The α-glucosidase inhibitory activity of an aqueous extract and compounds from the aerial parts of V. corymbosa was demonstrated with yeast and rat small intestinal α-glucosidases. The aqueous extract inhibited yeast α-glucosidase with a half maximal inhibitory concentration (IC₅₀) of 28.6 μg/mL. Bioassay-guided fractionation of the extract led to the isolation of several compounds, including one cyanogenic glycoside [prunasin (1)], five flavonoids [(−)-epi-catechin (2), hyperoside (3), isoquercetin (4), quercitrin (5) and quercetin-3-O-(6′′-benzoyl)-β-galactoside (6)] and two simple aromatic compounds [picein (7) and methylarbutin (8)]. The most active compound was 6 with IC₅₀ values of 30 μM in the case of yeast α-glucosidase, and 437 μM in the case of the mammalian enzyme. According to the kinetic analyses performed with rat and yeast enzymes, this compound behaved as mixed-type inhibitor; the calculated inhibition constants (K_i) were 212 and 50 μM, respectively. Molecular docking analyses with yeast and mammalian α-glucosidases revealed that compound 6 bind differently to these enzymes. Altogether, the results of this work suggest that preparations of V. corymbosa might delay glucose absorption in vivo.

An infusion prepared from the aerial parts of Salvia amarissima Ortega inhibited the enzyme protein tyrosine phosphatase 1B (PTP-1B) (IC₅₀~88 and 33 μg/mL, respectively). Phytochemical analysis of the infusion yielded amarisolide (1), 5,6,4′-trihydroxy-7,3′-dimethoxyflavone (2), 6-hydroxyluteolin (3), rutin (4), rosmarinic acid (5), isoquercitrin (6), pedalitin (7) and a new neo-clerodane type diterpenoid glucoside, named amarisolide G (8a,b). Compound 8a,b is a new natural product, and 2–6 are reported for the first time for the species. All compounds were tested for their inhibitory activity against PTP-1B; their IC₅₀ values ranged from 62.0 to 514.2 μM. The activity was compared to that of ursolic acid (IC₅₀ = 29.14 μM). The most active compound was pedalitin (7). Docking analysis predicted that compound 7 has higher affinity for the allosteric site of the enzyme. Gas chromatography coupled to mass spectrometry analyses of the essential oils prepared from dried and fresh materials revealed that germacrene D (15) and β-selinene (16), followed by β-caryophyllene (13) and spathulenol (17) were their major components. An ultra-high performance liquid chromatography coupled to mass spectrometry method was developed and validated to quantify amarisolide (1) in the ethyl acetate soluble fraction of the infusion of S. amarissima.