Inhibition of melanin production and tyrosinase activity by flavonoids isolated from Loranthus acutifolius

Abstract

Activity-guided fractionations of leaves and stems from Loranthus acutifolius led to the isolation of 2',4',6-trimethoxyflavone (1), 3',4',5-trihydroxy-6,7,8-trimethoxyflavone (2), 2'4'-dihydroxy-6'-methoxy-chalcone (3) and 4',5-dihydroxy-6,7,8-trimethoxyflavone (4). The potential for inhibition against melanin production and tyrosinase activity of these 4 compounds was tested in B16-F10 cells. 2',4',6-trimethoxyflavone, 3',4',5-trihydroxy-6,7,8-trimethoxyflavone, 2'4'-dihydroxy-6'-methoxy-chalcone and 4',5-dihydroxy-6,7,8-trimethoxyflavone showed an inhibitory activity of melanin production with IC₅₀ of 3.6 ± 0.05 μM, 8.1 ± 0.05 μM, 1.6 ± 0.03 μM and 6.5 ± 0.05 μM, respectively. In addition, 2',4',6-trimethoxyflavone, 3',4',5-trihydroxy-6,7,8-trimethoxyflavone, 2'4'-dihydroxy-6'-methoxy-chalcone and 4',5-dihydroxy-6,7,8-trimethoxyflavone were able to inhibit tyrosinase activity with IC₅₀ of 4.0 ± 0.03 μM, 11.3 ± 0.05 μM, 5.7 ± 0.02 μM and 8.6 ± 0.04 μM, respectively. This is the first time that these compounds are reported in the L. acutifolius species showing anti-melanogenic activities.

GRAPHICAL ABSTRACT

KEYWORDS:

• Loranthus acutifolius
• Lorathaceae
• flavonoids
• tyrosinase
• melanin
• B16-F10 cells

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This research project was supported by the National Herbarium of Bolivia, the Fundación de la Universidad Autónoma de Madrid (FUAM).