Flavonoids are a kind of essential substance for the human body because of their antioxidant properties and extremely high medicinal value. Citrus reticulata “Dahongpao” (DHP) is a special citrus variety that is rich in flavonoids, however little is known about its systematic flavonoids profile. In the present study, the presence of flavonoids in five important citrus varieties, including DHP, Citrus grandis Tomentosa (HZY), Citrus ichangensis Swingle (YCC), Citrus sinensis (L.) Osbeck (TC), and Citrus reticulata ‘Buzhihuo’ (BZH), was determined using a UPLC-ESI-MS/MS-based, widely targeted metabolome. Results showed that a total of 254 flavonoid metabolites (including 147 flavone, 39 flavonol, 21 flavanone, 24 anthocyanins, 8 isoflavone, and 15 polyphenol) were identified. The total flavonoid content of peels from DHP was the highest. DHP could be clearly separated from other samples through clustering analysis and principal component analysis (PCA). Further, 169 different flavonoid metabolites were observed between DHP peels and the other four citrus peels, and 26 down-regulated differential metabolites displayed important biological activities in DHP. At the same time, a unique flavonoid component, tricin 4′-O-syringyl alcohol, was only found in DHP, which could be used as a marker to distinguish between other varieties. This work might facilitate a better understanding of flavonoid metabolites between DHP peels and the other four citrus peels and provide a reference for its sufficient utilization in the future.

Aberrant activation of NLRP3 inflammasome has been implicated in the pathogenesis of diverse inflammation-related diseases, and pharmacological molecules targeting NLRP3 inflammasome are of considerable value to identifying potential therapeutic interventions. Cardamonin (CDN), the major active ingredient of the traditional Chinese medicinal herb Alpinia katsumadai, has exerted an excellent anti-inflammatory activity, but the mechanism underlying this role is not fully understood. Here, we show that CDN blocks canonical and noncanonical NLRP3 inflammasome activation triggered by multiple stimuli. Moreover, the suppression of CDN on inflammasome activation is specific to NLRP3, not to NLRC4 or AIM2 inflammasome. Besides, the inhibitory effect is not dependent on the expression of NF-κB-mediated inflammasome precursor proteins. We also demonstrate that CDN suppresses the NLRP3 inflammasome through blocking ASC oligomerization and speckle formation in a dose-dependent manner. Importantly, CDN improves the survival of mice suffering from lethal septic shock and attenuates IL-1β production induced by LPS in vivo, which is shown to be NLRP3 dependent. In conclusion, our results identify CDN as a broad-spectrum and specific inhibitor of NLRP3 inflammasome and a candidate therapeutic drug for treating NLRP3 inflammasome-driven diseases.

Idiosyncratic drug-induced liver injury (IDILI) is an infrequent but potentially serious disease that develops the main reason for post-marketing safety warnings and withdrawals of drugs. Epimedii Folium (EF), the widely used herbal medicine, has shown to cause idiosyncratic liver injury, but the underlying mechanisms are poorly understood. Increasing evidence has indicated that most cases of IDILI are immune mediated. Here, we report that icariside Ⅱ (ICS Ⅱ), the major active and metabolic constituent of EF, causes idiosyncratic liver injury by promoting NLRP3 inflammasome activation. ICS Ⅱ exacerbates NLRP3 inflammasome activation triggered by adenosine triphosphate (ATP) and nigericin, but not silicon dioxide (SiO₂), monosodium urate (MSU) crystal or cytosolic lipopolysaccharide (LPS). Additionally, the activation of NLRC4 and AIM2 inflammasomes is not affected by ICS Ⅱ. Mechanistically, synergistic induction of mitochondrial reactive oxygen species (mtROS) is a crucial contributor to the enhancing effect of ICS Ⅱ on ATP- or nigericin-induced NLRP3 inflammasome activation. Importantly, in vivo data show that a combination of non-hepatotoxic doses of LPS and ICS Ⅱ causes the increase of aminotransferase activity, hepatic inflammation and pyroptosis, which is attenuated by Nlrp3 deficiency or pretreatment with MCC950 (a specific NLRP3 inflammasome inhibitor). In conclusion, these findings demonstrate that ICS Ⅱ causes idiosyncratic liver injury through enhancing NLRP3 inflammasome activation and suggest that ICS Ⅱ may be a risk factor and responsible for EF-induced liver injury.

Pericarpium Citri Reticulatae (PCR), the mature fruit peel of Citrus reticulata Blanco and its different cultivars, is an important citrus by‐product with beneficial health and nutritive properties. However, due to the lack of value‐added methods for its development and utilization, a large amount of PCR is discarded or wasted. To explore a possibly more effective method to utilize PCR, we compared the chemical and biological differences before (CK) and after (CP) microbial transformation of PCR by Aspergillus niger. UPLC‐ESI‐MS/MS, HPLC, and LC‐MS methods were used to compare the chemical profiles of CK and CP. The results demonstrated that microbial biotransformation by A. niger could transform flavonoid compounds by utilizing the carbohydrate and amino acid nutrients in PCR. This could also promote the accumulation of polyhydroxyflavones compounds in CP. The antioxidant assay demonstrated that CP had significantly greater free radical‐scavenging activity than CK. The higher antioxidant activity of CP may result from the high level of flavonoids with associated phenolic hydroxyl groups. Microbial biotransformation is an effective method for improving the antioxidant capacity of PCR and may be effective and useful in other natural product situations.

There are thousands of traditional Chinese medicines in China, and they all have to be stored for a period of time for the reason of market price or other factors. But some traditional Chinese medicines especially need to be stored longer, and the clinical efficacy will be better. The cause and mechanism of this phenomenon have attracted much attention in recent years. In this study, we analyze the reason of “the longer storage period the better” of Pericarpium Citri Reticulatae (PCR); method of microscopic and molecular identification was used to identify the fungi separated and purified from PCR. The HPLC and UV spectrophotometry methods were used to determine the contents of flavonoids in PCR. The isolated fungi were inoculated into sterile samples to screen the fungi closely related to the change of flavonoids. The results indicate that the strain of Aspergillus niger could obviously promote the contents of flavonoids, and it could also increase the antioxidant effect of PCR. In conclusion, this study explains the reason of “the longer storage period the better” of PCR from the perspective of microbe, proving the beneficial effect of microorganism on the surface of PCR.