@conference{
author = "Isca, Vera and Bangay, Gabrielle and Princiotto, Salvatore and Dinić, Jelena and Pešić, Milica and Saraíva, Lucília and Afonso, Carlos and Rijo, Patrícia",
year = "2022",
abstract = "Plectranthus genus (Lamiaceae family) is widely used in traditional medicine, and the presence of
pharmacologically active compounds, specifically diterpenes, is well reported. The cytotoxic diterpene
royleanones 7α-acetoxy-6β-hydroxyroyleanone (Roy) and 6,7-dehydroroyleanone (DeRoy) are the
major compounds of P. grandidentatus Gürke (acetonic extract) and P. madagascariensis (Pers.) Benth.
(essential oil), respectively. In this work, Roy and DeRoy were investigated as potential antitumor
agents through the activation of protein kinase C (PKC) isoforms (α, βI, δ, ε and ζ) and inhibition of
the efflux pump, P-glycoprotein (P-gp). Additionally, the reactivity of Roy and DeRoy was explored
to synthesize a library of new derivatives to be also evaluated as cytotoxic agents. PKC-α, βI, δ, ε, and
ζ activation was tested on a yeast-based screening assay. Interestingly, one benzoylated derivative
showed selective PKC-δ activation, while DeRoy exhibited enhanced PKC activity in all tested
isoforms, compared to the positive control. Moreover, inhibition of P-gp activity was evaluated in
human non-small cell lung carcinoma NCI-H460 and its MDR counterpart NCI-H460/R. It was
possible to identify an analogue with P-gp inhibitory activity higher than the natural diterpenes Roy
and DeRoy, and comparable to Dexverapamil (positive control). Several other semi-synthetic
products are currently under investigation as potential chemotherapeutic agents.",
publisher = "STRATAGEM COST Action",
journal = "Abstract Book: STRATAGEM’s 5th Annual Meeting: New Diagnostic and Therapeutic Tools against Multidrug Resistant Tumours; 2022 Jun 29 - Jul 1; Coimbra, Portugal",
title = "Cytotoxic Activity of diterpenes from Plectranthus spp. for MDR cancer therapy",
pages = "73",
url = "https://hdl.handle.net/21.15107/rcub_ibiss_5622"
}