Naphthoquinone derivatives as potential immunomodulators: prospective for COVID-19 treatment.

Inflammation plays a crucial role in COVID-19, and when it becomes dysregulated, it can lead to severe outcomes, including death. Naphthoquinones, a class of cyclic organic compounds widely distributed in nature, have attracted significant interest due to their potential biological benefits. One such naphthoquinone is 3,5,8-trihydroxy-6-methoxy-2-(5-oxohexa-1,3-dienyl)-naphthanthene-1,4-dione (3,5,8-TMON), a compound produced by fungi. Despite its structural similarity to shikonin, limited research has been conducted to investigate its biological properties. Therefore, the objective of this study was to evaluate the effects of 3,5,8-TMON and its synthetic derivatives in the context of inflammation induced by lipopolysaccharide (LPS) and SARS-CoV-2 infection in vitro using cell cultures. 3,5,8-TMON was obtained by acid treatment of crude extracts of fermentation medium from Cordyceps sp., and two derivatives were accessed by reaction with phenylhydrazine under different conditions. The results revealed that the crude extract of the fungi (C. Ex) inhibited the activity of transcription factor NF-kB, as well as the production of nitric oxide (NO) and interleukin-6 (IL-6) when LPS induced it in RAW 264.7 cells. This inhibitory effect was observed at effective concentrations of 12.5 and 3.12 µg mL-1. In parallel, 3,5,8-TMON and the new derivatives 3 and 4 demonstrated the ability to decrease IL-6 production while increasing TNF, with a specific effect depending on the concentration. These concentration-dependent agonist and antagonist effects were observed in THP-1 cells. Furthermore, 3,5,8-TMON inhibited IL-6 production at concentrations of 12.5 and 3.12 µg mL-1 in Calu-3 cells during SARS-CoV-2 viral infection. These findings present promising opportunities for further research into the therapeutic potential of this class of naphthoquinone in the management of inflammation and viral infections.

Development of a validated ultra-high-performance liquid chromatography tandem mass spectrometry method for determination of acid diterpenes in Copaifera oleoresins.

Species of Copaifera genus (Fabaceae - Caesalpinoiodidaeae) produces an important commercial oleoresin that displays many medicinal properties. Copaifera oleoresins (COR) are composed mainly of a mixture of diterpenes and sequiterpenes, and the main reported acid diterpenes for this genus are kaurenoic, copalic, hardwickiic and polyaltic acids. An ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method was developed and validated for identification and quantification of nine acid diterpenes. The developed method was applied in the analyses of 10 authentic COR samples collected in the North and Southeast of Brazil and six commercial COR samples. Samples preparation consisted of simple dilution of oleoresins in methanol followed by filtration. Validation parameters of the method for nine acid diterpenes were satisfactory: selectivity/specificity was defined by retention time and MS/MS analyses for each analyte; generally all analytical curves presented r2>0.99, Lack-of-fit test not significant and RSD<20% for all concentration levels; limit of detection and limit of quantification were on the scale of nanogram per milliliter; inter- and intra-day precision and accuracy were adequate. Regarding the robustness, the method was sensible to small deliberate variations of temperature and additives to the mobile phase, such as formic acid and ammonium hydroxide. Results of 16 analyzed samples of COR showed qualitative and quantitative differences of acid diterpenes among all samples. The diterpenes ent-kaurenoic acid 1, ent-polyalthic acid 3, ent-copalic acid 5 and, ent-3-ß-acetoxy copalic acid 9 were found with more frequency in COR analyzed samples. Additionally, the content of the acid diterpenes found in 16 Copaifera oleoresin samples was analyzed by Principal Component Analysis (PCA), suggesting a botanical origin for the commercial samples. The developed UPLC method was shown to be reliable for the analysis of acid diterpenes in commercial Copaifera oleoresins.

Characterization of a microcystin and detection of microcystin synthetase genes from a Brazilian isolate of Nostoc.

A nostocalean nitrogen-fixing cyanobacterium isolated from an eutrophic freshwater reservoir located in Piracicaba, São Paulo, Brazil, was evaluated for the production of hepatotoxic cyclic heptapeptides, microcystins. Morphologically this new cyanobacterium strain appears closest to Nostoc, however, in the phylogenetic analysis of 16S rRNA gene it falls into a highly stable cluster distantly only related to the typical Nostoc cluster. Extracts of Nostoc sp. CENA88 cultured cells, investigated using ELISA assay, gave positive results and the microcystin profile revealed by ESI-Q-TOF/MS/MS analysis confirmed the production of [Dha(7)]MCYST-YR. Further, Nostoc sp. CENA88 genomic DNA was analyzed by PCR for sequences of mcyD, mcyE and mcyG genes of microcystin synthetase (mcy) cluster. The result revealed the presence of mcyD, mcyE and mcyG genes with similarities to those from mcy of Nostoc sp. strains 152 and IO-102-I and other cyanobacterial genera. The phylogenetic tree based on concatenated McyG, McyD and McyE amino acids clustered the sequences according to cyanobacterial genera, with exception of the Nostoc sp. CENA88 sequence, which was placed in a clade distantly related from other Nostoc strains, as previously observed also in the 16S rRNA phylogenetic analysis. The present study describes for the first time a Brazilian Nostoc microcystin producer and also the occurrence of demethyl MCYST-YR variant in this genus. The sequenced Nostoc genes involved in the microcystin synthesis can contribute to a better understanding of the toxigenicity and evolution of this cyanotoxin.