Rare ginsenosides: a unique perspective of ginseng research

•Rare ginsenosides (RGs), as the shining components, possessed great potential in drugs and nutraceuticals.•A total of 144 rare ginsenosides with diverse skeletons and bioactivities were isolated from Panax species.•RGs showed superior bioactivity for cardiovascular disease and cancer, in addition, they acted as natural ligands for some specific receptors.•The stereochemistry properties of RGs brought out diverse bioactivities, together with novel analytical strategies of phytochemistry.•Physico-chemical transformation, biotransformation, and biosynthesis are now serving as promising methods for RGs production.