No 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.

Black sesame pigment (BSP) was shown to bind lead, cadmium, and mercury at pH 7.0 and to a lower extent at pH 2.0. BSP at 0.05 mg/mL removed the metals at 15 μM to a significant extent (>65% for cadmium and >90% for mercury and lead), with no changes following simulated digestion. The maximum binding capacities at pH 7.0 were 626.0 mg/g (lead), 42.2 mg/g (cadmium), and 69.3 mg/g (mercury). In the presence of essential metals, such as iron, calcium, and zinc, BSP retained high selectivity toward heavy metals. Model pigments from caffeic acid, ferulic acid, and coniferyl alcohol showed lower or comparable binding ability, suggesting that the marked properties of BSP may result from cooperativity of different sites likely carboxy groups and o-diphenol and guaiacyl functionalities. Direct evidence for the presence of such units was obtained by structural analysis of BSP by solid-state Fourier transform infrared spectroscopy and (13)C nuclear magnetic resonance spectroscopy.

Black sesame pigment (BSP) represents a low cost, easily accessible material of plant origin exhibiting marked antioxidant and heavy metal-binding properties with potential as a food supplement. We report herein the inhibitory properties of the potentially bioaccessible fraction of BSP following simulated gastrointestinal digestion against key enzymes involved in Alzheimer’s disease (AD). HPLC analysis indicated that BSP is transformed under the pH conditions mimicking the intestinal environment and the most abundant of the released compounds was identified as vanillic acid. More than 80% inhibition of acetylcholinesterase-induced aggregation of the β-amyloid Aβ1-40 was observed in the presence of the potentially bioaccessible fraction of BSP, which also efficiently inhibited self-induced Aβ1-42 aggregation and β-secretase (BACE-1) activity, even at high dilution. These properties open new perspectives toward the use of BSP as an ingredient of functional food or as a food supplement for the prevention of AD.

Brazil has the greatest vegetal biodiversity in the world, but products derived from native species are not optimally utilized. Oxalis cordata and Xylopia aromatica are two underutilized species whose leaves and fruits, respectively, have been used as food in the 19th century. In this study, we used chemical and in vitro assays to evaluate the potential of these species as functional foods. The inhibitory activity on pancreatic lipase and DPP-IV were evaluated using the crude extracts and fractions ethyl acetate, butanol and water of these two species. For polyphenols determination, samples were prepared with different solvents and these were analysed by chromatographic and spectroscopic methods. Finally, fatty acids profile was determinated by gas chromatography. The crude extract (IC=0.84mg/ml), ethyl acetate extract (IC=0.88mg/ml) an aqueous fraction (IC=0.63mg/ml) of C. cordata were inhibitory on pancreatic lipase but inactive against dipeptidyl peptidase IV (DPP-IV). Extracts from X. aromatica were inactive against the lipase pancreatic enzyme, but a butanolic fraction inhibited DPP-IV (IC=0.71±0.05mg/ml). The phenolic acids orientin/isorientin, chlorogenic acid (0.32g/100g) and the flavonoid derivatives rutin (0.27g/100g), quercetin and luteolin were observed in all products. Additionally, fatty acid quantification showed that oleic (7.5g/100g) and linoleic acid (6.5g/100g) were predominant in X. aromatica fruit. This study confirms the potential for the use of both plants as functional foods due to their nutritional value, biological activity and important phytochemical content.