Self-assembled Natural Product-based Carrier-free Nanoplatforms for Efficient Bioactivity

Natural products featured by an abundant molecule skeleton and structural complexity exhibit extensive pharmacological or biological activities. Thus, natural active ingredients are an important source of drug research and development. However, the inherent defects, including low solubility, low bioavailability, and unacceptable off-target toxicity, affect their development into clinical drugs. Recently, carrier-free supermolecule nanodrugs have attracted considerable attention. These nanodrugs are self-assembled by pure drugs mainly through hydrophobicity, hydrogen bond, π-π stacking, and electrostatic interaction, which possess a high drug loading capability, enhanced water solubility of the drugs, and synergistic therapeutic efficacy. In this review, natural product-based carrier-free nanoplatforms with self-assembly for efficient bioactivity were examined. These self-assembled natural products included triterpenoids, alkaloids, flavonoids, and anthraquinones. Moreover, the morphology of the formed nanoplatforms could be a nanosphere, nanofiber, nanorod, or fibrillar network, and they could exhibit several bioactivities, such as antitumor, anti-inflammatory, immunoregulation, and liver protection. Briefly, we analyzed the types and sources, formation mechanism, biological activity, and mode of action of the nanomedicine, and discussed the future of this field. We believe this review would provide a landscape of natural product-based carrier-free nanoplatforms.