A new photosafety screening strategy based on in chemico photoreactivity and in vitro skin exposure for dermally-applied chemicals

Comparison of two biological systems used for phototoxicity testing: Cellular and tissue

The OECD has approved two similar methods for testing the phototoxic potency of chemicals. The first method, OECD 432, is based on the cytotoxicity properties of materials to the mouse 3T3 (clone A31) cell line (fibroblasts) after exposure to light. The second method, OECD 498, is based on the same properties but using reconstructed human epidermis - EpiDerm (stratified keratinocytes). The aim of this study was to compare these two methods using statistical tests (specificity, sensitivity, negative predictive value, positive predictive value and accuracy) and non-statistical characteristics (e.g. price and experimental duration, amount of material, level of complications, cell type, irradiation dose). Both tests were performed according to the relevant guidelines using the same 11 control substances. Higher performance values were observed for OECD 432 in both phototoxic and non-phototoxic classifications. The accuracy of OECD 432 was 90.9%, while that of OECD 498 was 72.7%. OECD 432 was also shorter and less expensive. On the other hand, OECD 498 was less complicated, and used human cells with stratum corneum, which better reflects real skin. This method can also be used with oily substances that are poorly soluble in water. However, both methods are important for testing the phototoxic properties of materials, and can be used alone or in a tiered strategy.

Cnidii Fructus: A traditional Chinese medicine herb and source of antiosteoporotic drugs

BACKGROUND

Osteoporosis (OP) is a prevalent chronic metabolic bone disease for which limited countermeasures are available. Cnidii Fructus (CF), primarily derived from Cnidium monnieri (L.) Cusson., has been tested in clinical trials of traditional Chinese medicine for the management of OP. Accumulating preclinical studies indicate that CF may be used against OP.

MATERIALS AND METHODS

Comprehensive documentation and analysis were conducted to retrieve CF studies related to its main phytochemical components as well as its pharmacokinetics, safety and pharmacological properties. We also retrieved information on the mode of action of CF and, in particular, preclinical and clinical studies related to bone remodeling. This search was performed from the inception of databases up to the end of 2022 and included PubMed, China National Knowledge Infrastructure, the National Science and Technology Library, the China Science and Technology Journal Database, Weipu, Wanfang, the Web of Science and the China National Patent Database.

RESULTS

CF contains a wide range of natural active compounds, including osthole, bergapten, imperatorin and xanthotoxin, which may underlie its beneficial effects on improving bone metabolism and quality. CF action appears to be mediated via multiple processes, including the osteoprotegerin (OPG)/receptor activator of nuclear factor-κB ligand (RANKL)/receptor activator of nuclear factor-κB (RANK), Wnt/β-catenin and bone morphogenetic protein (BMP)/Smad signaling pathways.

CONCLUSION

CF and its ingredients may provide novel compounds for developing anti-OP drugs.

Xanthotoxin (8-methoxypsoralen): A review of its chemistry, pharmacology, pharmacokinetics, and toxicity

Xanthotoxin (XAT) is a natural furanocoumarins, a bioactive psoralen isolated from the fruit of the Rutaceae plant Pepper, which has received increasing attention in recent years due to its wide source and low cost. By collecting and compiling literature on XAT, the results show that XAT exhibits significant activity in the treatment of various diseases, including neuroprotection, skin repair, osteoprotection, organ protection, anticancer, antiinflammatory, antioxidative stress and antibacterial. In this paper, we review the pharmacological activity and potential molecular mechanisms of XAT for the treatment of related diseases. The data suggest that XAT can mechanistically induce ROS production and promote apoptosis through mitochondrial or endoplasmic reticulum pathways, regulate NF-κB, MAPK, JAK/STAT, Nrf2/HO-1, MAPK, AKT/mTOR, and ERK1/2 signaling pathways to exert pharmacological effects. In addition, the pharmacokinetics properties and toxicity of XAT are discussed in this paper, further elucidating the relationship between structure and efficacy. It is worth noting that data from clinical studies of XAT are still scarce, limiting the use of XAT in the clinic, and in the future, more in-depth studies are needed to determine the clinical efficacy of XAT.

Strategic photosafety screening system consisting of in chemico photoreactivity and in vitro skin exposure for quinolone derivatives

The main objective of this study was to verify the applicable domain of a proposed photosafety screening system, consisting of a reactive oxygen species (ROS) assay and in vitro skin permeation test, for dermally-applied chemicals. Quinolones (QNLs) were selected as test compounds, including enoxacin, flumequine, moxifloxacin, nalidixic acid, orbifloxacin, and oxolinic acid. The ROS assay and in vitro skin permeation test were employed to evaluate photoreactivity and skin deposition of QNLs, respectively. All QNLs exhibited significant ROS generation on exposure to simulated sunlight; in particular, enoxacin was indicative of potent photoreactivity compared with the other 5 QNLs. Steady-state concentration values of flumequine and nalidixic acid were calculated to be 5.0 and 8.2 μg/mL, respectively, and higher than those of the other QNLs. Based on the photoreactivity and skin exposure of QNLs, the phototoxic risk was ranked, and the predicted phototoxic risk by the proposed system was mostly in agreement with observed in vivo phototoxicity, suggesting the applicability of the proposed strategy to photosafety assessment of QNLs. The proposed screening would be efficacious to predict phototoxic risk of dermally-applied chemicals.