Bioassay-Guided Phytochemical Investigation of Vietnamese Vitex rotundifolia Leaves and the Liverwort Ptychanthus striatus as Sources of SARS-CoV-2 Main Protease Inhibitors. - Nguyen HT; Tran TD; Duong TH; Bui TH; Pham NK; Pham MD; Phan HT; Mai DT; Pathummanee W; Pham DD; Jamnongkan T (Molecules (Basel, Switzerland), 2026)