The plant is already used commonly in Asia as a flavour additive for tea and other beverages, and is in high demand as a fragrance ingredient.
And, according to findings published in the journals LWT – Food Science and Technology it shows potential for inhibiting the action of the enzyme tyrosinase which is involved in the synthesis of melanin.
Anti-browning for food
As well as having cosmetic applications, the ingredient may also be useful for food processors and manufacturers as an additive to help slow or prevent the formation of dark colours, off flavours and a loss of nutritional content, said the researchers, led by Li-chen Wu from National Chi Nan University.
The Taiwanese researchers used acetone to obtain a phenolic rich extract which they then tested for antioxidant activity.
According to their findings, the extract contained 264.7 milligrams of gallic acid equivalents per gram of extract of phenolics, and 190.7 mg of catechin equivalents per gram of extract of flavonoids, and displayed good antioxidant activity when tested in the DPPH and ABTS radical-scavenging assays.
In terms of melanin formation, in vitro studies with B16F10 cells (a mouse melanoma model) showed a reduction in tyrosinase activity and melanin formation in a dose-dependent manner.
Luteolin behind inhibitory effect
Experiments to study how the extract may affect the oxidation of tyrosine revealed that the presence of luteolin in the extract was behind the “uncompetitive inhibitory effect upon the oxidation of tyrosine”.
“We have confirmed in current study that the OFE contained substantial amounts of total phenolic compounds and flavonoids, which not only acted as tyrosinase inhibitors but also provided antioxidant activity, as revealed by the scavenging activity toward ABTS and DPPH radicals,” said the researchers.
“Our findings support that O. fragrans is a potential natural, functional antioxidant food flavour additive. Additionally, because OFE inhibits melanin formation, it appears to have potential use as an anti-browning food additive, in skin-whitening cosmetics, or as a new drug for treating melanoma,” they added.
Source: LWT - Food Science and Technology
Volume 42, Issue 9, Pages 1513-1519
“Antioxidant activity and melanogenesis inhibitory effect of the acetonic extract of Osmanthus fragrans: A potential natural and functional food flavour additive”
Authors: L. Wu, L.-H. Chang, S.-H. Chen, N. Fan, J.A. Ho