Targeting human hyaluronidase hyal-1 with natural compounds

Lengers I, Orlando Z, Brandt S, Melzig MF, Buschauer A, Hensel A, Jose J

Abstract

The physiological and pathophysiological functions of the polysaccharide hyaluronic acid (HA) depend on its chain size. Space filling, anti-inflammatory and antiangiogenic effects are triggered by high molecular weightHA (HMW HA) (>20 kDa). Its hydrolysation by hyaluronidases leads to low molecular weight HA (LMW HA) (<20 kDa), resulting in inflammatory and angiogenic effects.1 Degradation of HA is mainly catalyzed by humanhyaluronidase Hyal-1. It has been shown, that the expression level of Hyal-1 is elevated in cancer cells, like prostate or bladder tumour cells.2,3 Therefore, Hyal-1 appears to be an interesting target for drug discovery.Surface display of active Hyal-1 on Escherichia coli via Autodisplay enables the screening for potential inhibitors in a whole cell system. Based on this technique we determined the inhibitory effect of different plantextractsand natural compounds on human Hyal-1. The IC50 values of Malvae sylvestris flos, Equiseti herba, Ononidis radix and Althaea officinalis were determined between 1.4 and 7.7 mg/mL. Furthermore, the IC50values of four saponines were determined. The obtained IC50 value for glycyrrhizic acid, a known Hyal-1 inhibitor, was 177 μM. The IC50 values for the identified novel inhibitors gypsophila saponin 2, SA1641, andSA1657 were 108 μM, 296 μM and 371 μM, respectively.4 These extracts and compounds can be used as a starting point for the synthesis of new small molecule inhibitors targeting human Hyal-1.Extracts of Althaea officinalis are indicated for patients who suffer for dry cough to smooth mouth membranes. In an eukaryotic cell assay with a HaCaT keratinocyte cell line, the gene expression of hyal-1 wasdetermined after treatment with 125 μg/mL and 250 μg/mL of a root extract of Althaea officinalis for 24 h. HaCaT keratinocytes were chosen as a model cell line to represent skin and mucosal epithelial cells, consideringthe topical application of Althaea officinalis in pharmaceutical usage. It has been demonstrated, that treatment with the Althaea officinalis decreases expression of hyal-1 gene in HaCaT cells by 30 %. In conclusion,Althaea officinalis does not only inhibit the enzymatic activity of Hyal-1 but also leads to a reduced in hyal-1 expression.