Unsustainable harvesting of Prunus africana tree threatens prostate treatment

Close up view of the flora in the region.


Over-harvesting of Prunus africana or Red Stinkwood in the wild for its medicinal properties has experts at the World Agroforestry Centre looking at locations in Kenya to develop tree farms.

The Prunus africana tree is prized for its bark to treat prostate gland disorders. According to a World Agroforestry study, published in the January - March 2012 issue of the journal Forest, Trees and Livelihood, cultivating the tree on farms will alleviate the threat of extinction caused by unsustainable wild harvests. The study also determined how old and large the tree should be to maximize the harvest of the tree's bark.

Lead scientists, Peter Gachie and his team focused on the species that are found in natural forests in Kenya because they were assumed to be the trees' true origin. Earlier research conducted by the Centre revealed that it takes 12-15 years to produce the bark that contains the active ingredient for the remedy for prostrate disorders. The current study reveals that mid-sized trees between 30-50cm diameter at breast height and mainly 40-55 years old give the best yields of this extract.

They compared bark extracts from five different forest zones in Kenya namely Timboroa, Eburu, Kinale, Kakamega and Kobujoi. Trees from Timboroa had the highest extract yields while Kakamega and Kinale samples had the highest number of compounds. The species is a highland forest tree that can also be found on the slopes of Mount Kenya, Mt Elgon, Cherengani hills, the Aberdares and Mau ranges. Previous research examining Prunus africana populations in Madagascar, Democratic Republic of Congo (DRC), Cameroon and Kenya found that Kenya populations of Prunus africana also have the highest concentration of active ingredients.

"Kenyan populations need to be collected, conserved, and domesticated as soon as possible," Gachie adds. "Public and commercial tree breeders and companies have an opportunity to integrate as many qualities from different Prunus africana populations as possible to improve the quality of the medicinal extract."

"This study could be a step to creating a database of high yielding Prunus africana trees," he concludes. "The findings should be integrated into breeding programmes by the scientists to integrate as many qualities from different Prunus africana trees as possible to improve the quality of the medicinal extract."

The World Agroforestry Centre is doing its part preserving these trees and shrubs by holding samples of most of the species with medicinal qualities in its gene bank, researching and growing these trees in plant nurseries at its headquarters in Nairobi as well as encouraging their cultivation and conservation on farms and landscapes. The Centre's gene bank holds close to 200 species.

According to the World Cancer Research Fund International, prostate cancer is the second most common cancer in men worldwide. Around 910,000 cases of prostate cancer were recorded in 2008, accounting for around 14 percent of all new cancer cases in men. It is predicted that the number of cases will almost double (1.7 million) by 2030.



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