Although the biggest market for skin whitening products remains Asia ($18bn according to trade event in-cosmetics Asia), demand for the products has been growing the world over on the back of the anti-ageing trend.
Furthermore, a number of the ingredients originally employed in such formulations have since been questioned on their safety, so the search for new ingredients is on.
According to scientists at the Palangkraya University, Indonesia, a number of the 14 traditionally used medicinal plants found in the remote Central Kalimantan province show antimelanogenesis activity.
Testing melanin activity
The team tested the extracts’ radical scavenging capability using the DPPH assay, their tyrosinase inhibiting action and their ability to inhibit melanin formation in B16 mouse melanoma cells.
DPPH is a popular method to screen for the antioxidant activity of plant extracts and several of the plants showed significantly potent free radical scavenging activity when compared with the alpha tocopherol used as a control.
Extracts from the root of Vitex pinnata, the aerial root of Dentdrophthoe petandra and the bark of the aerial root of Willughbeia coricea, showed the highest radical scavenging activity, according to the study.
Next the team investigated the tyrosinase inhibiting activity of the extracts. Tyrosinase is an enzyme involved in the production of melanin and many skin whitening ingredients target this enzyme in an attempt to reduce pigment production.
Total of 14 plants tested
Among the 14 plants tested it was the aerial root of the Dentdrophthoe petandra that illustrated the highest anti-tyrosinase activity at 74.3 per cent at 500 micro grams per millilitre. However, this was lower than the positive control kojic acid which showed 99.7 per cent inhibition.
In order to evaluate the effect of the extracts on the melanin synthesis in general and not concentrate solely in tyrosinase inhibition, the scientists looked at the extracts’ ability to inhibit melanin synthesis in B16 melanoma cells.
Eight of the plant extracts were found to inhibit melanin synthesis, some at low concentrations showing little toxicity, according to the study.
Combining the results the scientists conclude that the bark of the aerial root of Willughbeia coricea, and aerial root of the Dentdrophthoe petandra show both potent inhibition of melanin formation and tyrosinase activity combined with strong antioxidant qualities.
As little is known about these plants and their active compounds the team do not know exactly how these extracts work; further research into the makeup of the extracts is needed.
“The isolation and structural elucidation of the active constituents of the selected plants will provide useful leads in the development of skin-whitening agents,” wrote the authors.
Source: Journal of Natural Medicine
DOI 10.1007/s11418-009-0351-7
Evaluation of medicinal plants from Central Kalimantan for antimelanogenesis
Enos Tangke Arung, Irawan Wijaya Kusuma, Eva Oktoberiani Christy, Kuniyoshi Shimuzu, Ryuichiro Kondo