Drug Delivery Strategies for Avobenzone: A Case Study of Photostabilization

Computed libraries of avobenzone derivatives with sulfur groups as enhanced UVA filters

CONTEXT

Sunscreen formulations often contain avobenzone as a UVA filter to combat the deleterious effects of solar UV radiation. Avobenzone has notable drawbacks: (1) photounstability under UV radiation/sunlight and (2) tendency for skin penetration. The current report aims to improve both the intrinsic photostability and decrease the skin permeability of avobenzone through skeleton structure modification. The electron-donating -OMe group of avobenzone was replaced with diverse groups to compute molecular libraries of avobenzone derivatives. The studies were focused on the sulfur electron-withdrawing groups of avobenzone derivatives as the photostable UV filters contain -SO3H groups. The UV spectra and bond dissociation energy of Norrish type I cleavages were computed using density functional theory (DFT). The tendency for skin permeability was evaluated by calculating transdermal transportation rate and membrane permeability.

METHODS

A total of 2468 avobenzone derivatives were computed using the enumeration tool of the Schrödinger Material Suite platform. Searching for sulfur-containing derivatives yielded a total of 72 molecules, 23 of which exhibited electron-withdrawing properties. These molecules were evaluated for their UVA spectra using TDDFT with the B3LYP functional and a 6-311G + ** basis set. The bond dissociation energy for putative Norrish type I cleavages was calculated using the B3LYP functional in combination with the LACV3P** basis set. The membrane dG insert was calculated using the membrane permeability panel. The maximum transdermal transportation rate (Jm) was derived using the QikProp tool. These results indicate that avobenzone derivatives with sulfonic acid, sulfuric diamide, and sulfonamide functional groups demonstrated improved photochemical properties with a significant reduction in skin permeability compared to the native avobenzone.

Characterizing the Ultraviolet (UV) Screening Ability of L-5-Sulfanylhistidine Derivatives on Human Dermal Fibroblasts

Using sunscreens is one of the most widespread measures to protect human skin from sun ultraviolet radiation (UVR) damage. However, several studies have highlighted the toxicity of certain inorganic and organic UV filters used in sunscreens for the marine environment and human health. An alternative strategy may involve the use of natural products of marine origin to counteract UVR-mediated damage. Ovothiols are sulfur-containing amino acids produced by marine invertebrates, microalgae, and bacteria, endowed with unique antioxidant and UV-absorption properties. This study aimed to evaluate the protective effect of synthetic L-5-sulfanyl histidine derivatives, inspired by natural ovothiols, on human dermal fibroblasts (HDFs) upon UVA exposure. By using a custom-made experimental set-up to assess the UV screening ability, we measured the levels of cytosolic and mitochondrial reactive oxygen species (ROS), as well as cell viability and apoptosis in HDFs, in the presence of tested compounds, after UVA exposure, using flow cytometry assays with specific fluorescent probes. The results show that L-5-sulfanyl histidine derivatives display a UV screening capacity and prevent loss in cell viability, the production of cytosolic and mitochondrial ROS induced by UVA exposure in HDFs, and subsequent apoptosis. Overall, this study sheds light on the potential applications of marine-inspired sulfur-containing amino acids in developing alternative eco-safe sunscreens for UVR skin protection.

Stability and Properties of Ultraviolet Filter Avobenzone under Its Diketo/Enol Tautomerization Induced by Molecular Encapsulation with β-Cyclodextrin

Inclusion complexation of the sunscreen ingredient avobenzone (AVB) with β-cyclodextrin (β-CD) was investigated to improve its aqueous solubility and photostability; another ultraviolet (UV) filter, oxybenzone (OXB), and the phytochemical antioxidant curcumin (CUR) served as a comparison. In this study, the 1-octanol/water partition coefficients, acid dissociation constants, phase-solubility diagrams with β-CD, and ultraviolet-visible (UV-vis) spectral changes induced by UVA1 (365 nm) irradiation were evaluated. β-CD at concentrations 50-100 times that of AVB most effectively protected the photostability of AVB. Additionally, an UVA1-insensitive species with a diketo tautomer, which has an UVC-absorbing band and the potential to cause photodegradation, was stored in the inclusion complex. Acetonitrile-water mixtures at various volume ratios were screened to mimic the internal cavity of β-CD for the AVB tautomeric species using nuclear magnetic resonance (NMR) spectral integrals for the components. The results indicated that β-CD provides a hydrophobic environment similar to that of a 40-50% acetonitrile aqueous solution and enhances the photostability of AVB. However, excess β-CD induced a hyperchromic effect on the diketo tautomer. Aggregation of the AVB/β-CD inclusion complexes at β-CD concentrations of ≥2 mM enhances UVC band absorption. To avoid excess β-CD, a molar ratio of 50-100 of β-CD to AVB is recommended as the optimal composition. This study newly exhibited that the cavity of β-CD mitigates the reactivity of UVA1 toward AVB by inducing the diketo tautomer form of AVB within the cavity.

Demystifying the potential of lipid-based nanocarriers in targeting brain malignancies

Drug targeting for brain malignancies is restricted due to the presence of the blood-brain barrier (BBB) and blood-brain tumor barrier (BBTB), which act as barriers between the blood and brain parenchyma. Certainly, the limited therapeutic options for brain malignancies have made notable progress with enhanced biological understanding and innovative approaches, such as targeted therapies and immunotherapies. These advancements significantly contribute to improving patient prognoses and represent a promising shift in the landscape of brain malignancy treatments. A more comprehensive understanding of the histology and pathogenesis of brain malignancies is urgently needed. Continued research focused on unraveling the intricacies of brain malignancy biology holds the key to developing innovative and tailored therapies that can improve patient outcomes. Lipid nanocarriers are highly effective drug delivery systems that significantly improve their solubility, bioavailability, and stability while also minimizing unwanted side effects. Surface-modified lipid nanocarriers (liposomes, niosomes, solid lipid nanoparticles, nanostructured lipid carriers, lipid nanocapsules, lipid-polymer hybrid nanocarriers, lipoproteins, and lipoplexes) are employed to improve BBB penetration and uptake through various mechanisms. This systematic review illuminates and covers various topics related to brain malignancies. It explores the different methods of drug delivery used in treating brain malignancies and delves into the benefits, limitations, and types of brain-targeted lipid-based nanocarriers. Additionally, this review discusses ongoing clinical trials and patents related to brain malignancy therapies and provides a glance into future perspectives for treating this condition.

Understudied and underestimated impacts of organic UV filters on terrestrial ecosystems

Organic UV filters (OUVFs) are vital components in various personal care products (PCPs) and commercial goods, with the annual consumption estimated at 10,000 tons. Consequently, the unavoidable use of OUVFs in PCPs and other unregulated commercial applications could present a considerable risk to human and environmental health. These chemical entities enter terrestrial ecosystems through wastewater discharge, agriculture, atmospheric deposition, and recreational activities. Compared to aqueous ecosystems, the effects of OUVFs on terrestrial environments should be more studied and potentially underestimated. The present review addresses the abovementioned gap by summarizing 189 studies conducted between 2006 and 2024, focusing on the analytical measures, occurrence, and ecotoxicological effects of OUVFs on terrestrial ecosystems. These studies underscore the harmful effects of certain OUVFs on the development, reproduction, and endocrine systems of terrestrial organisms, highlighting the necessity for comprehensive toxicological assessments to understand their impacts on non-target species in terrestrial ecosystems. Besides, by underscoring the ecological effects of OUVFs, this review aims to guide future research and inform regulatory measures to mitigate the risks posed by these widespread contaminants. Meanwhile, interdisciplinary research is essential, integrating environmental science, toxicology, ecology, and chemistry to tackle OUVF challenges in terrestrial ecosystems.

Photoprotective properties of four structure propolis from Heterotrigona itama stingless beehive: Fractionation, bioactivity analysis, and chemical profiling

Heterotrigona itama stingless bee propolis extract is known for its diverse bioactive compounds, making it a potential natural shield against UV radiation. This research assesses the photoprotective potential of crude ethanol extract from H. itama propolis collected from four structures (involucrum, pillar, pot, and entrance) of five bee hives (H1-H5), totalling 20 samples. Initially, the samples underwent testing for SPF value and UV absorption spectra. The crude ethanol extract (E) from the involucrum (H4) with the highest SPF value and broadest spectrum was selected for fractionation using hexane and water. Subsequently, the extract (E) and its hexane (H) and water (W) fractions were subjected to SPF analysis, UVA/UVB absorption assessment, determination of total phenolic and flavonoid content, free radical scavenging capacity, anti-collagenase effects, and cytotoxicity assessment. Additionally, LC-MS/MS analysis was performed to identify chemical constituents in the active fraction (W). The extract E demonstrated an SPF of 8.23 ± 0.09 and UV absorption. Notably, its fraction W exhibited the highest SPF (16.55 ± 0.24) at 100 μg/mL, surpassing the H fraction (SPF 5.7 ± 0.45). Phenolic content was highest in the H fraction (388.95 ± 4.54 mg/g GAE DW), followed by the W fraction (286.76 ± 6.48 mg/g GAE DW) and crude E (91.83 ± 4.12 mg/g GAE DW) from the involucrum. Regarding flavonoids, the fraction W led with 79.82 ± 6.21 mg/g QE DW, followed by the H fraction (45.56 ± 0.05 mg/g QE DW) and E (34.57 ± 1.11 mg/g QE DW). The extract E also exhibited modest DPPH scavenging (EC50 = 120 μg/mL), while the H fraction demonstrated stronger activity (EC50 = 4.37 μg/mL), and the W fraction displayed moderate effects (EC50 = 17.55 μg/mL). Notably, the W fraction showed remarkable anti-collagenase activity, outperforming the positive control, EG. HaCaT cell cytotoxicity revealed that the extract E was cytotoxic, whereas the H and W fractions showed no toxicity. LC-MS/MS analysis identified bioactive flavonoids (e.g., pratensein, quercetin) in the W fraction. These findings highlight the superior photoprotective properties of the water fraction from the involucrum of H. itama stingless bee propolis extract, suggesting its potential as a natural and effective ingredient for sunscreen and skincare formulations.

Preformulation evaluation of selumetinib for topical application: skin distribution and photodegradation analysis using MALDI imaging and LC-MS/MS

Understanding drug behavior within the skin, especially for photosensitive compounds, is crucial for developing effective and safe topical therapies. This study employs Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry Imaging (MALDI-MSI) and Liquid Chromatography-Mass Spectrometry (LC-MS/MS) to investigate the skin permeation and photostability of selumetinib, a MEK inhibitor used in treating type 1 neurofibromatosis (NF1). The highest amounts of selumetinib in the skin sections were obtained when using the gel formulation, suggesting that it is to be preferred to cream formulations to achieve higher permeation of the drug. Our study also revealed that selumetinib is amenable to photodegradation in ex vivo skin explants, and yields one main degradation product, whose degradation is likely triggered by hydrogen abstraction. MALDI-MSI results showed selumetinib and its degradation product concentrate in skin appendages, indicating these structures might serve as drug reservoirs, potentially prolonging retention and efficacy. This study demonstrates that combining MALDI-MSI with LC/MS-MS can highly contribute to the characterization of the fate of photosensitive compounds in the skin, an essential prerequisite to the development of compound-specific photoprotective measures. It will also pave the way for innovative topical delivery strategies for NF1 treatment.

Environmental implications and nanotechnological advances in octocrylene-enriched sunscreen formulations: A comprehensive review

Ultraviolet (UV) radiation is a major contributor to skin aging, cancer, and other detrimental health effects. Sunscreens containing FDA-approved UV filters, like avobenzone, offer protection but suffer from photodegradation and potential phototoxicity. Encapsulation, antioxidants, and photostabilizers are strategies employed to combat these drawbacks. Octocrylene, an organic UV filter, utilizes nanotechnology to enhance sun protection factor (SPF). This review examines recent literature on octocrylene-enriched sunscreens, exploring the interplay between environmental impact, nanotechnological advancements, and clinical trial insights. A critical focus is placed on the environmental consequences of sunscreen use, particularly the potential hazards UV filters pose to marine ecosystems. Research in the Mediterranean Sea suggests bacterial sensitivity to these filters, raising concerns about their integration into the food chain. This review aims to guide researchers in developing effective strategies for photostabilization of UV filters. By combining encapsulation, photostabilizers, and antioxidants, researchers can potentially reduce phototoxic effects and contribute to developing more environmentally friendly sunscreens.

Next generation sequencing-aided screening, isolation, molecular identification, and antimicrobial potential for bacterial endophytes from the medicinal plant, Elephantorrhiza elephantina

Elephantorrhiza elephantina, a wild plant in southern Africa, is utilized in traditional medicine for various ailments, leading to its endangerment and listing on the Red List of South African Plants. To date, there have been no reports on bacterial endophytes from this plant, their classes of secondary metabolites, and potential medicinal properties. This study presents (i) taxonomic characterization of bacterial endophytes in leaf and root tissues using 16S rRNA, (ii) bacterial isolation, morphological, and phylogenetic characterization, (iii) bacterial growth, metabolite extraction, and LC-MS-based metabolite fingerprinting, and (iv) antimicrobial testing of bacterial crude extracts. Next-generation sequencing yielded 693 and 2,459 DNA read counts for the rhizomes and leaves, respectively, detecting phyla including Proteobacteria, Bacteroidota, Gemmatimonadota, Actinobacteriota, Verrucomicrobiota, Dependentiae, Firmicutes, and Armatimonodata. At the genus level, Novosphingobium, Mesorhizobium, Methylobacterium, and Ralstonia were the most dominant in both leaves and rhizomes. From root tissues, four bacterial isolates were selected, and 16S rRNA-based phylogenetic characterization identified two closely related Pseudomonas sp. (strain BNWU4 and 5), Microbacterium oxydans BNWU2, and Stenotrophomonas maltophilia BNWU1. The ethyl acetate:chloroform (1:1 v/v) organic extract from each isolate exhibited antimicrobial activity against all selected bacterial pathogens. Strain BNWU5 displayed the highest activity, with minimum inhibitory concentrations ranging from 62.5 μg/mL to 250 μg/mL against diarrhoeagenic Escherichia coli, Escherichia coli O157:H7, Salmonella enterica, antibiotic-resistant Vibrio cholerae, Staphylococcus aureus, Bacillus cereus, and Enterococcus durans. LC-MS analysis of the crude extract revealed common antimicrobial metabolites produced by all isolates, including Phenoxomethylpenicilloyl (penicilloyl V), cis-11-Eicosenamide, 3-Hydroxy-3-phenacyloxindole, and 9-Octadecenamide.

Adverse Effects of Avobenzone on Boar Sperm Function: Disruption of Protein Kinase A Activity and Tyrosine Phosphorylation

Avobenzone (AVO), an ultraviolet (UV) filter, is frequently used as an ingredient in personal cosmetics. This UV filter has been found to be easily exposed in swimming pools and beaches, and it has been detected in human urine and blood. Moreover, numerous studies have demonstrated that AVO exhibits endocrine-disrupting properties. Nevertheless, the effects of AVO on male fertility have not yet fully understood. Therefore, this study aimed to assess the effects of AVO on various sperm functions during capacitation. First, boar spermatozoa were treated with various AVO concentrations. After treatment, sperm motility and kinetic characteristics, capacitation status, intracellular adenosine triphosphate (ATP) levels, and sperm viability were evaluated. Moreover, Western blot analysis w.as conducted to evaluate protein kinase A (PKA) activity and tyrosine phosphorylation. As a result, AVO treatment significantly decreased total motility, progressive motility, and several kinetic characteristics at high concentrations (50 and 100 μM). Furthermore, the capacitation status dose-dependently decreased. Conversely, no significant differences in acrosome reaction, cell viability, and intracellular ATP levels were observed. However, the intracellular ATP level tended to decrease. In addition, AVO dose-dependently induced abnormal changes in PKA activity and tyrosine phosphorylation. Although AVO did not directly exert a toxic effect on cell viability, it ultimately negatively affected sperm functions through abnormal alterations in PKA activity and tyrosine phosphorylation. Thus, the potential implications on male fertility must be considered when contemplating the safe utilization of AVO.

Photoprotective Effects of Two New Morin-Schiff Base Derivatives on UVB-Irradiated HaCaT Cells

Ultraviolet (UV) radiation harms the skin, causing oxidative damage, inflammation, and disruption of the skin's barrier function. There is considerable interest in identifying new natural ingredients with antioxidant and anti-inflammatory properties to serve as adjuvants in sunscreens. The flavonoid morin (1) can undergo structural modifications to enhance its biological properties. The aim of this study was to synthesize two new morin-Schiff base derivatives, morin oxime (2) and morin semicarbazone (3), comparing their photoprotective effects with that of the parent compound on UVB-exposed HaCaT keratinocytes. The chemical structure of the novel compounds was revealed based on spectroscopic data analysis. Our findings demonstrated that derivatives 2 and 3 enhanced the light absorption capability in the UV-visible (vis) range compared to 1. Tested compounds exhibited a higher scavenger capacity than Trolox. Moreover, pre-treatment with all compounds protected HaCaT cells from UVB-induced cell death. Compound 3 demonstrated the strongest antioxidant effect, reducing reactive oxygen species (ROS) generation and, subsequently, malondialdehyde (MDA) levels. Additionally, compounds 2 and 3 exhibited greater anti-inflammatory effects than compound 1, significantly reducing interleukin (IL)-6 production levels at all tested concentrations. These findings have demonstrated, for the first time, a promising photoprotective activity of two new Schiff base derivatives and suggest their use as natural sunscreen ingredients.

Design of Proanthocyanidins and TiO2 Nanoparticles-Based Novel Emulsions as a Platform for UV Protection

A white oil-in-water novel emulsion stabilized by TiO2 nanoparticles with UVB shielding properties and proanthocyanidins with antioxidant activity was prepared, where the proanthocyanidins aggregated at the oil-water interface to reduce interfacial tension while TiO2 nanoparticles were dispersed in the continuous water phase to hinder droplet coalescence. It was found that the average oil droplet size was less than 10 μm and decreased with the increase of proanthocyanidins concentration, but the increase of the content of TiO2 nanoparticles had little effect on it. The combination of TiO2 nanoparticles and proanthocyanidins was versatile for oil phases with different polarities, and the resulting emulsion exhibited high stability in the face of centrifugation, heating and prolonging storage time. After encapsulating the UVA filter avobenzone in white oil, the emulsion was endowed with the ability to resist UVB and UVA. Further, the emulsion showed great free radical scavenging ability for superoxide anion radical (⋅O2 - ), hydroxyl radical (⋅OH) with the clearance rate of over 70 %, indicating the good antioxidant activity. The ingenious combination of UVB, UVA filter and antioxidant with emulsion as carrier provides a new idea for the preparation of full-band sunscreen emulsion.