Oenothera laciniata Hill Extracts Exhibits Antioxidant Effects and Attenuates Melanogenesis in B16-F10 Cells via Downregulating CREB/MITF/Tyrosinase and Upregulating p-ERK and p-JNK

Oenothera laciniata Hill is a perennial herb traditionally used to alleviate inflammatory complications. This study investigated the antioxidant and anti-melanogenic activities of O. laciniata. The methanolic extract (OLM) of O. laciniata and its different fractions, including ethyl acetate (OLEF), n-butanol (OLBF), and water (OLWF) fractions, were prepared. Antioxidant activities were evaluated by total phenolic content, the radical-scavenging effect on 2,2-diphenyl-1-picrylhydrazyl (DPPH^•), 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS^+•), and superoxide anion (O2^−•), reducing capacity, and metal chelating ability. OLM and its fractions exhibited potent antioxidant activity in these in vitro assays, with a correlation between radical-scavenging activity and total phenolic content. OLM and its fractions inhibited the mushroom tyrosinase activity superior to the reference control, ascorbic acid. In B16-F10 melanoma cells, OLM and its fractions significantly decreased melanin production and tyrosinase activity. Mechanistic investigations revealed that OLM and its fractions inhibited tyrosinase and TRP-2 expressions via downregulating MITF and phosphorylated CREB and differentially inducing ERK or JNK phosphorylation. Additionally, OLM and its fractions caused no significant cytotoxicity towards B16-F10 or skin fibroblast cells at concentrations used in these cellular assays. These findings demonstrated the potential of O. laciniata extracts as the ideal skin protective agent with dual antioxidant and anti-melanogenic activities.

In Vitro Anti-Wrinkle and Skin-Moisturizing Effects of Evening Primrose (Oenothera biennis) Sprout and Identification of Its Active Components

The present study aimed to investigate the effect of Oenothera biennis sprout extract (OBS-E) on skin-function improvement in an in vitro system and to identify its pharmaceutically active components. OBS-E showed antioxidant ability in radical scavenging and reducing power assays, significantly inhibited matrix metalloproteinases-1 and -2, and increased the production of type I collagen, indicating its anti-wrinkle activity. Furthermore, OBS-E significantly increased the level of hyaluronic acid (HA) and the expression of moisturizing genes, such as hyaluronic acid synthase 2 (HAS2) and aquaporin 3 (AQP3), indicating it is effective in enhancing skin hydration. High-performance liquid chromatography (HPLC) and mass spectrometry (MS) analyses showed that OBS-E contained high levels of polyphenolic acids, such as gallic acid and ellagic acid, in addition to flavonoid glycosides, such as luteolin 7-glucuronide and quercetin 3-glucuronide. Our results suggest that these major phytochemicals are likely to play crucial roles in the expression of antioxidant, anti-wrinkle, and moisturizing activities of OBS-E.

Antioxidant and Skin Anti-Aging Effects of Marigold Methanol Extract

The objective of this study was to evaluate the antioxidant and anti-aging effects of marigold methanol extract (MGME) in human dermal fibroblasts. Total polyphenolic and flavonoid contents in MGME were 74.8 mg TAE (tannic acid equivalent)/g and 85.6 mg RE (rutin equivalent)/g, respectively. MGME (500 μg/mL) increased 1,1-diphenyl-2-picryl hydrazyl (DPPH) and 2,2′-azino-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) radical-scavenging, and superoxide dismutase (SOD)-like antioxidant activities by 36.5, 54.7, and 14.8%, respectively, compared with the control. At 1,000 μg/mL, these activities increased by 63.7, 70.6, and 20.6%, respectively. MGME (100 μg/mL) significantly increased the synthesis of type 1 procollagen by 83.7% compared with control treatment. It also significantly decreased Matrix Metalloproteinase-2 (MMP-2) activity and MMP-1 mRNA expression by 36.5% and 69.5%, respectively; however, it significantly increased laminin-5 mRNA expression by 181.2%. These findings suggest that MGME could protect human skin against photo-aging by attenuating oxidative damage, suppressing MMP expression and/or activity as well as by stimulating collagen synthesis.

Anti-Photoaging Effects of Angelica acutiloba Root Ethanol Extract in Human Dermal Fibroblasts

The effects that ultraviolet rays elicit on collagen synthesis and degradation are the most common causes of wrinkle formation and photo-aging in skin. The objectives of this study were to evaluate the effects of Angelica acutiloba root ethanol extract (AAEE) to promote collagen synthesis and inhibit collagen degradation in human dermal fibroblasts. By examining total polyphenol and flavonoid contents, electron donating ability, radical scavenging activity, and superoxide dismutase-like activity, we found that AAEE exhibited fairly good antioxidant activity. Treatment with AAEE significantly increased type I procollagen production by cultured fibroblasts, as well as reduced ultraviolet-induced matrix metalloproteinase-1 (MMP-1) expression and MMP-2 activity in a dose-dependent manner (p < 0.05). In addition, AAEE significantly increased TIMP-1 mRNA expression (p < 0.05), although without an associated dose-dependent increase in TIMP-1 protein expression. In summary, we suggest that AAEE may be a potentially effective agent for the prevention or alleviation of skin-wrinkle formation induced by ultraviolet rays.

Anti-Melanogenic Effect of Oenothera laciniata Methanol Extract in Melan-a Cells

We evaluated the antioxidant activity and anti-melanogenic effects of Oenothera laciniata methanol extract (OLME) in vitro by using melan-a cells. The total polyphenol and flavonoid content of OLME was 66.3 and 19.0 mg/g, respectively. The electron-donating ability, 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical-scavenging activity, and superoxide dismutase (SOD)-like activity of OLME (500 μg/mL) were 94.5%, 95.6%, and 63.6%, respectively. OLME and arbutin treatment at 50 μg/mL significantly decreased melanin content by 35.5% and 14.2%, respectively, compared to control (p < 0.05). OLME and arbutin treatment at 50 μg/mL significantly inhibited intra-cellular tyrosinase activity by 22.6% and 12.6%, respectively, compared to control (p < 0.05). OLME (50 μg/mL) significantly decreased tyrosinase, tyrosinase-related protein-1 (TRP-1), TRP-2, and microphthalmia-associated transcription factor-M (MITF-M) mRNA expression by 57.1%, 67.3%, 99.0%, and 77.0%, respectively, compared to control (p < 0.05). Arbutin (50 μg/mL) significantly decreased tyrosinase, TRP-1, and TRP-2 mRNA expression by 24.2%, 42.9%, and 48.5%, respectively, compared to control (p < 0.05). However, arbutin (50 μg/mL) did not affect MITF-M mRNA expression. Taken together, OLME showed a good antioxidant activity and anti-melanogenic effect in melan-a cells that was superior to that of arbutin, a well-known skin-whitening agent. The potential mechanism underlying the anti-melanogenic effect of OLME was inhibition of tyrosinase activity and down-regulation of tyrosinase, TRP-1, TRP-2, and MITF-M mRNA expression.