*Article* **Ecofriendly Validated RP-HPTLC Method for Simultaneous Determination of the Bioactive Sesquiterpene Coumarins Feselol and Samarcandin in Five** *Ferula* **Species Using Green Solvents**

**Maged S. Abdel-Kader 1,2,\*, Mohammed H. Alqarni 1, Sura Baykan 3, Bintug Oztürk 3, Mohammad Ayman A. Salkini 1, Hasan S. Yusufoglu 4, Prawez Alam <sup>1</sup> and Ahmed I. Foudah <sup>1</sup>**


**Abstract:** An environmentally friendly unreported rapid and simple reverse-phase high-performance thin-layer chromatography (RP-HPTLC) has been designed for the simultaneous determination of bioactive sesquiterpene coumarins feselol and samarcandin in the methanol extract of five *Ferula* species. The method was developed using glass plates coated with RP-18 silica gel 60 F254S and a green solvent system of ethanol–water mixture (8:2 *v*/*v*) as mobile phase. After development, the plates were quantified densitometrically at 254 for feselol and samarcandin. Feselol and samarcandin peaks from methanol extract of five *Ferula* species were identified by comparing their single band at Rf = 0.43 ± 0.02 and Rf = 0.60 ± 0.01, respectively. Valid linear relationships between the peak areas and concentrations of feselol and samarcandin in the range of 1000–7000 ng/band respectively were obtained. The method was subjected to the validation criteria of the international conference on harmonization (ICH) for precision, accuracy, and robustness. The new method provides an analytical tool to enumerate the therapeutic doses of feselol and samarcandin in herbal formulations and/or crude drugs. The obtained results indicated that *F. drudeana* was the richest species in the more active samarcandin, with 0.573% *w*/*w*, while *F. duranii* had the largest quantity of the less active feselol, 0.813% *w*/*w*. *F. drudeana* was superior to the other species in the sum of the two active compounds, 1.4552% *w*/*w*, and was consequently expected to be the most active aphrodisiac among the five studied species.

**Keywords:** feselol; samarcandin; *Ferula*; HPTLC; ICH guidelines; quantitative
