Ocimum gratissimum

Ocimum gratissimum

African basil (Ocimum gratissimum L. 1753) is an annual herbaceous species belonging to the Lamiaceae family.

Systematics –
From a systematic point of view it belongs to:
Eukaryota Domain,
Kingdom Plantae,
Magnoliophyta Division,
Magnoliopsida class,
Lamiales Order,
Lamiaceae family,
Genus Ocimum,
Species O. gratissimum.
The following terms are synonymous:
– Ocimum frutescens Mill .;
– Ocimum sericeum Medik., 1780;
– Ocimum zeylanicum Medik., 1780;
– Ocimum petiolare Lam., 1785;
– Ocimum holosericeum J.F.Gmel., 1791;
– Ocimum urticifolium Roth, 1800;
– Ocimum viridiflorum Roth, 1800;
– Ocimum suave Willd., 1809;
– Ocimum viride Willd., 1809;
– Ocimum heptodon P. Beauv., 1818;
– Ocimum febrifugum Lindl., 1824;
– Ocimum villosum Weinm., 1824;
– Ocimum guineense Schumach. & Thonn. in C.F. Schumacher, 1827;
– Ocimum paniculatum Bojer, 1837;
– Ocimum anosurum Fenzl, 1844;
– Ocimum arborescens Bojer ex Benth. in A.P.de Candolle, 1848;
– Ocimum robustum B. Heyne ex Hook.f., 1885;
– Ocimum trichodon Baker ex Gürke in H.G.A. Engler, 1895;
– Ocimum dalabaense A. Chev. (Morot), 1909;
– Ocimum caillei A. Chev., 1920;
– Geniosporum discolor Baker, 1900.
Within this species, the following subspecies are recognized:
– Ocimum gratissimum subsp. gratissimum;
– Ocimum gratissimum subsp. iringense Ayob. ex A.J. Paton: subspecies present mainly in Tanzania, where it grows in the wild or cultivated in non-sandy soils from 700 to 1200 m s.l.m .;
– Ocimum gratissimum subsp. macrophyllum Briq .: present throughout the tropical belt from Africa to Asia, naturalized in South America and growing up to 1000 m s.l.m ..

Etymology –
The term Ocimum comes from the Greek ὤκῐμον ócimon basilico; this gives ὄζω ózo odorare, emanate odor: due to the characteristic scent of the plant.
The specific epithet gratis simum is the superlative of gratus pleasing, pleasant, gracious: very pleasant, due to the appearance, aroma or flavor of the fruit.

Geographic Distribution and Habitat –
African basil is a plant native to Africa, Madagascar, South Asia and the Bismarck archipelago and naturalized in Polynesia, Hawaii, Mexico, Panama, the West Indies, Brazil and Bolivia.
Its natural habitat is that of the areas along the shores of lakes, in the vegetation of the savannah, in the submontane forest and in disturbed soils, at altitudes from sea level to 2,382 meters in West Africa.

Description –
Ocimum gratissimum is a perennial shrub plant, evergreen, very branched, woody below with quadrangular stems and branches, pubescent in the younger parts and hairless in the older ones and that grows between 0.50 and 3 meters.
The leaves are lanceolate and serrated along the margins; they are opposite with 2-4.5 cm long petioles, slender, pubescent; the lamina is elliptical to ovate 3.5 – 16 cm long and 1 – 8.5 cm broad, membranous, glandular, wedge-shaped, entire, with crenate-indented margin, acute, puberulent or pubescent apex.
The flowers are gathered in an inflorescence which is a verticillaster, organized in terminal raceme, simple or branched, with a length of 5-30 cm; the spine is loose, softly pubescent; the bracts are sessile, ovate, 3-12 mm long and 1-7 mm broad, persistent, deciduous, sharp; the pedicel is 1–4 mm long, extended or ascending, slightly curved; the verticillastri are formed by 6-10 small, hermaphroditic flowers; bilabiate calyx, 2–3 mm long (5–6 mm in fruiting), the upper lip is pubescent, rounded and curved, reflected in the fruit, the lower lip with four, narrow, sharp teeth, the pair of central teeth are much shorter than the upper ones; corolla campanulata, 3.5-5 mm long, 2 lips, white-greenish, the outer part is pubescent, the upper lip is truncated, 4-cuneate, the lower lip is longer, declined, flat, whole, not membranous; the stamens are 4, declined, in 2 couplings, inserted on the tube of the corolla, filaments inserted distinctly, the upper pair with a pubescent tooth at the base; upper ovary, consisting of 2 carpels, each 2 cells, bicuneate type.
The fruit is divided into four more or less spherical lodges, dry, one seed for each lodge closed in a persistent chalice (the lower lip that closes the mouth of the fruit-bearing chalice); the lodges are subglobose, 1.5 mm long, wrinkled, brown in color; the external pericarp does not become mucilaginous in water.

Cultivation –
African basil is an often grown plant, primarily in the tropics, where it provides a range of culinary and medicinal applications and is an effective insect repellent. From this an essential oil is obtained, for which it is grown on a commercial scale, the oil is exported to many countries, while the leaves are sometimes sold in local markets in Africa.
The plant prefers rich, light, well-drained or dry soil and a location in full sun.
All parts of the plant are strongly scented.
The plant is grown in various parts. For example, it is transplanted to the Hong River Delta area in northern Vietnam in February-March, in southern Vietnam from May-August. The plants are transplanted with a 40 cm x 50 cm spacing.
The optimal harvest time for essential oil distillation is when the plant has 3 branches per plant, or 75% of the branches, are in bloom. In the north of Vietnam an average of 2 – 3 cuts per year can be obtained, in the south 4-5 cuts per year. In Vietnam, the Ocimum gratissimum remains productive for 5-10 years.
In India, yields of 70-75 tons per hectare of green grass have been experimentally obtained, producing 400 liters of essential oil in 2 years.
In Thailand, harvesting every 10-12 days produced an annual green grass yield of just 13 tons per hectare and an oil yield of nearly 200 liters.
Propagation can take place by seed, with germination rates that can be less than 10%. Normally it is sown in a nursery covering only the seed. Germination is generally fast; after which the seedlings are planted in individual pots when they are large enough to handle.
It can also be propagated by cuttings; these take about 28 days to take root.

Customs and Traditions –
Ocimum gratissimum is grown mainly for the extraction of essential oil, it is one of the richest species of Ocimum, widespread in various parts of the world. In the world the production of essential oil of Ocimum gratissimum is estimated at 50 tons / year, almost all absorbed by the producing countries.
This plant is widely used both in food and medicine and in the production of essential oils.
The preparations based on the whole plant are used both in Africa and in India as stomachic and in the treatment of sunstroke, migraine and influenza. The seeds have laxative properties and are prescribed against gonorrhea. The essential oil is applied against fever, inflammation of the throat, ears or eyes, stomach pains, diarrhea and skin diseases.
The essential oil has numerous traditionally known properties, even if some have been scientifically refuted, such as antidiarrheal, anti-inflammatory, antelmitic, hepatoprotective, antibacterial, antidiabetic, fungicidal. Instead, anticancer effects were found in vitro.
Remember that essential oil in high doses can be toxic.
In food use, fresh or preserved leaves are used, which are used in Thailand as a spice and in Sumatra for tea.
The leaves are cooked and eaten like herbs, alone or sometimes combined with other leaves and seeds of watermelon (Citrullus lanatus).
The leaves are also used as a flavoring with other foods.
It is a very popular food in West Africa.
Some varieties have lemon thyme-flavored leaves that can be used in salads and as a condiment as well as for making herbal teas.
The seeds are sometimes eaten like in India.
The concentrated essential oil of this plant has been shown to have repellent and potentially insecticidal properties against some insects, such as housefly.
It has also been shown to have a strong fungicidal action against some fungal pathogens such as Sclerotium rolfsii, Rhizoctonia spp. and Alternaria alternata.
In medicinal use, the leaves and stems are used internally in the treatment of a number of conditions including colds and flu, in particular chest colds; fever, sunburn, headache, impotence, flatulence, diarrhea, dysentery, postpartum problems and worms in children.
They are also applied externally to treat rheumatism and lumbago.
An essential oil obtained from the leaves showed a marked antibacterial activity.
The essential oil of the plant is used in perfumery.
Among other uses, it should be remembered that the plant is sometimes grown as a hedge.
The peeled twigs are used as chew sticks to clean teeth and maintain oral hygiene.
The fresh aboveground parts of the plant contain 0.8 – 1.2% essential oil. The chemical composition of this oil is variable; at least 6 chemotypes have been reported, characterized by the constituents of particular essential oils. These are:
– Eugenolo. This is the most important economically. It is a brownish-yellow to pale yellow liquid with a powerful, hot-spicy and aromatic smell, reminiscent of clove oil, but with a sweet-woody, almost floral top note. The dry-out is more bitter than that of clove oil. Analysis of a sample of an eugenol-type essential oil from Vietnam indicated that the main component was eugenol (71%) with small amounts of D-germacrene and (Z) -beta-ocimene. In a sample from southern China the eugenol content was up to 95%. Samples from Madagascar had eugenol content of 40-90%, with other components highly variable.
– Thymol. This used to be important, but most thymol is now produced synthetically, while natural thymol is mostly obtained from Thymus vulgaris or Trachyspermum ammi. Thymol-type oil is a dark yellow to orange-yellow or brownish liquid with a medicinal-spicy, warm, and somewhat herbaceous odor. Its flavor is warm, slightly astringent and burning, and has a sweet medicinal aftertaste. Analysis of several samples of essential oils of O. Gratissimum from Central and West Africa rich in thymol indicated that their main constituents were thymol, gamma-terpinen, p-cymene and eugenol. Concrete obtained by solvent extraction is much richer in thymol than distilled oil.
– Citral. The citral type, reported by Iran, Pakistan and India, is rich in citral (67%) and geraniol (26%).
– Ethyl cinnamate.
– Geraniol.
– Linalool.

Preparation Method –
African basil is a plant used, as mentioned, in the food and medicinal fields.
In food use, fresh or preserved leaves are used, which are used in Thailand as a spice and in Sumatra for tea.
The leaves are consumed after cooking as aromatic herbs, alone or sometimes combined with other leaves and seeds of watermelon (Citrullus lanatus) and sometimes also as a flavoring with other foods.
Some varieties have lemon thyme-flavored leaves that can be used in salads and as a condiment as well as for making herbal teas.
The seeds are sometimes eaten like in India.
The essential oil, extracted mainly from the leaves and the stem, is dark yellow in color tending to orange to brown, with a warm, slightly astringent and spicy flavor, with a sweet medicinal aftertaste.
The quantities of active ingredients may vary according to the geographical position and the harvesting period of the crop.

Guido Bissanti

Sources
– Acta Plantarum – Flora of the Italian Regions.
– Wikipedia, the free encyclopedia.
– Useful Tropical Plants Database.
– Conti F., Abbate G., Alessandrini A., Blasi C. (ed.), 2005. An annotated checklist of the Italian vascular flora, Palombi Editore.
– Pignatti S., 1982. Flora of Italy, Edagricole, Bologna.
– Treben M., 2000. Health from the Lord’s Pharmacy, Advice and experiences with medicinal herbs, Ennsthaler Editore.

Warning: Pharmaceutical applications and alimurgical uses are indicated for informational purposes only, they do not represent in any way a medical prescription; therefore no responsibility is taken for their use for curative, aesthetic or food purposes.