Nutraceutical and Functional Food Potentials of African Ebony (Diospyros mespiliformis) Tree Fruit Pulp

Abstract

Diospyros mespiliformis is an underutilized plant found in Northern Nigeria, reported for treatment of diseases. This study aimed to evaluate the antidiabetic and antioxidant potentials of Kano grown D. mespiliformis fruit pulp and its phytochemical profiles. The fruits were air dried, grounded into fine powder and proximate composition was determined. Extracts of aqueous, 50%, 60%, 70%, 80%, 90% and 100% ethanol were prepared. Alpha-glucosidase and α-amylase inhibition assays, total phenolics content (TPC), total flavonoids content (TFC) and DPPH radical scavenging assays were evaluated using standard methods. Phytochemical profiles of extracts were analyzed using liquid chromatographic mass spectrometry. The ash, crude fiber, protein, fat, total carbohydrate and moisture contents on dry weight basis were 6.3 ± 0.20%, 4.1 ± 0.72%, 6.9 ± 0.08%, 7.7 ± 0.02%, 66.2 ± 0.80% and 8.8 ± 0.23% respectively. The 60% ethanol gave the highest extraction yield, while the aqueous extract was the lowest. The inhibition assays indicated that 50% ethanol extract with IC₅₀ of 149.4 mg/mL had the highest inhibition against α-glucosidase activity while that of standard acarbose was 144.3 mg/mL. The 100% ethanol extract with the IC₅₀ value 299.58 mg/mL showed the highest inhibition against α-amylase activity, while that of standard acarbose was 228.9 mg/mL. The DPPH assay indicated that both 50% and 60% ethanol extracts, IC₅₀ values 150.1 ± 0.58 mg/mL and 150.6 ± 0.32 mg/mL respectively, had the highest antioxidant capacity, while that of standard ascorbic was 88.24 ± 0.21 mg/mL. Also, 50% ethanol gave the highest TPC, 167.22 ± 1.11 mg GAE/g, but the 60% ethanol gave the highest TFC (40.2 ± 1.60 mg GAE/g). Bioactive phytochemicals belonging to flavonoids, terpenoids, shogaols, allicin, linalool, and unsaturated fatty acids with health promoting effects were identified with their suggested names. Therefore, D. mespiliformis fruit pulp may be a good raw material for functional food and nutraceuticals against diabetes mellitus, oxidative stress and other chronic diseases.