Antioxidant and anti-diabetic activities in commercial and homemade pomegranate molasses in Lebanon

Pomegranate fruit and its derived products are rich sources of bioactive compounds. They have many biological activities. Pomegranate molasses (PM) is a thick, traditional Middle Eastern syrup used in many recipes for Lebanese and international cuisines. It is a highly nutritious product which makes it of great interest. The purpose of this study was to assess the phytochemical composition, antioxidant and anti-diabetic properties of homemade and commercial PM consumed in Lebanon using samples collected from households in rural areas (n = 4) and the market (n = 28). The objectives of this study were to determine their total phenolic content using the Follin-Ciocalteu method, their total flavonoid content using aluminum chloride method, their antioxidant activity using DPPH radical scavenging as well as ferrous ion chelating assays and their anti-diabetic activity using α-amylase and α-glucosidase inhibitory activities with acarbose, a known anti-diabetic drug, used as the standard reference. Homemade PM samples exhibited a higher antioxidant activity than commercial samples, with the most active homemade PM sample having IC₅₀ values of 0.09 mg/mL (DPPH radical scavenging assay) and 46.78% ferrous ion chelating assay). Homemade PM samples also showed higher anti-diabetic activity than commercial samples, with the most active homemade PM sample having an IC₅₀ values of 0.63 mg/mL (α-amylase inhibitory activity) and of 0.41 mg/mL (α-glucosidase inhibitory activity) and being almost as active as acarbose with both enzymes (1.5 times). Significant inverse strong/moderate correlations were observed between total phenolic content/total flavonoid content and the IC₅₀ value of DPPH radical scavenging assay, indicating positive associations between total phenolic and flavonoid contents and antioxidant activity. In addition, significant negative moderate correlations were observed between total phenolic/flavonoid contents and α-amylase inhibitory activity, indicating positive associations between total phenolic and flavonoid contents and anti-diabetic activity.