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BACKGROUND RESULTS CONCLUSION Loquat peel, often as food waste, is a valuable source of bioactive polysaccharides. However, study of such polysaccharides is insufficient, leaving a significant gap in understanding their preparation, structure and bioactivities.In this study, three types of loquat peel polysaccharides (LPWP, LPHP and LPNP) were sequentially extracted using hot water, HCl and NaOH solutions, respectively. Among them, LPWP was the purest, with a yield of 3.4% and molecular weight of 470.6 kDa, and it differed from LPHP and LPNP in structure, as evidenced by Fourier transform infrared spectroscopy, X‐ray diffraction and scanning electron microscopy, which demonstrated that LPWP consisted of more arabinose (Ara) but less galacturonic acid, rhamnose and galactose, with molar percentages of 71.3%, 23.3%, 3.5% and 1.9%, respectively. Besides, LPWP also exhibited superior antioxidant and antihyperglycemic activities in vitro, particularly in inhibiting α‐amylase and α‐glucosidase. Methylation and nuclear magnetic resonance analysis confirmed that LPWP was a methyl‐esterified pectic polysaccharide rich in branched arabinan, as evidenced by the notable proportion of α‐Ara residues, including T‐α‐Araf, 1,5‐α‐Araf and 1,2,3,5‐α‐Araf, with molar percentages of 27.1%, 23.1% and 10.2%, respectively. AFM imaging further revealed its branched‐chain morphology and aggregation behavior.This study highlights the potential of loquat peel polysaccharides as a bioactive ingredient with significant antioxidant and antihyperglycemic properties, particularly LPWP, which was found as a methyl‐esterified pectic polysaccharide with abundant‐branched arabinan. Our work provides valuable insights into the application of loquat peel polysaccharides in functional foods. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

AbstractStigma maydis (SM) possesses remarkable nutritional value due to the presence of health-protective chemical constituents in it. Despite its commercial uses, there is a lack of information on changes in the nutritional profile of SM during Shenke 601 waxy corn development by following four different maturity stages (silking stage; blister stage; milky stage; dough stage). In this study, the ideal times for the development of seven active compounds (polysaccharides, saponin, rutin, luteolin, quercetin, kaempferol and chlorogenic acid) were at the silking stage. The total flavonoid and total phenol content increased as the SM matured. Except for the above-mentioned active compounds, the content of major nutritional components of dough stage was higher than that of three other stages. The extract of Stigma maydis exhibited good α-amylase, α-glucosidase and pancreatic lipase inhibition activities. The ethanolic SM extracts showed better inhibitory effects than aqueous SM extracts with a dose–effect relationship. The hypoglycemic activity of ethanolic extract was higher than that of aqueous extract at each stage. This provided an important basis for the application of SM.

Cyclodextrins (CyDs) are cyclic oligosaccharides consisting of six to eight glucose residues. Administration of α-CyD (six glucose residues) inhibits sucrose-induced hyperglycemia in humans. Here we show that oral administration of α-CyD and dimethyl α-CyD suppresses sucrose-induced hyperglycemia in an in vivo evaluation system using silkworms. On the other hand, β-CyD (seven glucose residues), γ-CyD (eight glucose residues), and their derivatives did not show the suppressive effect. These findings suggest that dimethyl α-CyD is a new inhibitor against sucrose-induced hyperglycemia and the silkworm system is useful for evaluation of suppressive activities of α-CyD derivatives against postprandial hyperglycemia. [ABSTRACT FROM AUTHOR]

Biological activities of crustacean cardioactive peptide (CCAP; PFCNAFTGCa) and leucomyosuppressin (Lem-MS; pQDVDHVFLRFa) were studied in heterologous bioassays in the larvae and adults of Tenebrio molitor. CCAP exerted a reversible and dose-dependent cardio-stimulatory effect on the semi-isolated heart of the experimental beetles at a concentration of >10−7 M and induced an effect similar to the endogenic cardio-stimulatory peptide, proctolin. Injections of CCAP (10−9–10−3 M) into 4-day-old adult reproductive females increased the concentration of soluble proteins in hemolymph in comparison to the saline injected controls. Electrophoretic analyses indicated significant increase in the level of two proteins 130 and 170 kDa, and a partial increase of the level of 67-kDa protein. The studies indicated that CCAP increased also free hemolymph sugar concentration in young larvae and adults of the mealworm beetle. The cardio-inhibitory peptide Lem-MS exerted the opposite effect: at concentration 10−7–10−6 M, it significantly decreased the heartbeat frequency. The induced changes were dose-dependent and reversible, but at higher concentrations (>10−5 M) the stimulatory effect disappeared. Injections of the Lem-MS into young larvae at concentrations 10−9–10−3 M, also increased the free hemolymph sugar level similarly to the CCAP. This work demonstrates the pleiotropic effects of CCAP and Lem-MS in Tenebrio molitor. [ABSTRACT FROM AUTHOR]

Abstract: In the present study, the sinus gland peptide hormones were isolated from the freshwater field crab, Oziotelphusa senex senex by reverse-phase high performance liquid chromatography (HPLC) and the dual biological activity of isolated peptides were determined. Of the six eluted peaks, Oss-SGP 2 and 3 exhibited significant mandibular organ-inhibiting activity. In addition to mandibular organ-inhibiting activity, Oss-SGP 2 exhibited potent Y-organ inhibiting activity in vitro and Oss-SGP 3 exhibited significant hyperglycemic activity in vivo. Peptide fractions Oss-SGP 5 and 6 also exhibited significant hyperglycemic activity. The present study not only demonstrated the presence of pleiomorphic forms of peptides but also pleiotropic activities of eyestalk peptides of the crab O. senex senex. [Copyright &y& Elsevier]

The discovery of novel α-glucosidase inhibitors and anti-diabetic candidates from natural or natural-derived products represents an attractive therapeutic option. Here, a collection of acetylphenol analogues derived from paeonol and acetophenone were synthesized and evaluated for their α-glucosidase inhibitory activity. Most of derivatives, such as 9a – 9e , 9i, 9m–9n and 11d–1e , (IC 50 = 0.57 ± 0.01 μM to 8.45 ± 0.57 μM), exhibited higher inhibitory activity than the parent natural products and were by far more potent than the antidiabetic drug acarbose (IC 50 = 57.01 ± 0.03 μM). Among these, 9e and 11d showed the most potent activity in a non-competitive manner. The binding processes between the two most potent compounds and α-glucosidase were spontaneous. Hydrophobic interactions were the main forces for the formation and stabilization of the enzyme - acetylphenol scaffold inhibitor complex, and induced the topography image changes and aggregation of α-glucosidase. In addition, everted intestinal sleeves in vitro and the maltose loading test in vivo further demonstrated the α-glucosidase inhibition of the two compounds, and our findings proved that they have significant postprandial hypoglycemic effects. [ABSTRACT FROM AUTHOR]

Cyclodextrins (CyDs) are cyclic oligosaccharides consisting of six to eight glucose residues. Administration of α-CyD (six glucose residues) inhibits sucrose-induced hyperglycemia in humans. Here we show that oral administration of α-CyD and dimethyl α-CyD suppresses sucrose-induced hyperglycemia in an in vivo evaluation system using silkworms. On the other hand, β-CyD (seven glucose residues), γ-CyD (eight glucose residues), and their derivatives did not show the suppressive effect. These findings suggest that dimethyl α-CyD is a new inhibitor against sucrose-induced hyperglycemia and the silkworm system is useful for evaluation of suppressive activities of α-CyD derivatives against postprandial hyperglycemia.

Ethanolic extract of Mimosa pudica leaves given by oral route to mice at a dose of 250 mg/kg showed a significant hyperglycemic effect. [Copyright &y& Elsevier]