- Original article
- Open Access
Evaluation of clinical trial of atopic dermatitis by a topical cream containing the extracts from photosynthetic bacteria, Rhodobacter sphaeroides
© Kim et al. 2015
- Received: 20 July 2015
- Accepted: 22 July 2015
- Published: 12 August 2015
The photosynthetic bacteria Rhodobacter sphaeroides has been studied as a functional food source; however, in this clinical study, we report for the first time its use as a treatment for atopic dermatitis. Topical cream containing 10% (v/v) extract was demonstrated to have the ability to reduce skin moisture content loss and pruritus by 27.82% in clinical trials for atopic dermatitis compared with controls. In particular, there were statistically significant differences in the pH and temperature changes of the skin, skin firmness and general skin appearance. Changes in the skin pH were measured as 4.83, and there was a 3.37% change in temperature after 4 weeks of treatment. It was also found that there were great differences in wrinkle states according to the grading scale of patients before and after treatment with topical cream. Therefore, these results strongly suggest that extracts from photosynthetic bacteria can be employed to soothe atopic irritation as a new cosmetic bioresource.
- Atopic dermatitis
- Clinical research
- Photosynthetic bacteria
- Rhodobacter sphaeroides
Due to atmospheric pollution and changes in residential environments resulting from the rapid industrialization of modern society, the number of patients with atopic dermatitis has been recently increasing. Atopic dermatitis is a skin disease that may occur in any age group that is characterized by severe itch resulting from chronic inflammatory eczema. Genetic factors are strongly related to this disease, and stress, changes in external environments, and infection are major causes of atopic dermatitis aggravation. A major symptom of atopic dermatitis is severe itch, and this disease induces abrasions, erythematous eruption, blisters, and various lesions (Shultz and Hanifin 2002). Because the cause of the symptoms for atopic dermatitis has not been clearly established (Bos et al. 1992), studies of the cause have been unceasingly conducted. Although the management of environmental conditions that may be problematic and drug treatment centering on steroids and antihistamines are used as major treatment methods (Park et al. 2002), the symptoms of this disease are only temporarily relieved, and the aggravation and relief of symptoms are repeated. In addition, adverse affects to some external application products are emerging. Therefore, recent studies have mainly been conducted using products for external application containing oriental medicinal extracts with natural materials that enhance moisturizing effects as therapeutic agents for atopic dermatitis (Hong and Jung 2014). Although clinical effects from extracts from various natural products used as atopic dermatitis treatment materials have been demonstrated, no clear solution has been presented until now. Therefore, among the microorganisms that may be easily produced due to their ability to be cultured in large numbers, we aimed to identify the effects of the photosynthetic bacteria Rhodobacter sphaeroides on atopic dermatitis.
There have been reports indicating that the facultative anaerobic photosynthetic bacteria Rhodobacter sphaeroides produces SOD (superoxide dismutase) (Kim and Lee 2004). SOD is an anti-oxidant enzyme that has been reported to convert harmful oxygen radicals in the body into H2O2, and it has oxidation inhibitory functions via its conversion into water and oxygen by catalase to remove harmful active oxygen in vivo, thereby protecting living bodies (Cho and Choi 2013; McCord and Fridovich 1969). Although diverse studies on aging and disease have been conducted using eukaryotic organisms as materials, studies on microorganisms existing in the natural world in large numbers are insufficient. In addition, although photosynthetic bacteria have the abovementioned effects due to their ability to generate hydrogen, they are mainly studied for their function in alternative clean energy (Lee 1986), for use as materials in environmental industries such as livestock manure treatment and waste water purification, and for utilization as foods because they contain large amounts of nutrients (Lee and Lee 2000). In addition to studies on photosynthetic bacteria performed thus far, we utilized the established strengths of photosynthetic bacteria i.e., their production of SOD and catalase and their rich nutrients, to explore new functions of photosynthetic bacteria in relieving skin ailments such as atopic dermatitis by supplying nutrients to the skin and removing harmful active oxygen from the body with the view of preparing a new horizon for photosynthetic bacteria. In addition, we conducted clinical trials for the first time using a formulation for atopic dermatitis to identify the value of photosynthetic bacteria for the treatment of this disease.
Preparation of a topical cream for clinical trials
The formulation of a topical cream used for clinical trials
Rhodobacter sphaeroide extracts
Water surface region
Carbopol # 940
Borage seed oil
Vitamin E acetate
Licollice BG 100
For more detailed processing for making the topical cream, the water phase was heated to 80–85°C to become transparent. Afterward, a carbopol #940, as a thickner I was added. A preservative, oil part I, and 10% (v/v) of photosynthetic bacteria extract were placed in the oil part in order and heated to 85–90°C. Afterward, after confirming that oil part I was completely melted, oil part II was added at 80°C. The oil part was continuously mixed until the oil phase was completely dissolved with a paddle mixer at 900–1,000 rpm. After confirming that the oil part content was completely dissolved, the oil part was added to the water phase at 75–80°C to conduct the 1st emulsification. Afterward, the solution was homogenized 3 min using a homo mixer at 4,000–4,500 rpm. When the homogenization was completed, the extract and a fragrance was added to the solution at 55°C, and the solution was again homogenized for 5 min using a homo mixer at 4,000–4,500 rpm. A pH conditioning agent was added at 45–50°C, and the solution was again homogenized for 3 min using a homo mixer at 3,500–4,000 rpm. Finally, Rheocare ATH was added to the solution, and the solution was homogenized for 5 min using a homo mixer at 3,500–4,000 rpm to make the formulation.
As a negative control, the cream containing the same basal formulation in Table 1 without only the photosynthetic bacteria extract was used since this formulation is commonly used for the base of most topical creams in Korea (Yu et al. 2004). For a positive control, commercial product (expressed as a control product in this work), a Atopalm® mile cream (ATOPALM, Daejeon, Korea) was used in the experiments, and the composition of major components was as follows: glycerin, propanediol, myristoyl, capric tryglyceride, polyglyceryl-10 distearate, glyceryl stearate, cetearyl alcohol, grape seed oil (3%, v/v), jojoba seed oil, Portulacae Herba extract (5%, v/v), sorbitan stearate, olive oil, hydrogenated vegetable oil, phytosterol, sodium hyaluronate (1%, w/v), tocopheryl acetate, allantoin, stearic acid, carbomer, arginine, dimethicone, 1,2-hexanediol, and caprylyl glycol, tropolone, etc.
Evaluation of the clinical efficacy for atopic dermatitis
Groups of the patients participating in the clinical trials
Number of people
Measurement of the skin moisture content and trans-epidermal water loss
Skin moisture content was measured from the skin of test subjects who used the test formulation for 0–4 weeks with a corneometer (GmbH, Cologne, Germany) (Yu et al. 2004) by placing the corneometer probe into contact with the skin, and the average value of five measurements was used. The amount of trans-epidermal water loss was also measured from dry areas of the skin of test subjects who used the photosynthetic bacteria formulation for 0–4 weeks using a Vapometer (Delfin Technologies Ltd, Kuopio, Finland), which measures the amount of trans-epidermal water loss based on the Fick’s law for diffusion, and lower values indicated better skin conditions.
The changes of pH and temperature of the patient skin
Skin pH was measured with a skin pH meter (PH905, Courage-Khazaka electronic GmbH, Cologne, Germany) because the acid mantles in the skin play the role of antibiotic defensive barriers. Therefore, if the pH of the skin increases, the possibility of skin inflammation due to various bacteria also increase. Skin temperature was also measured with a skin thermometer (ST500, Courage-Khazaka electronic GmbH, Cologne, Germany), which is a device used to measure skin temperature by sensing infrared rays emitted from the atopic dermatitis areas of the skin.
General high-resolution photograph acquisition
Photographs of atopic dermatitis regions of test subjects were taken before and after treatment (for 4 weeks) with the topical cream by a high-resolution camera (D3300, Nikon, Tokyo, Japan).
Measurement of Visual Analogue Scale (VAS) for the relief of pruritus
The test subjects were instructed to mark the degree of itch they felt on a 10 cm line by indicating higher degrees with longer lines, and the lengths marked were measured. VAS evaluation for pruritus was conducted by comparing the lengths of the lines indicating the degree of pruritus before and after treatment with the topical cream (Hong et al. 2008).
Measurement of the Scoring Atopic Dermatitis (SCORAD) index
The SCORAD index (Stalder and TaÏeb 1993) was modified to evaluate the areas of atopic dermatitis symptoms and the degree of the symptoms in the head, trunk, arms, and legs. This experiment was conducted by dermatologists, and subjective symptoms were evaluated by medical examinations through interviews.
All experimental data were performed in triplicate and processed by two-way ANOVA using the software Statistical Analysis System (SAS). The minimum difference in significance level was set to p < 0.05.
Measurement of the water content of skin
Upon reviewing the results, it can be observed that the skin water content increased at 2 and 4 weeks of use of the products compared with before using the products in the group that used the clinical trial formulation and the control group. In the case of the test formulation, the water content increased by 51.85% after 5 weeks of use compared with before using the formulation, and it increased by 79.44% after 4 weeks of use. Given that in a previous study of the effects of oriental medicinal materials on atopic dermatitis the skin water content increased by approximately 21% 6 weeks after use compared with before using the materials, the photosynthetic bacteria clinical formulation used in this study may be judged as being effective for water content (Kang et al. 2009). In the control group, the water content increased 36.62% after 2 weeks of use and 51.18% after 4 weeks of use. Compared with the control group, the group that used the clinical trial formulation had 15.23% higher water content after 2 weeks of use and 28.26% higher water content after 4 weeks of use. Although both the control product and the photosynthetic bacteria clinical trial formulation included materials helpful for skin water content as part of materials needed for their formulation, given that these materials are generally necessary for cosmetic formulation and the differences between the two are remarkable, it can be judged that the clinical trial formulation is much more effective for skin water content than existing products.
Measurement of the amount of trans-epidermal water loss
Measurement of the trans-epidermal moisture loss in the skin
Test product (g/h m2)
Control product (g/h m2)
(a) Trans-epidermal moisture loss
20.31 ± 7.38Aa
19.45 ± 6.84Aa
17.10 ± 6.64Ba
18.38 ± 5.52Bb
14.66 ± 7.31Ca
17.41 ± 5.40Bb
(b) The percentage of the trans-epidermal moisture loss changes from the zero day of the treatment
Changes in the temperature and pH of the skin
Measurement of the skin temperature upon treatment with the topical cream
Test product (°C)
Control product (°C)
(a) Skin temperature
30.46 ± 1.19Aa
30.44 ± 0.84Aa
30.38 ± 7.14Aa
30.31 ± 0.74Aa
29.41 ± 1.04Aa
29.57 ± 0.90Aa
(b) The percentage of skin temperature changes from the zero day of the treatment
Evaluation of the pruritus VAS and SCORAD index
Evaluation of the SCORAD index after treatment with the topical cream
(a) SCORAD index
21.76 ± 6.07Aa
21.59 ± 8.24Aa
20.00 ± 7.14Ba
20.00 ± 7.87Ba
17.05 ± 8.00Ca
16.95 ± 7.60Ca
(b) The percentage of SCORAD index changes from the zero day of the treatment
Photographic observation of the atopic dermatitis regions before and after the treatments
In this study, the efficacy of the extracts from photosynthetic bacteria for relieving atopic dermatitis was clinically demonstrated for the first time in the form of a topical cream. The topical cream containing 10% (v/v) extract demonstrated more beneficial effects for skin water content and the amount of trans-epidermal water loss. This result also indicated that this unique formulation could relieve xeroderma, which is a general symptom of atopic dermatitis, and it may also be effective for treating atopic dermatitis. Together with maintaining large skin water content, this cream was capable of maintaining relatively low skin temperature, which could reduce the feeling of itch in the skin. The pH of the skin was also maintained as slightly acidic with the treatment with this cream because healthier skin is closer to being slightly acidic and the potential of the formulation as a countermeasure against atopic dermatitis, which is characterized by alkaline skin, was reported (Yun et al. 2008). From these results, it appears that topical creams containing the extracts from photosynthetic bacteria should be effective for treating or at least soothing atopic dermatitis although some of the formulation chemicals (glycerin, Jojoba oil, SC-glucan) in Table 1 could possibly affect skin water content retention and skin protection. However, the amount of these chemicals is small enough to be negligible for influencing efficacy compared with other commercially available cosmetics. With regards to the SCORAD index of this trial, the values decreased over time after the use of the topical cream, and these results are similar to or even better that that of existing cosmetics.
Based on the above results of pH and water contents changes as well as SCORAD index, it could tell that the effects of the test topical cream for relieving atopic dermatitis may be attributed to the removal of reactive oxygen species (ROS) in the skin, which is a major cause of inflammation by the super oxide dismutase (SOD) and catalase produced by photosynthetic bacteria (Cho and Choi 2013). Therefore, it is very positive that the photosynthetic bacteria formulation in this cream showed remarkable enhancement, compared to those of commercially used topical cream for atopic dermatitis. However, interestingly enough, the VAS scales for pruritus felt by the patients did not improve much in the clinical trial compared with existing cosmetics, which should also be considered when applying this cream to a broad spectrum of patients.
HYL conceived experiments; NYK and JSC conducted experiments; NYK and HYL wrote the manuscript. All authors read and approved the final manuscript.
Compliance with ethical guidelines
Competing interests The authors declare that they have no competing interests.
Ethics and consent This study was approved by the local ethics committee, and all patients were notified about this study and participated with the written consent.
Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.
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