Researchers explore herbal treatments for diabetes

Diabetes is an important human ailment afflicting many fromkvarious walks of life in different countries. In many countries of the world, including Nigeria, it is proving to be a major health problem, especially in the urban areas. In the last few years, researchers have assessed a number of African medicinalplants as potentially emerging alternative/adjunct treatment for diabetes and diabetes-related metabolic disorders. These are herbs used in the community for management of diabetes.Three prominent herbs for the treatment of diabetes in South-Western Nigeria are Momordica foetida (identical with Momordica charantia but commonly referred to as bitter melon or Ejinrin wewe in Yoruba), bitter leaf and mistletoe. In a study to assess the relative effects of aqueous leaf extract of Momordica foetida,
bitter leaf and mistletoe at lowering blood
glucose levels in experimental animals,
researchers found out that extract of
Momordica foetida caused maximal anti-
diabetic effect in six hours, bitter leaf in 10
hours, while mistletoe continued to cause
reduction after 10 hours.
Interestingly, they found that the three
extracts made with water caused greater
blood glucose reductions than
glibenclamide, a standard medicine for
diabetes in the diabetic rats, but exhibited
comparable effects with chlorpropamide
(another standard medicine for diabetes)
and insulin.
Writing in the 2008 publication of the
African Journal of Endocrinology and
Metabolism, the researchers stated:
”Mistletoe is more effective in lowering
blood glucose than Momordica foetida and
bitter leaf in alloxan-induced diabetic rats,”
while cautioning that mistletoe be used in
situations that require more subtle
reductions and in conditions in which
prolonged hypoglycaemic actions are
desirable.
The study entitled “Comparative effects of
three herbs and standard hypoglycaemic
agents on blood glucose in
normoglycaemic, hyperglycaemic and
Alloxan-induced diabetic male rats” was
carried out by Abraham Osinubi and Enye
LA from the Lagos State University College
of Medicine, Ikeja, Lagos State in
collaboration with Adesiyun A.E and Ajayi
G.O from University of Lagos.
Based on the findings of this investigation,
they suggested that the plant extracts could,
at least in part, stimulate insulin production
and glucose utilisation, like glibenclamide
and chlorpropamide, to bring about their
blood glucose reductions in the
experimental animals used.
In addition, it was observed that aqueous
leaf extracts of Momordica foetida had
faster onset of regulating blood sugar level
than bitter leaves and mistletoe while
mistletoe has a longer anti-diabetic action
than Momordica foetida and bitter leave.
Previously, Dr. Abraham Osinubi had
reported in the Medical Journal of Islamic
World Academy of Sciences that the
administration of the aqueous extract of
bitter leaf at a concentration of 500 mg/kg
of body weight significantly decreased the
levels of blood glucose. The blood sugar
lowering effect of fresh bitter leaf was
equally comparable with that of
chlorpropamide, a standard diabetes drug.
Triplochiton scleroxylon (African Obeche or
African white wood) is one of the over 30
medicinal plants used by Nigerian diabetics
to treat their conditions, especially amongst
the rural and impoverished urban dwellers.
Investigations on this herb carried out by
T.P. Prohp from the College of Health
Sciences, Niger Delta University, Wilberforce
Island, Bayelsa State and I.O. Onoagbe from
the University of Benin, Edo State, stated
that extract of African Obeche may be
useful in the treatment of diabetes mellitus
with the added advantage that it may not
contain destructive chemical substances
capable of damaging the heart.
The researchers in this 2009 study
published in the Pakistan Journal of
Nutrition attributed its blood sugar lowering
and diabetic-protective effects to chemical
substances such as alkaloids and flavonoids
present in African Obeche.
Certainly, herbs used for diabetes are not
different from one part of Nigeria to
another. An assessment on medicinal plants
used in North-Western Nigeria for the
treatment of diabetes mellitus listed the 10
most patronised plants as Moringa oleifera
(Horse dish tree or drumstick tree.), cotton,
Calotropis procera (Sodom apple), Cassia
goratensis (Golden shower), bitter leaf,
mahogany, mango, Angeissus leiocarpus
(Giant fern), Senna occidentalis (Coffee
senna or rere in Yoruba) and Cassia arereh
(Indian senna).
E. U. Etuk and B. J. Mohammed from the
Department of Pharmacology, College of
Health Sciences, Usmanu Danfodiyo
University, Sokoto stated in the 2009
edition of the African Journal of Pharmacy
and Pharmacology that all the extracts of
the selected plants (200 mg/kg) exhibited
various degrees of blood glucose lowering
activity.
According to their results, “bitter leaf (67
per cent), Sodom apple leaf(59 per cent),
leaf of Golden shower (53 per cent) and
mango leaf (35per cent) extracts produced
a significant reduction in blood glucose
levels in diabetic rats while bark of gaint
fern (30 per cent), bark of Indian senna (19
per cent), cotton leaf (17 per cent),
Mahogany Bark (4 per cent), leaf of Coffee
senna (4 per cent) and leaf of Horse dish
tree (4 per cent) produced a non significant
effect. Bitter leaf was ranked highest both
by the informant consensus and biological
evaluation.”
Nonetheless, a group of researchers believe
that the blood-sugar lowering effect of
bitter leaf may be similar to other
indigenous vegetables such as Solanum
incanum (garden egg plant or anara in
Igbo) and Gongronema latifolium (utazi in
Igbo or ewe-itaji in Yoruba).
Reporting in the 2009 publication of the
Pakistan Journal of Nutrition, the
researchers from the University of Nigeria,
Nsukka, namely, V. Uchenna Okolie; E.
Chinwe Okeke; O. Ijeoma Ehiemere and O.
Pauline Ezenduka, declared that its
consumption can ensure a reduction in
blood glucose as well as cause higher
insulin sensitivity in humans.
The study involved eight participants taking
the water extracts of these vegetables;
another eight others chewed the leaves
raw, while the last group served as control
for the study. Blood glucose levels were
checked at fasting and at 30 minutes
intervals for two hours.
Compared with other vegetables, they
found that garden egg plant elicited
significant reductions in blood glucose
levels when it was checked.
A herbal formulation prepared with Alstonia
congensis bark and Xylopia aethiopica
fruits in equal proportion is one of the
popular local herbal preparations employed
in the treatment of diabetes and it is
consumed over a long period of time in the
course of treatment.
X. aethiopica commonly known as Negro
pepper fruits, Ethiopian pepper, African
pepper or Guinea pepper is locally called
“Uda” by the Igbos of Nigeria is a highly
valued medicinal plant. Alstonia congensis is
referred to as ahun in Yoruba.
In an assessment of these preparation,
scientists stated in the 2008 publication of
the African Journal of Biotechnology that
the preparation had good blood-sugar-
lowering effect and that it also had some
beneficial effects on cardiovascular risk
factors.
However, the researchers namely,
Ogbonnia, S. and Enwuru, V. N. from the
Faculty of Pharmacy, University of Lagos
College of Medicine Campus, Idi-Araba,
Lagos, and Adekunle, A. A. and Bosa, M. K.
from the Department of Botany and
Microbiology, University of Lagos, Akoka,
Lagos, added the caveat that its prolonged
usage has a tendency to cause kidney
problems.
Meanwhile, other plant materials that
scientists suggested may be helpful in the
treatment of diabetes includes the seeds of
Parinari curatellifolia known locally as
“Ebere” in Yoruba are commonly used in
the Nigerian folk medicine for the treatment
of diabetes.