Ehretia asperula from Vietnam: Evaluation of genetic diversity, bioactive compound, and micropropagation

Ehretia asperula Zoll. et Mor. ("Xạ đen") is a valuable medicinal plant widely used in traditional Vietnamese medicine due to its rich content of bioactive compounds. This study investigated the phytochemical composition, antioxidant activity, and genetic diversity of samples collected from three regions in Vietnam. ITS marker and methods for quantifying secondary metabolites were used to assess the genetic diversity and chemical composition of E. asperula across different collection sites. Although ITS1 sequence analysis showed no significant genetic variation among accessions, there were notable differences in secondary metabolite content. Plants from Hoa Binh province contained the highest levels of total phenolic, flavonoids, and rosmarinic acid, followed by those from Dong Nai and Vinh Phuc provinces. Among the tested solvents, an ethanol-water (30 : 70, v/v) proved most effective for extracting the targeted compounds. In addition, a micropropagation protocol was successfully established using nodal explants from the plants collected from Hoa Binh province. Optimal surface sterilization was achieved with 0.1% HgCl₂ for 16 min. Shoots were most efficiently regenerated from nodal explants on MS medium supplemented with 3.0 mg l^-1 kinetin. Shoot proliferation was most effective on MS medium supplemented with 1.5 mg l^-1 2-isopentenyladenine, while root induction reached 100% efficiency on MS medium containing 1.0 mg l^-1 indole-3-butyric acid. These findings highlight the potential of E. asperula as a sustainable natural antioxidant source and support its continued use in traditional medicine.