Phenolic profile and in vitro anti-diabetic activity of acorn from four African Quercus species (Q. suber, Q. canariensis, Q. coccifera and Q. ilex)

Abstract

In this investigation we studied the phenolic profile of acorn extracts from four Quercus species. We evaluated whether the phenolic compounds could inhibit the metabolism of carbohydrates. Four different Quercus species were studied; Q. suber, Q. canariensis, Q. coccifera and Q. ilex. The total phenolic content was determined using Folin-Ciocalteu's reagent and its identification was conducted using HPLC-UVDAD. The α-amylase inhibition assay was performed using the sensitive agar diffusion method. Q. suber and Q. canariensis were characterized by the highest phenolic content (2950.98 mg EGA/g and 4380.69 mg EGA/g, respectively). Chlorogenic acid was identified as the major compound in extracts from Q. ilex, Q. coccifera and Q. suber. Whereas, Coumarin was determined as the major compound in Q. canariensis extract (44.65%). The application of Q. canariensis showed ahigher effect than that of the positive control (43.42%). This inhibition is likely due to the high polyphenol content in the acorns of this species.