Antibacterial and Anti-inflammatory Activity of Extracts and Major Constituents Derived from Stachytarpheta indica Linn. Leaves and Their Potential Implications for Wound Healing.

Wounds of various types continue to have a severe socioeconomic impact on the cost of health care. Globally, there has been increased interest surrounding the identification of bioactive compounds that promote or modulate the wound healing process. Stachytarpheta indica Linn. is traditionally used to heal wounds and relieve inflammation; however, the theorised pharmacological properties have not yet been scientifically validated. In this study, dried and ground plant leaves were extracted with water and methanol, which were then subjected to various analyses. The antimicrobial activity of the plant extracts and isolated compounds was determined using well diffusion assays, while the minimum inhibitory concentrations were determined with a colorimetric assay. Morphological changes of human keratinocytes in response to plant extracts were observed with differential interference contrast microscope imaging. Cell viability, proliferation, and migratory effects post-treatment with the plant extracts were also evaluated via colorimetric cytotoxicity assays and a real-time cell analyser protocol. Anti-inflammatory effects of plant extracts and isolated compounds were evaluated by flow cytometry and cyclooxygenase and lipoxygenase enzyme inhibition assays. Three active compounds, i.e. ipolamiide, verbascoside and iso-verbascoside, were isolated from S. indica leaves. Verbascoside demonstrated broad-range antibacterial activity and imposed strong inhibition at 9.77 µg/mL against Staphylococci spp. S. indica extracts (0.1-0.2 mg/mL) were shown to improve human keratinocyte proliferation up to 60% and induce morphological changes by producing cytoplasmic projections at concentrations higher than 0.4 mg/mL. Plant extracts (6.25-100 µg/mL) and individual compounds (3.125-50 µg/mL) elicited strong anti-inflammatory effects by suppressing the expression of interleukin-8 and inhibiting cyclooxygenase-1 and 5-lipoxygenase enzymes. Collectively, these results indicate that plant extracts and isolated compounds derived from S. indica have the potential to inhibit bacterial growth, promote tissue regeneration and reduce inflammation, hence, potentially providing the basis for a novel therapeutic for the treatment of wounds.

TaNF-YB3 is involved in the regulation of photosynthesis genes in Triticum aestivum.

Nuclear factor Y (NF-Y) transcription factor is a heterotrimer comprised of three subunits: NF-YA, NF-YB and NF-YC. Each of the three subunits in plants is encoded by multiple genes with differential expression profiles, implying the functional specialisation of NF-Y subunit members in plants. In this study, we investigated the roles of NF-YB members in the light-mediated regulation of photosynthesis genes. We identified two NF-YB members from Triticum aestivum (TaNF-YB3 & 7) which were markedly upregulated by light in the leaves and seedling shoots using quantitative RT-PCR. A genome-wide coexpression analysis of multiple Affymetrix Wheat Genome Array datasets revealed that TaNF-YB3-coexpressed transcripts were highly enriched with the Gene Ontology term photosynthesis. Transgenic wheat lines constitutively overexpressing TaNF-YB3 had a significant increase in the leaf chlorophyll content, photosynthesis rate and early growth rate. Quantitative RT-PCR analysis showed that the expression levels of a number of TaNF-YB3-coexpressed transcripts were elevated in the transgenic wheat lines. The mRNA level of TaGluTR encoding glutamyl-tRNA reductase, which catalyses the rate-limiting step of the chlorophyll biosynthesis pathway, was significantly increased in the leaves of the transgenic wheat. Significant increases in the expression level in the transgenic plant leaves were also observed for four photosynthetic apparatus genes encoding chlorophyll a/b-binding proteins (Lhca4 and Lhcb4) and photosystem I reaction centre subunits (subunit K and subunit N), as well as for a gene coding for chloroplast ATP synthase γ subunit. These results indicate that TaNF-YB3 is involved in the positive regulation of a number of photosynthesis genes in wheat.

TaNF-YC11, one of the light-upregulated NF-YC members in Triticum aestivum, is co-regulated with photosynthesis-related genes.

Nuclear factor Y (NF-Y) is a heterotrimeric transcription factor complex. Each of the NF-Y subunits (NF-YA, NF-YB and NF-YC) in plants is encoded by multiple genes. Quantitative RT-PCR analysis revealed that five wheat NF-YC members (TaNF-YC5, 8, 9, 11 and 12) were upregulated by light in both the leaf and seedling shoot. Co-expression analysis of Affymetrix wheat genome array datasets revealed that transcript levels of a large number of genes were consistently correlated with those of the TaNF-YC11 and TaNF-YC8 genes in three to four separate Affymetrix array datasets. TaNF-YC11-correlated transcripts were significantly enriched with the Gene Ontology term photosynthesis. Sequence analysis in the promoters of TaNF-YC11-correlated genes revealed the presence of putative NF-Y complex binding sites (CCAAT motifs). Quantitative RT-PCR analysis of a subset of potential TaNF-YC11 target genes showed that ten out of the 13 genes were also light-upregulated in both the leaf and seedling shoot and had significantly correlated expression profiles with TaNF-YC11. The potential target genes for TaNF-YC11 include subunit members from all four thylakoid membrane-bound complexes required for the conversion of solar energy into chemical energy and rate-limiting enzymes in the Calvin cycle. These data indicate that TaNF-YC11 is potentially involved in regulation of photosynthesis-related genes.

Genome-wide identification and expression analysis of the NF-Y family of transcription factors in Triticum aestivum.

Nuclear Factor Y (NF-Y) is a trimeric complex that binds to the CCAAT box, a ubiquitous eukaryotic promoter element. The three subunits NF-YA, NF-YB and NF-YC are represented by single genes in yeast and mammals. However, in model plant species (Arabidopsis and rice) multiple genes encode each subunit providing the impetus for the investigation of the NF-Y transcription factor family in wheat. A total of 37 NF-Y and Dr1 genes (10 NF-YA, 11 NF-YB, 14 NF-YC and 2 Dr1) in Triticum aestivum were identified in the global DNA databases by computational analysis in this study. Each of the wheat NF-Y subunit families could be further divided into 4-5 clades based on their conserved core region sequences. Several conserved motifs outside of the NF-Y core regions were also identified by comparison of NF-Y members from wheat, rice and Arabidopsis. Quantitative RT-PCR analysis revealed that some of the wheat NF-Y genes were expressed ubiquitously, while others were expressed in an organ-specific manner. In particular, each TaNF-Y subunit family had members that were expressed predominantly in the endosperm. The expression of nine NF-Y and two Dr1 genes in wheat leaves appeared to be responsive to drought stress. Three of these genes were up-regulated under drought conditions, indicating that these members of the NF-Y and Dr1 families are potentially involved in plant drought adaptation. The combined expression and phylogenetic analyses revealed that members within the same phylogenetic clade generally shared a similar expression profile. Organ-specific expression and differential response to drought indicate a plant-specific biological role for various members of this transcription factor family.