The bark of African star apple has been shown to be more effective than chloroquine in treating malaria without any toxic side effects. CHUKWUMA MUANYA writes.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 udala 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.
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