USE OF LECYTHIS PISONIS OIL IN COSMETIC CREAMS 245 quality, and the levels found in arils are comparable with those found in sesame seeds (3 mg/100 g), raw nuts, and chickpeas (5 mg/100 g) (22). In addition, the oil from L. pisonis could be considered nontoxic and safe for use , be- ing classifi ed as category 5 (24). Biochemical assays showed no signifi cant differences among the groups for liver and kidney damage and that an estimated lethal dose is 5.000 mg/kg. Regarding acute toxicity, the LD50 of L. pisonis oil in mice was 2.000 mg/kg, corr espond- ing to an LD50 in humans of 405.6 mg/kg. This elevated safe dose could indicate safe application of the oil in products, including topical applications on the face (unpublished results). The cell survival varied between 98.3 ± 5.2 and 119.3 ± 6.4 for L929 cells and be tween 113.4 ± 19.9 and 149.5 ± 10.9 for HaCat cells, corresponding to the highest and lowest concentrations of the oil tested, respectively. So, it is possible to infer that the oil is non- toxic because it did not affect the cell growth. The pharmaceutical form used to incorporate the oil from L. pisonis was cream, as it i s widely used and accepts well the oil compounds. Analyses of the formulation indicated that the base cream produced is oil-in-water (O/W) emulsion, meaning that oil micelles are dispersed in an aqueous medium. Such emulsions are smooth and easily removed with water (25). Different lipids that enhance the scattering coeffi cient, such as the green oils from macadamia nuts, wheat germ, and grape seeds, might be used in an O/W emulsion (25). The concentrations of oil used in the formulations were based on studies of other cosmetic formulations with oil using 0.5–10% oil (26,27). Considering macroscopic aspects, in all samples except F3, no phase separation or chan ges in texture or odor were observed (Table III). The changes in sample F3 could be attributed to the oil concentration (10%), where despite maintaining the texture, the formulation was less viscous, i.e., when corroborated by the centrifugation test, small droplets were noticed on the surface of F3. All formulations containing the oil remained stable with no color change during the te sts. As excepted, sample F3 presented more pronounced odor after the second cycle of heating and a paler color and rougher texture, different from the other samples, which remained smooth and shiny. The most stable formulations were those with concentrations of 1 and 5% nut oil, in agreement with Christoph et al. (26), where the concentration of melaleuca oil in formulations ranged from 0.5% to 5%. The control samples remained stable, becoming harder when frozen and regaining nor- mal characteristics after 30 min at room temperature. The importance of the pH control in a formulation over the entire period relevant to p roduct use is that it should maintain a value between 5.5 and 6.5 to be compatible with the skin pH and remain stable (28), as alteration of pH might decrease the stability of the formulation (16). In the tested formulations, the pH decreased during exposure to heat in the stability test (Table III), indicating that a stability process affects the formulation, but still remains within the acceptable value. The skin pH is believed to be slightly acidic (4.6–5.8), providing bactericidal and fungi- cidal protection at the surface (29). The determination and control of skin pH are desir- able characteristics of cosmetic products to avoid skin damage and could be controlled by the use of additives, such as antioxidants and vitamin E, to stabilize the oil.

Table III Physical–Chemical Characteristics of the Formulations Phase separation Texture Odor pH Spreadability Viscosity BST AST BST AST BST AST BST AST BST (cm)2 AST (cm)2 Time 0 (cP) 30 days (cP) Viscosity retrenchment (%) F0 S S S S S S 5.27 ± 0.01 4.77 ± 0.01* 11.15 ± 0.75 13.42 ± 0.38 59,802 38,073* 36.33 F1 S S S S S S 5.26 ± 0.02 4.77 ± 0.00* 11.14 ± 0.34 14,41 ± 1.39 60,359 25,830* 57.21 F2 S S S S S S 5.21 ± 0.01 4.78 ± 0.01* 11.54 ± 0.46 19,78 ± 1.47 60,272 21,536* 64.26 F3 S NS S S S S 5.17 ± 0.01 4.78 ± 0.01* 11.74 ± 0.17 18.39 ± 2.48 27,357 18,861* 31.06 BST: before stability test AST: after stability test. Evaluation of phase separation—S: stable (no phase separation) NS: nonstable (small drops of L. pisonis nut oil). Odor evaluation—S: stable (odor of cupuaçu essence) S: stable with a slight odor of L. pisonis nut oil. Texture evaluation—S: stable (smooth and shiny texture) NS: not stable (rough and opaque texture). * 0.05. JOURNAL OF COSMETIC SCIENCE 246