Chemometric Analysis Based on GC-MS Chemical Profiles of Three <i>Stachys</i> Species from Uzbekistan and Their Biological Activity

The chemical composition of the essential oils (EOs) of <i>Stachys byzantina</i>, <i>S. hissarica</i> and <i>S. betoniciflora</i> growing in Uzbekistan were determined, and their antioxidant and enzyme inhibitory activity were assessed. A gas chromatography-mass spectrometry (GC-MS) analysis revealed the presence of 143 metabolites accounting for 70.34, 76.78 and 88.63% of the total identified components of <i>S. byzantina</i>, <i>S. hissarica</i> and <i>S. betoniciflora,</i> respectively. Octadecanal (9.37%) was the most predominant in <i>S. betoniciflora</i>. However, n-butyl octadecenoate (4.92%) was the major volatile in <i>S. byzantina.</i> Benzaldehyde (5.01%) was present at a higher percentage in <i>S. hissarica.</i> A chemometric analysis revealed the ability of volatile profiling to discriminate between the studied <i>Stachys</i> species. The principal component analysis plot displayed a clear diversity of <i>Stachys</i> species where the octadecanal and benzaldehyde were the main discriminating markers. The antioxidant activity was evaluated in vitro using 2,2-diphenyl-1-picryl-hydrazyl (DPPH), 2,2-azino bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS), cupric reducing antioxidant capacity (CUPRAC), ferric reducing power (FRAP), chelating and phosphomolybdenum (PBD). Moreover, the ability of the essential oils to inhibit both acetyl/butyrylcholinesterases (AChE and BChE), α-amylase, α-glucosidase and tyrosinase was assessed. The volatiles from <i>S. hissarica</i> exhibited the highest activity in both the ABTS (226.48 ± 1.75 mg Trolox equivalent (TE)/g oil) and FRAP (109.55 ± 3.24 mg TE/g oil) assays. However, <i>S. betoniciflora</i> displayed the strongest activity in the other assays (174.94 ± 0.20 mg TE/g oil for CUPRAC, 60.11 ± 0.36 mg EDTA equivalent (EDTAE)/g oil for chelating and 28.24 ± 1.00 (mmol TE/g oil) for PBD. Regarding the enzyme inhibitory activity, <i>S. byzantina</i> demonstrated the strongest AChE (5.64 ± 0.04 mg galantamine equivalent (GALAE)/g oil) and tyrosinase inhibitory (101.07 ± 0.60 mg kojic acid equivalent (KAE)/g) activity. The highest activity for BChE (11.18 ± 0.19 mg GALAE/g oil), amylase inhibition (0.76 ± 0.02 mmol acarbose equivalent (ACAE)/g oil) and glucosidase inhibition (24.11 ± 0.06 mmol ACAE/g oil) was observed in <i>S. betoniciflora</i>. These results showed that EOs of <i>Stachys</i> species could be used as antioxidant, hypoglycemic and skincare agents.