Lack of in vitro antihyaluronidase activity of methanolic leaf extract of Indigofera tinctoria L and methanolic stem bark extract of Stereospermum suaveolens DC

Abstract

Objective: To assess the antihyaluronidase activity of methanolic leaf extract of Indigofera tinctoria L (I. tinctoria) (family: Fabaceae/Leguminosae) and stem bark extract of Stereospermum suaveolens DC (S. suaveolens) (family: Bignoniaceae) in vitro with a view to develop an antiaging skin formulation. Materials and Methods: The antihyaluronidase activity of different concentrations (0.19 mg/mL, 0.38 mg/mL, 0.75 mg/mL, 1.5 mg/mL, and 3.0 mg/mL) of methanolic leaf extract of I. tinctoria, methanolic stem bark extract of S. suaveolens, and reference drug epigallocatechin gallate (EGCG) of different concentrations (12.5 μg/mL, 25 μg/mL, 50 μg/mL, 100 μg/mL, and 200 μg/mL) were determined spectrophotometrically using hyaluronic acid (from rooster combs) and bovine testicular hyaluronidase. Results: There is no in vitro antihyaluronidase activity in the methanolic extracts of I. tinctoria leaves and S. suaveolens stem bark even at high concentrations. On the contrary, EGCG, the reference agent, showed marked concentration-dependent (r2 = 0.92) antihyluronidase activity [in terms of percentage inhibition: half maximal inhibitory concentration (IC 50 ) 92.64 ± 0.64 μg/mL]. Conclusion: It is unlikely that skin antiaging effects of I. tinctoria leaves and S. suaveolens stem bark, as claimed in traditional and folk medicines in Sri Lanka, are mediated via antihyaluronidase activity.