Institute of Quality Standards and Testing Technology for Agro Products

Thiosulfate serves as a critical intermediate in the sulfur biogeochemical cycle and is frequently oxidized by the sulfur oxidation (Sox) system to sulfate in bacteria. Cupriavidus pinatubonensis JMP134 employs a complete Sox system to oxidize S2O32- to SO42-, yet the regulatory mechanisms underlying this process remain unclear. A regulator gene located adjacent to the sox genes cluster encodes an ArsR-type transcriptional regulator (SoxR). Here we report the regulation of the sox genes by SoxR in C. pinatubonensis JMP134. The sox genes are transcribed as an operon from a promoter in the front of soxR. SoxR binds to DNA 23-bp downstream of the transcription start site, blocking the sox transcription. We present evidence that SoxR does not directly respond to S2O32- but instead reacts with reactive sulfane sulfur via Cys43 and Cys98, and this interaction is contingent upon a functional Sox system. These findings will deepen our understanding of the regulation of the Sox system in bacteria.

Di-(2-ethylhexyl) phthalate (DEHP) is a prevalent plasticizer that has been demonstrated to induce male reproductive toxicity through the disruption of spermatogenesis. Icariin (ICA), a bioactive compound derived from the traditional Chinese medicine Epimedium, holds significant potential in the treatment of male infertility. However, its clinical utilization is constrained by low absorption and fast metabolism upon oral administration. Herein, we first developed ICA-loaded chondroitin sulfate (CS) and polyvinylpyrrolidone K30 (PVP K30) microneedle (MN) patches (ICA MNs) for treating DEHP-induced testicular dysfunction. The results found that ICA MNs significantly reduced DEHP-induced oxidative stress and apoptosis in GC-1 cells by modulating the Keap1/Nrf2/HO-1 pathway. In addition, ICA MNs mitigated DEHP-induced testicular damage, sperm irregularities, and blood-testis barrier impairment in rats, surpassing the efficacy of oral ICA treatment. Proteomic analysis indicated a restoration of the testicular proteome toward normal levels after ICA MN treatment. Comprehensive safety assessments revealed no adverse systemic effects, highlighting the biocompatibility of ICA MNs. These findings suggest ICA MNs as a promising therapeutic approach for male infertility associated with DEHP exposure, offering targeted and efficient transdermal delivery.

The honeys produced by Apis mellifera ligustica Spinola (A. mellifera) and Apis cerana cerana Fabricius (A. cerana) are the two predominant varieties in terms of global yield, each recognized for its distinct functional properties. Our previous studies identified the characteristic markers distinguishing A. cerana honey and A. mellifera honey. However, the mechanistic links between species-specific metabolism and functional properties remain unclear, presenting a formidable challenge. This study aimed to elucidate how bee species-specific metabolism shapes honey bioactivity. We used topological and enrichment analyses to map the characteristic markers onto metabolic pathways. Also, we quantified the in vitro antioxidant capacity of both honeys and their respective markers via 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging assays. We further evaluated the anti-inflammatory efficiency of these honeys in lipopolysaccharide-stimulated Caco-2 cells by measuring cytokine expression and cellular responses. Tryptophan metabolism primarily contributed to the formation of honey in both A. cerana and A. mellifera. A. cerana preferentially metabolized tryptophan via the indoleacetic acid pathway, yielding higher concentrations of methyl indole-3-acetate (MIA), whereas A. mellifera favored the kynurenine pathway, producing elevated levels of kynurenic acid (KYNA). Both compounds enhanced intestinal barrier integrity through their antioxidant and anti-inflammatory activities, despite differing in their specific mechanisms and efficacy. MIA exhibited superior anti-inflammatory and antioxidant properties compared with KYNA, which directly correlated with the enhanced bioactivity of A. cerana honey. KYNA primarily strengthened barrier function by upregulating the expression of tight junction proteins Zonula occludens protein-1(ZO-1), claudin-1, and occludin, whereas MIA demonstrated greater efficacy in suppressing the expression of inflammatory proteins. Correlation analyses confirmed MIA and KYNA as the key drivers of the intestinal barrier-protective activities of honey. The complementary mode of action-KYNA providing structural reinforcement and MIA offering anti-inflammatory modulation-highlights the synergistic bioactivity underlying the protective properties of honey. These findings provide a mechanistic understanding of how bee species-specific tryptophan metabolism in A. cerana and A. mellifera drives the bioactivity divergence in honey, with MIA and KYNA linked to differential antioxidant and intestinal anti-inflammatory activities.