Moringa oleifera trees grow well in Jamaica and their parts are popularly used locally for various purposes and ailments. Antioxidant activities in Moringa oleifera samples from different parts of the world have different ranges. This study was initiated to determine the antioxidant activity of Moringa oleifera grown in Jamaica. Dried and milled Moringa oleifera leaves were extracted with ethanol/water (4:1) followed by a series of liquid–liquid extractions. The antioxidant capacities of all fractions were tested using a 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. IC₅₀ values (the amount of antioxidant needed to reduce 50% of DPPH) were then determined and values for the extracts ranged from 177 to 4458 μg/mL. Extracts prepared using polar solvents had significantly higher antioxidant capacities than others and may have clinical applications in any disease characterized by a chronic state of oxidative stress, such as sickle cell anemia. Further work will involve the assessment of these extracts in a sickle cell model of oxidative stress.

Dioscorea spp. is known for its myriad medicinal properties. D. alata, specifically crude extracts, have displayed potent anticancer properties. However, the chemical constituents of these extracts have not been examined. The aim of this study is to determine the chemical composition and antioxidant characteristics of the active extracts from D. alata tuber. Chemoinformatic profiling of the Jamaican Dioscorea alata cultivar white yam tuber was generated by a sequential Soxhlet extraction of dried milled tuber, producing five crude extracts: hexane (E-1), diethyl ether (E-2), acetone (E-3), ethanol (E-4) and water (E-5). The analytes within the five extracts were dissolved in 0.1% DMSO and their anticancer activity was determined using DU145 prostate cancer cells. Both the acetone and the ethanolic extract were able to induce greater than 50% cell death at 50 µg/mL. The order of growth inhibition of the extracts in DU-145 cell is E3 (IC₅₀, 10.81 µg/mL) > E-4 (IC₅₀ 24.17 µg/mL) > E-1 (IC₅₀ > 100 µg/mL) ≥ E-2 (IC₅₀ > 100 µg/mL) ≥ E-5 (IC₅₀ > 100 µg/mL). Phytochemical screening of both E-3 and E-4 revealed the presence of all major classes of secondary metabolites except tannins. Resins were also absent in the E-3 extract. Phenolic quantification indicated that E-3 and E-4 possessed GAEs of 31 ± 1.1 and 72 ± 1.8 mg per g of sample, respectively. Inversely, E-3 displayed greater antioxidant capability with IC₅₀ of 82.9 µg/mL compared to E-4 (166.9 µg/mL); however, neither was comparable to citric acid (33.6 µg/mL). The extract E-3 was further isolated by HPLC into 11 fractions. Fractions 4 and 5 possessed potent cell growth inhibitory effects. GCMs of fractions 4 and 5 showed they possessed numerous saturated fatty acids with pharmacological relevance. The presence of these compounds shows potential for exploitation of D. alata extracts for pharmacological purposes.