Health risks from the harmful mineral elements’ extractability in the Lubumbashi’s three most used medicinal plants root barks

Background

To date, no studies have been reported on the mineral element’s extractability in medicinal plants from Lubumbashi, despite the harmful mineral element’s accumulation in medicinal plant species from this region. This study evaluates (i) the extractability of mineral elements in aqueous extracts of root barks from 3 of Lubumbashi’s most used medicinal plants and (ii) the health risk from the harmful mineral elements bioaccessibility.

Methods

Root bark powders of Oldfieldia dactyllophylla (Welw.exOliv.) J. Léonard, Phyllanthus muellerianus (Kuntze) Exell, and Securidaca longepedunculata Fresen, collected from 3 sites in the Lubumbashi region, were macerated (2 h, 6 h, 12 h, and 24 h), infused and decocted in distilled water. These extracts, corresponding crude samples (powders), and used solvent were subjected to inductively coupled plasma atomic emission spectroscopy.

Results

4 macroelements (Ca, K, Na, Mg), 6 trace elements (Co, Cu, Fe, Mn, Zn, Se), and 5 non-essential elements (Ag, Al, Cd, Pb, Ni), were detected and quantified in the crude sample of each species. Cd, Co, Fe, and Na were most extracted (82.5, 64.3, 89.8, and 55.6 % respectively) by infusion in P. muellerianus; Mg by infusion (41.3 %), and Cd by decoction (37.1 %) in O. dactylophylla; as well as Se and Co by infusion (74.6 and 55.4 % respectively) in S. longepedunculata. Mineral elements daily intake trough the studied extracts decreased in order P. muellerianus > S. longepedunculata > O. dactyllophylla, reflecting the mineral content of their crude drugs, and showing the dangerousness of P. muellerianus, known to bioaccumulate harmful minerals including Cd and Pb. Target hazard quotients (HTQ) were > 1 for Al, Cd and Pb, multiplying the non-carcinogenic toxic hazard index (HI) by 40, 22, and 32 respectively for infused, decocted and 24 h macerated P. muellerianus. However, the carcinogenic risk was significantly negligible (CR < 0.0001) for extracts of all the analyzed species.

Conclusion

Ingestion of 367 mL of O. dactyllophylla root bark aqueous extracts would be harmless, whereas extraction on the same samples of S. longepedunculata and P. muellerianus should preferably be 2 to 12 h maceration.