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 (IC50)
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