Solid‐state cross‐polarization magic angle spinning 13C and 15N NMR characterization of Sepia melanin, Sepia melanin free acid and Human hair melanin in comparison with several model compounds

Adhyaru, Bhavin; Akhmedov, Novruz G.; Katritzky, Alan R.; Bowers, Clifford R.

doi:10.1002/mrc.1193

Cited by 67 publications

(100 citation statements)

References 16 publications

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“…4B) and GSM120386 (Fig. S1D) confirm the presence of aliphatic groups 0-90 ppm (CH x , CNH 2 ), aromatic groups 90-160 ppm (CH x , C─O, C 2 NH) and carboxylic acid groups and ketones 160-200 ppm (C═O, COO), consistent with those previously reported for S. officinalis (33). The spectra of the background sediments of GSM 122841 and GSM 120386 lack the aromatic, carboxylic acid, and ketone signals present in the fossil pigment ( Fig.…”

Section: Resultssupporting

confidence: 89%

Direct chemical evidence for eumelanin pigment from the Jurassic period

Glass

Ito

Wilby

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

172

168

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Melanin is a ubiquitous biological pigment found in bacteria, fungi, plants, and animals. It has a diverse range of ecological and biochemical functions, including display, evasion, photoprotection, detoxification, and metal scavenging. To date, evidence of melanin in fossil organisms has relied entirely on indirect morphological and chemical analyses. Here, we apply direct chemical techniques to categorically demonstrate the preservation of eumelanin in two >160 Ma Jurassic cephalopod ink sacs and to confirm its chemical similarity to the ink of the modern cephalopod, Sepia officinalis. Identification and characterization of degradation-resistant melanin may provide insights into its diverse roles in ancient organisms.

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Section: Resultssupporting

confidence: 89%

Direct chemical evidence for eumelanin pigment from the Jurassic period

Glass

Ito

Wilby

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

172

168

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“…Figure 5 showed the 13 C CP/MAS NMR spectra for natural squid ink melanin and soluble fraction B. Both of the two samples showed similar peaks among three characteristic spectral regions as described in the previously literature for the NMR of the melanin (Adhyaru et al 2003;Tian et al 2003, Jalmi et al 2012: (1)δ10-95 ppm was assigned to aliphatic carbons, which was due to proteinaceous material; (2)δ95-165 ppm was assigned to aromatic carbons, including indole or pyrrole type carbons within the polymer; (3)δ165-200 ppm, carbonyl carbon atoms in amides, carboxylates and quinones, which came from the carbonyl in the oxidized quinone form of DHI and DHICA. More specifically, the signals near~δ30ppm and~δ50ppm were assigned to aliphatic groups which come from dihydroderivatives of DHICA, DHI (Knicker et al 1995;Adhyaru et al 2003;Tian et al 2003;Jalmi et al 2012); the signals near~δ103ppm was suggestive of C-3 of indole nucleus, which was from the anomeric carbon of carbohydrates; the peak near~δ130ppm was assigned to aromatic group; the signal near~δ174ppm was due to carbonyl group present as carboxylic acid group, which was derived from DHICA, and the degradation products of DHI and DHICA.…”

Section: Nmr Spectrumsupporting

confidence: 65%

“…In comparison with the fraction B, natural melanin exhibited higher intensity of signals in the rangeδ95-165 ppm. This was presumably attributable to the greater percentage of protonated carbon atoms (δ95-130 ppm) and quaternarycarbon atoms in the melanin backbone (δ130-145 ppm) (Adhyaru et al 2003), which indicated that aromatic structure was broken down in some extent through the degradation process.…”

Section: Nmr Spectrummentioning

confidence: 99%

Preparation of water-soluble melanin from squid ink using ultrasound-assisted degradation and its anti-oxidant activity

Guo

Chen

et al. 2013

J Food Sci Technol

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Water-soluble squid melanin fractions were firstly prepared using ultrasound-assistant degradation method under alkaline condition, which is optimized by response surface methodology. The processing melanin fractions were divided into different molecular weight (Mw) fractions by membrane separation (below 10 kDa, among 10-50 kDa and over 50 kDa). The AFM image and particle-size analysis showed monomer units of the melanin were destroyed, and huge polymers were degraded into smaller soluble particles after ultrasound. While, UV, IR and solid 13 C NMR spectra indicated that the basic structure of melanin fraction was still retained after ultrasound process. Further analysis showed soluble melanin fractions obtained in 0.5 and 1 M NaOH, with Mw above 10 kDa exhibited much higher in vitro antioxidant potency. The IC 50 of these fractions (IC 50 among 19-80 μg) on scavenging O 2¯i s more efficient than carnosine (IC 50 = 355 μg/ml.), a commercialized antioxidant. They (IC 50 mong 115-180 μg/ml) are as efficient as carnosine (IC 50 = 110 μg/ml) on scavenging OH. Our research has reported a novel method for preparation of water-soluble melanin fractions from squid ink, which could be a promising free radical scavenger from nature resource.Keywords Squid ink melanin . Water-soluble . Ultrasound . Structure, anti-oxidation Practical applicationWe developed a novel method using ultrasound processing to obtain water-soluble squid ink melanin under alkaline condition. Our results showed that soluble squid ink melanin fraction as a natural pigment, is a new free radical scavenger with a promising prospect. The excellent solubility can increase absorption and enhance utilization rate in vivo, providing a potential prospect for squid ink melanin products as a nature antioxidant.

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“…Solid State CP-MAS NMR-Based on expected chemical shifts of model compounds and published NMR assignments (26) of Sepia melanin, the 13 C CP-MAS NMR data collected for hydrolyzed Glycera jaw residue fit well (Fig. 4).…”

Section: Resultsmentioning

confidence: 71%