Chemical profiling of Thevetia peruviana leaves cytotoxic active extracts enhanced by microemulsion formulation

Background Natural products played an essential role as a complementary cytotoxic agent avoiding complications of other therapies. In phytoformulation research, herbal drugs of nano-size have attracted more attention for more bioavailability and less active dose. We aim in this work to introduce new non-mutagenic cytotoxic agent from Thevetia peruviana leaves extracts and potentiate the activity by loading upon microemulsion formulations as an advanced mode of drug delivery system. Results Thevetia peruviana toxicity test revealed its safety (LD 50 = 3.083 g/kg). In vivo genotoxicity tests measuring chromosomal aberrations were done to prove non-mutagenicity of the plant for both somatic and germ cells. The plant showed antioxidant activity with 121.215, 128.925, and 120.098 mg/g extract, calculated as Trolox equivalent (TE/g) for DPPH, ABTS, and FRAP assays, respectively. Successive extracts of the plant were incorporated in microemulsion formulations (MEF) and characterized for their electrical conductivity, poly-dispersity index, and in vitro drug release action. Cytotoxic activity of successive extracts was investigated against breast MCF7 and liver HEPG2 carcinoma cell lines before and after loading upon MEs. Enhancement in activity was detected for both pet. ether and ethanol MEFs, as IC 50 of pet. ether extract decreased from 25 to 6.5 μg/ml against MCF7 cell line, while ethanol formulation recorded IC 50 = 3.58 μg/ml against HEPG2 cell line after showing no activity of the extract at the tested concentrations. Regarding metabolites of polar fraction, total ethanol extract was estimated for total phenolic and flavonoid contents to record 47.7941 mg GAE/g calculated as gallic acid equivalent and 32.7667 mg CE/g measured as catechin equivalent, respectively. HPLC analysis for polar fraction recorded twelve compounds identified according to the available authentics with rutin the major flavonoid (7.33 mg/g) and rosmarinic acid (13.48 mg/g) the most abundant phenolic acid. Phytoconstituents of non-polar fraction were investigated after saponification of pet. ether extract using GC/MS analysis revealed the identification of 88.02% of the total unsaponifiable matter and 89.17 % of the total saponifiable matter. Conclusion Thevetia peruviana is a safe cytotoxic agent. Microemulsion formulations of active extracts potentiate the cytotoxic actions against HEPG2 and MCF7 cell lines with better bioavailability and less medicinal doses.