Work

Melanin with putative p-coumaric acid-related structural features from tamarind (Tamarindus indica L.) and black pepper seeds (Piper nigrum L.)

Year: 2026

Type: article

Abstract: This study investigates melanin isolated from tamarind and black pepper seeds to elucidate its molecular composition and structural features. Spectroscopic analysis by nuclear magnetic resonance and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry indicated that the melanin was predominantly composed of aromatic units, with mass spectral features consistent with those of p -coumaric acid ( p -CA) derived structures. Density functional theory calculations of the p -CA monomers and dimers revealed multiple reactive sites that may contribute to the formation of structurally diverse oligomeric assemblies. Furthermore, electron paramagnetic resonance (EPR) spectroscopy indicated that the experimental g-factors are compatible with cationic species, particularly for oligomeric models containing C 5 -O′ C4 linkages. These findings provide crucial insights into the molecular structure and potential reactivity of melanin from tamarind and black pepper seeds, supporting its relevance in future functional and application-oriented studies.

Source: Journal of Food Composition and Analysis

DOI: 10.1016/j.jfca.2026.109450