Phytochemical Characterization of Low Molecular Weight Constituents from Marshmallow Roots (<i>Althaea officinalis</i>) and Inhibiting Effects of the Aqueous Extract on Human Hyaluronidase-1

Abstract

Extract RE was obtained from the roots of Althaea officinalis in a yield of 8.1%, related to the dried plant material, by extraction with MeOH–H 2 O (1:1), followed by precipitation with EtOH to remove high molecular weight constituents. Phytochemical investigation of RE revealed the presence of N -phenylpropenoyl- l -amino acid amides 1 – 5, 8% glycine betaine 6, about 9% total amino acids with proline as the main compound, and about 61% mono- and oligomeric carbohydrates with sucrose as the main compound. Further fractionation revealed the presence of a hypolaetin diglycoside ( 12 ) and four hypolaetin glycosides ( 7 – 9 and 11 ) with O -sulfocarbohydrate moieties; additionally, 4′- O -methylisoscutellarein-8- O -β- d -(3″- O -sulfo)glucuronopyranoside ( 10 ) and the diglycosylated coumarin haploperoside D ( 13 ) were identified. The hypolaetin- O -sulfoglycosides 7 – 10 are new natural products. RE inhibited the enzymatic activity of surface-displayed human hyaluronidase-1 on Escherichia coli F470 cells with an IC 50 of 7.7 mg/mL. RE downregulated mRNA expression of hyal-1 in HaCaT keratinocytes at 125 and 250 μg/mL, respectively. These data contribute to a deeper phytochemical understanding of marshmallow root extracts and to the positive influence of extracts used for therapy of irritated and inflamed buccal tissue and cough.