vendredi 2 novembre 2018

Miscellaneous activities of Nigella Nigella sativa L

Miscellaneous activities of  Nigella (Nigella sativa L.)
1)Antispasmodic: In the early experimental work on N. sativa, which began in the 1980s, the alcoholic seed extract was fractionated by column chromatography on alumina to yield two organic fractions that showed hypotensive activities when tested on dogs. Fractionation of the alcohol–water extracts of the seeds afforded an organic fraction that displayed antispasmodic activity when tested on isolated rabbit intestine (Zawahry, 1963). The volatile oil was found to have some anti-oxytoxic potential based on in vitro experiments carried out on the uterine smooth muscle of rats and guinea pigs using isolated uterine horns (Aqel and Shaheen, 1996). However, the effects were concentration dependent and reversible by tissue washing. The volatile oil of N. sativa has been tested in vitro on the vascular smooth muscle, and it inhibited the norepinephrine-induced contractions of rabbit aortic rings in a solution containing Ca e+ ions; the activity was dose dependent and reversible (Aqel, 1992). In other studies the volatile oil functioned as a direct tracheal smooth muscle relaxant and a Ca 2+ antagonist (Aqel, 1992; Tanira et al., 1996), in which contractions were induced by histamine and acetylcholine, respectively.

2) Anti-hypertensive: In animal experiments, the volatile oil showed potent centrally acting antihypertensive properties that were partly attributed to the presence of thymoquinone in the oil (Mahfouz et al., 1962; E1-Tahir et al., 1993). Experiments evaluating the effects of nigella volatile oil (30–120 zl/kg) on the arterial blood pressure and heart rate of urethane-anesthetized guinea pigs have indicated that the oil has cardiovascular-depressant effects which were speculated to be thymoquinonerelated (El-Tahir and Ageel, 1994)

3) Analgesic: N. sativa oil has been shown to display CNS–depressant and potent analgesic properties in laboratory animal experiments. The analgesic activity of the oil has been attributed to the speculative presence of an opioid principle in the oil (Khanna et al., 1993).

4) Growth-regulating: The effect of the seed oil on growth regulation in Dysdercus similis (F) has been examined. Petroleum ether fractions of the seeds at concentrations of 10.3–62.5 ppm were tested for growth–regulating [juvenile hormone (JH)] activity against larvae of D. similis (F). The Nigella sativa fraction showed high JH activity and this was considered to be due the fatty acid content in the seed extract (Kumar and Thakur, 1989).

5) Bronchodilatory: The bronchodilatory effects of the plant extract have long been known and studied (Mahfouz and El-Dakhakhny, 1966). Animal experiments have indicated that the volatile oil may act as a centrally acting stimulant of the respiratory system, provided the thymoquinone content in the oil can be removed (El-Tahir et al., 1993). Nigellone is thought to be a promising substance for the prevention and control of bronchial asthma and other allergic conditions (Chakravarty, 1993). The role N. sativa oil in the management of wheeze associated lower respiratory tract illness in children has also been investigated (Ahmad et al., 2009).

6) Gastroprotective: N. sativa seeds in the diet have a favourable effect on the lipid profi le by lowering the triglyceride, total cholesterol and LDL cholesterol and increasing the HDL cholesterol in albino rats (Buriro and Tayyab, 2007). The gastroprotective effects of N. sativa oil on the formulation of stress gastritis have been reported in hypothyroidal rats (Abdel-Sater, 2009). Gastric antiulcer effects have also been reported by Rajkapoor et al. (2002).

7) Other health effects:
• N. sativa and gluthione have an antiperoxidative effect and are also benefi cial in protecting against ionizing radiation-related tissue injury (Cemek et al., 2006). The radioprotective properties of the seed oil of N. sativa were discussed by Abdel Salarn et al. (1998); its use showed signifi cant improvement in DNA, RNA, super oxide dismatase (SOD) and glutathurane (GSH) profi les and thereby enhanced longevity in animals. The expressed oil of N. sativa was the subject of earlier studies on radioprotection and has been shown to normalize enzymatic changes in the liver tissue that occur as a result of exposure to ionizing radiation in rabbits (Karawya et al., 1994; E1-Bahy, 1997).
• Ethanolic nigella extract helped in reducing the number of calcium oxalate deposites on ethylene glycol-induced kidney calculi (Hadjzadeh et al., 2007).
• The use of N. sativa oil to treat and heal chemically-induced wounds in rabbit skin was found to be effective (Zinadah-Abu, 2009).
• The alcoholic extract of N. sativa, administered orally on a daily basis, clearly improved the reproductive performance of male rats (Noor, 2008; Al-Sa’aidi et al., 2009) and brought about increased spermatogenesis in male albino rats (Mohammed et al., 2009).
 • Thymoquinone, the principal active component of nigella seeds (Hosseinzadeh and Parvardeh, 2004), has been shown to suppress epileptic seizures in rats (Hosseinzadeh et al., 2005).
• Nigella powder can be used as vinegar and applied on spots caused by vitiligo, followed by exposure to sunlight. A decoction of seeds mixed with sesame oil is used externally in various skin eruptions. Nigella has also proved useful in the treatment of dermatitis (Zedlitz et al., 2002).

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