Phenylpropanoids and flavonoids from Phlomis kurdica as inhibitors of human lactate dehydrogenase.

Two flavonoids, jaceosidin 7-O-β-d-glucopyranosyl-(1→2)-β-d-glucopyranoside (1) and hispidulin 7-O-β-d-glucopyranosyl-(1→2)-β-d-glucopyranoside (2), and one phenylpropanoid, 3,3'-dimethyl-lunariifolioside (3), along with 11 known compounds (4-14), were isolated from the aerial parts of Phlomis kurdica growing in Jordan. Structures of 1-3 were elucidated on the basis of spectroscopic data. These isolated compounds were assayed for their inhibitory activity against isoform 5 of human lactate dehydrogenase. Compound 4, luteolin 7-O-β-d-glucopyranoside, showed an IC50 value comparable to that of galloflavin, used as reference compound. Docking studies were carried out to hypothesize the interaction mode of compound 4 in the enzyme active site.