Optimization of luteolin derivative extraction conditions of Avicennia officinalis L. leaf extract

Avicennia officinalis L. is a medium-sized evergreen mangrove shrub belonging to the Acanthaceae family. The leaves of this plant are widely used in traditional medicine across Asia. Recently, demand for this herb and its extracts has increased, particularly for herbal product development. This study aimed to optimize the ultrasound-assisted extraction (UAE) of A. officinalis leaves and quantify luteolin-7-O-glucuronide (L7Gn) and luteolin-7-O-rutinoside (L7R) using high-performance liquid chromatography (HPLC). The optimal UAE conditions were a liquid-to-solid ratio of 10:1, extraction with 50% ethanol for 20.4 minutes, as determined by the Box–Behnken design. Under these conditions, the extract contained 124.65 mg of L7Gn and 67.22 mg of L7R per 100 g of dried leaf powder. These optimized parameters were used to validate the quantification method. Bioactive compounds from the A. officinalis leaf extract were identified by ultra-fast liquid chromatography coupled with a diode array detector. The method was then applied to quantify L7Gn and L7R in leaf samples collected from Ngoc Hien District, Ca Mau Province, Vietnam. The ethanol extracts contained L7Gn levels ranging from 2.50 to 2.91 mg/g and L7R levels ranging from 1.58 to 1.73 mg/g. This is the first study to quantify L7Gn and L7R in A. officinalis leaves. The findings provide initial scientific evidence and establish a foundation for further research on this species.