Background The fronds of Drynaria quercifolia have traditionally been used in rheumatic pain management. The goal of the present study was to validate the potent anti-inflammatory and anti-rheumatoid properties of the methanolic-extract of its rhizome using in vitro, in vivo and in silico strategies. Methods The plant was collected and the methanolic extract was prepared from its rhizome. Protein denaturation test, hypotonicity and heat-induced haemolysis assays were performed in vitro. The in vivo anti-rheumatoid potential was assessed in Freund’s complete adjuvant (FCA)-induced Wistar rat model through inflammatory paw-edema, haematological, biochemical, radiological and histopathological measurements. Moreover, metabolites of methanolic extract were screened by gas chromatography-mass spectrometry (GC-MS) and 3D molecular structures of active components were utilized for in silico docking study using AutoDock. Results In vitro results evinced a significant (p < 0.05) anti-inflammatory activity of the rhizome methanolic extract in a dose-linear response. Further, Drynaria quercifolia rhizome methanolic extract (DME) significantly ameliorated rheumatoid arthritis as indicated by the inhibition of arthritic paw-edema (in millimeter) in the rat rheumatoid arthritis models in both the low (57.71 ± 0.99, p < 0.01) and high dose groups (54.45 ± 1.30, p < 0.001) when compared to arthritic control. Treatment with DME also normalized the haematological (RBC, WBC, platelet counts and hemoglobin contents) and biochemical parameters (total protein, albumin, creatinine and ceruloplasmin) significantly (p < 0.05), which were further supported by histopathological and radiological analyses. Furthermore, GC-MS analysis of DME demonstrated the presence of 47 phytochemical compounds. Compounds like Squalene, Gamma Tocopherol, n-Hexadecanoic acid showed potent inhibition of cyclooxygenase-2 (COX-2), tumor necrosis factor (TNF-α), and interleukin (IL-6) in the docking analysis. Conclusion Results from in vivo and in vitro studies indicated that DME possesses a potent anti-inflammatory and anti-arthritic activity. In silico studies delineated the emergent potent inhibitory effects of several bio-active components on the target inflammatory markers (COX-2, TNF-α and IL-6).

Frankia forms a nitrogen-fixing symbiosis with actinorhizal plants. We report a draft genome sequence for Frankia sp. strain BCU110501, a nitrogen-fixing actinobacterium isolated from nodules of Discaria trinevis grown in the Patagonia region of Argentina.

We report here the genome sequence of Frankia sp. strain CN3, which was isolated from Coriaria nepalensis. This genome sequence is the first from the fourth lineage of Frankia, strains of which are unable to reinfect actinorhizal plants. At 10 Mb, it represents the largest Frankia genome sequenced to date.

BackgroundActinobacteria have adapted to contrasted ecological niches such as the soil, and among others to plants or animals as pathogens or symbionts. Mycobacterium genus contains mostly pathogens that cause a variety of mammalian diseases, among which the well-known leprosy and tuberculosis, it also has saprophytic relatives. Streptomyces genus is mostly a soil microbe known for its secondary metabolites, it contains also plant pathogens, animal pathogens and symbionts. Frankia, a nitrogen-fixing actinobacterium establishes a root symbiosis with dicotyledonous pionneer plants. Pathogens and symbionts live inside eukaryotic cells and tissues and interact with their cellular environment through secreted proteins and effectors transported through transmembrane systems; nevertheless they also need to avoid triggering host defense reactions. A comparative genome analysis of the secretomes of symbionts and pathogens allows a thorough investigation of selective pressures shaping their evolution. In the present study, the rates of silent mutations to non-silent mutations in secretory proteins were assessed in different strains of Frankia, Streptomyces and Mycobacterium, of which several genomes have recently become publicly available.ResultsIt was found that secreted proteins as a whole have a stronger purifying evolutionary rate (non-synonymous to synonymous substitutions or Ka/Ks ratio) than the non-secretory proteins in most of the studied genomes. This difference becomes statistically significant in cases involving obligate symbionts and pathogens. Amongst the Frankia, secretomes of symbiotic strains were found to have undergone evolutionary trends different from those of the mainly saprophytic strains. Even within the secretory proteins, the signal peptide part has a higher Ka/Ks ratio than the mature part. Two contrasting trends were noticed amongst the Frankia genomes regarding the relation between selection strength (i.e. Ka/Ks ratio) and the codon adaptation index (CAI), a predictor of the expression rate, in all the genes belonging to the core genome as well as the core secretory protein genes. The genomes of pathogenic Mycobacterium and Streptomyces also had reduced secretomes relative to saprophytes, as well as in general significant pairwise Ka/Ks ratios in their secretomes.ConclusionIn marginally free-living facultative symbionts or pathogenic organisms under consideration, secretory protein genes as a whole evolve at a faster rate than the rest and this process may be an adaptive life-strategy to counter the host selection pressure. The higher evolutionary rate of signal peptide part compared to mature protein provides an indication that signal peptide parts may be under relaxed purifying selection, indicative of the signal peptides not being secreted into host cells. Codon usage analysis suggests that in actinobacterial strains under host selection pressure such as symbiotic Frankia, ACN, FD and the pathogenic Mycobacterium, codon usage bias was negatively correlated to the selective pressure exerted o...

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