On the effects of a plant extract of Orthosiphon stamineus on sebum-related skin imperfections.Int J Cosmet Sci 2011; 33(1):44-52IJ
Overproduction of sebum is very common and results in an undesirable oily, shiny complexion with enlarged pores. Sebum secretion is basically under the control of 5-α reductase, and more particularly under that of type 1 isozyme. But it is also highly sensitive to environmental factors such as temperature, humidity and food. Moreover, in Asia, the edicts of a flawless facial skin turn oily skin into a major concern for Asian women. We identified Orthosiphon stamineus leaf extract as an interesting ingredient for reducing the oily appearance of skin thanks to its ability to reduce 5-α reductase type 1 expression in normal human epidermal keratinocytes in vitro. This was confirmed ex vivo, where Orthosiphon stamineus leaf extract was shown to reduce 5-α reductase activity as well as the production of squalene, one of the main components of sebum that was used as a tracer of sebum. To evaluate the efficacy of Orthosiphon stamineus leaf extract at reducing sebum-related skin imperfections in vivo, we performed two different clinical studies, one in France on a panel of Caucasian volunteers and the other one in Thailand on a panel of Asian volunteers. Using instrumental techniques as well as clinical evaluation and self-evaluation, we could highlight that an O/W cosmetic formula containing 2% of Orthosiphon stamineus leaf extract could visibly reduce the oily appearance of skin as well as the size of pores, thus leading to a significant improvement of complexion evenness and radiance. Overall, the results obtained were better than those observed with the same formula containing 1% of zinc gluconate, an ingredient frequently used in oily skin care products.