By Chukwuma Muanya
African star apple also known as Agbalumo (Yoruba), Udara (Igbo) in Nigeria, is associated with the dry season and has been enjoyed over the years by Nigerians as a fruit. But more studies are supporting its folklore use for treating diseases such as diabetes, heart diseases and drug resistant bacteria.
Botanically called Chrysophyllum albidum, white star apple belongs to the Sapotaceae family. It is distributed throughout the southern part of Nigeria. In Southwestern Nigeria, the fruit is called agbalumo and popularly referred to as udara in Southeastern Nigeria. Chrysophyllum albidum is a popular tropical fruit tree and widely distributed in the low land rain forest zones and frequently found in villages.
The fleshy pulp of the fruits is eaten especially as snack and its fruit has been found to have higher contents of ascorbic acid than oranges and guava. It is also reported as an excellent source of vitamins, irons, flavours to diets. The seeds are also used for local games or discarded.
Chrysophyllum albidum fruit is common in both urban and rural centres especially during the months of December to April. The fruits are not usually harvested from the trees, but left to drop naturally to the ground where they are picked.
A recent study by researchers at the Department of Biological Sciences, College of Science and Technology, Covenant University Ogun State in Nigeria showed that the local cherry fruit, African star apple (Agbalumo, Udara) lowered blood sugar and cholesterol, and could be useful in preventing and treating heart diseases.
The study titled, “Effects of ethanolic leaf extract of Chrysophyllum albidum G. on biochemical and haematological (blood-related) parameters of albino Wistar rats” was published in African Journal of Biotechnology.
Previous studies indicate that the roots, barks and leaves of Chrysophyllum albidum have been employed in folk medicine for the treatment of diseases. The bark is used for the treatment of yellow fever and malaria, while the leaf is used as an emollient and for the treatment of skin eruption, stomachache and diarrhoea. The cotyledons from the seeds of Chrysophyllum albidum are used as ointments in the treatment of vaginal and dermatological infections in Western Nigeria.
The fruit pulp is rich in Vitamin C and iron and an excellent source of raw material for industries. Tannins, flavonoids, terpenoids, proteins, carbohydates and resins are the phytochemicals that have been reported in Chrysophyllum albidum. Methanolic extract of the cotyledons from the seeds of Chrysophyllum albidum led to the isolation of eleagnine, tetrahydro- 2 -methylharman and skatole.
Eleagnine was found to be the main compound responsible for its antimicrobial activity. Eleagnine was further shown to exhibit anti-nociceptive, anti-inflammatory and antioxidant activities. The seed cotyledon has been reported to possess anti-hyperglycemic (lowers high blood sugar) and hypolipidemic (lower blood cholesterol) effects.
The researchers investigated the effect of oral administration of the leaf extract of Chrysophyllum albidum G. on biochemical and haematological parameters in albino rats for 16 days.
The researchers write: “In conclusion, the study has demonstrated that the leaf extract of Chrysophyllum albidum may not cause any adverse effect on the biochemical and haematological indices of toxicity. Moreover, the extract was found to possess anti-platelet and hypoglycemic (lowers blood sugar) properties and might be employed in the management of myocardial infarction (heart attack) and diabetes mellitus, respectively. Further investigation is needed to establish the anti-platelet property of the extract.”
Another study by researchers at the Forest Research Institute, Ibadan, Oyo State, showed that star apple leaves exhibited strong antibacterial activity against common bacteria isolates.
The study titled, “Antibacterial activity and phytochemical screening of Chrysophyllum albidum leaves” was published in Asian Journal of Food and Agro-Industry.
Preliminary phytochemical screening of Chrysophyllum albidum leaves for secondary metabolites showed the presence of tannin, anthraquinone and cardiac glycosides in the plant samples. The samples were devoid of saponin, alkaloids and reducing sugars.
The researchers write: “Biological actions are primarily due to these components in a very complicated concert of synergistic or antagonistic activities. Mixtures of such chemicals show a broad spectrum of biological effects and pharmacological properties.
“The antimicrobial properties of the plant observed in this study could be attributed to the presence of tannin, anthraquinone and cardiac glycosides. The results showed that the test organisms were susceptible to the water extracts based on their zones of inhibition, which ranged from 10 to 27 mm. Escherichia coli showed the highest susceptibility of 27. All the organisms were sensitive at all concentrations except Escherichia coli, which was not sensitive at 125 µg/mL and 250 µg/mL. The least activity 10 mm was detected at 125 µg/mL concentration with.
“The methanolic extract of Chrysopyllum albidum leaves exhibited some antimicrobial activity against all the microorganisms tested as assessed by zones of inhibition that ranged from (25±0 to 35±0.40mm).
Escherichia coli had the highest susceptibility at 250 µg/mL concentrations with zone of inhibition of 35±0.40 mm. There was increase in the zone of inhibition for Escherichia coli from 30 (±0.15) mm at 125 µg/mL to 35 (±0.40) mm and 35±0.21 at 250 µg/mg and 500 µg/mL respectively. Salmonella typhi and Shigella spp had a zone of inhibition of 35 mm at all concentrations except at 500 µg/mg where Shigella spp. which had zone of inhibition of 30 (±0.30) mm.
“These results suggest that water and methanolic extracts from the leaves of Chrysophylum albidum may contain active agent(s). This provides the basis for their folkloric use as cure for some human ailments like skin infection, diarrhoea and stomachache, which are as a result of infections and inflammatory reactions. It is suggested that more research be conducted to further isolate, identify, characterise and elucidate the bioactive compounds from Chrysophylum albidum.
“In conclusion, the result of this study justifies the traditional uses of the leaves of Chrysophylum albidum for therapeutic purposes. The findings could also be of commercial interest to both pharmaceutical companies and research institute in the production of new drugs.”
Researchers have also studied the nutritional value and mineral contents of Chrysophyllum albidum fruit. According to the study published in Journal of the Science of Food and Agriculture, fresh fruit samples, both untreated and treated with 2,4-dichlorophenoxyacetic acid, were investigated.
– Chukwuma Muanya
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