Inhibitory Effects of Artemisia afra Extracts on the Bio-Activity of Banana Tyrosinase

Abstract

Melasma, formerly known as chloasma, is an acquired pigmentary condition, occurring most commonly on the face of humans. This disorder, which is more prevalent in females and darker skin types, is predominantly attributed to Ultraviolet (UV) exposure and hormonal influences. This condition is caused by an over-production of melanin, a pigment that gives color to the skin, hair, and eyes as well as protecting the skin against harmful ultraviolet radiation. The enzyme tyrosinase plays an important role in the biosynthesis of melanin from the amino acid, tyrosine. When this enzyme is inhibited, the bio-production of melanin can be limited and this bio-control of melanin synthesis could be used to manage melasma. Although several tyrosinase inhibitors are known, the search for natural inhibitors continues especially substances that do not negatively affect health. Water and methanol extractions from the stem and leaves of Artemisia afra were investigated for their potential inhibitory effect of tyrosinase extracted from the pulp and peel of bananas. The extent of tyrosinase inhibition was concluded while the enzyme was bio-converting L-DOPA into dopachrome with the amount of dopachrome produced determined spectrophotometrically at 475 nm. Both methanol and water extractions from the leaves and stem of A. afra caused an inhibition of the tyrosinase activity. It was also confirmed that bananas could be utilized as a tyrosinase resource.