Two new ent-kaurane glucosides from the fruits of Xanthium strumarium subsp. sibiricum

Discovery of natural AMPK activator from the fruits of Xanthium sibiricum Patr.: Xanthiumine A, protoberberine alkaloid with unique C28 skeleton

Two protoberberine alkaloids with a unique C28 skeleton, named xanthiumines A (1) and B (2), respectively, were isolated from the fruits of Xanthium sibiricum Patr. Their structures including absolute configurations were unequivocally established by the comprehensive NMR and MS spectroscopic data analysis together with gauge-independent atomic orbital (GIAO) NMR calculations, and electronic circular dichroism (ECD) calculations. Compounds 1 and 2 are the first examples of natural protoberberine alkaloid with a phenolic acid group at C-13a. Their plausible biosynthetic pathway was proposed on the basis of the coexisting alkaloid monomer as the precursor. Furthermore, the effects and related molecular mechanism of compound 1 on hepatic lipid accumulation were also investigated in oleic acid (OA)-treated HepG2 cells.

Phytochemical investigation of the fruits of Xanthium strumarium and their cytotoxic activity

Eight pentacyclic triterpenoids including two new ones (1, 2) were isolated from the fruits of Xanthium strumarium. Their structures were elucidated by extensive spectroscopic analysis. All isolates were evaluated for in vitro cytotoxic activity on HepG2, A549, HCT116 and SW480 cancer cells. Among them, the new compound 2 was found to exhibit significant cytotoxic activity on A549, HCT116 and SW480 cancer cells with IC₅₀ values of 9.68, 4.27 and 7.58 μM, respectively. Further, 2 was selected for cell cycle analysis and results revealed that 2 could cause HCT116 cell cycle arrest in G1 phase. In addition, Annexin V-FITC/PI staining assay showed that 2 could induce the death of HCT116 cells.

Novel kojic acid derivatives with anti-inflammatory effects from Aspergillus versicolor

Two novel kojic acid derivatives, kojicones A and B (1 and 2), along with the precursors kojic acid (3) and (2R,4R)-4-hydroxy-5-methoxy-2,4-dimethyl-2- [(2R)-2-methylbutyryloxy]-5-cyclohexen-1,3-dione (4), were isolated from a fungal strain Aspergillus versicolor. Their structures and absolute configurations were accurately confirmed by HRESIMS data, NMR analysis, and electronic circular dichroism (ECD) calculations. Kojicones A and B were the first examples of kojic acid adducts with cyclohexen-1,3-dione possessing unprecedented tricycle skeletons. Compounds 1-3 were found to have inhibition on the NO production of murine RAW 264.7 cells. They can also reduce the mRNA expression of four cytokines (IL-6, IL-1β, TNF-α, and iNOS) and promote the expression of IL-4 at 20 μM. Moreover, kojic acid (3) could treat the DSS (dextran sulfate sodium)-induced colitis on mice with the effectiveness similar to that of the positive control. The results suggested that kojic acid and its derivatives could be a promising anti-inflammatory source for the medicinal and cosmetic industry.

Induction of metabolic variability of the endophytic fungus Xylaria sp. by OSMAC approach and experimental design

This work has as the main focus, to analyze the behavior of physic-chemical variations from the fungus Xylaria sp., through the OSMAC (One Strain, Many Compounds) approach as an efficient way of obtaining new compounds. To perform such inductions and to explore the variability of the metabolic network of this microorganism, a factorial design was designed to induce variability (or enhancement) of metabolites. In view of chemometric insights, the planned inductions were imposed on the microorganism and variations in the chemical profile were observed in the crude extracts. Through mass spectrometry (HR-ESI-MS) and nuclear magnetic resonance-based profiles, combined with multivariate analysis through Principal Component Analysis (PCA), it was observed a marked variability of signals, confirming the efficacy in the metabolic alteration, defining the culture medium and agitation as the most important variables in the metabolic variability of the fungus. However, the extract mass is more significant for the agitation variable, and there is no relationship between the mass of crude extract and the amount of molecular signals of the complex matrices studied.