Cytotoxic evaluation and concurrent analysis of two diterpenes in the chloroform extract of Plectranthus barbatus using a validated HPTLC-UV method

The objective of this study was to develop a validated high-performance thin layer chromatography (HPTLC) method for the concurrent analysis of two diterpenes Sugiol (compound 1) and 11,14-dihydroxy-8,11,13-abietatrien-7-one (compound 2) in Plectranthus barbatus chloroform extract (PBCE) and to investigate cytotoxicity of both compounds. The chromatographic estimations were carried out using toluene : ethyl acetate : formic acid (8.2:1.3:0.5 v/v/v) as mobile phase. The compact spots of biomarkers were scanned at λ_max= 275 nm. Cytotoxic evaluation of both compounds was performed using follicular thyroid cancer cells (FRO cells). A well resolved, compact and intense peaks of compound 1 (R_f = 0.550 ± 0.001) and compound 2 (R_f = 0.700 ± 0.002) were recorded. The proposed method for both compounds was recorded as simple, linear, precise (% RSD = 1.02-1.25), accurate (98-100%), robust and sensitive for the analysis of both compounds. Cytotoxicity evaluation showed significant cell cytotoxicity at 100 μg/mL concentration against the FRO cancer cells after 72 h of incubation. Both compounds were recorded as cytotoxic, however compound 1 showed significant cytotoxic effects. The proposed HPTLC method was found to be suitable for routine analysis of these two biomarkers in chloroform extract of P. barbatus. Both compounds were found to be cytotoxic against FRO cancer cells.