Southern Magnolia to Desensitize Sensitive Skin

May 11, 2012 | Contact Author | By: CLR Chemisches Laboratorium Dr. Kurt Richter GmbH, Berlin, Germany
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Title: Southern Magnolia to Desensitize Sensitive Skin
rednessx sensitive skinx magnoliax inflammationx anti-irritantx
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PhytoDefense CLR™ (INCI: Glycine Soja (Soybean) Oil (and) Dicaprylyl Ether (and) Magnolia Grandiflora Bark Extract (and) Lauryl Alcohol) is a lipophilic active based on southern magnolia (Magnolia grandiflora). It is especially designed for the pre- and post-treatment of sensitive skin to significantly reduce neurogenic inflammation as well as skin redness after mechanical stress. PhytoDefense CLR™ is unpreserved but stabilized with a natural rosemary extract concentrate as an antioxidant.

Neurogenic Inflammation and Erythema

To exacerbate the complexity of sensitive skin, it has been recognized that there are many additional factors that come into play. These include: the mental and physical state of a person, cultural factors (e.g., skin care routines), age, environmental factors (e.g., temperature, humidity, pollution), diet (e.g., spicy food, alcohol, coffee), seasonal variations and the use of pharmaceuticals. All these factors can negatively influence skin, making it more sensitive. Erythema is well-known in stressed skin. Often provoked by sunlight in normal skin, erythema is a much more frequent occurrence in sensitive skin. Mechanical stress is a very well-known cause of erythema in sensitive skin and it is something to which skin is virtually constantly exposed—friction from clothes, shoes and diapers are considered some of the many sources for mechanical stress for skin. Fabrics are an important factor, as are working with the hands, waxing and, most well-known of all, shaving: 41% of all people report sensitive skin symptoms after shaving.

Effective Clinical Evaluation

In 1977, Frosch and Kligman developed a clinical test method with which they were able to objectively determine whether or not a person had sensitive skin. In this method, an aqueous solution of lactic acid is applied on the nasolabial fold, i.e., the area between the nose and the mouth where the “smile lines” develop, and the surrounding area of the cheek. The level of neurogenic discomfort, assessed subjectively, is then given a score. People who clearly feel discomfort of the skin are distinguished from those who do not feel any discomfort. In this way, Frosch and Kligman were able to differentiate between people with sensitive skin (“stingers”) and people without sensitive skin. In relation, CLR has developed PhytoDefense CLR™ based on a lipophilic extract of the bark of Magnolia grandiflora specifically to effectively treat sensitive skin, addressing its most significant problems, neurogenic inflammation as well as skin redness induced by mechanical stress. Both parameters were extensively assessed in two different in vivo studies with a large number of volunteers, described here.

In vivo Assays

Neurogenic inflammation: stinging evaluation

PhytoDefense CLR™ was assessed using the protocol developed by Frosch and Kligman to determine whether it can help in reducing neurogenic inflammation in sensitive skin.

Study design

  1. A total of 33 volunteers with sensitive skin (“stingers”) were selected.
  2. Areas A and B were defined: nasolabial fold and surrounding area of the cheek. Area A was on the right side of the face, area B on the left.
  3. At the start of the study a 10% aqueous solution of lactic acid on areas A and B was applied to each volunteer to evaluate how strong their skin discomfort was (stinging evaluation).
  4. For four weeks, the test products were applied twice daily application. A formulation containing 3% PhytoDefense CLR™ was applied on area B and the corresponding placebo (vehicle alone) on area A.
  5. Another stinging evaluation was performed.

Stinging evaluation

  1. Sweating was induced by facial sauna for 15 min; volunteers' faces were subsequently dried.
  2. A 10% aqueous lactic acid solution was then applied by a laboratory technician using a cotton-tipped swab.
  3. At t = 10 sec, 2.5 min, 5 min, 8 min and 15 min, subjective evaluations of the intensity of burning, stinging and/or itching sensation were recorded.

Scoring system

0: no reaction
0.5: slight prickling and tingling
1: moderate prickling and tingling
2: slight burning, stinging, itching

Results

On average, the treatment with PhytoDefense CLR™ resulted in a reduction of skin discomfort by 45%, whereas the placebo only showed a reduction with an average of 24%. Especially 8 min and 15 min after applying the lactic acid solution, skin treated with PhytoDefense CLR™ showed a much stronger reduction of skin discomfort than placebo-treated skin, approx. 56% compared to approx. 17% (see Figure 1).

Erythema: Mechanical Stress—Shaving Irritation Study

In order to assess whether PhytoDefense CLR™ is beneficial in reducing skin redness after mechanical stress, a shaving irritation study was performed. As mentioned above, 41% of all people show sensitive skin symptoms after shaving.

Study protocol

  1. A total of 25 volunteers were selected.
  2. Four test areas were defined and divided over both volar forearms of each volunteer: for the test formulation with 3% PhytoDefense CLR™; for the placebo (vehicle alone); to be left untreated; and as the positive control (non-treated, non-shaved).
  3. To perform the shaving study, on days 1, 2 and 3, shaving of the three test sites was carried out (excluding the positive control) without lubricant and using a disposable shaver. Subsequently, the test, control and placebo formulations were applied in a controlled manner to the relevant areas.
  4. On day 4, chromameter measurements were performed on all four test areas to determine a*- values.

Results

The area treated with the placebo reduced the level of erythema development by about 11%, whereas the area treated with 3% PhytoDefense CLR™ had a much more noticeable effect: erythema was reduced by 27%, considerably better than the placebo (see Figure 2).

Conclusion

PhytoDefense CLR™ strongly and positively influences the most important features of sensitive skin, neurogenic inflammation and mechanical stress-induced erythema, which was proven in two elaborate in vivo studies on 33 and 25 volunteers, respectively. PhytoDefense CLR™ is a tailor-made active ingredient for pre- and post-treatments of sensitive skin.

 

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Figure 1. Facial stinging sensation (score)

On average the treatment with PhytoDefense CLR™ resulted in a reduction of skin discomfort by 45%, whereas placebo only showed a reduction with an average of 24%.

Figure 2. Reduction of formation of erythema (%)

The placebo reduced the development of erythema by about 11%, whereas the area treated with 3% PhytoDefense CLR™ reduced erythema by 27%.

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