Flavonoids are well known for their extensive health benefits. However, few studies compared the differences between flavonoid O-glycoside and C-glycoside. In this work, flavonoid O-glycoside (isoquercitrin), C-glycoside (orientin), and their aglycones (quercetin and luteolin) were chosen to compare their differences on antioxidant activities and metabolism during in vitro digestion and in vivo. In vitro digestion, the initial antioxidant activity of the two aglycones was very high; however, they both decreased more sharply than their glycosides in the intestinal phase. The glycosidic bond of flavonoid O-glycoside was broken in the gastric and intestinal stage, while the C-glycoside remained unchanged. In vivo, flavonoid O-glycoside in plasma was more elevated than C-glycoside on the antioxidant activity; however, flavonoid C-glycoside in urine was higher than O-glycoside. These results indicate that differences of flavonoid glycosides and their aglycones on antioxidant activity are closely related to their structural characteristics and metabolism in different samples. Aglycones possessed higher activity but unstable structures. On the contrary, the sugar substituents reduced the activity of flavonoids while improving their stability and helping to maintain antioxidant activities after digestion. Especially the C-glycoside was more stable because the stability of the C–C bond is higher than that of the C–O bond, which contributes to the difference between flavonoid O-glycoside and C-glycoside on the absorption and metabolism in vivo. This study provided a new perspective for comparing flavonoid O-glycoside, flavonoid C-glycoside, and their aglycones on their structure–activity relationship and metabolism.

The reported association of Moringa oleifera seeds and allergic disease clinically resembling occupational asthma in cosmetic manufacturing workers has resultedin the need to identify such components in the manufacturing process. However, Moringa oleifera leaves from the same plant, an important food ingredient, have limited immunotoxicity data. This study aimed to determine if Moringa oleifera leafproteins (MLP) can elicit allergic responses in BALB/c mice. The BALB/c mice were sensitized twice and challenged 10 times to evaluate the potential allergenicityof MLP in vivo. The results showed increased levels of mast cells, total and specific IgE and IgG, severe signs of systemic anaphylaxis, and reduced body temperature compared with controls. The sensitized mice serum observed enhanced levels of histamine and Th-related cytokine release. Compared with the control group, increased levels of interleukins IL-4, IL-9, and IL-17A and enhanced expression and secretion of normal T cells were found in the culture supernatant of splenocytes treated with MLP.This study suggeststhat MLPcanelicit allergic responses; this providesmore comprehensive guidance for identifying new allergen candidates and developing hypoallergenic MLP products.

In the early stage of this study, three strains of Lactobacillus with anti-soybean allergy potential were screened: Lactobacillus acidophilus CICC 6081, Lactobacillus delbrueckii subsp. Bulgaricus CICC 6103 and Lactobacillus plantarum subsp. Plantarum CICC 20988. The aim of this study was to analyze the desensitization effect of three strains of Lactobacillus administered by gavage to soybean-allergic mice through the differentiation of immune cells in intestinal lymph nodes and the changes to gut microbiota. The results showed that the three strains of Lactobacillus could stimulate the proliferation of dendritic cells (DCs) and regulate the balance of Th1/Th2 differentiation in the MLNs and PPs of soybean-allergic mice. Furthermore, the Th17/Tregs cell-differentiation ratio in the MLNs of the Lactobacillus-treated mice was significantly lower than that of the allergic mice (p < 0.05). Compared to the control group, the Shannon, Sobs and Ace indexes of intestinal microbiota in the allergic mice were significantly increased (p < 0.05), and the proportion of Clostridiales was significantly higher (p < 0.05), which was reversed by Lactobacillus gavage. In conclusion, the three strains of Lactobacillus can inhibit the intestinal mucosal immune response and regulate gut microbiota balance in soybean-allergic mice.

This study investigated the structural characteristics, bioavailability, and metabolism of lotus plumule flavonoid C-glycosides (LPF C-Gly), lotus plumule flavonoid O-glycosides (LPF O-Gly), and lotus leaf flavonoids (LLF). Through preparative chromatography isolation, we found that LLF primarily consisted of quercetin-O-glycosides, while LPF O-Gly was predominantly composed of quercetin and luteolin derivatives, and LPF C-Gly mainly contained apigenin and luteolin glycosides. In vitro digestion and fermentation tests demonstrated that during the digestion process, the antioxidant activity of LPF O-Gly decreased to a level comparable to that of LPF C-Gly. After 48 hours of fermentation, the retention rate of LPF C-Gly (89.19%) was significantly higher than that of LPF O-Gly (19.39%) and LLF (9.42%). Animal experiments demonstrated that LPF C-Gly exhibited significantly higher activity in urine during 12-24 h compared to LLF and LPF O-Gly，explain the stability of C-glycosides metabolism. It significantly enhanced the α-diversity of intestinal microbiota, increased the abundance of Bacteroidetes and Proteobacteria, inhibited pathogen colonization, and demonstrated significant microbiota-modulating effects. Our findings demonstrate that LPF C-Gly modulates gut health through the microbiota-metabolite axis, whereas LPF O-Gly acts as a systemic bioactive regulator during in vitro digestion and fermentation processes, highlighting their distinct roles in health modulation.