Cytoprotective effect of Fridericia chica (Bonpl.) L.G. Lohmann extract associated with geranylgeraniol enriched-fraction from Bixa orellana L. on epithelial cells treated with bisphosphonate.

Bisphosphonates are drugs used to treat bone disorders. The chronic use of bisphosphonates is associated with the occurrence of medication-related osteonecrosis of the jaw (MRONJ). Previous data reported the positive effects of Geranylgeraniol on different cell types treated with Bisphosphonates. Foregoing work done by our research group demonstrated the wound healing capacity of Fridericia chica (Bonpl.) L.G.Lohmann standardized ethanol extract. Herein in vitro cytoprotective synergistic effect of the association of F. chica extract associated with an enriched geranylgeraniol fraction on keratinocytes exposed to zoledronic acid is reported. An association of F. chica at 1 and 5 µg/mL with geranylgeraniol at 15 µg/mL, increased cell viability by 73.5% and 71.1%, respectively. This treatment did not increase tumor cells viability; whereas the clonogenic potential assessment showed that, the association with F. chica (5 µg/mL) reversed the effects of zoledronic acid on the cells. This study provides data for a potential treatment for MRONJ.

EGFR-targeted prodrug activation using bioorthogonal alkene-azide click-and-release chemistry.

Epidermal growth factor receptor (EGFR) is overexpressed in many cancers and therefore serves as an excellent target for prodrug activation. Functionalised trans-cyclooctenes (TCO) were conjugated to an EGFR antibody (cetuximab), providing a reagent for pre-targeting and localisation of the bioorthogonal reagent. The TCOs react with a 4-azidobenzyl carbamate doxorubicin prodrug via a [3 + 2]-cycloaddition and subsequent self-immolation leads to release of doxorubicin (click-and-release). In vitro cell-based assays demonstrated proof-of-concept, that cetuximab conjugated to highly strained TCO (AB-d-TCO) could bind to the EGFR in a melanoma cell line, and selectively activate the doxorubicin prodrug. In a non-EGFR expressing melanoma cell line, no significant prodrug activation was observed. In vivo experiments using this combination of AB-d-TCO and the azido-doxorubicin prodrug in a murine melanoma model revealed no significant anti-tumour activity or increased survival, suggesting there was insufficient prodrug activation and drug release at the tumour site.