HPLC-DAD Phenolic Composition, Antioxidant, Anticholinesterase, Antidiabetic and Anti-quorum Sensing Properties of Bitter Kola (Garcinia kola) and Kolanut (Cola acuminata)

Background: Eating Cola acuminata and Garcinia cola nuts in African societies symbolizes in socio-cultural hospitality. They stimulate the nervous system, reduce fatigue and sleep. Objectives: To determine the phenolic composition and bioactivities of G. kola and C. acuminata. Materials and Methods: Hydro-ethanol extracts of the nuts were prepared and their phenolic profiles determined using HPLC-DAD. Antioxidant, anticholinesterase, antidiabetic, antimicrobial, antibiofilm and anti-quorum sensing properties were determined. Results: The most abundant phenolic compound was caffeic acid (105.4±0.75 mg/g) in C. acuminata and myricetin (277.2±0.90 mg/g) in G. kola. The extracts showed good antioxidant activity in five complementary assays and G. kola was more active than both α-tocopherol and BHA standards in the DPPH•, CUPRAC and ABTS•+ assays while C. acuminata was more active than only the α-tocopherol standard in the same assays. Activities were close to those of standards in the β-Carotene-linoleic acid and metal chelation assays. Both extracts had good inhibition of Butyrylcholinesterase (BChE) and Acetylcholinesterase (AChE) with IC50 values 63.27±0.98 μg/mL and 94.15±1.05 μg/mL for C. acuminata and G. kola respectively compared to 5.50±0.25 μg/mL for galantamine in the AChE assay. In the BChE assay, the inhibitory activity was higher for G. kola (IC50 = 38.66±0.80 μg/ mL) that the standard galantamine (IC50 = 42.20±0.48 μg/mL) while that for C. acuminata (IC50 = 87.31±0.77 μg/mL) was moderate. The extracts inhibited α-amylase and α-glucosidase with G. kola (IC50=18.43±0.74 μg/mL) being more active than standard acarbose (IC50=20.52±0.84 μg/mL in the α-glucosidase assay. The nuts could inhibit expression of virulence factors in Chomobacterium violaceum CV12472 by disrupting violacein production and flagellated Pseudomonas aeruginosa PA01 by disrupting swarming motility. Conclusion: The results indicate good nutraceutical potential of both nuts.