Development of novel alternative hair dyes to hazardous para-phenylenediamine.

Most of the permanent hair dye products contain p-phenylenediamine (PPD), a well-known skin sensitizer. PPD may cause cutaneous reactions and leads to allergic contact dermatitis (ACD), a condition with major medical and financial repercussions. Hair dye-induced ACD represents a growing concern both for consumers and the cosmetics industry. In this study we introduced novel side chains on the PPD molecule with the goal of overcoming the hazard potential of PPD. Our strategy relies on the replacement of the colorless PPD with new, larger and intrinsically colorled PPD derivatives to reduce dermal penetration and thus the skin sensitization potential. We synthesized two oligomers with bulky side-chains, which displayed 7-8 times lower cytotoxicity than PPD, a significantly weaker sensitization potential (22.0 % and 23.8 % versus 55.5 % for PPD) in the Direct Peptide Reactivity Assay, minimal cumulative penetration through excised skin and an intrinsic ability to colour and preserve the nuance when applied on bleached hair. The lower skin permeation and sensitizing potential are absolutely crucial and give a clear advantage of our products over other standards. These novel PPD hair dyes show significantly less hazard potential than PPD and may, upon further risk assessment studies, replace PPD in consumer care products.

Cutaneous Malassezia: Commensal, Pathogen, or Protector?

The skin microbial community is a multifunctional ecosystem aiding prevention of infections from transient pathogens, maintenance of host immune homeostasis, and skin health. A better understanding of the complex milieu of microbe-microbe and host-microbe interactions will be required to define the ecosystem's optimal function and enable rational design of microbiome targeted interventions. Malassezia, a fungal genus currently comprising 18 species and numerous functionally distinct strains, are lipid-dependent basidiomycetous yeasts and integral components of the skin microbiome. The high proportion of Malassezia in the skin microbiome makes understanding their role in healthy and diseased skin crucial to development of functional skin health knowledge and understanding of normal, healthy skin homeostasis. Over the last decade, new tools for Malassezia culture, detection, and genetic manipulation have revealed not only the ubiquity of Malassezia on skin but new pathogenic roles in seborrheic dermatitis, psoriasis, Crohn's disease, and pancreatic ductal carcinoma. Application of these tools continues to peel back the layers of Malassezia/skin interactions, including clear examples of pathogenicity, commensalism, and potential protective or beneficial activities creating mutualism. Our increased understanding of host- and microbe-specific interactions should lead to identification of key factors that maintain skin in a state of healthy mutualism or, in turn, initiate pathogenic changes. These approaches are leading toward development of new therapeutic targets and treatment options. This review discusses recent developments that have expanded our understanding of Malassezia's role in the skin microbiome, with a focus on its multiple roles in health and disease as commensal, pathogen, and protector.

Specific Targeting of Melanotic Cells with Peptide Ligated Photosensitizers for Photodynamic Therapy.

A strategy combining covalent conjugation of photosensitizers to a peptide ligand directed to the melanocortin 1 (MC1) receptor with the application of sequential LED light dosage at near-IR wavelengths was developed to achieve specific cytotoxicity to melanocytes and melanoma (MEL) with minimal collateral damage to surrounding cells such as keratinocytes (KER). The specific killing of melanotic cells by targeted photodynamic therapy (PDT) described in this study holds promise as a potentially effective adjuvant therapeutic method to control benign skin hyperpigmentation or superficial melanotic malignancy such as Lentigo Maligna Melanoma (LMM).