Recovery of health-promoting phenolic compounds from clove basil (Ocimum gratissimum L.) by aqueous extraction and ultrafiltration

Clove basil, a medicinal plant found in tropical areas, presents significant phytochemicals with high antioxidant capacity. In this study, we investigated the extraction kinetics of phenolic compounds from clove basil leaves, followed by the concentration and purification of the extract by ultrafiltration. The extraction profile followed the pseudo-second-order kinetic model and the maximum total phenolic content (TPC) of 320.29 ± 1.82 mg of gallic acid equivalents (GAE) per g of dried extract (mg_GAE g⁻¹) was achieved after 120 min of aqueous extraction at 75 °C and solid: liquid ratio of 1:100. The DPPH assay revealed an antioxidant capacity of 2493.54 ± 77.61 µmol of Trolox equivalent (TE) per g of dried extract (µmol _TE g⁻¹) for the clove basil extract. The aqueous extract presented concentrations of 22.18 ± 0.16 and 5.96 ± 0.34 mg g⁻¹ for rosmarinic and chlorogenic acids, respectively, and significant quantities of other phenolic acids. Ultrafiltration through a 10 kDa polymeric membrane was efficient in producing a clear permeate stream by reducing 64.82 ± 7.77 % of total solids and 84.01 ± 1.13 % of turbidity. The membrane filtration retained 76.80 ± 0.59 % of polyphenol compounds and 52.52 ± 0.04 % of rosmarinic acid. Thus, the ultrafiltration process is an appropriate alternative for recovering and concentrating bioactive molecules from clove basil leaf extract.