Formulation and Evaluation of Anti-Acne Lotion Containing Red Ginger (Zingiber officinalle Roscoe) Essential Oil

Red ginger (Zingiber officinalle Roscoe) has been empirically used as antibacterial agent. This study was aimed to formulate anti-acne lotion containing red ginger essential oil and to evaluate its antibacterial activity against Propionibacterium acnes and Staphylococcus epidermidis. Extraction and distillation of 10 kg of red gingers were performed to obtain its essential oils. The lotions were prepared using oil in water (o/w) base with various concentration of red ginger essential oils, i.e., 2.5%, 5%, and 7.5%. The lotion was assayed to determine organoleptic, homogeneity, pH, viscosity, and irritation-inducing level. Antibacterial activity test was conducted using disk-difussion method. Results indicated that the 7.5% concentration exerted the strongest activity in inhibiting P. acnes (inhibition zone 12.4 mm) and S. epidermidis (inhibition zone 29 mm). In conclusion, anti-acne lotion containing 7.5% of red ginger essential oil was effective to control acne inducing bacteria and fulfilled the required standards.


Introduction
Acne is one of the most common skin disorders which is characterized by chronic inflammation of pilosebaceous units. Pathogenic mechanism of acne includes increased sebum production, P. acnes and S. epidermidis colonization, follicular hyperkeratinization, and the products of inflammation. 1 Red ginger (Zingiber officinalle Roscoe) has been widely studied as a medicinal plant. Its secondary metabolites include flavonoids, phenols, glycosides, triterpenoid, essential oils and tannins. Several previous studies showed that red ginger extract had anti-bacterial activity against P. acnes, S. epidermidis, S. aureus and E. coli. 2,3 Essential oil of red ginger also exhibited potential anti-bacterial activity against P. acnes, P. aeruginosa, S. aureus, and S. epidermidis. [4][5][6] Nevertheless, there is limited information regarding formulation and evaluation of anti-acne lotion containing red ginger essential oil. Therefore, this study was conducted to formulate anti-acne lotion containing red ginger essential oil and to evaluate its anti-bacterial activity against P. acnes and S. epidermidis.

Extraction of essential oil
Steam distillation was conducted at Bogor Spice and Medicinal Plant Research Center (Balitro) laboratory to obtain red ginger essential oil. A total of 10 kg of red ginger that had been washed and chopped were placed into a glass flask. Through an inlet, steam was injected to the flask, resulting in the vaporized compounds that subsequently underwent condensation process. The essential oil was then purified by adding Na 2 SO 4 to eliminate water content. Characteristics of essential oil were examined based on Indonesian National Standard No. 061312-1998.

Formulation of anti-acne lotion
The lotions were prepared using oil in water (o/w) base with various concentration of red ginger essential oils, i.e., 2.5%, 5%, and 7.5%.The formula was based on previous research conducted by Indriati et al. 7 The oil phase consisted of PEG-40 hydrogenated castrol oil and caprylic, while the water phase consisted of distilled water, methyl paraben, propyl paraben and glycerin. The oil and water phase were heated at 70 0 C and mixed using homogenizer at 500 rpm for 15 minutes. Subsequently, ethanol was added after the temperature decreased. Essential oil was then added and mixed until homogenous.

Anti-bacterial activity test
Anti-bacterial activity tests against S. epidermidis and P. acnes were performed using disk-diffusion method. Acnol was used as positive control, while distilled water was used as negative control. 0.5 ml culture containing approximately 10×10 6 bacteria was mixed into agar media solution until homogenous. It was then placed to sterile petri dish until solid. Subsequently, paper disk was placed on the media. Approximately 20 μl of lotions were injected on the paper disk. It was then incubated at 35 ± 2 0 C for 24-48 hours. The inhibition zone was then measured using a ruler. Formula with the best antibacterial activity was assayed to determine its organoleptic, homogeneity, pH, viscosity, and irritation-inducing level. Homogeneity was evaluated by pressing the lotions which was placed on transparent glass with other transparent instrument to Results and Discussion Distillation process of 10 kg of red ginger resulted in 24 ml of essential oils. We found that our red ginger essential oil fulfilled all the requirements of Indonesian National Standard No. 06-1312-1998, indicating that this essential oil had good quality. The result can be seen in the Table 1.
Results indicated that lotion containing 7.5% of red ginger essential oil exerted the strongest activity in inhibiting P. acnes (inhibition zone 12.4 mm) and S. epidermidis (inhibition zone 29 mm). The lowest anti-bacterial activity was shown by formula I, which contained  Table 3. Anti-bacterial Activity of Red Ginger Essential Oil Lotion 5% of red ginger essential oil. Formula III had greater inhibition zone compared to positive control against P. acnes, but had slightly smaller inhibition zone against S. epidermidis.
Organoleptic examination was intended to evaluate physical properties of the lotion. Results showed that the lotion was yellow, had distinctive aroma of ginger, and had no sediment. Homogeneity test was performed since it is critical to ensure the active substances are dispersed evenly in the base formula. Results showed that the lotion was homogeneous and met the desired criteria.
The degree of acidity (pH) is a very important parameter in a cosmetic product because the pH of cosmetics influences its absorption on the skin. Cosmetics with very high or low pH are likely to induce irritation. The results showed that the pH of the lotion was 7.42. The pH requirements for cosmetic preparations range from 4.5 to 7.5. 10,11 Viscosity is a measure of a fluid resistance to flow. Viscosity may affect skin retention of the dosage form. 10 The results showed that the viscosity of the lotion was 526 cP, which fulfilled the requirement from of Food and Drug Administration (viscosity of a good lotion should be < 30,000 cP). 12 Irritation test was performed to evaluate the occurence of side effects on the skin. The 24-hours observation showed that the lotion did not cause itching and inflammaiton of the skin, implying that the formula did not induce skin irritation. Further study is encouraged to evaluate long-term stability and effectiveness of red ginger essential oil lotion.

Conclusions
Anti-acne lotion containing 7.5% of red ginger essential oil was effective to control acne inducing bacteria and fulfilled the required standards.