Perspectives and strategies of alternative methods used in the risk assessment of personal care products

Impact of Portuguese propolis on keratinocyte proliferation, migration and ROS protection: Significance for applications in skin products

OBJECTIVE

Propolis has been used since antiquity, but recent reports of its biological properties hint that it could be employed as a topical pharmaceutical and cosmetic ingredient. This work aims to probe the action of Portuguese propolis extracts on skin cells, providing mechanistic insights into its mode of action and preliminarily assessing its applicability as a skin repair ingredient.

METHODS

The total phenolic content of propolis extracts was measured by the Folin Ciocalteu method. The cytotoxic effect of propolis extracts in human keratinocytes was determined and non-cytotoxic concentrations of the extracts were used to study the impact on collective cell migration, cell cycle and intracellular ROS levels.

RESULTS

o significant impact was observed in collective cell migration, but one of the extracts mildly increased G2 phase while reducing the % of sub-G1 at a non-cytotoxic concentration. The two extracts with higher phenolic content strongly prevented intracellular cellular ROS accumulation upon exposure to TBHP. Collectively, these results indicate that the putative beneficial effects of propolis extracts in skin repair may not be attributable to induction of collective cell migration but could be partially ascribed to the protection from oxidative stress, which could act in synergy with its well-known antimicrobial activity.

CONCLUSION

These data support the applicability of this material in topical and cosmetic formulations and further in vivo assays should be conducted to fully characterize its efficacy and safety.

Ex vivo model of human skin (hOSEC) for assessing the dermatokinetics of the anti-melanoma drug Dacarbazine

Alternative models to replace animals in experimental studies remain a challenge in testing the effectiveness of dermatologic and cosmetic drugs. We proposed a model of human organotypic skin explant culture (hOSEC) to assess the profile of cutaneous drug skin distribution, adopting dacarbazine as a model, and respective new methodologies for dermatokinetic analysis. The viability tests were evaluated in primary keratinocytes and fibroblasts, and skin by MTT and TTC assays, respectively. Then, dacarbazine was applied to the culture medium, and the hOSEC method was applied to verify the dynamics of skin distribution of dacarbazine and determine its dermatokinetic profile. The results of cell and tissue viability showed that both were considered viable. The dermatokinetic results indicated that dacarbazine can be absorbed through the skin, reaching a concentration of 36.36 µg/mL (18,18%) of the initial dose (200 µg/mL) after 12 h in culture. Histological data showed that the skin maintained its structure throughout the tested time that the hOSEC method was applied. No apoptotic cells were observed in the epidermal and dermal layers. No visible changes in the dermo-epidermal junction and no inflammatory processes with the recruitment of defense cells were observed. Hence, these findings suggest that the hOSEC concept as an alternative ex vivo model for assessing the dynamics of skin distribution of drugs, such as dacarbazine, and determining their respective dermatokinetic profiles.

Skin irritation potential of cosmetic preservatives: An exposure-relevant study

BACKGROUND

Preservatives represent one of the main causes of skin irritation and contact allergies.

AIMS

To comprehensively evaluate the skin irritation potential of phenoxyethanol, methylparaben, propylparaben, imidazolidinyl urea, and DMDM hydantoin under regulatory acceptable concentrations.

METHODS

A patch test and repeated open application test (ROAT) were applied to evaluate skin irritation in vivo. In vitro alternative methods consisting of the keratinocyte cytotoxicity assay, red blood cell (RBC) test, and hen's egg test-chorioallantoic membrane (HET-CAM) were performed to elucidate the mechanism of preservative-induced irritation responses.

RESULTS

The patch test showed that all test substances showed a weak erythema response. Propylparaben had the highest occlusive irritancy potential in the patch test, owing to damage to the cell membrane. The two formaldehyde releasers showed noticeable skin irritation potential in the ROAT through their cytotoxicity to keratinocytes, while a visible response was observed after applying phenoxyethanol and the two parabens. No filtration was noticed in the in vivo tests, which might be attributed to the failure of subcutaneous vessel alteration by the preservatives.

CONCLUSIONS

Commonly used cosmetic preservatives have minor skin irritation potential with mild erythema reaction under practical use, especially formaldehyde releasers and propylparaben.

In vitro culture systems as an alternative for female reproductive toxicology studies

Studies have shown that daily exposure to different products, whether chemical or natural, can cause irreversible damage to women’s reproductive health. Therefore it is necessary to use tests that evaluate the safety and efficacy of these products. Most reproductive toxicology tests are performedin vivo. However, in recent years, various cell culture methods, including embryonic stem cells and tissues have been developed with the aim of reducing the use of animals in toxicological tests. This is a major advance in the area of toxicology, as these systems have the potential to become a widely used tool compared within vivotests routinely used in reproductive biology and toxicology. The present review describes and highlights data onin vitroculture processes used to evaluate reproductive toxicity as an alternative to traditional methods usingin vivotests.

The insect repellents: A silent environmental chemical toxicant to the health

In recent years, a large number of insect repellents have been developed with the idea of consumer benefits. In addition to already known advantageous application of insect repellents, there is increasing concern about the potential toxicity in environment leading to health caused by random use of these compounds. An increasing number of evidence suggests that insect repellents may trigger undesirable hazardous interactions with biological systems with a potential to generate harmful effects including intermediate metabolites. Biotransformation followed by bioaccumulation (vice e versa) may be an important phenomenon for toxic response of this chemicals. In this review, we have summarized the current state of knowledge on the insect repellent toxicity, including biochemical pathway alteration under in vitro and in vivo conditions considering different classes of organisms, from lower to higher vertebrate. Furthermore, we have tried to incorporate the effects of insect repellent in light of some clinical reports. We hope this review would provide useful information on potential side effects of uncontrolled use of insect repellents.

Review of reviews on exposures to synthetic organic chemicals and children's neurodevelopment: Methodological and interpretation challenges

Environmental epidemiology data are becoming increasingly important in public health decision making, which commonly incorporates a systematic review of multiple studies. This review addresses two fundamental questions: What is the quality of available reviews on associations between exposure to synthetic organic chemicals and neurodevelopmental outcomes? What is the value (e.g., quality and consistency) of the underlying literature? Published reviews on associations between synthetic organic environmental chemical exposures and neurodevelopmental outcomes in children were systematically evaluated. Seventy-four relevant reviews were identified, and these were evaluated with respect to four methodological characteristics: (1) systematic inclusion/exclusion criteria and reproducible methods for search and retrieval of studies; (2) structured evaluation of underlying data quality; (3) systematic assessment of consistency across specific exposure-outcome associations; and (4) evaluation of reporting/publication bias. None of the 74 reviews fully met the criteria for all four methodological characteristics. Only four reviews met two criteria, and six reviews fulfilled only one criterion. Perhaps more importantly, the higher quality reviews were not able to meet all of the criteria owing to the shortcomings of underlying studies, which lacked comparability in terms of specific research question of interest, overall design, exposure assessment, outcome ascertainment, and analytic methods. Thus, even the most thoughtful and rigorous review may be of limited value if the underlying literature includes investigations that address different hypotheses and are beset by methodological inconsistencies and limitations. Issues identified in this review of reviews illustrate considerable challenges that are facing assessments of epidemiological evidence.