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 alpha-tocopherol and BHA standards in the DPPH center dot, CUPRAC and ABTS center dot+ assays while C. acuminata was more active than only the alpha-tocopherol standard in the same assays. Activities were close to those of standards in the beta-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 mg/mL and 94.15 +/- 1.05 mg/mL for C. acuminata and G. kola respectively compared to 5.50 +/- 0.25 mg/mL for galantamine in the AChE assay. In the BChE assay, the inhibitory activity was higher for G. kola (IC50 = 38.66 +/- 0.80 mg/ mL) that the standard galantamine (IC50 = 42.20 +/- 0.48 mg/mL) while that for C. acuminata (IC50 = 87.31 +/- 0.77 mg/mL) was moderate. The extracts inhibited alpha-amylase and alpha-glucosidase with G. kola (IC50=18.43 +/- 0.74 mg/mL) being more active than standard acarbose (IC50=20.52 +/- 0.84 mg/mL in the alpha-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.

Automated summary

Nigerian nuts, G. kola and C. acuminata, have high phenolic content and exhibit antioxidant, antidiabetic, and antimicrobial activities.