STAR APPLE BARK PROVIDES ANTI-MALARIA DRUG

The bark of African star apple has been
shown to be more effective than
chloroquine in treating malaria without
any toxic side effects.
IT is time to savour the African star apple or
rather local cherry. The brownish fruit
(when ripe) of this local delicacy is on
display in almost all the markets especially
in southern Nigeria. African cherry is
synonymous with harmattan. It is usually
harvested or rather the plant sheds its fruits
during the season.
African star apple, also known as
Chrysophyllum albidum belongs to the
family Sapotaceae. The plant is known as
udara in Igbo and agbalumo in Yoruba.
The fruit of African star apple has been
found to have a very high content of
ascorbic acid (Vitamin C) with 1000 to 3,300
mg of ascorbic acid per 100 g of edible fruit
or about 100 times that of oranges and 10
times that of guava or cashew.
Also, several other components of the tree
including the roots and leaves are
reportedly used for medicinal purposes.
Until now, the bark is used as a remedy for
yellow fever and malaria while the leaves
are used as emollients and for the treatment
of skin eruption, diarrhoea and
stomachache. Eleagnine, an alkaloid isolated
from C. albidum seed cotyledon has been
reported to have anti-nociceptive, anti-
inflammatory and antioxidant activities.
But a new study published recently in
Journal of Physiology and Pathphysiology
suggest that the extracts of the bark of
African star apple could provide the next
best anti-malarial drug. Indeed, the extract
was found to be more effective than
chloroquine in treating malaria.
The study titled “Anti-plasmodial and
toxicological effects of methanolic bark
extract of Chrysophyllum albidum in albino
mice” was authored by E. O. Adewoye of
the Department of Physiology, College of
Medicine, University of Ibadan; A. T. Salami
of the Department of Nursing Science, Lead
City University, Ibadan; and V. O. Taiwo of
the Department of Veterinary Pathology,
University of Ibadan, Oyo State.
The researchers evaluated the anti-
plasmodial, hematological, serum
biochemical and pathological effects of
Chrysophyllum albidum methanolic bark
extract using Swiss albino male mice as
models.
According to the study, the LD50 of the
methanolic extract was 1850 mg/kg body
weight. C. albidum methanolic bark extract
(750 - 1500 mg/kg/day) exhibited
significant schizontocidal activities both in a
four-day (early) infection and in an
established (greater than seven days)
infection with a considerable mean survival
time comparable to that of chloroquine.
The LD50 is a standardised measure for
expressing and comparing the toxicity of
chemicals. The LD50 is the dose that kills half
(50 per cent) of the animals tested (LD =
“lethal dose”). The animals are usually rats
or mice, although rabbits, guinea pigs,
hamsters, and so on are sometimes used.
Schizontocides are drugs used in the
treatment of malaria, which act against
blood stage parasites. Despite the name,
formed schizonts are in fact relatively drug
resistant. The earlier parasite stages- mature
trophozoites are more drug-sensitive.
Examples of schizontocides are quinine and
artesunate.
The researchers said that the plant extract
treated mice did not develop appreciable
anaemia. This observation shows that the
methanolic extract of C. albidum contains
anti-plasmodial substance(s) which help to
reduce parasitaemia and hence the rate of
erythrocyte (red blood cell) destruction
during infection.
Plasmodial describes a protozoan of the
genus Plasmodium, which includes the
parasites that cause malaria.
According to the study, the organ and tissue
pathology during infection was milder at
low doses, compared to the untreated mice
and insignificant at higher doses of the
extract, showing that the extract is non-
toxic. It also validates the local consumption
of the extracts of C. albidum as an anti-
malarial agent.
Indeed, the results from this investigation
suggest that the methanolic extract of the
bark of C. albidum has anti-plasmodial
activities and is non-toxic to mice when
administered even at 1,500 mg/kg/day. It,
however, appears to be more effective at a
dose of 1,000 mg/kg/day.
An earlier study on the life span of the mice
infected with Plasmodium berghei berghei
revealed that it is between the seven to 10
days post-innoculation. This is in line with
the drug treatment employed both in the
suppressive and established or Rane test in
this study. This time frame was used in
order to prevent the death of animals
before the end or drug treatment regime
during the experiment.
It had been reported that plants whose
phyto-chemical compounds include
alkaloids, anthraquinones and saponins
may have antimalarial activities. These
reports are similar to those obtained in this
study as methanoic bark extract of C.
albidum contains alkaloids, anthraquinones,
saponins, cardenolides and tannins. These
phytochemical compounds were also similar
to those reportedly found in the leaves and
stems of C. albidum.
Saponins have been found to have
antiprotozoan activities as well as possible
defaunating agents in the rumen. This
property has been exploited in the
treatment of protozoal infections in other
animals. Triterpenoid and steroid saponins
have been found to be detrimental to
several infectious protozoans, one of which
is Plasmodium falciparum.
This report supports what was observed in
this experiment both in the suppressive and
established infections. The mechanism of
action by which saponins work, might be
through their toxicity to protozoans, which
may be widespread and non-specific. It
might also be as a result of their detergent
effect on the cell membranes.
C. albidum has also been found to contain
alkaloids and these have been associated
with medicinal uses for centuries, though
other possible roles have not been
examined. One of the most common
biological properties of alkaloids is their
toxicity against cells of foreign organisms
like bacteria, viruses and protozoans to
which malaria parasites belong. These
activities have been widely studied for their
potential use in the elimination and
reduction of human cancer cell lines.
Alkaloids also possess anti-inflammatory,
anti- asthmatic and anti-anaphylactic
properties with consequences of altered
immunological status in vivo. The
significant reduction in parasitic load in
infected mice treated with methanolic
extract of C. albidum prevented rapid
destruction of parasitized red blood cells
and development of mild and insignificant
anaemia on days five and seven.
The results also show that chloroquine at 10
mg/kg/day is equally effective in
prevention of anaemia due to its anti-
protozoan effect in infected mice. It is
noteworthy, however, that all the infected
mice treated or untreated developed
leucocytosis, which was most severe in
mice treated with chloroquine. The
leukocytosis may be an indication of
enhanced granulopoiesis and
lymphocytosis as cellular and humoral
responses, respectively to the protozoan
infection. This is corroborated by enhanced
serum globulin levels (hyperglobulinemia)
and reactive spleens in infected mice in this
study.