GROWTH INHIBITION OF CORYNEFORM BACTERIA 215 Table I Minimum Bactericidal Concentration (MBC) of HGQ for 30 Species of Coryneform Bacteria Isolated From Human Underarms Strain no. Species MBC (% HGQ) 1 C. fiikeium (0.025 2 C. pilosum (0.025 3 C. pilosum (0.025 4 C. pyogenes (0.025 5 Group I (0.025 6 B-1 (0.025 7 C. jeikeium O. 1 8 C. kutscheri O. 1 9 C. pilosum O. 1 10 Group I 0.1 11 Group I 0.1 12 Group I 0.1 13 Group I 0.1 14 B-3 0.1 15 C. cystidis O. 3 16 C. jeikeium O. 3 17 C. minutissimum O. 3 18 C. xerosis 0.3 19 C. xerosis 0.3 20 C. xerosis O. 3 21 Group A-4 0.3 22 Group F-2 0.3 23 Group I 0.3 24 C. jeikeium 1.0 25 C. xerosis 1.0 26 Group I 1.0 27 Group I 1.0 28 Group I 1.0 29 Group I 1.0 30 B-1 1.0 the group with strong body odor, i.e., those really in need of a deodorant, give better results with soap containing the active ingredient than with a placebo (Table II, Figure 2). The differences are highly significant. The deodorant effect is comparable to that obtained with soaps containing trichlorocarbanilide (24). It can thus be concluded (Table III) that the deodorant effect of HGQ is also comparable to that of 2,4,4'-trichloro-2'-hydroxydiphenyl ether in the practical test. The alleged natural deodorant principle does not necessarily depend on an antimicrobial effect in the sense of killing bacteria (bactericidal effect). Metabolic deactivation and growth inhi- bition alone (bacteriostatic effect) should also give satisfactory results. ECOCOMPATIBILITY HGQ and its individual components and 2,4,4'-trichloro-2'-hydroxydiphenyl ether and 2,2'-methylenebis(6-bromo-4-chlorophenol) were tested for their biodegradability. The

216 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS 60 50 40 30 20 10 high body odor HGQ TCC HGQ TCC [• better product •7• no difference • blank sample better Figure 2. Comparison of the deodorant effect of soaps containing either a natural active substance mixture (HGQ) or TCC (0.26%), solubilized with nonylphenolethoxylate 9 (24) (x = statistically significant difference). Table II Sniff Test: Sniff Potential Assessment Scale 0 Fresh, pleasant odor (faint scent of perfume, conditioner) 1 Fresh, pleasant odor 2 Faint musty odor 3 Unpleasant, distinctly musty odor 4 Unpleasant, faint odor of sweat 5 Unpleasant, strong odor of sweat P Strong perfume masking everything else The sniff potential is assessed by three experts. latter two substances were widespread, especially in the deodorant sector, and served as the standards (4). Biological degradability is tested by measuring the amount of oxygen required for oxidation. A distinction is made between the chemical oxygen demand (COD) and the biological oxygen demand (BOD). Chemical oxygen demand is a constant and corresponds to the amount of chromium(VI) compounds--expressed as oxygen relative to a 1-1iter sample of water--consumed under defined conditions by the reducing components of contaminated water. Biological oxygen demand is defined as the amount of oxygen required by microorgan- isms from activated sludge basins for oxidative degradation of the organic substances