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ZINC GLUCONATE
Principal indications: excess sebum, spots, skin blemishes
PURE ACTIVE A20
Bibliographical summary
 
  • INCI name: ZINC GLUCONATE
  • Molecule more than 97% pure obtained by biosynthesis
 

Zinc is one of the most abundant elements in trace amounts in the human body (approximately 2 g). It is present in all cells and takes part in approximately 200 enzymatic reactions. Zinc holds an important place in the skin: It is needed for cell division, tissue growth and tissue regeneration. Generally speaking, zinc is also involved in:
• Immune system function
• The transport of vitamins A and E
• The incorporation of fatty acids in the phospholipids
• Inhibition of the activity of 5-α-reductase involved in sebum secretion
• Inhibition of the activity of the enzyme bringing about the degradation of triglycerides into free fatty acids
• Melanin synthesis

It has also been ascribed with an antioxidant and cicatrizing action. Zinc is one of the main astringent and antiseptic constituents in cosmetics. In order to guarantee its stability and availability, it is used in zinc gluconate form.

 

  • ACTION MECHANISMS / PROOFS OF EFFECTIVENESS

Zinc is a powerful 5α-reductase inhibitor [2, 3]. This enzyme catalyzes the conversion of androgens into DHT (dihydrotestosterone), which fixes on to the receptors located on the sebaceous glands. This fixation brings about sebum production. By inhibiting this enzyme, zinc alleviates hyperseborrhea.

In vivo tests have confirmed this action in zinc [2]. Measurement of sebum production on the skin's surface during topical treatment containing zinc shows a reduction in the quantity of sebum produced.

Moreover, zinc ions exert an anti-inflammatory action. Indeed, on keratinocyte cultures, zinc reduces activation of these same cells. It reduces the production of TNF-α and maintains cell viability [4].

In vitro, zinc brings about a reduction in oxidative stress. It is therefore part of the large family of antioxidants. Firstly, it is thought to form mercaptides with the thiol groups in the protein membranes, thus preventing the formation of free radicals with other metal ions. In addition, it is thought to maintain the activity and structure of superoxide dismutase. Finally, it is thought to increase the concentration of metallothioneins, which destroy free radicals [5].

Zinc is also known for its antiseptic activity. Studies have been conducted on cultures of microorganisms such as E. Coli, S. Aureus and C. Albican. These show that zinc has the ability to inhibit bacterial and fungistatic proliferation [1].

Finally, a cicatrizing action has been shown [6, 7].

 

  • OUR EXPERT'S OPINION

As a 5-α-reductase modulator, zinc is well known and established. It also has an antimicrobial activity, which is variable, however, depending on the form of salt used and its associations (copper, for example).

Its recommendation for acne-prone oily skin is customary.

Its availability continues to be an issue. "Organic" salt forms are preferable to mineral salts. Salicylate, acetate and gluconate are the ones most generally used.

Owing to its chelating character, zinc may also interact with certain formula excipients (free doublets like hydroxyls) and find itself trapped in complexes that have to be exchanged in the biological environment. As a precautionary measure, this should therefore be confirmed by testing.

A concentration of 3% could be interesting for its gluconate form. However, we must have a measured expectation on the activity obtained in the short term in all cases. Used on its own, it is more of a background modulator (oily skin). Good, fast effectiveness in acne requires its combination with, at the very minimum, a keratolytic like salicylic acid.

 

  • EFFECTIVE DOSE

The body of publications and scientific studies, customary usages of this active and our expert's opinion concur in using Zinc Gluconate pure Active at the dose of 435 mg per bottle.

 

  • SCIENTIFIC STUDIES

[1] Determining the minimum inhibitive concentration of actives Test Report B09-00026 Dr C LENS F THERY

Activity Method and Duration Products tested and dose Results
Inhibitive activity in relation to microorganisms Product brought into contact with a concentrated titrated nutrient broth.
The following concentrations of zinc sulphate are tested:
0.25, 0.5, 0.75, 1 and 1.5% in relation to S Aureus and E Coli
0.75, 1, 1.5, 2 and 2.5% in relation to C Albicans
After 24 hours' incubation at 32°C, microbial growth is assessed. A census is taken.
The minimum inhibitive concentration is assessed and corresponds to the first concentration making it possible to retrieve the initial inoculum.
0.25, 0.5, 0.75, 1, 1.5, 2 and 2.5% zinc sulphate or gluconate The minimum inhibitive concentrations were assessed:
-Less than 0.25% zinc sulphate i.e. 0.4% zinc gluconate, for S Aureus and E Coli,
-Less than 0.75% zinc sulphate i.e. 1.2% zinc gluconate, for C Albicans
It is therefore concluded that zinc inhibits bacterial and fungistatic proliferation.

 

  • BIBLIOGRAPHICAL REFERENCES

[2] Effect of a topical erythromycin-zinc formulation on sebum delivery. Evaluation by combined photometric-multi-step samplings with Sebutape. Pierard GE and Pierard-Franchimont C, Clinical and Experimental Dermatology, 18(5):410-413. 1993.

[3] Inhibition of 5α-réductase activity in human skin by Zinc and azelaic acid. Stramatiadis D et al, British Journal of Dermatology,119(5): 627-632. 1988.

[4] Protective effect of Zinc on keratinocyte Activation markers induced by interferon or nickel. Gueniche A, Acta Derm Venereol,75(1): 19-23. 1995.

[5] Antioxidant-like properties of Zinc In Activated Andothelial Cells. Hennig B and McClain GJ, Journal of the American College of Nutrition, 18(2):152–158. 1999.

[6] Zinc in wound healing : theoretical, experimental and clinical aspects. Lansdown ABG et al, Wound rep reg, 15(1):2-16. 2007.

[7] In vitro modulation of keratinocyte wound healing integrins by zinc, copper and manganese. Tenaud I et al, British Journal of Dermatology, 140,(1):26-34. 1999.

This information is given for informative purposes. In no event does it constitute medical information, nor engage our liability. These documents may be copied and reproduced exclusively for informative purposes for personal and private use. All and any use of copies or reproductions for other purposes is expressly forbidden and shall engage the user's liability under Article L 122-3 of the Intellectual Property Code.