Chemical and Functional Characterization of Extracts from Leaves and Twigs of Acacia dealbata

The purpose of this work was to evaluate the recovery of bioactive extracts from Acacia dealbata leaves and twigs and to characterize their chemical composition and functional properties. Fresh and air-dried samples were extracted by maceration at room temperature and by hot extraction at 60 degrees C using aqueous solutions of acetone, ethanol, and methanol. The highest extraction yields (14.8 and 12.0% for dried leaves and twigs, respectively) were obtained with 70% acetone, for both extraction procedures. Extracts were characterized for total phenolics content (TPC), total flavonoid content (TFC) and total proanthocyanidin content (TPrAC). Bioactive extracts with high TPC (526.4 mg GAE/g extract), TFC (198.4 mg CatE/g extract), and TPrAC (631.3 mg PycE/g extract) were obtained using maceration, a technically simple and low-energy process. The non-polar fraction of selected extracts was characterized using gas chromatography and time of flight mass spectrometry (GC-TOFMS). The main components detected were phytol, squalene, alpha-tocopherol, lupenone, and lupeol. The antioxidant activity of the extracts was characterized through DPPH and FRAP assays. Antimicrobial activity of the extracts against different bacteria was also determined. The highest DPPH and FRAP activities were obtained from dried twigs from Alcobaca (1068.3 mg TE/g extract and 9194.6 mmol Fe2+/g extract, respectively). Extracts from both leaves and twigs showed antimicrobial properties against Staphylococcus aureus, Staphylococcus epidermidis, methicillin resistant Staphylococcus aureus (MRSA), Enterococcus faecalis, Bacillus cereus, Streptococcus mutans, and Streptococcus mitis. The results obtained demonstrate the feasibility of recovering valuable components from these biomass fractions that may be further valorized for energy production in a biorefinery concept.

Automated summary

The purpose of this study was to evaluate the recovery and characterization of bioactive extracts from Acacia dealbata leaves and twigs. The results showed that using 70% acetone solution for maceration extraction yielded the highest content of phenolics, flavonoids, and proanthocyanidins. The non-polar fraction of the extracts was mainly composed of phytol, squalene, alpha-tocopherol, lupenone, and lupeol. The extracts exhibited antioxidant and antimicrobial activities. The findings demonstrate the feasibility of recovering valuable components from these biomass fractions for further utilization in biorefinery.