Melanin: Production from Cheese Bacteria, Chemical Characterization, and Biological Activities

Abstract

Pigments are compounds of importance to several industries, for instance, the food industry, where they can be used as additives, color intensifiers, and antioxidants. As the current trend around the world is shifting to the use of eco-friendly commodities, demand for natural dyes is increasing. Melanins are pigments that are produced by several microorganisms. Pseudomonas putida ESACB 191, isolated from goat cheese rind, was described as a brown pigment producer. This strain produces a brown pigment via the synthetic Müeller-Hinton Broth. This brown compound was extracted, purified, analyzed by FTIR and mass spectrometry, and identified as eumelanin. The maximum productivity was 1.57 mg/L/h. The bioactivity of eumelanin was evaluated as the capacity for scavenging free radicals (antioxidant activity), EC50 74.0 ± 0.2 μg/mL, and as an acetylcholinesterase inhibitor, with IC50 575 ± 4 μg/mL. This bacterial eumelanin did not show cytotoxicity towards A375, HeLa Kyoto, HepG2, or Caco2 cell lines. The effect of melanin on cholesterol absorption and drug interaction was evaluated in order to understand the interaction of melanin present in the cheese rind when ingested by consumers. However, it had no effect either on cholesterol absorption through an intestinal simulated barrier formed by the Caco2 cell line or with the drug ezetimibe.

Therapeutic potential of enzymatically extracted eumelanin from squid ink in type 2 diabetes mellitus ICR mice: Multifaceted intervention against hyperglycemia, oxidative stress and depression

“…(iii) A band at 1400–1300 cm −1 corresponds to the CH in‐plane bending vibrations, CO isostretching vibrations and CC single bond skeleton vibrations. These characteristic absorption peaks were highly consistent with those reported for eumelanin and natural squid eumelanin, 33 and the characteristic groups of eumelanin were still retained after complex enzyme extraction.…”

Suggested Sustainable Medical and Environmental Uses of Melanin Pigment From Halotolerant Black Yeast Hortaea werneckii AS1

“…In the DPPH radical scavenging experiment, H. werneckii AS1 melanin recorded an IC 50 value of 61.38 μg/ml. Such a result (with an IC 50 value below 100 μg/ml) was in the range of values recorded by the purified melanin pigment from Aspergillus bridgeri , with a radical scavenging activity IC 50 of 54.12 μg/ml ( Kumar et al, 2011 ), as well as a eumelanin pigment from Pseudomonas putida ESACB191 with IC 50 at 74 μg/ml, compared to 170.3 μg/ml for commercial Sepia officinalis melanin ( Ferraz et al, 2021 ). Furthermore, the IC 50 of H. werneckii R23 melanin on DPPH radicals was 28.11 ± 10.76 μg/ml, which was 21 times beyond the standard trolox IC 50 of 1.334 ± 0.20 μg/ml ( Wilson, 2016 ).…”

“…The fact that melanin has a complex structure of various compounds with hydroxyl and aromatic groups that can easily be stabilized through donating hydrogen to the DPPH radical explains its high antioxidant activity. Natural antioxidants are recommended for use in food, cosmetic, and pharmaceutical industries ( Kumar et al, 2011 ; Ferraz et al, 2021 ). Therefore, H. werneckii AS1 can be recommended as a promising natural antioxidant due to its considerable antioxidant potential.…”

“…Similarly, but at a higher concentration, purified melanin from Dietzia schimae NM3 at a concentration of up to 250 μg/ml showed no toxicity toward normal human fibroblast cell culture (HFB) ( Eskandari and Etemadifar, 2021 ). Also, P. putida ESACB 191 melanin tested against A375, HeLa Kyoto, HepG2, and Caco2 cell lines, showed an elevated IC 50 values of 1.77, 2.51, 0.89, and 1.08 mg/ml, respectively ( Ferraz et al, 2021 ). Furthermore, melanin from Y. lipolytica W29 was found to exert no toxic effect on mouse fibroblast NIH3T3 and human keratinocyte HaCaT cell lines with a 20% reduction of the metabolic activity of the cells at a concentration of 100 μg/ml ( Ben Tahar et al, 2019 ).…”

Stress Dependent Biofilm Formation and Bioactive Melanin Pigment Production by a Thermophilic Bacillus Species from Chilean Hot Spring

“…Melanin pigments from different origins; fungi, animal retinal cells, plant shells, and bacteria are well known for their photoprotective activity as antioxidants [67,[71][72][73][74][75]. In recent times, melanin nanoparticles are also being reported for increased shelf life as antioxidants [76].…”