Can
extracts of bitter kola (Garcinia kola), garden egg (Solanum melongena)
and pepper fruit (Dennettia tripetala) provide the elusive natural cure
for eye diseases especially cataracts and glaucoma? CHUKWUMA MUANYA
writes.
UNTIL now, they are renowned for their bitter and
peppery tastes. They have been validated in clinical trials for
treating various ailments such as osteoarthritis, food poisoning,
indigestion, and heartburn, among many other disease indications.
But now researchers are adding more feathers to their caps. Extracts of
bitter kola, garden egg and pepper fruit have shown promise as the next
best eye drugs in town.
Garcinia kola of the family
Guttiferaceae is an indigenous herb in Nigeria colloquially referred to
as “bitter kola”, “false kola” or “male kola.” Garcinia kola has been
shown to have anti-inflammatory, anti-parasitic, antimicrobial and
antiviral properties.
Botanically called Dennettia tripetala,
pepper fruit belongs to the plant family Annonaceae. It is called Ako in
Edo, Nkarika in Ibibio, Mmimi in Igbo, and Ata igbere in Yoruba.
Botanically called Solanum melongena, garden egg or bitter tomato is an
economic flowering plant belonging to the family Solanaceae.
Professor of Ophthalmology at Lagos University Teaching Hospital (LUTH),
Adebukunola O Adefule-Ositelu, told participants at an exhibition on
natural medicine in Lagos organised by the National Agency for Food,
Drug Administration and Control (NAFDAC) to mark the 2013 African
Traditional Medicine Day that her team has patented eye drops made with
bitter kola for preventing blindness in patients with glaucoma.
The ophthalmologist said: “I got the mixture from one of my patients who
I promised we will work on it. I can tell you authoritatively now that
we have done extensive research on this extract as an eye drop and we
are successfully using it in our clinic in successfully treating
patients with glaucoma.”
The study by Adefule-Ositelu and her
team published recently in Middle East African Journal of Ophthalmology
concluded: “Topical Garcinia kola 0.5 per cent aqueous eye drops are as
effective as timolol maleate 0.5 per cent eye drops in lowering
Intraocular Pressure (IOP) in newly diagnosed glaucoma and ocular
hypertensive patients. The mean IOP reducing efficacy after six months
of use was similar in both groups. Garcinia kola extract may represent
an alternate topical medication for patient with open angle glaucoma and
ocular hypertensives in a resource limited population.”
The
study is titled “Efficacy of Garcinia kola 0.5 per cent aqueous eye
drops in patients with primary open-angle glaucoma or ocular
hypertension.”
The other members of the research team
include: Adebayo K Adefule from the Department of Ophthalmology, LUTH,
Idi-Araba, Bernice O. Adegbehingbe, Olayinka O. Adegbehingbe, and Elsie
Samaila from Departments of Surgery, (Ophthalmology Unit) and
Orthopaedic Surgery and Traumatology, Obafemi Awolowo University,
Ile-Ife, and Kehinde Oladigbolu of the Department of Surgery, National
Eye Centre, Kaduna.
Also, Nigeria researchers have shown that eating pepper fruits could decrease the risk of blindness caused by glaucoma.
The researchers at the Department of Optometry Abia State University,
Uturu, Abia State, have demonstrated how a meal rich in pepper fruit
reduces the risk of glaucoma by stabilising the Intra Ocular Pressure
(IOP) of the eye.
The study is titled “Effect of Dennettia
tripetela Seed Intake on the Intra Ocular Pressure (IOP) of normotensive
Emmetropic Nigerian Igbos.” Normotensive is having normal blood
pressure.
Emmetropia describes the state of vision where an
object at infinity is in sharp focus with the eye lens in a neutral or
relaxed state. This condition of the normal eye is achieved when the
refractive power of the cornea and the axial length of the eye balance
out, which focuses rays exactly on the retina, resulting in perfect
vision. An eye in a state of emmetropia requires no correction.
According to the Abia State University study, results obtained showed
that consumption of 0.75g of seed gradually reduced the mean IOP from
15.6mmHg to 11.20mmHg, (25.64 per cent reduction) after 60 minutes; and
gradually reversed towards baseline value at 120mins-post ingestion. The
mean induced change in IOP at 60 minutes was 4.00mmHg. The effect was
found to be statistically significant.
The researchers wrote:
“Result obtained from this study showed that ingestion of 0.75g of
reduced the Intra Ocular Pressure (IOP) of normotensive emmetropes
though not sustained. At 30 minutes post consumption of pepper fruit,
the IOP was reduced by 17.30 per cent (12.90mmHg) from the mean baseline
of 15.60mmHg.
“This decrease in IOP was consistent at 60
minutes (a 25.64 per cent reduction 11.20mmHg) and then started
reverting towards baseline. This decrease was, therefore, not found to
be sustained after 60 minutes post consumption of the seeds. The IOP
returned almost to baseline after 120 minutes (a mean of 15.40mmHg) post
ingestion of 0.75g.
“There was a statistically significant
reduction of IOP after 30 minutes and 60 minutes. This reduction in IOP
recorded was probably due to the ascorbic acid, magnesium, flavonoid,
melatonin, thiamin, vitamin B, lipoid acid content of Ascorbic acid had
been established to support the osmotic influx of water following
osmolarity elevation of blood artificially leading to the fall in IOP.
“The effect of flavonoid in IOP reduction is thought to be as a result
of the reduction in excessive permeability of blood aqueous membrane
within the eye. The presence of lipoic acid (fatty acid) probably helped
in the reduction of IOP by increasing glutathione in red blood cells
and lacrimal fluid of glaucomatous patients thereby reducing the IOP.
“Finally, the presence of melatonin, thiamine (vitamin B) and vitamin B
perhaps also contributed to the reduction in IOP. This is due to the
fact that melatonin levels have been found to decrease in glaucomatous
patient and normal diurnal rhythms of IOP fluctuation reflect
melatoninrhythms.”
Also, Nigerian researchers led by the former
Director General of NAFDAC and professor of pharmacology at University
of Nigeria (UNN), Prof. Dora Nkem Akunyili have demonstrated how a meal
of garden egg would be of benefit to patients suffering from raised
intraocular pressure (glaucoma) and convergence insufficiency, as well
as in diseases associated with hyperlipidemia (high lipids/fats) such as
ischaemic heart diseases and arteriosclerosis (stiffening of the
arteries).
Botanically called Solanum melongena, garden egg or
bitter tomato is an economic flowering plant belonging to the family
Solanaceae.
The study on garden egg and glaucoma is titled
“Effects of Solanum melongena (garden egg) on some visual functions of
visually active Igbos of Nigeria.”
The study was published in
Journal of Ethnopharmacology by S. A. Igwe of the Department of
Pharmacology and Therapeutics, College of Medicine and Health Sciences,
Abia State University, Uturu, Dora N. Akunyili of the Department of
Pharmacology and Therapeutics, University of Nigeria Teaching Hospital,
Enugu; and C. Ogbogu of the School of Optometry, Abia State University,
Uturu.
The effects of bolus consumption of 10 gram of S.
melongena were undertaken on visually active male volunteers so as to
determine its ocular complications. Results of the study showed that
the pupil size was reduced (23 per cent), Near Point of Convergence
(NPC) was decreased (nine per cent) and the Anecortave Acetate (AA) was
increased (22 per cent) and the intraocular pressure dropped by 25 per
cent while there was no effect on Visual Acuity (VA), and the habitual
phoria. Anecortave (rINN) is a novel angiogenesis inhibitor used in the
treatment of the exudative (wet) form of age-related macular
degeneration (blindness).
The miotic effect lowered the
intraocular pressure appreciably and the reduced NPC, which was still
within normal range, did not produce any vision discomfort. The
increased AA and convergence excess positively correlated provide an
efficient visual mechanism.
The researchers concluded: “It is
suggested that S. melongena would be of benefit to patients suffering
from raised intraocular pressure (glaucoma) and convergence
insufficiency.”
Also, two earlier studies published in Archives
of Ophthalmology offer hope of reducing risk of blindness due to
Age-related Macular Degeneration (AMD) and cataract.
Three
leading causes of blindness are age-related macular degeneration,
diabetic retinopathy, and retinopathy related to premature birth. All
three conditions involve retinopathy, which is the abnormal development
of blood vessels in the eye.
Researchers have found that regular
consumption of fish; nuts, olive oil and other foods containing
omega-three fatty acids and avoiding trans-fats may significantly lower
the risk for AMD.
Food sources of omega-3s include leafy green
vegetables, walnuts, flaxseeds and fatty fish such as salmon, herring
and sardines. Omega-6s are found in meat and vegetable oils such as
safflower oil, sunflower oil, corn oil, and soy oils.
Previous
studies have shown that extracts of carrots, garlic, pumpkin (Ugu in
Igbo), amaranth (commonly called green vegetable) aniseed, almonds
contain antioxidants that may decrease the development or progression of
cataract.
Several research studies show that the antioxidant
properties of vitamins C and E contained in these plants may protect
against the development and progression of cataracts.
Early
evidence also suggested that the carotenoids lutein and zeaxanthin,
which are also antioxidants, might also be protective against cataracts.
Some recent studies compared diet and supplement intake of the
antioxidant vitamins C and E with the development of cataracts. However,
naturopaths recommend eating plenty of fruits and vegetables.
IOP is the pressure within the eyeball as a result of the constant
formation and drainage of the aqueous humour. It is the internal
pressure of which allows the eye to hold on to its shape and function
properly. Intraocular pressure is controlled primarily by the rate of
secretion or rate of drainage of the aqueous humour. These will be
building up pressure leading to increased risk of optic nerve damage, a
pathological condition called glaucoma.
Glaucoma is rated as the
second leading cause of vision loss worldwide. It is also estimated
that 66.8 million people are affected by glaucoma worldwide and 6.7
million are bilaterally blind because of the disease. It was said to
affect individuals of all age groups but is more prevalent after the
fourth decade of life.
Glaucoma is a leading cause of
irreversible blindness. The progression of this disease can be reduced
or stopped by lowering IOP with medication and surgery. Among the
several options available for medical therapy of elevated IOP, topical
b-blockers and the prostaglandin F2á analogs, such as latanoprost, are
the most commonly prescribed first-line therapies?
In Nigeria,
the most commonly available IOP reducing agents are beta-blockers
(mainly timolol maleate 0.5 per cent eye drops) and prostaglandins
(mainly latanoprost 0.005 per cent). Latanoprost 0.005 per cent is more
effective than timolol maleate 0.5 per cent in reducing diurnal IOP
fluctuations. This is clinically important because optic nerve damage is
accelerated by IOP fluctuations.
However, both drugs are
expensive and there is poor compliance with long-term use in Nigerian
patients. Several studies have compared the efficacy of other topical
glaucoma treatments in various settings. The current challenge was to
search for an alternative medication that is affordable, available and
effective in lowering IOP in a limited resource economy.
A
recent study reported a reduction in subchondral pressure and pain in
knee osteoarthritis due to bitter kola. Bitter kola has also proven safe
in human eyes and its systemic blood pressure lowering effects has been
published in previous studies.
The researchers wrote: “During
the initial stages of this study, Alcon Research Laboratories Inc United
States of America (U.S.A.), was consulted to perform chromatography and
pharmacodynamics analyses of the Garcinia kola nut extract. Results of
analyses indicated that Garcinia kola extract inhibits the active
process of aqueous secretion mediated through selective ion transport
across basolateral membranes of non-pigmented ciliary epithelium.
The enzymes involved in the transport are sodium potassium activated
adenosine triphosphate and carbonic anhydrase. Some have proposed the
IOP lowering activity of Garcinia kola is a combination of a
vasodilation effect, which reduces aqueous production through the
lowering of perfusion pressure, and a miotic effect, which increases
outflow facility.
The researchers wrote: “The aim of this study
was to compare the efficacy and safety of G. kola 0.5 per cent aqueous
eye drops to that of timolol maleate 0.5 per cent in newly diagnosed
patients with primary open-angle glaucoma (POAG) or ocular hypertension
(OH). The primary outcome measure was the change in IOP over 24 weeks.”
The researchers said the results of the current study indicate that
Garcinia kola 0.5 per cent aqueous eye drops are as effective as timolol
in reducing IOP in newly diagnosed patients with POAG or OH.
Additionally, the outcomes confirm the efficacy of timolol among
Nigerians with POAG and OH. Timolol and G. kola aqueous eye drops were
effective in the reduction of IOP at 6, 12 and 24 weeks. G. kola had a
significant IOP lowering effect at 12 weeks compared to timolol.
Chromatography has established that G. kola extracts have similar
features to some commonly used glaucoma medications.
They
explained: “In the G. kola group, IOP reduction from baseline to the
sixth week was approximately 24 per cent and 25 per cent in the
timolol-treated eyes. The mean IOP reduction at six months in the G.
Kola group and timolol-treated eyes was 47.8 per cent and 48.2 per cent,
respectively with no statistically significant difference between
groups.
“The significantly greater IOP lowering effect after six
weeks of treatment was due to poor drug compliance initially in the
majority of subjects. Most subjects exhausted their assigned drug
earlier than expected and stopped further treatment a few days prior to
the upcoming follow up. Hence the IOP reduction was minimal six weeks
into the study compared to subsequent visits.
“Furthermore,
subjects did not contact the study coordinator for additional medication
because they felt that the treatment had no effect. However, they were
counselled on the importance of continuing medication regardless of
their perceptions for the duration of the study and there was better
compliance from six weeks onwards.
“Since glaucoma has been
found to be one of the leading causes of blindness worldwide the need
for cheaper and acceptable adjuvant remedy becomes necessary Therefore
ingestion should be encouraged as an adjuvant in the treatment of
glaucoma.”