162 PRESERVATIVES Formula 3: Benzoic acid. Formula 4: Sodium dehydroacetate.
Table 1: Microbial effectiveness. MIC values
Species
Gram Negative Escherichia coli
Pseudomonas aeruginosa
Gram Positive Staphylococcus aureus Propionibacterium acnes
Mould Fungii Aspergillus niger Malassezia furfur Yeasts
Candida albicans
These organic acids are capryloyl glycine (Formula 1), undecylenoyl glycine (Formula 2), benzoic acid (Formula 3) and sodium dehydroacetate (Formula 4).
N-capryloyl glycine N-capryloyl glycine, also known as N-octanoyl glycine (CAS No. 14246-53-8) is also well-known for its action against naturally occurring microflora that is resident on the skin. The use of this antimicrobial was suggested way back in 1996, as a non-preservative substance that can inhibit microbial growth in cosmetics.10 It offers derma-protection for the restoration of the skin’s acid mantle and purification through dandruff reduction by the inhibition of Pityrosporum ovale. It is commercially available under the trade name Lipacide C8G from Seppic.
N-undecylenoyl glycine Almost four decades ago N-undecylenoyl amino acids were reported for the treatment of skin disorders. One of them is N-undecylenoyl glycine (CAS No 54301-26-7) a well-known derma-purifier with very pronounced anti-acne and anti-dandruff activity. It is commercially available under the trade name Lipacide UG from Seppic, France.12
Seppic reported cosmetic
compositions containing undecylenoyl glycine along with capryloyl glycine in 1999. Corinne Stolz, (US 20010002257A1) disclosed compositions comprising undecylenoyl glycine and capryloyl glycine along with tannin rich plant extracts that showed activity against skin flora.13 Interestingly, in 2004, the use of a combination of wasabi extract along with undecylenoyl glycine and capryloyl glycine
7 6 5 4 3 2 1 0
Malassezia furfur MTCC 1374 Aspergillus niger ATCC 16404 Candida albicans ATCC 10231 Pseudomonas aeruginosa ATCC 15442 Propionibacterium acnes MTCC 1951 Escherichia coli ATCC 8739 Staphylococcus aureus ATCC 6538
MIC Value (%)
0.5 0.4
0.3 0.5
0.3 0.5
0.5
as co-preservatives for protection of personal care preparations was reported by D. Misner.14 Kabara et al. (US Pat 2007/ 0196315 A1) preserved botanical extracts with capryloyl glycine, undecylenoyl glycine, and glyceryl monolaurate and pentylene glycol.15
Benzoic acid
The maximum allowed concentration of benzoic acid (CAS No 65-85-0) (Cosmetics Directive Annex VI) is 2.5% in ‘rinse-off’ and 0.5% in ‘leave-in’ product. For oral products it is permissible concentration is 1.7%. It is a well-known antimicrobial with specific action against fungi. Hence it is widely used in food products as preservative.
Sodium dehydroacetate
The maximum authorised concentration of sodium dehydroacetate (CAS number 520-45-6) according to Cosmetics Directive Annex VI is 0.6 %. In the US and EU the maximum allowed concentration is 0.6% whereas in Japan is it is 0.5% in finished personal care products. It is a good fungicide and mild bactericide.
Figure 1: Challenge Test of Shampoo with 1% GalguardNT at 6.0 pH. PERSONAL CARE EUROPE
Conclusion Minimum growth inhibitory concentrations (MIC) against typical microbes are listed in Table 1. MIC numbers range from 0.3% to 0.5 %. The challenge test data of typical rinse-off and leave-on formulations are depicted in Figures 1 & 2. Galguard NT is a preservative system based on a synergistic blend of organic acids that is easy to use in personal care formulations. Galguard NT provides effective broad spectrum activity against yeast, moulds, and bacteria. It is free from all toxic antimicrobials such as parabens, formaldehyde donors, isothiazolinones, and phenolic/halogenated molecules (IPBC, triclosan, chlorhexidine). It has ease of incorporation in cosmetic formulations where cold processing is required. Galguard NT is globally acceptable and free from any regulatory issue. Galguard NT can be used both ‘leave-on’ and ‘rinse-off’ formulations within effective pH range of 3 to 6.
PC April 2018
days 0
24 hrs
48 hrs
days 7 Time
days 14
days 21
days 28
Log reduction cfu/gm
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