Elucidation of chemical compounds in different extracts of two Lavandula taxa and their biological potentials: Walking with versatile agents on the road from nature to functional applications

Due to their health-promoting and nutraceutical properties, lavenders are frequently employed in the food and pharmaceutical industries. Here, we focused on investigate the chemical profile of hexane, MeOH, and water extracts of leaf, flower, and root of L. pedunculata and L. stoechas and to assess their antioxidant, enzyme inhibitory, and antibacterial properties. The highest total polyphenolic and flavonoids contents were recorded from the water and MeOH extracts of the leaf and flower of L. stoechas, respectively. Our HPLC/MS/MS analysis detected over 90 secondary metabolites, consisting of both known and novel terpenoids, polyphenols, flavonoids, and their derivative. Water leaf extract of L. stoechas displayed significantly (p < 0.05) the highest antiradical, Cu2+ and Fe3+ reducing capacity while hexane extract of the leaf and MeOH extract of the flower of L. pedunculata revealed the best metal chelating ability and total antioxidant activity respectively. The hexane extract of the leaf of L. pedunculata exerted the highest acetylcholinesterase and tyrosinase inhibition activity, whereas the hexane extracts from L. stoechas leaf and L. pedunculata root recorded the highest ability to inhibit the butyrylcholinesterase and ⍺-amylase enzymes respectively. The water extracts of the leaf of the two species, besides the hexane extract of the leaf of L. pedunculata exerted the best inhibition effect against the α-glucosidase. The sensitivities of Gram-positive and Gram-negative bacteria species against different extracts at two different concentrations were tested based on agar well diffusion assay. According to the result, we found that the n-hexane extract of L. stoechas-flowers showed the highest antibacterial activity. In conclusion, the results suggest that both Lavandula species have promising potential as sources of bioactive agents for various industrial applications.