African flora has the potential to fight multidrug resistance of cancer

Abstract

Background: Continuous efforts from scientists of diverse fields are necessary not only to better understand the mechanism by which multidrug-resistant (MDR) cancer cells occur, but also to boost the discovery of new cytotoxic compounds to fight MDR phenotypes.

Objectives: The present review reports on the contribution of African flora in the discovery of potential cytotoxic phytochemicals against MDR cancer cells. Methodology. Scientific databases such as PubMed, ScienceDirect, Scopus, Google Scholar, and Web of Knowledge were used to retrieve publications related to African plants, isolated compounds, and drug resistant cancer cells. The data were analyzed to highlight cytotoxicity and the modes of actions of extracts and compounds of the most prominent African plants. Also, thresholds and cutoff points for the cytotoxicity and modes of action of phytochemicals have been provided.

Results: Most published data related to the antiproliferative potential of African medicinal plants were from Cameroon, Egypt, Nigeria, or Madagascar. The cytotoxicity of phenolic compounds isolated in African plants was generally much better documented than that of terpenoids and alkaloids.

Conclusion: African flora represents an enormous resource for novel cytotoxic compounds. To unravel the full potential, efforts should be strengthened throughout the continent, to meet the challenge of a successful fight against MDR cancers.

Figure 1

Cytotoxic terpenoids isolated from African medicinal plants with documented effects on MDR cancer cells. Alpha-hederin (1), galanal A (2), galanal B (3), jaeschkeanadiol p-hydroxybenzoate (4), 11-oxo-α-amyryl acetate (5), and elatunic acid (6).

Figure 2

Cytotoxic phenolics isolated from African medicinal plants with documented activity on MDR cancer cells. Naringenin (7), kaempferol-3,7,4′-trimethylether (8), candidone (9), 4-hydroxy-2,6-di-(3′,4′-dimethoxyphenyl)-3,7dioxabicyclo-(3.3.0)octane (10), futokadsurin B (11), gancaonin Q (12), 6-prenylapigenin (13), 6,8-diprenyleriodictyol (14), 4-hydroxylonchocarpin (15), xanthone V₁ (16), 2-acetylfuro-1,4-naphthoquinone (17), 2,2′,5,6′-tetrahydroxybenzophenone (18), isogarcinol (19), isoxanthochymol (20), guttiferone E (21), abyssinone IV (22), sigmoidin I (23), atalantoflavone (24), sophorapterocarpan A (25), bidwillon A (26), neocyclomorusin (27), 6α-hydroxyphaseollidin (28), neobavaisoflavone (29), 4′-hydroxy-2′,6′-dimethoxychalcone (30), cardamomin (31), 2′,4′-dihydroxy-3′,6′-dimethoxychalcone (32), (S)-(–)-pinostrobin (33), (S)-(–)-onysilin (34), alpinetin (35), guieranone A (36), neobavaisoflavone (37), sigmoidin H (38), isoneorautenol (39), 8-hydroxycudraxanthone G (40), morusignin I (41), cudraxanthone I (42), and excelsaperoxide (43).

Figure 3

Cytotoxic Alkaloids (44–49) and a thiophene (49) isolated from African medicinal plants with relevance to MDR cancer cells. Arborinin (44), buesgenine (45), isofagaridine (46), maculine (47), kokusaginine (48), and 2-(penta-1,3-diynyl)-5-(4-hydroxybut-1-ynyl)-thiophene (49).