VdP5CDH is involved in melanin formation, stress resistance and play a regulatory role in virulence of Verticillium dahliae.

Introduction: Verticillium dahliae, a soil-borne fungal pathogen, can cause cotton Verticillium wilt. In this study, VdP5CDH, the member of the ALDH_F4-17 family of carboxylate dehydrogenases, was identified in the genome of V. dahliae and investigated function in regulating virulence by generating gene deletion mutants and complementary mutants. Methods: Homologous recombination method was used to construct mutants, transcriptome sequencing revealed gene-related metabolic pathways, and disease degree of cotton was observed through pathogen infection experiments. Results: The conidial surface of VdP5CDH deletion strains was dented and shriveled, and the number of conidial spores increased. Compared with the wild-type (WT), the mycelial diameter of deletion mutants increased by 10.59%-11.16%, the mycelial growth showed irregular branching patterns, and misaligned arrangement. Although capable of penetrating cellophane, deletion mutants were unable to produce melanin. VdP5CDH was mainly associated with glucose metabolism, nitrogen metabolism, ABC transporter activity as well as various amino acid metabolic processes. After gene knockout, raffinose and pectin were used as the main carbon sources to promote the growth of strains and the growth rate of deletion strains in the medium containing raffinose was higher than that of WT. Consequently, the deletion mutant strains decreased utilization efficiency with which they utilized various nitrogen sources. The deletion mutants maintain responsiveness to osmotic stress and oxidative stress stimuli. Additionally, compared to WT strains, the deletion mutant strains exhibited differences in culture temperature tolerance, UV exposure response, and fungicide sensitivity. After cotton was infected with deletion strains conidial suspension, its disease index increased dramatically, while it gradually decreased after spraying with 2 mM glutamate in batches. With the increase of spraying times, the effect was more significant, and the disease index decreased by 18.95%-19.66% at 26 dpi. Discussion: These results indicated that VdP5CDH regulates the pathogenicity of fungi and controls mycelia growth, melanin formation, conidia morphology, abiotic stress resistance, and the expression of infecting structure-related genes.

Central Role of Hypothalamic Circuits for Acupuncture's Anti-Parkinsonian Effects.

Despite clinical data stretching over millennia, the neurobiological basis of the effectiveness of acupuncture in treating diseases of the central nervous system has remained elusive. Here, using an established model of acupuncture treatment in Parkinson's disease (PD) model mice, we show that peripheral acupuncture stimulation activates hypothalamic melanin-concentrating hormone (MCH) neurons via nerve conduction. We further identify two separate neural pathways originating from anatomically and electrophysiologically distinct MCH neuronal subpopulations, projecting to the substantia nigra and hippocampus, respectively. Through chemogenetic manipulation specifically targeting these MCH projections, their respective roles in mediating the acupuncture-induced motor recovery and memory improvements following PD onset are demonstrated, as well as the underlying mechanisms mediating recovery from dopaminergic neurodegeneration, reactive gliosis, and impaired hippocampal synaptic plasticity. Collectively, these MCH neurons constitute not only a circuit-based explanation for the therapeutic effectiveness of traditional acupuncture, but also a potential cellular target for treating both motor and non-motor PD symptoms.

Yellowness in skin complexion: Analysis of self-perception of women in China evaluated against clinical parameters of yellowness.

BACKGROUND: Skin "yellowness" is an abstract and subjective term, without a definitive measurement protocol. Objectives were to analyze Chinese women's self-perception of skin yellowness and associated parameters and identify objective clinical measurements that correlate with these perceptions. METHODS: Following focus group discussions, criteria for skin yellowness were defined, and validated by volunteer rankings of facial images. A typology study of 185 women was performed. Participants were grouped into yellow (Color Uniformity, Brightness and Transparency (CUBT) yellow scale grade > 3, chromameter b* value > 16) and non-yellow (CUBT yellow scale grade < 2, b* value < 14) groups. Participants self-evaluated their skin on yellowness, transparency, skin uniformity, dullness, radiance, oiliness, and texture. Expert assessments were performed to grade sebaceous pores, ocular area pigmentation, pigmentary spots and CUBT scores. Instrumental analysis of the skin was employed using corneometer, sebumeter, mexameter chromameter, and AGE reader. RESULTS: Women in the yellow group self-evaluated their skin as significantly duller, less uniform, and less radiant than women in the non-yellow group (P ≤ 0.05). Higher levels of ocular area pigmentation and lower facial skin uniformity and brightness (P < 0.001) were observed in women with yellow skin. CUBT expert grading showed lower pink skin color, but significantly higher beige, yellow, and olive pigmentation (P ≤ 0.05) in women in the yellow skin group. Melanin and b* values were significantly higher in women with yellow skin while L value was significantly lower. CONCLUSION: Self-perceived skin yellowness in Chinese women correlates to chromameter and mexameter measurements, as well as expert evaluation of ocular pigmentation and CUBT parameters.

Ciliary length variations impact cilia-mediated signaling and biological responses.

Primary cilia are thin hair-like organelles that protrude from the surface of most mammalian cells. They act as specialized cell antennas that can vary widely in response to specific stimuli. However, the effect of changes in cilia length on cellular signaling and behavior remains unclear. Therefore, we aimed to characterize the elongated primary cilia induced by different chemical agents, lithium chloride (LiCl), cobalt chloride (CoCl2), and rotenone, using human retinal pigmented epithelial 1 (hRPE1) cells expressing ciliary G protein-coupled receptor (GPCR), melanin-concentrating hormone (MCH) receptor 1 (MCHR1). MCH induces cilia shortening mainly via MCHR1-mediated Akt phosphorylation. Therefore, we verified the proper functioning of the MCH-MCHR1 axis in elongated cilia. Although MCH shortened cilia that were elongated by LiCl and rotenone, it did not shorten CoCl2-induced elongated cilia, which exhibited lesser Akt phosphorylation. Furthermore, serum readdition was found to delay cilia shortening in CoCl2-induced elongated cilia. In contrast, rotenone-induced elongated cilia rapidly shortened via a chopping mechanism at the tip of the cilia. Conclusively, we found that each chemical exerted different effects on ciliary GPCR signaling and serum-mediated ciliary structure dynamics in cells with elongated cilia. These results provide a basis for understanding the functional consequences of changes in ciliary length.

Nanohybrid-Based Redox Homeostasis Perturbators Escaped from Early Lysosomes toward Amplified Sensitization of Tumor Cells and Photothermally Maneuvered Pyroptosis Therapy.

Reactive oxygen species (ROS) hold great potential in tumor pyroptosis therapy, yet they are still limited by short species lifespan and limited diffusion distance. Inducing cells into a metastable state and then applying external energy can effectively trigger pyroptosis, but systemic sensitization still faces challenges, such as limited ROS content, rapid decay, and short treatment windows. Herein, a nanohybrid-based redox homeostasis-perturbator system was designed that synergistically induce early lysosomal escape, autophagy inhibition, and redox perturbation functions to effectively sensitize cells to address these challenges. Specifically, weakly alkaline layered double hydroxide nanosheets (LDH NSs) with pH-responsive degradation properties enabled early lysosomal escape within 4 h, releasing poly(L-dopa) nanoparticles for inducing catechol-quinone redox cycling in the cytoplasm. The intracellular ROS levels were systematically rebounded by 3-4 times in tumor cells and lasted for over 4 h. Subsequently induced lysosomal stress and Ca2+ signaling activation resulted in severe mitochondrial dysfunction, as well as a perilous metastable state. Thereby, sequential near-infrared light was applied to trigger amplified stress through a local photothermal conversion. This led to sufficiently high levels of cleaved caspase-1 and GSDMD activation (2.5-2.8-fold increment) and subsequent pyroptosis response. In addition, OH- released by LDH elevated pH to alleviate the limitation of glutathione depletion by quinones at acidic pH and inhibit protective autophagy. Largely secreted inflammatory factors (2.5-5.6-fold increment), efficient maturation of dendritic cells, and further immune stimulation were boosted for tumor inhibition as a consequence. This study offers a new paradigm and insights into the synergy of internal systematic cellular sensitization and sequential external energy treatment to achieve tumor suppression through pyroptosis.

New Aspects Regarding the Fluorescence Spectra of Melanin and Neuromelanin in Pigmented Human Tissue Concerning Hypoxia.

Melanin is a crucial pigment in melanomagenesis. Its fluorescence in human tissue is exceedingly weak but can be detected through advanced laser spectroscopy techniques. The spectral profile of melanin fluorescence distinctively varies among melanocytes, nevomelanocytes, and melanoma cells, with melanoma cells exhibiting a notably "red" fluorescence spectrum. This characteristic enables the diagnosis of melanoma both in vivo and in histological samples. Neuromelanin, a brain pigment akin to melanin, shares similar fluorescence properties. Its fluorescence can also be quantified with high spectral resolution using the same laser spectroscopic methods. Documented fluorescence spectra of neuromelanin in histological samples from the substantia nigra substantiate these findings. Our research reveals that the spectral behavior of neuromelanin fluorescence mirrors that of melanin in melanomas. This indicates that the typical red fluorescence is likely influenced by the microenvironment around (neuro)melanin, rather than by direct pigment interactions. Our ongoing studies aim to further explore this distinctive "red" fluorescence. We have observed this red fluorescence spectrum in post-mortem measurements of melanin in benign nevus. The characteristic red spectrum is also evident here (unlike the benign nevus in vivo), suggesting that hypoxia may contribute to this phenomenon. Given the central role of hypoxia in both melanoma development and treatment, as well as in fundamental Parkinson's disease mechanisms, this study discusses strategies aimed at reinforcing the hypothesis that red fluorescence from (neuro)melanin serves as an indicator of hypoxia.

Transcriptomic and Metabolomic Analyses Reveal Molecular Regulatory Networks for Pigmentation Deposition in Sheep.

Domestic animals have multiple phenotypes of skin and coat color, which arise from different genes and their products, such as proteins and metabolites responsible with melanin deposition. However, the complex regulatory network of melanin synthesis remains to be fully unraveled. Here, the skin and tongue tissues of Liangshan black sheep (black group) and Liangshan semi-fine-wool sheep (pink group) were collected, stained with hematoxylin-eosin (HE) and Masson-Fontana, and the transcriptomic and metabolomic data were further analyzed. We found a large deposit of melanin granules in the epidermis of the black skin and tongue. Transcriptome and metabolome analysis identified 744 differentially expressed genes (DEGs) and 443 differentially expressed metabolites (DEMs) between the pink and black groups. Gene ontology (GO) and Kyoto encyclopedia of genes and genomes (KEGG) enrichment analyses revealed the DEGs and DEMs were mainly enriched in the pathways of secondary metabolic processes, melanin biosynthesis processes, melanin metabolism processes, melanosome membranes, pigment granule membranes, melanosome, tyrosine metabolism, and melanogenesis. Notably, we revealed the gene ENSARG00020006042 may be a family member of YWHAs and involved in regulating melanin deposition. Furthermore, several essential genes (TYR, TYRP1, DCT, PMEL, MLANA, SLC45A2) were significantly associated with metabolite prostaglandins and compounds involved in sheep pigmentation. These findings provide new evidence of the strong correlation between prostaglandins and related compounds and key genes that regulate sheep melanin synthesis, furthering our understanding of the regulatory mechanisms and molecular breeding of pigmentation in sheep.

Laser Depigmentation: A Case Report.

The pigmented lesions of the oral cavity may be endogenous or exogenous. Among the options for depigmenting these areas, laser therapy stands out for being a minimally invasive procedure. This study aims to report a clinical case of the gingival depigmentation technique using a high-power diode laser in the anterior maxillary region, for the ablation of the pigmented tissue to improve gingival aesthetics. The patient had an aesthetic complaint of the darkened aspect of the gingiva in the anterior maxillary portions. After local anesthesia, we started depigmentation with a high-power diode laser and performed ablation from the attached gingiva toward the free marginal gingiva. The patient returned after 30 and 180 days presenting healthy gingiva and absence of melanin repigmentation. Thus, we concluded that the diode laser was a good alternative for melanin depigmentation because it is a procedure with lower morbidity and satisfactory results.

Inkjet-Printed Bio-Based Melanin Composite Humidity Sensor for Sustainable Electronics.

A lack of sustainability in the design of electronic components contributes to the current challenges of electronic waste and material sourcing. Common materials for electronics are prone to environmental, economic, and ethical problems in their sourcing, and at the end of their life often contribute to toxic and nonrecyclable waste. This study investigates the inkjet printing of flexible humidity sensors and includes biosourced and biodegradable materials to improve the sustainability of the process. Humidity sensors are useful tools for monitoring atmospheric conditions in various fields. Here, an aqueous dispersion of black soldier fly melanin was optimized for printing with a cosolvent and deposited onto interdigitated silver electrodes on flexible substrates. Impedance spectroscopy demonstrated that adding choline chloride increased the ion concentration and AC conductivity by more than 3 orders of magnitude, resulting in a significant improvement in sensing performance and reduced hysteresis. The devices exhibit fast detection (0.8 ± 0.5 s) and recovery times (0.8 ± 0.3 s), with a 170 ± 40-fold decrease in impedance for relative humidity changes from 30% to 90%. This factor is lowered upon prolonged exposure to high humidity in tests over 72 h during which a stable operation is reached. The low embodied energy of the sensor, achieved through material-efficient deposition and the use of waste management byproducts, enhances its sustainability. In addition, approaches for reusability and degradability are presented, rendering the sensor suitable for wearable or agricultural applications.

The structural complexity of pyomelanin impacts UV shielding in Pseudomonas species with different lifestyles.

Pyomelanin, a polymeric pigment in Pseudomonas, arises mainly from alterations in tyrosine degradation. The chemical structure of pyomelanin remains elusive due to its heterogeneous nature. Here, we report strain-specific differences in pyomelanin structural features across Pseudomonas using PAO1 and PA14 reference strains carrying mutations in hmgA (a gene involved in pyomelanin synthesis), a melanogenic P. aeruginosa clinical isolate (PAM), and a melanogenic P. extremaustralis (PexM). UV spectra showed dual peaks for PAO1 and PA14 mutants and single peaks for PAM and PexM. FTIR phenol : alcohol ratio changes and complex NMR spectra indicated non-linear polymers. UVC radiation survival increased with pyomelanin addition, correlating with pigment absorption attenuation. P. extremaustralis UVC survival varied with melanin source, with PAO1 pyomelanin being the most protective. These findings delineate structure-based pyomelanin subgroups, having distinct physiological effects.

The Invisible Fraction within Melanin Capable of Absorbing UV Light and with Fluorescent Properties: Is It Lacking Consideration?

Expanding on earlier observations, we show that many melanin materials, in vitro synthesized from a wide range of precursors, can be fractionated into a dark-colored precipitate and a near-colorless, dispersible fraction. The dispersible fractions exhibited absorbance in the UVA and UVB range of the electromagnetic spectrum, but none in the visible range. In addition, fluorescent properties were associated with all dispersible fractions obtained. FT-IR spectroscopic analyses were performed to compare both types of fractions. Overall, it appears that some of the properties associated with melanin (UV absorbance, fluorescence) may not necessarily reside in the dark-colored portion of melanin, but in a colorless fraction of the material. It remains to be seen whether any of these in vitro observations have any relevance in vivo. However, we raise the possibility that the presence of a colorless fraction within melanin materials and their associated properties may have received inadequate attention. Given the important association between melanin, UV protection, and skin cancer, it is worthwhile to consider this additional aspect of melanin chemistry.

Melanin-Like Nanomedicine Functions as a Novel RPE Ferroptosis Inhibitor to Ameliorate Retinal Degeneration and Visual Impairment in Dry Age-Related Macular Degeneration.

Ferrous ion accumulation and lethal oxidative stress mediate irreversible retinal pigment epithelial (RPE) cell ferroptosis and subsequent photoreceptor degeneration, a potential key pathogenic factor in the onset of dry age-related macular degeneration (dAMD), causing irreversible vision loss in the global elderly population. However, currently, no effective interventional treatment strategy exists in clinical practice. Herein, lesion site-targeted melanin-like nanoparticles, named ConA-MelNPs, are designed as a novel ferroptosis inhibitor for retinal degenerative diseases. ConA-MelNPs possessed chelating iron ion characteristics, alleviating severe mitochondrial damage caused by oxidative stress and protecting RPE cells from ferroptosis induced by sodium iodate (NaIO3). In a preclinical dAMD mouse model, a single intravitreal injection of ConA-MelNPs yielded significant responses in electroretinograms and visually-driven optomotor responses in visually impaired mice, resisting the challenge posed by secondary NaIO3-induced injuries, with the long-term sustainability of its therapeutic effect. Mechanistically, ConA-MelNPs achieve a therapeutic effect by interrupting the detrimental cascade involving "RPE cell ferroptosis, lethal oxidative stress, and microglial proinflammatory activation," affording the restoration of retinal homeostasis. The synthesized ConA-MelNPs demonstrated good biosafety, with no detected ophthalmic or systemic side effects. Collectively, ConA-MelNPs are proposed as a promising therapeutic option for atrophic retinal diseases such as dAMD.

How frequently are insects wounded in the wild? A case study using Drosophila melanogaster.

Wounding occurs across multicellular organisms. Wounds can affect host mobility and reproduction, with ecological consequences for competitive interactions and predator-prey dynamics. Wounds are also entry points for pathogens. An immune response is activated upon injury, resulting in the deposition of the brown-black pigment melanin in insects. Despite the abundance of immunity studies in the laboratory and the potential ecological and evolutionary implications of wounding, the prevalence of wounding in wild-collected insects is rarely systematically explored. We investigated the prevalence and potential causes of wounds in wild-collected Drosophilidae flies. We found that 31% of Drosophila melanogaster were wounded or damaged. The abdomen was the most frequently wounded body part, and females were more likely to have melanized patches on the ventral abdomen, compared with males. Encapsulated parasitoid egg frequency was approximately 10%, and just under 1% of Drosophilidae species had attached mites, which also caused wounds. Wounding is prevalent in D. melanogaster, likely exerting selection pressure on host immunity for two reasons: on a rapid and efficient wound repair and on responding efficiently to opportunistic infections. Wounding is thus expected to be an important driver of immune system evolution and to affect individual fitness and population dynamics.

Monte Carlo simulation of the effect of melanin concentration on light-tissue interactions for transmittance pulse oximetry measurement.

Significance: Questions about the accuracy of pulse oximeters in measuring arterial oxygen saturation ( SpO 2 ) in individuals with darker skin pigmentation have resurfaced since the COVID-19 pandemic. This requires investigation to improve patient safety, clinical decision making, and research. Aim: We aim to use computational modeling to identify the potential causes of inaccuracy in SpO 2 measurement in individuals with dark skin and suggest practical solutions to minimize bias. Approach: An in silico model of the human finger was developed to explore how changing melanin concentration and arterial oxygen saturation ( SaO 2 ) affect pulse oximeter calibration algorithms using the Monte Carlo (MC) technique. The model generates calibration curves for Fitzpatrick skin types I, IV, and VI and an SaO 2 range between 70% and 100% in transmittance mode. SpO 2 was derived by inputting the computed ratio of ratios for light and dark skin into a widely used calibration algorithm equation to calculate bias ( SpO 2 - SaO 2 ). These were validated against an experimental study to suggest the validity of the Monte Carlo model. Further work included applying different multiplication factors to adjust the moderate and dark skin calibration curves relative to light skin. Results: Moderate and dark skin calibration curve equations were different from light skin, suggesting that a single algorithm may not be suitable for all skin types due to the varying behavior of light in different epidermal melanin concentrations, especially at 660 nm. The ratio between the mean bias in White and Black subjects in the cohort study was 6.6 and 5.47 for light and dark skin, respectively, from the Monte Carlo model. A linear multiplication factor of 1.23 and exponential factor of 1.8 were applied to moderate and dark skin calibration curves, resulting in similar alignment. Conclusions: This study underpins the careful re-assessment of pulse oximeter designs to minimize bias in SpO 2 measurements across diverse populations.

A Repurposing Pipeline to Candidate-Suitable Inhibitors of Tyrosinase: Computational and Bioassay Studies.

INTRODUCTION: Tyrosinase, a metalloprotein enzyme, plays a crucial role in melanin synthesis by hydroxylating L-tyrosine to L-dopa. However, the accumulation of melanin can lead to hyperpigmented spots, raising aesthetic concerns. METHODS: In this study, we developed a pipeline to repurpose FDA-approved drugs as potential tyrosinase inhibitors. A structure-based screening study was conducted using 1,650 drugs to identify probable inhibitors based on binding energies. RESULTS: From the cluster analysis of binding interaction profiles, 16 compounds were selected as candidates. Montelukast emerged as the final candidate due to its favorable ADME properties. Bioassay evaluation revealed an IC50 value of 14.79 ± 0.87 µM for Montelukast, compared to kojic acid (IC50 = 31.02 ± 2.01 µM). Molecular dynamics simulation and g_MMPBSA free energy calculation studies were performed for the Tyrosinase-Montelukast complex. CONCLUSION: These findings enhance our understanding of Tyrosinase-Montelukast interactions and underscore Montelukast's potential as a tyrosinase inhibitor. This could have implications in dermatological applications and beyond, suggesting Montelukast as a promising candidate for further development in this regard.

Effect of proton pump inhibitors on susceptibility and melanogenesis of Sporothrix species.

Introduction. Sporotrichosis is a subcutaneous infection caused by dimorphic Sporothrix species embedded in the clinical clade. Fungi have virulence factors, such as biofilm and melanin production, which contribute to their survival and are related to the increase in the number of cases of therapeutic failure, making it necessary to search for new options.Gap statement. Proton pump inhibitors (PPIs) have already been shown to inhibit the growth and melanogenesis of other fungi.Aim. Therefore, this study aimed to evaluate the effect of the PPIs omeprazole (OMP), rabeprazole (RBP), esomeprazole, pantoprazole and lansoprazole on the susceptibility and melanogenesis of Sporothrix species, and their interactions with itraconazole, terbinafine and amphotericin B.Methodology. The antifungal activity of PPIs was evaluated using the microdilution method, and the combination of PPIs with itraconazole, terbinafine and amphotericin B was assessed using the checkerboard method. The assessment of melanogenesis inhibition was assessed using grey scale.Results. The OMP and RBP showed significant MIC results ranging from 32 to 256 µg ml-1 and 32 to 128 µg ml-1, respectively. Biofilms were sensitive, with a significant reduction (P<0.05) in metabolic activity of 52% for OMP and 50% for RBP at a concentration of 512 µg ml-1 and of biomass by 53% for OMP and 51% for RBP at concentrations of 512 µg ml-1. As for the inhibition of melanogenesis, only OMP showed inhibition, with a 54% reduction.Conclusion. It concludes that the PPIs OMP and RBP have antifungal activity in vitro against planktonic cells and biofilms of Sporothrix species and that, in addition, OMP can inhibit the melanization process in Sporothrix species.

Comparison between clinical and computerized methods for assessing gingival pigmentation.

Background and Objective: Digital computerized assessment can provide objective values for the measurement of gingival pigmentation. This study aims to compare the Commission Internationale de l'Eclairage Lab color space (CIELAB) values and the computerized intensity values (CIVs) from digital imaging with clinical evaluations using the Dummett-Gupta Oral Pigmentation Index (DOPI) for assessing gingival pigmentation in a multi-ethnic population. Methodology: Digital photographs of 188 participants were taken using standardized parameters. The buccal gingival pigmentation was evaluated using three methods (a) a clinical evaluation by two independent assessors using the DOPI, (b) the CIELAB values using the Adobe Photoshop® software (Version 23.1.1) and (c) the CIV calculated using the ImageJ software (Version 1.53k). A hierarchical clustering analysis was used to identify colour groups that clustered together. Agreement between the clinical and digital categorization of the pigmentation was carried out using weighted kappa analysis. Agreements between CIELAB and CIV were compared using intra-class correlation coefficient. Results: There was a statistically significant difference in the DOPI, the L*, a*, and b* coordinates, and the CIV between the different ethnic groups of the participants. Cluster analysis for the CIELAB and CIV both identified four clusters. The gingival pigmentation categorization using the L*, a*, and b* values moderately agreed with the clinical evaluation using the DOPI index while the categorization with the CIV was in slight agreement with the clinical evaluations. Conclusion: This study identified four clusters of gingival pigmentation in 188 multi-ethnic participants. The clusters, determined by CIELAB values, align with the clinical assessment of gingival pigmentation. Digital measurements derived from clinical photographs can serve as an effective means of pigmentation measurement in dental clinics.

Isolation, purification, and physio-chemical characterization of melanin pigment from nigerseed hulls (Guizotia abyssinica).

Plant melanin, a natural pigment, has gained significant attention recently due to its potential therapeutic and industrial applications. In this study, melanin pigments were extracted from Nigerseed hulls (NH) via alkali and acid extraction methods, followed by acid hydrolysis, organic solvent treatment, and repeated precipitation. The solubility of NH melanin was assessed, revealing solubility in alkali and dimethyl sulfoxide (DMSO) but insolubility in other common organic solvents. High-performance liquid chromatography (HPLC) was employed to measure the purity of NH melanin in comparison to standard melanin, while elemental analysis indicated a similarity between melanin extracted from nigerseed hulls and the standard counterpart. LC-MS data revealed a molecular weight of NH melanin. Furthermore, the stability of melanin was evaluated under varying conditions including temperature, oxidants, reducing agents, light exposure, and metal ion presence. Results demonstrated significant effects of Mg2+, Cu2+, and Fe2+ metal ions on melanin stability, with a minor effect observed for Ca2+, while sodium hyposulfite was found to destabilize the pigments. Our findings suggest that nigerseed hulls hold promise as a novel source for efficient melanin production, with potential applications in the food sector, food packaging, and biomedical fields.