Black Sesame Pigment: DPPH Assay-Guided Purification, Antioxidant/Antinitrosating Properties, and Identification of a Degradative Structural Marker

Abstract

An improved purification procedure leading to black sesame ( Sesamum Indicum L.) pigment was developed involving fat removal by treatment of ground black sesame seeds with dichloromethane followed by an optimized hydrolytic protocol with 6 M HCl, at 100 °C, overnight. The black pigment thus obtained displayed good antioxidant efficiency by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical assay (82% reduction at 0.5 mg/mL), good ferric ion-reducing capacity (61 μM Trolox equivalent concentration at 0.5 mg/mL), and potent antinitrosating properties (74% inhibition of 2,3-diaminonaphthalene (DAN) nitrosation at gastric pH at 2.5 mg/mL). A synthetic pigment obtained by oxidative polymerization of coniferyl alcohol (polyconiferyl alcohol, PCA), the putative biosynthetic precursor to the sesame pigment, was characterized as a reference standard. FT IR spectra of the purified sesame pigment and PCA supported the structural similarity. HPLC analysis of degradation products by alkaline hydrogen peroxide of purified black sesame pigment showed the formation of vanillic acid (VA) as the main isolable fragment. Similar yields of VA were obtained by degradation of PCA. A positive correlation between VA yields and DPPH activity was determined in samples of different purities. It is suggested that VA is a structural marker of black sesame pigment, confirming the biosynthetic origin from coniferyl alcohol and pointing to the o-methoxyphenol motif as the key factor accounting for the potent antioxidant properties of the pigment.

Anti-Amyloid Aggregation Activity of Black Sesame Pigment: Toward a Novel Alzheimer’s Disease Preventive Agent

“…Based on the previous finding that vanillic acid (VA) represents one of the main fragments following chemical degradation of BSP [ 46 ] and on the results of total reflectance Fourier transform infrared (ATR-FTIR) and solid-phase NMR experiments [ 47 ], it has been proposed that ortho -methoxyhydroxy units are represented to a significant extent in the backbone of BSP, although ortho -diphenols and phenolic acids are present as well. To further confirm this hypothesis, BSP was subjected to alkali fusion under reducing conditions.…”

“…BSP was prepared from black sesame seeds ( Sesamum indicum L.) as previously described [ 46 ]. Pepsin from porcine gastric mucosa, pancreatin from porcine pancreas, porcine bile extract, 4-hydroxy-3-methoxybenzoic acid (VA), 4-hydroxybenzoic acid, 3,4-dihydroxybenzoic acid, KOH, NaOH, Na 2 S 2 O 4 , AChE from Electrophorus electricus (E.C.3.1.1.7, Type VI-S), acethylthiocholine iodide, 5,5′-dithiobis-2-nitrobenzoic acid (DTNB), BChE from equine serum (E.C.3.1.1.8), butyrylthiocholine iodide, thioflavin T, 1,1,1,3,3,3-hexafluoro-2-propanole (HFIP) and BACE1 activity detection kit were purchased from Sigma-Aldrich (Milan, Italy); synthetic Aβ 1-40 and 1-42 (human sequence) were from Bachem (Bubendorf, Switzerland).…”

“…More recently, several studies have been focused on the peculiar properties of the insoluble pigment of black sesame seeds [ 45 ]. In particular, we recently developed an improved purification procedure to obtain black sesame pigment (BSP), involving fat removal by treatment of ground black sesame seeds with dichloromethane followed by an optimized hydrolytic protocol with 6 M HCl, at 100 °C, overnight [ 46 ]. The black pigment thus obtained displayed good antioxidant efficiency in the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical assay, good ferric ion-reducing capacity and potent antinitrosating properties.…”

Natural Phenol Polymers: Recent Advances in Food and Health Applications

“…The black pigment was purified by hydrolytic treatment of the seeds after removal of lipid components, but its insolubility hampered a detailed structural analysis. Solid state spectroscopy coupled to chemical degradation methodologies and model studies indicated coniferyl alcohol-derived units as the main structural components [16,17] (Figure 2). …”

Effect of black sesame (Sesamum indicum) and flaxseed flour (Linum usitatissimum) on bread quality using surface response methodology

“…Kiran and Asad (2008) showed that seeds and oil of S. indicum L. have considerable healing activity when administered orally or topically. The black sesame pigment obtained by removal of the fat content using dichloromethane and hydrolytic protocol displays considerable antioxidant and antinitrosant effects (Panzella et al 2012). It has been shown that the black sesame cream presents considerable antioxidant potential (Silva et al 2011).…”