Virtual screening of the potential lead chemotherapeutic phytochemicals from medicinal plants has useful application in the field of in-silico modelling and computer-based drug design by orienting and scoring ligands in the active binding site of a target protein. The phytochemical investigation of the
Pterocephalus frutescens extract in n-butanol resulted in the isolation and structure elucidation of three iridoids and four flavonoids which were identified as Geniposide (
1), Geniposidic acid (
2), Nepetanudoside C (
3), Isovitexin (
4), Luteolin-7-O-glucoside (
5) Isoorientin (
6) and Orientin (
7), respectively. Molecular docking studies were used to compare the binding energies of the isolated phytochemicals at four biological cancer-relevant targets; namely, aromatase, carbonic anhydrase IX, fatty acid synthase, and topoisomerase II-DNA complex. The docking study concluded that the isolated compounds have promising cytotoxic activities, in particular, Luteolin-7-O-glucoside (
5) and Orientin (
7) which exhibited high binding affinities among the isolated compounds at the active sites of the target enzymes; Aromatase (−8.73 Kcal/mol), and Carbonic anhydrase IX (−8.92 Kcal/mol), respectively, surpassing the corresponding binding scores of the co-crystallized ligands and the reference drugs at these target enzymes. Additionally, among the isolated compounds, Luteolin-7-O-glucoside (
5) showed the most outstanding binding affinities at the active sites of the target enzymes; Fatty acid synthase, and Topisomerase II-DNA complex with binding scores of −6.82, and −7.99 Kcal/mol, respectively. Finally, the SwissADME online web tool predicted that most of these compounds possessed acceptable oral bioavailability and drug likeness characteristics.
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