Mulberry (Morus alba L.) is a flowering tree traditionally used in Chinese herbal medicine. Mulberry leaf flavonoids (MLFs) have been reported to exert important anti-inflammatory and antioxidant properties. The purpose of this study was to select the MLF with the best anti-inflammatory and antioxidative activities from MLFs eluted by different ethanol concentrations (30%, 50%, and 75%) and explore its pharmacological properties. Three types of MLFs inhibited the production of nitric oxide (NO), prostaglandin E2 (PGE2), inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), and inflammatory cytokines in lipopolysaccharide (LPS)-induced RAW 264.7 cells. All MLFs boosted the antioxidative capacity by decreasing the reactive oxygen species (ROS) production and the scavenging of 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radicals and improving the metal ion chelating activity and reducing power. The results revealed that the MLFs eluted by 30% ethanol exhibited the best anti-inflammatory and antioxidative activities. A nontargeted metabolomic analysis was used to analyze 24 types of differential flavonoids between the MLFs. Quercetin, kaempferol, and their derivatives in 30%MLF were more abundant than the other two MLFs. Furthermore, we evaluated the pharmacological activities of 30%MLF in dextran sodium sulfate (DSS)-induced ulcerative colitis (UC) mice. The 30%MLF could alleviate the clinical symptoms, reduce the secretion of inflammatory cytokines, and inhibit the activation of the inflammatory pathway in DSS-induced colitis mice. This study will provide valuable information for the development of MLFs eluted by 30% ethanol as a functional food.

Mulberry, an important woody tree, has strong tolerance to environmental stresses, including salinity, drought, and heavy metal stress. However, the current research on mulberry resistance focuses mainly on the selection of resistant resources and the determination of physiological indicators. In order to clarify the molecular mechanism of salt tolerance in mulberry, the physiological changes and proteomic profiles were comprehensively analyzed in salt-tolerant (Jisang3) and salt-sensitive (Guisangyou12) mulberry varieties. After salt treatment, the malondialdehyde (MDA) content and proline content were significantly increased compared to control, and the MDA and proline content in G12 was significantly lower than in Jisang3 under salt stress. The calcium content was significantly reduced in the salt-sensitive mulberry varieties Guisangyou12 (G12), while sodium content was significantly increased in both mulberry varieties. Although the Jisang3 is salt-tolerant, salt stress caused more reductions of photosynthetic rate in Jisang3 than Guisangyou12. Using tandem mass tags (TMT)-based proteomics, the changes of mulberry proteome levels were analyzed in salt-tolerant and salt-sensitive mulberry varieties under salt stress. Combined with GO and KEGG databases, the differentially expressed proteins were significantly enriched in the GO terms of amino acid transport and metabolism and posttranslational modification, protein turnover up-classified in Guisangyou12 while down-classified in Jisang3. Through the comparison of proteomic level, we identified the phenylpropanoid biosynthesis may play an important role in salt tolerance of mulberry. We clarified the molecular mechanism of mulberry salt tolerance, which is of great significance for the selection of excellent candidate genes for saline-alkali soil management and mulberry stress resistance genetic engineering.

Mulberry sclerotiniose caused by Ciboria shiraiana is a devastating disease of mulberry (Morus alba L.) fruit in Northwest China. At present, no disease-resistant varieties are used in production, as the molecular mechanisms of this disease are not well understood. In this study, to explore new prevention methods and provide direction for molecular breeding, transcriptomic sequencing and un-targeted metabolomics were performed on healthy (CK), early-stage diseased (HB1), and middle-stage diseased (HB2) mulberry fruits. Functional annotation, gene ontology, a Kyoto encyclopedia of genes and genomes (KEGG) analysis, and a Mapman analysis of the differentially expressed genes revealed differential regulation of genes related to plant hormone signal transduction, transcription factors, and phenylpropanoid biosynthesis. A correspondence between the transcript pattern and metabolite profile was observed in the phenylpropanoid biosynthesis pathway. It should be noted that the log2 ratio of eugenol (isoeugenol) in HB1 and HB2 are 85 times and 23 times higher than CK, respectively. Our study shows that phenylpropanoid biosynthesis may play an essential role in response to sclerotiniose pathogen infection and eugenol(isoeugenol) enrichment in mulberry fruit, which may provide a novel method for mulberry sclerotiniose control.

Mulberry (Morus alba L.) has been an economically important food crop for the domesticated silkworm, Bombyx mori, in China for more than 5000 years. However, little is known about the mechanism underlying mulberry response to environmental stress. In this study, quantitative proteomics was applied to elucidate the molecular mechanism of drought response in mulberry. A total of 604 differentially expressed proteins (DEPs) were identified via LC-MS/MS. The proteomic profiles associated with antioxidant enzymes, especially five glutathione peroxidase (GPX) isoforms, as a scavenger of reactive oxygen species (ROS), were systematically increased in the drought-stressed mulberry. This was further confirmed by gene expression and enzymatic activity. Furthermore, overexpression of the GPX isoforms led to enhancements in both antioxidant system and ROS-scavenging capacity, and greater tolerance to drought stress in transgenic plants. Taken together, these results indicated that GPX-based antioxidant enzymes play an important role in modulating mulberry response to drought stress, and higher levels of GPX can improve drought tolerance through enhancing the capacity of the antioxidant system for ROS scavenging.

Mulberry (Morus alba) twigs and leaves, rich in flavonoids, polyphenols, polysaccharides, and alkaloids with multi-target regulatory properties on glucose/lipid metabolism, were evaluated for their anti-obesity effects using methanol-extracted twigs (MTE) and aqueous-extracted leaves (MLE) in high-fat diet (HFD)-induced obese mice. Both extracts significantly ameliorated obesity-related metabolic dysregulation, as evidenced by attenuated body weight gain, visceral fat accumulation, serum lipid profiles, homeostatic model assessment of insulin resistance (HOMA-IR), and hepatic inflammation compared to HFD controls (p < 0.05). Concurrently, MTE and MLE enhanced systemic antioxidant capacity and elevated high-density lipoprotein cholesterol (HDL-C) levels. Notably, high-dose MTE (MTEH, 1000 mg/kg) markedly reduced perirenal adiposity while increasing brown adipose tissue mass (p < 0.05). Mechanistic investigations revealed that MTEH reshaped gut microbiota composition by suppressing Firmicutes and Enterococcus, while enriching beneficial Faecalibaculum and Bifidobacterium spp. (p < 0.05). Furthermore, cecal short-chain fatty acid (SCFA) profiling demonstrated MTEH and MLEH-mediated metabolic reprogramming, characterized by increased propionic acid and decreased butyric acid, suggesting microbiota-dependent modulation of host energy metabolism. These findings collectively highlight the potential of mulberry extracts as multi-targeted nutraceuticals for obesity intervention via gut microbiota–SCFA axis regulation.

Mulberry (Morus spp.) is valued for sericulture, medicine, and ecological restoration of degraded lands. Phospholipase A (PLA) enzymes hydrolyze membrane lipids and play critical roles in plant growth and stress responses, yet the PLA family in mulberry remains uncharacterized. Here, we performed genome-wide identification of Morus notabilis PLA genes in order to systematically analyze their phylogenetic relationships and gene structures, and profile their expression across tissues and under drought and salt stress, thereby providing candidate genes for future functional studies on stress tolerance. Fifty non-redundant PLA genes were identified and classified into three subfamilies: pPLA (22), PLA2 (nine), and PLA1 (19). Most predicted PLA proteins are small (100–500 aa) with predicted instability. Gene structures varied from 1 to 21 exons, and subfamily specific conserved domains (patatin/C2, PLATZ, lipase_3) were detected. Promoters contained stress- and hormone-responsive elements. Expression patterns across five tissues revealed distinct preferential patterns: 56% of genes showed highest expression in roots, with one-fifth in leaves. Under stress, 10 and 12 MnPLA genes were increased >2-fold (log₂FC > 1.0) by drought and salt, respectively. Notably, XP_010108435.1 and XP_024022961.1 exhibited leaf-specific high expression and were salt-induced (log₂FC > 1.0); XP_010090405.1 (leaf-specific low) was drought-induced (log₂FC > 1.0); and XP_024023462.1 (root-specific high) was induced by both stresses. These results provide a basis for functional studies and genetic improvement of stress tolerance in mulberry.