African Pear |
African pear tops list of novel plants for drug-resistant malaria
Commonly called African pear, native pear or bush butter, Dacryodes
edulis belongs to the plant family Burseraceae. It called safoutier in
French. In Nigeria, it is ibe in Kalabari; boshu in Bokyi; orunmwun in
Edo (indicating something edible); ube in Ibo; orumu in Urhobo; and
elemi in Yoruba.
It is usually eaten in Nigeria with corn (maize). They go hand in hand.
The fruit is oval in shape and matures within the months of May and
July. The fruit pulp -the fleshy parts of the body- is boiled, roasted
or eaten raw as a dessert fruit. The pulp may also be boiled or roasted
to form a kind of butter.
The season for African pear, local pear or rather native pear is here
again! It is usually eaten as snack, but recent scientific findings
suggest they might provide the next best anti-malaria drug, toothpaste
and skin care product.
Researchers have identified the compounds responsible for the
anti-malarial activity of African pear, Dacryoedes edulis, and their
suitability as leads for the treatment of drug resistant malaria.
The study published in PLOS ONE is titled “New Antimalarial Hits from
Dacryodes edulis (Burseraceae) – Part I: Isolation, In Vitro Activity,
In Silico “drug-likeness” and Pharmacokinetic Profiles.”
According to the study, five compounds were isolated from ethyl
acetate and hexane extracts of D. edulis stem bark and tested against
3D7 (chloroquine-susceptible) and Dd2 (multidrug-resistant) strains of
Plasmodium falciparum, using the parasite lactate dehydrogenase method.
Cytotoxicity studies were carried out on LLC-MK2 monkey kidney
epithelial cell-line. In silico analysis was conducted by calculating
molecular descriptors using the MOE software running on a Linux
workstation.
The “drug-likeness” of the isolated compounds was assessed using
Lipinski criteria, from computed molecular properties of the geometry
optimized structures. Computed descriptors often used to predict
absorption, distribution, metabolism, elimination and toxicity (ADMET)
were used to assess the pharmacokinetic profiles of the isolated
compounds.
Anti-plasmodial activity was demonstrated for the first time in five
major natural products previously identified in D. edulis, but not
tested against malaria parasites.
The most active compound identified was termed DES4. It had IC50
values of 0.37 and 0.55 µg/mL, against 3D7 and Dd2 respectively. In
addition, this compound was shown to act in synergy with quinine,
satisfied all criteria of “Drug-likeness” and showed considerable
probability of providing an antimalarial lead.
The remaining four compounds also showed anti-plasmodial activity,
but were less effective than DES4. None of the tested compounds was
cytotoxicity against LLC-MK2 cells, suggesting their selective
activities on malaria parasites.
The researchers concluded: “Based on the high in vitro activity, low
toxicity and predicted “Drug-likeness” DES4 merits further investigation
as a possible drug lead for the treatment of malaria.”
They added: “The emergence and spread of resistance to frontline
anti-malarials is a real challenge to malaria control, which can be
addressed by expanding the arsenal of antimalarial products. Medicinal
plants are well known sources of antimalarials. Over a thousand plant
species are commonly used across Africa for prevention and/or treatment
of malaria symptoms, and some of these had been revealed as housing
uniquely effective antimalarial. The examples of quinine and artemisinin
isolated from Cinchona species and Artemisia annua -source of
Artemisinin Combination Therapies (ACTs)- are highly illustrative.
“Previous investigations demonstrated the analgesic,
anti-inflammatory, anti-allergic, anti-cancer and antimicrobial and
antimalarial activity of D. edulis, and significant anti-plasmodial
activity had also been recorded for this plant, with IC50 below 10 µg/mL
on drug resistant malaria parasites. However the bioactive ingredients
were yet to be identified. Moreover, the stem bark which is preferably
employed in Cameroonian folk medicine is still to be fully
investigated.”
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