented when bruised, the aroma varying by chemotype (often camphoraceous or lemon-like). Small white to pale lavender, two-lipped flowers are borne in whorls along slender terminal racemes, subtended by leafy bracts. The fruit comprises four small nutlets enclosed in the persistent calyx; the seeds become conspicuously mucilaginous when wetted, a property exploited in cooling drinks. The plant favours warm, open, disturbed habitats, cultivated ground, and roadsides, and is widely grown as a culinary and medicinal herb across Africa, South and Southeast Asia, and the Americas.
Active Constituents
Camphor
Monoterpene ketoneConcentration: Up to ~34% in some leaf-oil chemotypes
Camphor is a dominant volatile in some O. americanum chemotypes. It contributes the characteristic aroma and rubefacient/antimicrobial and mild analgesic properties, but is a potential neurotoxin in large internal doses.
1,8-Cineole (eucalyptol)
Monoterpene ether (oxide)Concentration: ~17–26% depending on chemotype
1,8-Cineole is a frequent major component of the leaf oil and confers anti-inflammatory, mucolytic and antimicrobial activity.
Linalool
Monoterpene alcoholConcentration: ~19–20% in some chemotypes
Linalool is a major constituent of several accessions and contributes sedative, anti-inflammatory and broad antimicrobial effects, and was implicated in the anti-arthritic activity of the oil.
Citral (geranial + neral)
Acyclic monoterpene aldehydeConcentration: Dominant (>80% combined) in lemon/lime-scented chemotypes
In lime-basil chemotypes citral (geranial and neral) predominates, giving the strong lemony aroma and marked antioxidant, antimicrobial and larvicidal activity.
(Z)-Methyl cinnamate
Phenylpropanoid esterConcentration: Up to ~29% in methyl-cinnamate chemotypes
Methyl cinnamate is the leading volatile in certain chemotypes and contributes aroma and antimicrobial/insecticidal activity.
Flavonoids and phenolic acids
Flavonoid / phenolicConcentration: Present in leaf extracts (not quantified)
Non-volatile phenolics, flavonoids and tannins detected in the leaves account for much of the antioxidant activity of aqueous and alcoholic extracts.
⚠ Drug Interactions
Antidiabetic drugs
Ocimum extracts have shown hypoglycaemic tendencies in traditional use and some animal work; concurrent use with glucose-lowering drugs could theoretically add to their effect.
Clinical note: Theoretical; no controlled human interaction data specific to O. americanum.
Anticoagulant / antiplatelet drugs
Eugenol and related phenolics present in some Ocimum oils can inhibit platelet aggregation in vitro; large medicinal doses of the oil could theoretically add to antiplatelet/anticoagulant therapy.
Clinical note: Theoretical, relevant mainly to concentrated essential oil rather than culinary use.
Preparation Methods
Leaf infusion / decoction
Parts: Leaf
A decoction or infusion of the leaves is used traditionally across Africa and tropical Asia for colds, fever, cough, indigestion and diarrhoea. Fresh or dried leaves are steeped in hot water and taken as a tea.
Essential oil (steam distillation)
Parts: Leaf, Flowering tops
Steam-distilled leaf oil is used topically (diluted) and as a natural antimicrobial, insect repellent and larvicide. As with all essential oils it should be diluted before skin application and not taken internally in concentrated form.
Culinary herb
Parts: Leaf, Seed
The aromatic leaves flavour soups and dishes, and the mucilaginous seeds are used in cooling drinks, reflecting the plant's widespread food use where medicinal doses are modest.
Clinical Studies
Anti-inflammatory activity of Ocimum americanum L. essential oil in experimental model of zymosan-induced arthritis
The essential oil (26 components; linalool 19.6% and 1,8-cineole 17.3% principal) and its main constituents inhibited leukocyte influx into the synovial space, reduced zymosan-induced paw oedema, and protected against synovial leukocyte infiltration and cartilage destruction in arthritic mice, demonstrating significant anti-inflammatory activity.
Chemical compositions, antioxidant, antimicrobial, and mosquito larvicidal activity of Ocimum americanum L. and Ocimum basilicum L. leaf essential oils
Leaf essential oils of O. americanum and O. basilicum were characterised by GC-MS and showed notable DPPH antioxidant activity, antimicrobial inhibition zones, and larvicidal activity against Aedes aegypti, supporting the plant's use against microbial and mosquito-borne threats.
Historical Texts
African and South/Southeast Asian ethnomedicine
Traditional (long-standing folk use)Ayurvedic-influenced Indian folk practice
Traditional Indian systemsReferences
- Yamada, A. N.; Grespan, R.; Yamada, A. T.; et al.. Anti-inflammatory activity of Ocimum americanum L. essential oil in experimental model of zymosan-induced arthritis . American Journal of Chinese Medicine (2013) [DOI]
- Wirtu, S. F.; Mishra, A. K.; Jule, L. T.; Ramaswamy, K.. Ocimum basilicum and Ocimum americanum: A Systematic Literature Review on Chemical Compositions and Antimicrobial Properties . Natural Product Communications (2024) [DOI]
This information is for educational purposes only and is not intended to replace professional medical advice. Always consult a qualified healthcare provider before using any herbal remedy, especially if you are pregnant, nursing, or taking medications.
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