Antioxidant Polyphenols from Lespedeza bicolor Turcz. Honey: Anti-Inflammatory Effects on Lipopolysaccharide-Treated RAW 264.7 Macrophages.

Although the honey produced by Lespedeza bicolor Turcz. is precious because of its medicinal value, its pharmacological mechanism is still unclear. Here, its anti-inflammatory and antioxidant functions on lipopolysaccharide (LPS)-treated murine RAW 264.7 macrophages were analyzed using targeted and non-targeted metabolomics. Results showed that twelve polyphenols were identified in L. bicolor honey using UHPLC-QQQ-MS/MS. L. bicolor honey extract could scavenge the free radicals DPPH• and ABTS+ and reduce Fe3+. Furthermore, pretreatment with L. bicolor honey extract significantly decreased NO production; suppressed the expression of COX-2, IL-10, TNF-α, and iNOS; and upregulated HO-1's expression in the cells with LPS application. UHPLC-Q-TOF-MS/MS-based metabolomics results revealed that L. bicolor honey extract could protect against inflammatory damage caused by LPS through the reduced activation of sphingolipid metabolism and necroptosis pathways. These findings demonstrate that L. bicolor honey possesses excellent antioxidant and anti-inflammatory activities.

Kaempferol-3-O-galactoside as a marker for authenticating Lespedeza bicolor Turcz. monofloral honey.

Honey produced from Lespedeza bicolor Turcz. (L. bicolor) is highly valued and relatively rare, leading to adulterated or ersatz substitutes in the marketplace, with no reliable authentication methods available for enforcement of regulations. Here, we characterize the physicochemical parameters (water content, pH, sugar content, amylase activity, and 5-hydroxymethylfurfural content) in L. bicolor honey and palynological characteristics of L. bicolor pollen as reference for assessment of quality and monoflorality. Mass spectrometry with Orthogonal Partial Least Square Discriminant Analysis of chemical constituent data from L. bicolor, chaste, acacia, jujube, and linden honeys, all commonly sold in China, identified kaempferol-3-O-galactoside as a candidate chemical marker of L. bicolor honey. We validated this screening method and quantified kaempferol-3-O-galactoside in L. bicolor, but not other honeys, at concentrations between 90.2 and 430.1 µg/kg, with high sensitivity (LOD = 0.002 mg/kg), linearity (R2 ≥ 0.99), and recovery (90.2%-110.6%), supporting its use in authenticating L. bicolor honey.

Safflomin A: A novel chemical marker for Carthamus tinctorius L. (Safflower) monofloral honey.

Monofloral safflower honey (MSH), produced from nectar of the medicinal Carthamus tinctorius L., has been shown with excellent nutritional value and biological activity. However, current MSH authenticity verification is insufficient. Herein, we fully characterized MSH from a metabolomic perspective and proposed a chemical marker for its authentication. Using palynological analysis, we confirmed the botanical origin of MSH. Ultra-high-performance liquid chromatography/quadrupole time-of-flight mass spectrometry (UHPLC/Q-TOF-MS) was applied further to compare MSH/safflower components. MSH and safflowers shared 1297 tentatively identified compounds, of which safflomin A was identified as a reliable characteristic indicator. When applied to commercial non-safflower honeys, none tested safflomin A positive. Solid phase extraction coupled UHPLC/Q-TOF-MS method revealed the LOD and LOQ of safflomin A in MSH to be 0.006 and 0.02 mg/kg, respectively, with concentrations ranging from 0.86 to 3.91 mg/kg. Collectively, safflomin A can be applied as a chemical marker for fingerprinting the botanical origin of safflower honey.

Extract of Unifloral Camellia sinensis L. Pollen Collected by Apis mellifera L. Honeybees Exerted Inhibitory Effects on Glucose Uptake and Transport by Interacting with Glucose Transporters in Human Intestinal Cells.

Bee pollen possesses potential hypoglycemic effects but its inhibitory mechanisms on glucose absorption and transportation in intestinal cells still need to be clarified. Here, we determined the inhibitory effects of bee pollen extract originating from Camellia sinensis L. (BP-Cs) as well as its representative phenolic compounds on glucose uptake and transport through a human intestinal Caco-2 cell monolayer model. It showed that three representative phenolic compounds, including gallic acid (GA), 3-O-[6'-O-(trans-p-coumaroyl)-ß-d-glucopyranosyl]kaempferol (K1), and 3-O-[2',6'-di-O-(trans-p-coumaroyl)-ß-d-glucopyranosyl]kaempferol (K2), with contents of 27.7 ± 0.86, 9.88 ± 0.54, and 7.83 ± 0.46 µg/mg in BP-Cs extract, respectively, exerted mutual antagonistic actions interacting with glucose transporters to inhibit glucose uptake and transport based on their combination index (CI) and molecular docking analysis. K1, K2, and GA might compete with d-glucose to form hydrogen bonds with the same active residues including GLU-412, GLY-416, GLN-314, and TRP-420 in GLUT2. These findings provide us a deep understanding of the mechanisms underlying the anti-hyperglycemia by bee pollen, which provide a new sight on dietary intervention strategies against diabetes.