Agriculture Reference
In-Depth Information
Family —
Malvaceae
Common Names —
Roselle, red sorrel, zobo, Jamaican sorrel, Indian sorrel, bissap, karkadeh,
hibiscus flower,
African Names —
Hausa: abin kan iyaka, zobo; Igbo: okworo-ozo; Yoruba: amukan; Swahili:
ufuta, ufuta dume
Description —
The shrub is erect, slightly branched with a smooth or slightly hispid plant
that can grow up to 4 m in height. The stem is glabrous to sparsely pubescent, sometimes sparsely
prickly, green or reddish. It has lobed leaves and big yellow flowers with a purple center. The epi-
calyx and calyx are fleshy and succulent, bright red and persistent. The fleshy calyx is situated at
the base of the flowers and is about 1.5-2 cm wide and on maturity of the fruit becomes enlarged
to 3-3.5 cm. The plant takes about 6 months to mature, and it is harvested at the fruiting stage.
Hibiscus flower, as the harvested product is called, is edible with a sweet-sour taste.
Habitat and Distribution —
Hibiscus sabdariffa
originated from Africa, where it may have
been domesticated in Sudan and northern Nigeria about 6000 years ago, first for its seed and later
for leaf and calyx production. However, apparently truly wild plants of
Hibiscus sabdariffa
have
been collected in Ghana, Niger, Nigeria, and Angola. It is believed that the vegetable types were
introduced to India and the Americas in the seventeenth century. Selection for fiber production
took place in Asia, where cultivation is reported from the beginning of the twentieth century (e.g.,
in India, Sri Lanka, Thailand, Malaysia, and Java). Roselle is now found throughout the tropics. In
tropical Africa, it is especially common in the savanna region of West and Central Africa. It is often
found as an escape from cultivation.
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Ethnomedicinal Uses —
Zobo is used throughout West and North Africa as a vegetable and
a tonic for the improvement of general body function, blood circulation, and hypertension. Leaves
are used as a gargle for cough, toothache, and throat inflammation. It is reported as providing good
relief for coughs, biliousness, and symptoms of plethora. The flowers are applied in wound dress-
ing. The root is effective for application to abscesses and bronchitis. Calyces are used to produce a
beverage, which serves as a blood tonic and for high blood pressure. Whole dried aerial parts have
been used for sexual asthenia, cough, peristalsis, toothache, boils, bronchitis, and conjuctivitis; as a
poultice, diuretic, mouthwash, and laxative; and to ease childbirth.
Constituents —
Many chemical constituents have been isolated from the calyx and flowers of
roselle. These include alkaloids, ascorbic acid, β-carotene, anisaldehyde, arachidic acid, citric acid,
malic acid, tartaric acid, glycine, betaine, trigonelline; anthocyanins as cyanidin-3-rutinoside, del-
phinidin, delphinidin-3-glucoxyloside (also known ashibiscin, the major anthocyanin in
H. sabdar-
iffa
flowers), delphinidin-3-monoglucoside, cyanidin-3-monoglucoside, cyanidin-3-sambubioside,
cyanidin-3,5-diglucoside; the flavonols glycosideshibiscetin-3-monoglucoside, gossypetin-3-glu-
coside, gossypetin-7-glucoside, gossypetin-8-glucoside, and sabdaritrin; quercetin, protocatechuic
acid (PCA), pectin, polysaccharides, mucopolysaccharides, stearic acid, and wax.
646,647
The phytos-
terols campasterol, stigmasterol, ergosterol, β-sitosterol, and α-spinasterol have been reported from
the seed oil.
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The petals yielded 65% (dry weight) of mucilage, which on hydrolysis gave galac-
tose, galacturonic acid, and rhamnose. In addition to these compounds,
Hibiscus sabdariffa
extract
(HSE) contains complex polyphenolic acids (1.7% dry weight), flavonoids (1.43% dry weight), and
anthocyanins (2.5% dry weight).
Pharmacological Studies —
The various biological activities associated with
Hibiscus sabdar-
iffa
can be related to the compounds found in the shrub. These molecules are bioactive in several
biological models and responsible for the pharmacological effects presented by the extracts of this
species. Various antioxidant constituents are found in the calyx and flower petals of roselle, such
as hibiscus anthocyanins (HAs), quercetin, ascorbic acid, steroid glycosides (such as β-sitosteroid
glycoside), and PCA.
It has antispasmodic, anthelminthic, and bactericidal properties. The antihypertensive and car-
dioprotective effects of tea made from roselle calyces have been demonstrated in various animal
