Phytochemical analysis and antibacterial activity of extracts from Palestinian Aleppo pine seeds, bark and cones

Abstract

Pinus halepensis (Aleppo pine) is one of the most common trees that are known for their medicinal and economic importance in the Mediterranean region. This work aimed to determine the total phenolic, flavonoid and lipid contents, as well as to study the antioxidant and antibacterial activities of extracts obtained from different parts (cones, bark and seeds) of Pinus halepensis trees cultivated in Palestine. Two extraction techniques (maceration and Soxhlet) using thee different solvents (ethanol, 80 % methanol and hexane) were applied. The results showed that among all extracts, methanolic extract of cones had the highest total phenolic content (431.38 mg equivalent gallic acid/g extract) and the best total flavonoid content (193.25 mg catechin equivalent/g extract) and demonstrated the highest antioxidant activity with EC50 of 1.48 µg/mL. The highest total lipid content using hexane as extraction solvent was found for the extract from seeds (30.1 %). The antibacterial activity of the extracts was studied using agar dilution method against Shigella, Escherichia coli and Staphylococcus aureus. Solutions of the obtained extracts with the concentration range of 10-5 to 10-2 g extract/mL in 20 % aqueous DMSO exhibited 15-80 %, 20-80 % and 20-95 % bacterial inhibition of Shigella, Escherichia coli and Staphylococcus aureus, respectively.