Stability and solubility of trans-resveratrol are strongly influenced by pH and temperature

Hormetic shifting of redox environment by pro-oxidative resveratrol protects cells against stress

Resveratrol has gained tremendous interest owing to multiple reported health-beneficial effects. However, the underlying key mechanism of action of this natural product remained largely controversial. Here, we demonstrate that under physiologically relevant conditions major biological effects of resveratrol can be attributed to its generation of oxidation products such as reactive oxygen species (ROS). At low nontoxic concentrations (in general <50µM), treatment with resveratrol increased viability in a set of representative cell models, whereas application of quenchers of ROS completely truncated these beneficial effects. Notably, resveratrol treatment led to mild, Nrf2-specific gene expression reprogramming. For example, in primary epidermal keratinocytes derived from human skin this coordinated process resulted in a 1.3-fold increase of endogenously generated glutathione (GSH) and subsequently in a quantitative reduction of the cellular redox environment by 2.61mVmmol GSH per g protein. After induction of oxidative stress by using 0.78% (v/v) ethanol, endogenous generation of ROS was consequently reduced by 24% in resveratrol pre-treated cells. In contrast to the common perception that resveratrol acts mainly as a chemical antioxidant or as a target protein-specific ligand, we propose that the cellular response to resveratrol treatment is essentially based on oxidative triggering. In physiological microenvironments this molecular training can lead to hormetic shifting of cellular defense towards a more reductive state to improve physiological resilience to oxidative stress.

Electrosprayed nanocomposites based on hyaluronic acid derivative and Soluplus for tumor-targeted drug delivery

Nanocomposite (NC) based on hyaluronic acid-ceramide (HACE) and Soluplus (SP) was fabricated by electrospraying for the tumor-targeted delivery of resveratrol (RSV). Amphiphilic property of both HACE and SP has been used to entrap RSV in the internal cavity of NC. Electrospraying with established experimental conditions produced HACE/SP/RSV NC with 230nm mean diameter, narrow size distribution, negative zeta potential, and >80% drug entrapment efficiency. Sustained and pH-dependent drug release profiles were observed in drug release test. Cellular uptake efficiency of HACE/SP NC was higher than that of SP NC, mainly based on HA-CD44 receptor interaction, in MDA-MB-231 (CD44 receptor-positive human breast cancer) cells. Selective tumor targetability of HACE/SP NC, compared to SP NC, was also confirmed in MDA-MB-231 tumor-xenograted mouse model using a near-infrared fluorescence (NIRF) imaging. According to the results of pharmacokinetic study in rats, decreased in vivo clearance and increased half-life of RSV in NC group, compared to drug solution group, were shown. Given that these experimental results, developed HACE/SP NC can be a promising theranostic nanosystem for CD44 receptor-expressed cancers.

Synthesis and Biological Evaluation of Resveratrol Derivatives as Melanogenesis Inhibitors

Resveratrol (1), a naturally occurring stilbene compound, has been suggested as a potential whitening agent with strong inhibitory activity on melanin synthesis. However, the use of resveratrol in cosmetics has been limited due to its chemical instability and poor bioavailability. Therefore, resveratrol derivatives were prepared to improve bioavailability and anti-melanogenesis activity. Nine resveratrol derivatives including five alkyl ether derivatives with C₂H₅, C₄H₉, C₅H₁₁, C₆H₁₃, and C₈H₁₇ (2a–2e) and four ester derivatives with CH₃, CH=C(CH₃)₂, CH(C₂H₅)C₄H₉, C₇H₁₅ (3a–3d) were newly synthesized and their effect on melanin synthesis were assessed. All the synthetic derivatives efficiently reduced the melanin content in α-MSH stimulated B16F10 melanoma cells. Further investigation showed that the inhibitory effect of 2a on melanin synthesis was achieved not by the inhibition of tyrosinase activity but by the inhibition of melanogenic enzyme expressions such as tyrosinase and tyrosinase-related protein (TRP)-1. Our synthetic resveratrol derivatives have more lipophilic properties than resveratrol by the addition of alkyl or acyl chains to free hydroxyl moiety of resveratrol; thus, they are expected to show better bioavailability in skin application. Therefore, we suggest that our synthetic resveratrol derivatives might be promising candidates for better practical application to skin-whitening cosmetics.