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α-Glucosidase inhibitors (AGIs) represent a class of oral antidiabetic drugs that delay the absorption of ingested carbohydrates, reducing the postprandial glucose and insulin peaks to reach normoglycaemia. In this study, a bioassay-guided fractionation of the ethanolic extract of the aerial parts of Achillea fragrantissima (Forssk.) Sch. Bip. growing in Egypt led to the isolation of a new potent AGI; acacetin-6-C-(6″-acetyl-β-D-glucopyranoside)-8-C-α-L-arabinopyranoside (5) alongside with four known compounds: chondrillasterol (1), quercetin-3,6,7-trimethyl ether (chrysosplenol-D) (2), isovitexin-4'-methyl ether (3) and isovitexin (4). The structure of the new compound (5) was elucidated on the basis of its spectral data, including HR-FAB-MS, UV, (1)H NMR, (13)C NMR, (1)H-(1)H COSY, HSQC and HMBC. The new compound (5) exhibited the most significant α-glucosidase inhibitory activity (IC₅₀ 1.5 ± 0.09 μg/mL). Under the assay conditions, all the tested compounds were more potent than the positive control acarbose (IC50 224 ± 2.31 μg/mL).

Essential oils obtained by steam distillation from the aerial parts of Achillea fragrantissima (Forssk.) Sch. Bip. and the flower, leaf and stem of A. santolina L. as well as their lipophilic constituents obtained by solvent extraction were analysed using GLC and GLC-mass spectrometry. Nineteen constituents in the essential oil of A. fragrantissima were identified, in addition to 41 compounds from its n-hexane-ether extract. The hydrodistilled oil and the solvent extract contain santolina alcohol, artemisia alcohol, artemisia ketone, cis-thujone and trans-thujone as major constituents. In A. santolina altogether 54 volatile components were detected. The major components were 1,8-cineole, fragranol, fragranyl acetate and terpin-4-ol. Furthermore, the essential oils and the n-hexane-ether extracts of the two plants were screened for their antimicrobial activity.