quinta-feira, 8 de novembro de 2012

Nigéria: Researchers validate local herbs for hypertension, stroke-related diseases

Can a combination of waterleaf, guava leaf, garlic, scent leaf, avocado, bitter leaf, onion, pawpaw leaf be the elusive cure for hypertension, stroke and other cardiovascular ailments? 

Chukwuma Muanya writes.

IN recent times hypertension and its related complications such as stroke and heart attack have been on the prowl. The victims include young and old, rich and poor.

Until now, several studies have shown hypertension is a silent - killer whose onset of complications is insidious. Researchers have confirmed that such complications as cardiac remodeling, hypertrophy, renal impairment, nephropathies and ocular complications such as retinopathies and cardiovascular accident or stroke are associated with hypertension.

However, a recent study by Nigerian researchers published in Ethnobotanical Leaflets has unveiled 14 local plants that could be effectively used to manage hypertension, stroke and their complications.

The local plants according to the study titled: “Phytochemical Analysis of Medicinal Plants Used for the Management of Hypertension by Esan people of Edo State, Nigeria” include: Guava (Psidium guajava), West African Black Pepper or Ashanti pepper (Piper guineense, Uziza in Igbo and Ata iyere in Yoruba), mistletoe (Loranthus spectobulus), waterleaf (Talinum triangulare), Nigerian senna/negro coffee (Senna occidentalis), swizzle stick (Rauwolfia vomitoria), garlic (Allium sativum), onion (Allium cepa), pawpaw (Carica papaya), asthma herb (Euphorbia hirta), scent leaf (Ocimum gratissimum), avocado (Persea americana), cow-foot (Peperomia pellucida), and bitter leaf (Vernonia amygdalina).

The researchers from the Departments of Botany and Pharmacology and Therapeutics, and Medical Laboratory Sciences, Ambrose Alli University, Ekpoma, Delta State, wrote: “In the present study, the plants which were identified by various herbalists in Esanland for the management of hypertension were examined for alkaloids, inulins, flavonoids, cardiac glycosides, tannins and saponins. The results of the various phytochemical tests revealed that alkaloids, saponins, inulins, tannins, flavonoids and cardiac glycosides were present in the plants studied.

“Cardiac glycosides were present in all the species studied while alkaloids were present in all except A. sativum, A. cepa, O. gratissimum, P. americana. Saponnins are present in all except the seeds of Negro coffee (S. accidentalis), while tannins are present in all except bulbs of garlic (A. sativum). Flavonoids were absent in the leaves of scent leaves (O. gratissimum), pawpaw (C. papaya), pear leaves (P. americana) silver bush (P. pellucida), and climbing pepper (Piper guineensis).

“From the present study as well as interviews with the local herbalists. It could be concluded that plants that possessed tannins, cardiac glycosides and alkaloids are the most effective for managing hypertension and also providing protection for the heart. The general use of plants such as A. sativum, A. cepa, C. papaya, E. hirta, O. gratissimum, P. americana, P. pellucida, P. guajava, P. guineensis, V. amygdalina, R. vomitoria, L. spectobulus, T. triangulare, and S. occidentalis in the management of hypertension and other disease condition in Esanland has also been reported in other parts of Nigeria and West Africa.

“The different herbs encountered at the different herbal homes have different medicinal properties and many of them have multiple uses and hence used for the management of more than one ailment. Thus Esan people have used some of these medicinal plants for controlling and managing hypertension and other types of ailments over the years. Gill (1992), Anslem (2006) and Okoli et al (2007) have reported the effectiveness of garlic, leaves of avocado pear, pawpaw, bitter and mistletoe for the treatment of hypertension in Nigeria. Similarly, Ayitey - Smith (1989) has reported the use of avocado pear, and bitter leaf for the management of hypertension and other disease conditions in Ghana.

“Garlic has been confirmed to be very effective in the treatment of hypertension. The bulbs of garlic are blended with honey for the purpose of hypertension. The unripe rind of pawpaw is peeled and soaked in water and after three days, a cup is taken daily. The leaves are also used for treating hypertension. Leaves of avocado pear are cut into pieces, dried and made into tea, for the management of hypertension. Odugbemi (2006) has also documented the efficacy of the cotyledons of avocado pear seed for the treatment of hypertension. The cotyledons are cut into pieces, dried and grinded into powder. A dessertspoonful in 200ml hot water taken after meals gives relieve for the ailment.

“According to Odugbemi (2006) silver bush (P. pellucida) is also very effective in the treatment of hypertension. This is also in line with earlier reports by Ayitey-Smith (1989) in Ghana, and Anslem (2006) in Nigeria. P. guajava leaves are soaked in salt water, washed and squeezed and product made up with fresh water to give a greenish liquid that is taken, one glass two times daily for one week to increase blood level and offer protection against heart attack. According to Addae- Mensah (1989) and Odugbemi (2006), climbing black pepper has been confirmed to be very active in the treatment of hypertension.

“Also, the fresh leaves of V. amygdalina are chewed and swallowed or ground, or stirred in water, and the liquid taken, to manage hypertension (Ayitey-Smith, 1989 and Okoli et al 2007). Gill (1992) has reported that a typical herbal preparation for managing hypertension in South west Nigeria contains Gladiolus, Sanseveira and Citrus spp.”

Also, a recent study published in Journal of Neurological Sciences (Turkish), has demonstrated the beneficial potential of waterleaf in the enhancement of the brain activities and as pro-cognitive and neuro-protective agent.

The researchers concluded: “Consumption of waterleaf going by this investigation can be recommended as food supplement to protect the brain cells and provide numerous other functions that are beneficial to the body. Prior studies have shown that consumption of vegetables and other food supplements rich in polyphenols can reduce age-related neurological disorders.”

“In this investigation, we demonstrated the beneficial potential of waterleaf in the enhancement of the brain activities in Swiss albino mice and by extension, may be recommended as pro-cognitive and neuro-protective agent. It is recommended that further studies be carried out to corroborate these findings.”

Nutritionally, waterleaf has been shown to possess the essential nutrients like B- carotene, minerals (such as calcium, potassium and magnesium), pectin, protein and vitamins. Waterleaf has been also implicated medically in the management of cardiovascular diseases like stroke, obesity, and traditionally it is used as softener of other vegetable species.

Waterleaf’s crude protein content compares favourably with that of cowpea, peanut, millet, and cashew nuts. Akachuku and Fawusi investigated the crude protein content of waterleaf leaves and tender stems and found it to be as high as 29.4 per cent and 13.4 per cent, respectively. Sridhar and Lakshminarayana also gave a report on high total lipids, essential oils, and alpha-tocopherols and beta-tocopherols in Talinum triangulare.

Brain has intrinsically moderate activities of catalase. Brain is an organ in which homeostasis must be strictly maintained, based on a high dependence on oxidative phosphorylation.

Results of phytochemical analysis of waterleaf published in Pakistan Journal of Nutrition revealed that the leaves contain an appreciable amount of flavonoids, alkaloids, saponins, among others and low level of toxicants like tannins, since it contains substantial amount of bioactive compounds. “It can, therefore, be concluded that waterleaf leaves can contribute significantly to the health management of man and should be recommended in our daily nutritional need.” 

Data: 08.11.2012
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File:Talinum crassifolium 2.jpg
Talinum triangulare (sinônimo T. fruticosum)

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