Prenylated flavonoids are a unique class of naturally occurring flavonoids that exist especially for the plant's self-defensive strategy. This special class of flavonoids increases the bioactivities of their backbone flavonoids with non-prenylation; therefore, prenylated flavonoids have more potential to be developed and utilized. The number, position and type of the prenyl group on the flavonoids backbone structure may have close relationships with the bioactivities of flavonoids. PubMed and WEB OF KNOWLEDGE® were used to search articles published in English between 1 January 2002 and 31 December 2012, which discuss the structure-activity relationship between prenylated flavonoids and their bioactivities. It is proposed that the prenyl-moiety makes the backbone compound more lipophilic, which leads to its high affinity with cell membranes. The prenylation brings the flavonoids with enhancement of antibacterial, anti-inflammatory, antioxidant, cytotoxicity, larvicidal as well as estrogenic activities. However, it is reported that the prenyl-moiety decreases the bioavailability and plasma absorption of prenylated flavonoids. The prenyl group affects the bioactivities of flavonoids in certain ways, while the action mechanisms and the structure-activity relationship as well as more in vivo studies even clinical validation trials need to be further investigated.

Background and purpose:  Icariin may be the active ingredient in Herba Epimedii, a Chinese herb commonly used for treatment of osteoporosis. The present study aims to delineate the mechanism(s) by which icariin prevents bone loss after ovariectomy (OVX) in vivo and stimulates osteoblastic functions in vitro.Experimental approach:  Ovariectomized or sham‐operated C57BL/6 mice were treated with vehicle, 17β‐oestradiol or icariin for 6 weeks. Total and trabecular bome mineral density (BMD) as well as polar stress‐strain index of distal femur were measured by peripheral computed tomography. The mRNA expressions of OPG and RANKL in tibia were studied by RT‐PCR. Interactions between the oestrogen receptor (ER) antagonist ICI182,780 and icariin were studied in UMR 106 cells. The functional transactivation of ERα and ERβ as well as ERα phosphorylation by icariin were also assessed.Key results:  Icariin suppressed the loss of bone mass and strength in distal femur and increased the mRNA expression ratio of OPG/RANKL in tibia, following OVX. Icariin increased ER‐dependent cell proliferation, alkaline phosphatase (ALP) activity, gene expression of OPG and the OPG/RANKL ratio in UMR 106 cells. Icariin did not activate ERE‐luciferase activity in UMR 106 cells, via the ERα or the ERβ‐mediated pathway, but it did increase ERα phosphorylation at Ser118.Conclusions and implications:  Our results indicate that icariin exerts anabolic effects in bone possibly by activating ER in a ligand‐independent manner. Its ability to prevent OVX‐induced bone loss without inducing uterotrophic effects supports its use as an alternative regimen for management of postmenopausal osteoporosis.

Drug delivery is a key component of nanomedicine, and conventional delivery relies on the adsorption or encapsulation of drug molecules to a nanomaterial. Many delivery vehicles contain metal ions, such as metal–organic frameworks, metal oxides, transition metal dichalcogenides, MXene, and noble metal nanoparticles. These materials have a high metal content and pose potential long‐term toxicity concerns leading to difficulties for clinical approval. In this review, recent developments are summarized in the use of drug molecules as ligands for metal coordination forming various nanomaterials and soft materials. In these cases, the drug‐to‐metal ratio is much higher than conventional adsorption‐based strategies. The drug molecules are divided into small‐molecule drugs, nucleic acids, and proteins. The formed hybrid materials mainly include nanoparticles and hydrogels, upon which targeting ligands can be grafted to improve efficacy and further decrease toxicity. The application of these materials for addressing cancer, viral infection, bacterial infection inflammatory bowel disease, and bone diseases is reviewed. In the end, some future directions are discussed from fundamental research, materials science, and medicine.