214 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS RESULTS The study of 530 axillary swabs and their bacteria isolates reveals a total of 30 coryne- form bacteria (Figure 1). These include C. jeikeium, pathogenic bacteria resistant to antibiotics. All of the C. species listed in Table I are virtually destroyed in the suspen- sion test in the range of 0.025 % to 1% HGQ (99.99% reduction of the initial microbial count). Table I shows that six of the strains studied were already inactivated by a HGQ concentration below 0.025%, another 8 below 0.1%, 9 below 0.3%, and 7 strains below a HGQ concentration of 1%. Although no correlation could be determined between the HGQ sensitivity and specific corynebacteria, there was definitely one between the HGQ sensitivity and the survival time of individual strains. Strains 1-6, which were especially sensitive to HGQ, had the shortest survival times, both on blood agar plates and in the stab culture when stored in the refrigerator. Assessment of the inhibitory (deodorizing) effect of a formulation on skin odor should not be based on the antimicrobial range of the preparation alone. It should also include other specifically use-related tests to enable decisions appropriate to the composition of the preparation. Deodorants are usually assessed by means of the sniff test (8), a sensory method that is based on the evaluation of the underarm odor of a consumer group consisting of at least 30 subjects by a panel of experts with a reliable judgment of odors. The active complex, HGQ, whose effect is to be evaluated in this case, is composed of three natural products that possess some bacteriostatic properties. When the whole group is evaluated after regular use of deodorants and the formulations containing the active ingredient are compared with those containing no active ingredient, the following results are obtained: 100 80 60 40 20 , _•. [23] .................. I41 .................. L[6] ............... 0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 HGQ-concentration [%] Figure 1. Minimal bactericidal concentration of HGQ against 30 strains of corynebacteria.

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