Stevia rebaudiana (Asteraceae), a perennial plant, has been used as a low-calorie sweetener and is being developed as a therapeutic agent for diabetes, hypertension, myocardial diseases, and microbial infections. Despite the common use of its leaves and stem, the bioavailability of the components present in S. rebaudiana flowers, when used as ingredients of cosmetics, has not been well investigated. Herein, we investigated the antioxidative and antimelanogenic effects of an aqueous extract of S. rebaudiana flowers (Stevia-F). Total flavonoid and phenolic content in Stevia-F were determined to be 8.64 ± 0.23 ㎎ of quercetin equivalents/100 g and 631.5 ± 2.01 ㎎ of gallic acid equivalents/100 g, respectively. The IC50 values of Stevia-F for reducing power, and 2,2-diphenyl-1-picryl-hydrazyl-hydrate radical, hydrogen peroxide, and nitric oxide scavenging activities were 5541.96, 131.39, 466.34, and 10.44 ㎍/mL, respectively. Stevia-F showed inhibitory effects on the tyrosinase (IC50 = 134.74 ㎍/mL) and α-glucosidase (IC50 = 114.81 ㎍/mL) activities. No significant cytotoxicity of Stevia-F was observed in B16F10 cells, treated with up to 100 ㎍/mL of the extract for 24 and 48 h (p > 0.05). Stevia-F (1–100 ㎍/mL) suppressed α-melanocyte stimulating hormone-induced melanin production in B16F10 cells (p < 0.05) and also inhibited the cellular tyrosinase activity (p < 0.05). Overall, our results show that Stevia-F possesses potential for inhibiting tyrosinase and α-glucosidase activities and has significant antioxidant capacity. The antimelanogenic potential of Stevia-F should extend the usage of S. rebaudiana flowers in the development of skinwhitening products.

Background : Stevia rebaudiana (Asteraceae), a perennial plant, has been used as a low caloric sweetener and therapeutic agent for diabetes, hypertension, myocardial, and antimicrobial infections. It has been commonly used leaves and stems because of their high anti-oxidative potential. The present research was carried out to explore anti-oxidative and anti-melanogenic effects of aqueous extract of Stevia rebaudiana Bertoni flos in B16F10 cells. Methods and Results : Anti-oxidant activity of Stevia flos extract (SFE) was determined by using 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical scavenging assay, nitric oxide (NO) radical scavenging method, and reducing power method. The results showed that the total phenolic content of SFE was 63.154 ± 0.0002 ㎍·QE/100㎎ and the total flavonoid was 8.64 1 ± 0.002 ㎍·GAE/100㎎. SFE exhibited a big significant effect on NO radical scavenging activity (IC50: 179.6 ㎍/㎖) comparing with standard ascorbic acid (IC50: 368.6 ㎍/㎖), and showed concentration dependent DPPH radical scavenging activity (IC50: 131.8 ㎍/㎖). Anti-melanogenic effect of SFE was also examined with B16F10 melanocytes. The amount of melanin synthesis followed by α-melanocyte stimulating hormone on B16F10 cells were significantly reduced in the presence of SFE treatment (p < 0.05). SFE also suppressed the tyrosinase activity (p < 0.05) and α-glucosidase activity (p < 0.05). Conclusion : These results provide evidence Stevia rebaudiana flos has an antioxidant potency and can be used as an anti-melanogenic agent.

Angelica tenuissima, also known as Ligusticum tenuissimum, is classified as a food-related plant and has been used as traditional medicines treating headache and anemia in Asia. However, its anti-melanogenic effect has not been reported in detail. When the extract of Angelica tenuissima (ATE) was prepared by the extraction with 70% EtOH at 80°C (final yield = 22%), the contents of decursin and Z-ligustilide in ATE were determined 0.06% and 8.43%, respectively. Total flavonoid and phenolic content in mg ATE were 5.52±0.07 ㎍ quercetin equivalents and 237.27±13.24 ㎍ gallic acid equivalents, respectively. Antioxidant capacity of ATE determined by DPPH and ABTS assay was increased with a dose dependent manner up to 1000 ㎍/㎖. The amount of melanin synthesis followed by α-melanocyte stimulating hormone on B16F10 cells were significantly reduced in the presence of ATE (250 to 1000 ㎍/㎖, p<0.05). ATE (125 to 1000 ㎍/㎖, p<0.05) suppressed the tyrosinase activity but did not show any significant effect on α-glucosidase activity at the same condition. Taken together, ATE possesses tyrosinase inhibitory potential with significant antioxidant capacities. These effects of ATE might be involved in suppression of melanin synthesis, at least, in B16F10 cells. The anti-melanogenic potential of ATE will provide an insight into developing a new skin whitening product.

In this study, we investigated the anti oxidative potential and protective effects of water extract of Leonurus sibiricus L. leaf (LSLW) against ultraviolet B (UVB)-induced oxidative damage in human keratinocytes (HaCaT cells). To evaluate the anti oxidative activity of LSLW, we measured DPPH radical, hydroxyl radical, hydrogen peroxide, superoxide anion scavenging activities, lipid peroxidation inhibition, and reducing power of LSLW. For induction of oxidative stress in HaCaT cells, the cells were irradiated with UVB at 40 mJ/㎠. To investigate the protective effects of LSLW against UVB, we measured cell viability and apoptotic bodies using annexin V staining. LSLW showed anti oxidative activities by scavenging DPPH radical, hydroxyl radical, hydrogen peroxide, superoxide anion and by reducing lipid peroxidation. In addition, LSLW showed high reducing values. The UVB-induced oxidative conditions led to cell apoptosis. However, treatment with LSLW ameliorated oxidative stress conditions, including inhibition of cell death, apoptotic body. Taken together, LSLW exhibited anti oxidative and protective effects against UVB-induced damage in HaCaT cells. Thus, LSLW could be useful for the development of cosmetics for UVB-induced skin aging.

본 연구에서는 까마귀쪽나무 잎과 열매 추출물의 항염증 활 성을 비교하고자 마우스 대식세포주인 RAW 264.7 cell에서 LPS에 의해 유도된 COX-2/PGE2와 iNOS/NO 및 염증성 cytokine 인 TNF-α, IL-1β, IL-6의 생성 억제 정도를 확인하였다. 그 결 과, 동일한 농도 조건(10 ㎍/㎖)에서 까마귀쪽나무의 열매 추출 물이 잎 추출물에 비해 NO, PGE2, iNOS, 염증성 cytokine인 TNF-α, IL-1β, IL-6의 생성량 모두에서 억제 효능이 우수하게 나타났다. 따라서 까마귀쪽나무가 보여주는 항염증 효과적 측 면과 안전성의 두가지 측면을 고려할 때, 까마귀쪽나무의 열매 추출물이 저농도에서 잎 추출물보다 항염증 효과가 우수하거나 동등하며, 그 안전성이 크다고 판단됨으로 까마귀쪽나무의 열 매추출물이 항염증 효능을 가진 기능성 식품 소재로써 개발 가 능성이 있음을 제시한다.