Preparation of melanin from Catharsius molossus L. and preliminary study on its chemical structure

Xiao

et al. 2018

IJMS

In this study, melanin (BgM) was obtained from Boletus griseus. The chemical composition and structure of BgM were characterized by UV-visible absorption spectrum, Fourier transform infrared spectrum, elemental analysis, nuclear magnetic resonance, pyrolysis gas chromatography mass spectrometry, and ultra-performance liquid chromatography–high resolution mass spectrometry. The percentage contents of C, H, N, S and O elements were 56.38%, 5.86%, 6.17%, 2.44%, and 28.04%, and the S/N and C/N ratios were 0.17 and 10.66, respectively. The UV-vis spectrum of BgM showed a maximum absorption peak at 214 nm. Characteristic absorption peaks were observed at 3426, 1600 and 1105 cm−1, and BgM contained phenolic hydroxyl, amidogen, carbonyl, methylene, and methyl groups. Moreover, BgM is an eumelanin, and its main skeleton has both a benzene ring and an indole, and the branched chain mainly consists of alkanes, alcohols, and fatty acids. BgM was hydrolyzed by H2O2 and four compounds were tentatively analyzed from the UPLC-MS/MS profile. The chemical structure of BgM was characterized as 5,6-dihydroxyindole eumelanin, and the condensed molecular formula is [C28(OR1)4(OR2)3H11O6N4]n.

Section: Resultsmentioning

confidence: 99%

Study on the Preparation and Chemical Structure Characterization of Melanin from Boletus griseus

Xiao

et al. 2018

IJMS

“…It was recorded in Shen-Nong-Ben-Cao-Jing, a classical ancient Chinese medical book, and has been used for centuries in China due to its multiple functions such as arresting convulsion, removing blood stasis, relaxing the bowels, and counteracting toxins [1]. Previous chemical investigations revealed that C. molossus contains melanin [2] and imidazole compounds [3]. The extract of C. molossus was found to have antitumor [4], anti-benign prostatic hyperplasia [5,6], and cardiovascular activities [7].…”

Section: Introductionmentioning

confidence: 99%

Identification of N-Acetyldopamine Dimers from the Dung Beetle Catharsius molossus and Their COX-1 and COX-2 Inhibitory Activities

Lü

Sun

et al. 2015

Molecules

“…Moreover, in the pyrolysis, degradation products of the SM of Inonotus obliquus were identified high proportions of benzaldehyde and benzylic acid, as well as hexadecanoic acid (Mazurkiewicz, ); hexadecanoic acid was a hydrolysis product of the SMRT and SMBT. However, a high proportion of toluene, pyridine, and other unidentified compounds were reported in the pyrolysis products of the insoluble melanins of Bacillus subtilis (Gómez‐Marín & Sánchez, ); whereas the pyrolysis products of the melanins of Catharsius molossus L. included pyrrole, indole, phenol, and their alkyl derivatives, characteristic degradation products of eumelanins (Xin et al, ). These results are different to those reported in this research for the SM of R. echinocarpa , and it could be due to differences in melanin sources and extraction methods (Pío‐León et al, ; Sava, Yang, et al, ).…”

Section: Resultsmentioning

confidence: 99%

“…The temperatures of the highest weight loss of the SMRT and SMBT were similar to those obtained for SM of other sources such as Inonotus obliquus (400°C) (Mazurkiewicz, ) and Bacillus thuringiensis (320°C) (Aghajanyan et al, ), as well as for insoluble melanins of Klebsiella sp. GSK (300°C) (Sajjan et al, ) and Catharsius molossus L. (256°C) (Xin et al, ). However, the degradation temperatures of the insoluble melanins of Vitex mollis and R. echinocarpa (≅ 350°C) were higher than that of the SM of R. echinocarpa ; a difference that could be explained by the presence of carbohydrates in the structures of the SM (Montes‐Avila et al, ).…”

Section: Resultsmentioning

confidence: 99%

Soluble melanins of the Randia echinocarpa fruit – Structural characteristics and toxicity

et al. 2019

The water-soluble melanins (SM) of Randia echinocarpa fruit possess interesting biological activities and have been scarcely characterized. In this study, SM were obtained at boiling (SMBT) and room (SMRT) temperatures and characterized by UV-Vis, IR, thermogravimetric analysis, and GC-MS of the hydrolysis products of the SM; besides, the solid-state 13 C NMR, elemental analysis, and acute and sub-acute toxicity of the SMBT were determined. SMBT and SMRT contain organic acids and carbohydrates and their spectroscopic signals and thermograms were similar, but the SMBT yield was higher.The SMBT were characterized by their elemental composition (C 48.260 ± 0.011%, N 3.693 ± 0.009% and H 6.093 ± 0.076%) consistent with the presence of aromatic rings and eumelanins, degradation temperature at 300°C, 13 C NMR signals supporting melanin-bonding with carbohydrates and organic acids, and innocuity in Balb/C mice (acute assay, LD 50 > 5 g/kg b.w.; sub-acute assay, no lethality at 500 mg/kg b.w. for 30 days). Practical applicationsThe consumption of melanins has been associated with health benefits because of their biological activities (e.g., antioxidant, immunostimulatory, UV-and radiationprotective). Randia echinocarpa is employed in Mexican traditional medicine against chronic degenerative diseases (e.g., cancer and diabetes) and ailments of organs (e.g., kidney and lung) and systems (e.g., circulatory and gastrointestinal). The R. echinocarpa fruit contains water-soluble melanins (SM) that inhibit carbohydrate-digestive enzymes and show high antioxidant activity; thus, SM could be useful for the prevention and treatment of diabetes. This study showed that the SM structure contains melanin-bonding organic acids and carbohydrates, which could be associated with the SM solubility and higher yield, and that SMBT were innocuous in the acute and sub-acute assays in mice. Thus, the R. echinocarpa SMBT could be used as safe potential ingredients to develop functional products. K E Y W O R D Sdietary supplements, elemental analysis, functional food, melanin, solid-state carbon-13 magnetic resonance spectroscopy, thermogravimetry, toxicity 2 of 12 | GIL-AVILÉS et AL.