Catechins and Derived Procyanidins in Red and White Sorghum: Their Contributions to Antioxidant Activity

Use of Botanical Ingredients: Nice Opportunities to Avoid Premature Oxidation of NABLABs by Increasing Their ORAC Values Strongly Impacted by Dealcoholization or Pasteurization

Even when fresh, non-alcoholic, and low-alcoholic beers (NABLABs) exhibit significant staling defects due to premature oxidation. In this study, the antioxidant power of eleven fresh commercial NABLABs was assessed by means of three different assays: the oxygen radical absorbance capacity (ORAC), the linoleic acid-induced oxidation (TINH), and the indicator time test (ITT). Only the first two assays, both involving radicalar degradations initiated by AAPH, were found to correlate with each other. NABLABs displayed lower ORAC values than conventional beers (on average, 6127 μmol eq. Trolox/L), except for three samples made with special-colored malts or dry-hopped. Dealcoholization was the step with the greatest impact on the ORAC value (up to a 95% loss) and on flavan-3-ols, sotolon, and polyfunctional thiols, while pasteurization strongly affected color, TBA, and Strecker aldehydes. ORAC assays applied to hop, alternative cereals, and various botanical ingredients indicated that mashing with red sorghum, dry hopping/spicing, and wood maturation could bring the antioxidant power of a NABLAB close to those of conventional beers. With an ORAC value not reached by any other tested botanical ingredient (5234 µmol eq. Trolox/g), African Vernonia amygdalina leaves (traditionally used for Rwandan Ikigage beers) emerged here as the best candidate.

Effect of the nixtamalization process on the protein bioaccessibility of white and red sorghum flours during in vitro gastrointestinal digestion

Protein bioaccessibility is a major concern in sorghum (Sorghum bicolor L. Moench) due to potential interactions with tannins affecting its nutritional value. Technological treatments such as boiling or alkaline cooking have been proposed to address this problem by reducing tannin-protein interactions. This research aimed to evaluate the impact of nixtamalization in the protein bioaccessibility from two sorghum varieties (red and white sorghum) during in vitro gastrointestinal digestion. Nixtamalization increased protein bioaccessibility in the non-digestible fraction (NDF) (5.26 and 26.31% for red and white sorghum, respectively). However, cooking showed a higher permeation speed of protein from red sorghum flours at the end of the intestinal incubation (9.42%). The SDS-PAGE profile of the digested fraction (DF) at 90 min of intestinal incubation indicated that, for red sorghum, cooking allows the formation of α and γ-kafirins while nixtamalization increase α-kafirin release. Principal Components Analysis (PCA) showed the association between nixtamalization and dissociation of δα kafirin complexes and increased protein content in the digestible fraction. In silico interactions indicated the highest biding energies for (+)-catechin and kafirin fractions (β-kafirin: -7.0 kcal/mol; γ-kafirin: -5.8 kcal/mol, and δ-kafirin: -6.8 kcal/mol), suggesting a minor influence of depolymerized proanthocyanidin fractions with sorghum proteins as a result of the nixtamalization process. In conclusion, nixtamalization increased the bioaccessibility of sorghum proteins, depolymerizing condensed tannins, and breaking protein-tannin complexes. Such technological process improves the nutrimental value of sorghum, supporting its inclusion in the human diet.

A Mechanistic Model of Mass Transfer in the Extraction of Bioactive Compounds from Intact Sorghum Pericarp

The extraction of phytochemical compounds from intact red sorghum grains was developed as an alternative process for producing bioactive material in the pharmaceutical industry. A mechanistic model is needed to better understand the process and enable predictive simulations for designing commercial-scale extraction systems. This paper presents a mathematical model for predicting phytochemical concentrations in the solvent and inside the pericarp of the grain at different positions during the extraction. The model is based on the mass transfer mechanism from inside the pericarp to its solid surface by diffusion, and then from the surface to a solvent during the extraction of bioactive compounds. It was numerically solved while using finite-difference approximation. The parameters considered were effective diffusivity inside the pericarp (Dep), mass transfer coefficient from the pericarp surface to the solvent (kc), and distribution coefficient (H). The model simulates the extraction performance, including the yield and bioactive compounds’ concentrations in the extract and inside the pericarp at various positions and times. A sensitivity analysis of the changes in each involved parameter provided sufficient information for increasing the performance of the model. A validation test that compared the results of the simulation with those of established analytical solutions showed that the model has high accuracy. Hence, the model can be applied in quantitative evaluations to improve productivity in the pharmaceutical industry.

Comparison of the effect of chemical composition of anthocyanin-rich plant extracts on colon cancer cell proliferation and their potential mechanism of action using in vitro, in silico, and biochemical assays

The objective was to compare the anti-proliferative effect of anthocyanin-rich plant extracts on human colon cancer cells and determine their mechanism of action. Eleven extracts were tested: red (RG) and purple grape, purple sweet potato, purple carrot, black and purple bean, black lentil (BL), black peanut, sorghum (SH), black rice, and blue wheat. HCT-116 and HT-29 inhibition correlated with total phenolics (r=0.87 and 0.77, respectively), delphinidin-3-O-glucoside concentration with HT-29 inhibition (r=0.69). The concentration inhibition fifty (IC₅₀) for BL, SH, RG on HT-29 and HCT-116 cell proliferation ranged 0.9-2.0mg/mL. Extracts decreased expression of anti-apoptotic proteins (survivin, cIAP-2, XIAP), induced apoptosis, and arrested cells in G1. Anthocyanins exhibited tyrosine kinase inhibitory potential in silico and biochemically; cyanidin-3-O-glucoside had one of the highest binding affinities with all kinases, especially ABL1 (-8.5kcal/mol). Cyanidin-3-O-glucoside and delphinidin-3-O-glucoside inhibited EGFR (IC₅₀=0.10 and 2.37µM, respectively). Cyanidin-3-O-glucoside was the most potent anthocyanin on kinase inhibition.

Occurrence and Antioxidant Activity of C1 Degradation Products in Cocoa

Procyanidin C1 is by far the main flavan-3-ol trimer in cocoa. Like other flavan-3-ols, however, it suffers a lot during heat treatments such as roasting. RP-HPLCHRMS/MS(ESI(-))analysis applied to an aqueous model medium containing commercial procyanidin C1 proved that epimerization is the main reaction involved in its degradation (accounting for 62% of degradation products). In addition to depolymerization, cocoa procyanidin C1 also proved sensitive to oxidation, yielding once- and twice-oxidized dimers. No chemical oligomer involving the native trimer was found in either model medium or cocoa, while two C1 isomers were retrieved. C1 degradation products exhibited antioxidant activity (monitored by RPHPLC-Online TEAC) close to that of C1 (when expressed in µM TE/mg·kg-1).

Degradation of (-)-epicatechin and procyanidin B2 in aqueous and lipidic model systems. first evidence of "chemical" flavan-3-ol oligomers in processed cocoa

Despite the key role of flavan-3-ols in many foods, very little is yet known concerning the modification of their chemical structures through food processes. Degradation of model media containing (-)-epicatechin and procyanidin B2, either separately or together, was monitored by RP-HPLC-DAD-ESI(-)-MS/MS. Medium composition (aqueous or lipidic) and temperature (60 and 90 °C) were studied. In aqueous medium at 60 °C, (-)-epicatechin was mainly epimerized to (-)-catechin, but it was also oxidized to "chemical" dimers, a "chemical" trimer, and dehydrodi(epi)catechin A. Unlike oxidation, epimerization was enhanced at 90 °C. In lipidic medium, epimerization proved slow but degradation was faster. Procyanidin B2 likewise proved able to epimerize, especially at 90 °C and in aqueous medium. At high temperature only, the interflavan linkage was cleaved, yielding the same compounds as those found in the monomer-containing model medium. Oxidation to procyanidin A2 was also evidenced. With little epimerization and slow oxidation even at 90 °C, procyanidin B2 proved more stable in lipidic medium. Synergy was also observed: in the presence of the monomer, the dimer degradation rate increased 2-fold at 60 °C. This work states for the first time the presence of newly formed flavan-3-ol oligomers in processed cocoa.

Phytochemicals in sweet sorghum ( Dura ) and their antioxidant capabilities against lipid oxidation

Hydrophilic (HPE) and lipophilic (LPE) extracts were obtained from the Louisiana sweet sorghum millets. Nine major hydrophilic phytochemicals were quantified at levels of 8.9 μg/g for cinnamic acid to 1570.0 μg/g for apigeninidin. Lipophilic phytochemicals (α- and γ-tocopherol, lutein, and β-carotene) were quantified at levels of 7.7, 145.7, 4.8, and 18.8 μg/g, respectively. The total phenolic contents of HPE and LPE were 768.9 and 97.6 μg of catechin equivalent/g, respectively, while DPPH activities were 6.5 and 0.8 μmol of Trolox equivalent/g for HPE and LPE, respectively. In an emulsion model, HPE exhibited higher capability of inhibiting cholesterol oxidation and stabilizing linoleic acid than LPE. Inhibition rates of cholesterol oxidation for HPE and LPE at 40 μg/mL were 92.2% and 65.4%, respectively. Retention rates of linoleic acid were 70.4% for HPE and 33.6% for LPE at a given concentration. Thus, HPE of sweet sorghum millet has potential in functional food applications.