Inhibition of monoamine oxidase A (Mao-A) enzyme by some medicinal herbs

Monoamine oxidase (MAO) is a flavin-containing enzyme responsible for the metabolism and regulation of neurotransmitter amines and plays a role in neuropsychiatric disorders such as depression and mania. In this study, the inhibitory effects of different concentrations of solutions prepared using distilled water, ethanol, ethyl acetate, petroleum ether, and mixed extracts of Hypericum perforatum, Ginkgo biloba , Lavandula angustifolia, Zingiber officinale, Tilia tomentosa., Cinnamomum aromaticum, Menthae piperita, Thymus cherlerioides, Portulaca oleracea, Trachystemon orientalis, Allium sativum, Petroselinum crispum, and Spinacia oleracea were investigated on monoamine oxidase obtained from rat liver. It was determined that the best inhibitor plant extract for MAO, which has a value of IC₅₀, was 0.071 mg/mL and with a ratio of inhibition of 70.15% ethanol extract of Hypericum perforatum. Following H. perforatum, the best inhibition effects were observed with the ethanol extract of Spinacia oleracea (IC₅₀ = 0.074 mg/mL), Ginkgo biloba (IC₅₀ = 0.075 mg/mL), Allium sativum (IC₅₀ = 0.080 mg/mL), and the distilled water extract of H. perforatum (IC₅₀ value of 0.081 mg/mL), respectively. The findings demonstrate that these species can inhibit the enzyme, highlighting their potential as therapeutic agents for neurological disorders.