Green synthesis, characterization and biological activities of silver nanoparticles synthesized from Neolamarkia cadamba.

Background and purpose: Metal nanoparticles are essential due to their unique catalytic, electrical, magnetic, and optical characteristics, as well as their prospective use in sensing, catalysis, and biological research. In recent years, researchers have focused on developing cost-effective and eco-friendly biogenic practices using the green synthesis of metal nanoparticles (AgNP). Experimental approach: In the present study, the aqueous extracts prepared from the leaf, stem, bark, and flower of Neolamarkia cadamba were used for the synthesis of silver nanoparticles. Synthesized silver nanoparticles were characterized using UV-Visible spectroscopy, zeta potential, dynamic light scattering, scanning electron microscope (SEM), and EDAX. Key results: The current study showed absorption of synthesized AgNPs at 425, 423, 410, and 400 nm. Dynamic light scattering of AgNPs Showed size distribution of AgNPs synthesized from leaf, stem, and flower aqueous extracts ranges from 80-200 nm and AgNPs prepared from bark extract ranges from 100-700 nm. Zeta-potential of the biosynthesized AgNPs was found as a sharp peak at -23.1 mV for the leaf, -27.0 mV for the stem, -34.1 mV for the bark, and -20.2 mV for the flower. Silver nanoparticles and crude extracts of Neolamarkia cadamba showed effective antibacterial, antifungal, and antioxidant activities. Conclusion: Silver nanoparticles have substantial antibacterial activity against Gram-positive bacteria and also exhibit the utmost antifungal activity against Aspergillus niger. The study concludes that the green synthesis of silver nanoparticles from N. cadamba leaf, stem, bark, and flower extract is a reliable and eco-friendly technique.

Prospects and progress in the production of valuable carotenoids: Insights from metabolic engineering, synthetic biology, and computational approaches.

Carotenoids are isoprenoid pigments synthesized exclusively by plants and microorganisms and play critical roles in light harvesting, photoprotection, attracting pollinators and phytohormone production. In recent years, carotenoids have been used for their health benefits due to their high antioxidant activity and are extensively utilized in food, pharmaceutical, and nutraceutical industries. Regulation of carotenoid biosynthesis occurs throughout the life cycle of plants, with vibrant changes in composition based on developmental needs and responses to external environmental stimuli. With advancements in metabolic engineering techniques, there has been tremendous progress in the production of industrially valuable secondary metabolites such as carotenoids. Application of metabolic engineering and synthetic biology has become essential for the successful and improved production of carotenoids. Synthetic biology is an emerging discipline; metabolic engineering approaches may provide insights into novel ideas for biosynthetic pathways. In this review, we discuss the current knowledge on carotenoid biosynthetic pathways and genetic engineering of carotenoids to improve their nutritional value. In addition, we investigated synthetic biological approaches for the production of carotenoids. Theoretical biology approaches that may aid in understanding the biological sciences are discussed in this review. A combination of theoretical knowledge and experimental strategies may improve the production of industrially relevant secondary metabolites.

Identifying a Carotenoid Cleavage Dioxygenase 4a Gene and Its Efficient Agrobacterium-Mediated Genetic Transformation in Bixa orellana L.

Carotenoids are metabolized to apocarotenoids through the pathway catalysed by carotenoid cleavage oxygenases (CCOs). The apocarotenoids are economically important as it is known to have therapeutic as well as industrial applications. For instance, bixin from Bixa orellana and crocin from Crocus sativus are commercially used as a food colourant and cosmetics since prehistoric time. In our present study, CCD4a gene has been identified and isolated from leaves of B. orellana for the first time and named as BoCCD4a; phylogenetic analysis was carried out using CLUSTAL W. From sequence analysis, BoCCD4a contains two exons and one intron, which was compared with the selected AtCCD4, RdCCD4, GmCCD4 and CmCCD4a gene. Further, the BoCCD4a gene was cloned into pCAMBIA 1301, transformed into Agrobacterium tumefaciens EHA105 strain and subsequently transferred into hypocotyledons and callus of B. orellana by agro-infection. Selection of stable transformation was screened on the basis of PCR detection by using GUS and hptII specific primer, which was followed by histochemical characterization. The percent transient GUS expression in hypocotyledons and callus was 84.4 and 80 %, respectively. The expression of BoCCD4a gene in B. orellana was confirmed through RT-PCR analysis. From our results, the sequence analysis of BoCCD4a gene of B. orellana was closely related to the CsCCD4 gene of C. sativus, which suggests this gene may have a role in various processes such as fragrance, insect attractant and pollination.

Inhibitory effect of apocarotenoids on the activity of tyrosinase: Multi-spectroscopic and docking studies.

In this present study, the inhibitory mechanism of three selected apocarotenoids (bixin, norbixin and crocin) on the diphenolase activity of tyrosinase has been investigated. The preliminary screening results indicated that apocarotenoids inhibited tyrosinase activity in a dose-dependent manner. Kinetic analysis revealed that apocarotenoids reversibly inhibited tyrosinase activity. Analysis of fluorescence spectra showed that apocarotenoids quenched the intrinsic fluorescence intensity of the tyrosinase. Further, molecular docking results implied that apocarotenoids were allosterically bound to tyrosinase through hydrophobic interactions. The results of the in vitro studies suggested that higher concentrations of bixin and norbixin inhibited tyrosinase activity in B16F0 melanoma cells. Our results suggested that apocarotenoids could form the basis for the design of novel tyrosinase inhibitors.

Inhibitory effect of brazilein on tyrosinase and melanin synthesis: Kinetics and in silico approach.

In our present study, the inhibitory effect of brazilein from Caesalpinia sappan on tyrosinase activity was investigated through multi-spectroscopic and molecular docking techniques. The result has shown that brazilein reversibly inhibited tyrosinase in a mixed type manner. The interaction of brazilein with the amino acid residues of tyrosinase has been validated through fluorescence quenching studies. Copper interaction studies suggested that brazilein could bind with copper ions of the enzyme. Circular dichroism analysis confirmed that brazilein induced secondary structural changes in tyrosinase. Docking studies further authenticate that brazilein forms hydrophobic and hydrogen bonding with the active site residues of tyrosinase. Moreover, in vitro studies confirmed that the inhibitory mechanism of cellular tyrosinase and melanin synthesis by brazilein in B16F0 melanoma cells. These results suggested that brazilein act as a potential tyrosinase inhibitor and it would contribute as a of novel tyrosinase inhibitor in food, cosmetic and pharmaceutical industry.