Spectral analysis, in vitro cytotoxicity and antibacterial studies of bioactive principles from the leaves of Conocarpus lancifolius, a common tree of Jazan, Saudi Arabia

The objective of the present study was to analyse the bioactive compounds of the leaves of Conocarpus lancifolius (C. lancifolius). The GC-MS analysis of the hot methanolic extract of the leaves (HMEL) of C. lancifolius exhibited the bioactive compounds such as 1-(3-Methoxy-2-nitrobenzyl) iso quinoline, morphin-4-ol-6,7-dione, 1-bromo-N-methyl-, phytol, hexadecanoic acid, 2,3-dihydroxypropyl ester, 2,2':4',2”-terthiophene, ethyl iso-allocholate, caryophyllene oxide, campesterol, epiglobulol, cholestan-3-ol, 2-methylene-, (3á,5à)-, dasycarpidan-1-methanol, acetate (ester) and oleic acid, eicosyl ester. The FT-IR analysis of HMEL of C. lancifolius showed a unique peak at 3184, 2413, 1657 cm-1 representing coumaric acid, chlorogenic acid and ferulic acid. The HMEL of C. lancifolius was actively inhibiting the proliferation of breast cancer cells MCF-7 ATCC at the concentration of 72.66 ± 8.21 µg/ml as IC50 value. The HMEL of C. lancifolius also revealed a good spectrum of activity against Gram-positive and Gram-negative bacterial cultures screened in this work. The activity observed has shown more or less similar effects against screened bacteria. However, the magnitude of potentiality was significantly lesser compared to standard ciprofloxacin disc at p< 0.001 level (99% confidence intervals). Furthermore, the study demonstrating the bioactive compounds can be isolated from the leaves of C. lancifolius.

Expression of phenylalanine ammonia lyases in Synechocystis sp. PCC 6803 and subsequent improvements of sustainable production of phenylpropanoids

Background Phenylpropanoids represent a diverse class of industrially important secondary metabolites, synthesized in plants from phenylalanine and tyrosine. Cyanobacteria have a great potential for sustainable production of phenylpropanoids directly from CO2, due to their photosynthetic lifestyle with a fast growth compared to plants and the ease of generating genetically engineered strains. This study focuses on photosynthetic production of the starting compounds of the phenylpropanoid pathway, trans-cinnamic acid and p-coumaric acid, in the unicellular cyanobacterium Synechocystis sp. PCC 6803 (Synechocystis). Results A selected set of phenylalanine ammonia lyase (PAL) enzymes from different organisms was overexpressed in Synechocystis, and the productivities of the resulting strains compared. To further improve the titer of target compounds, we evaluated the use of stronger expression cassettes for increasing PAL protein levels, as well as knock-out of the laccase gene slr1573, as this was previously reported to prevent degradation of the target compounds in the cell. Finally, to investigate the effect of growth conditions on the production of trans-cinnamic and p-coumaric acids from Synechocystis, cultivation conditions promoting rapid, high density growth were tested. Comparing the different PALs, the highest specific titer was achieved for the strain AtC, expressing PAL from Arabidopsis thaliana. A subsequent increase of protein level did not improve the productivity. Production of target compounds in strains where the slr1573 laccase had been knocked out was found to be lower compared to strains with wild type background, and the Δslr1573 strains exhibited a strong phenotype of slower growth rate and lower pigment content. Application of a high-density cultivation system for the growth of production strains allowed reaching the highest total titers of trans-cinnamic and p-coumaric acids reported so far, at around 0.8 and 0.4 g L−1, respectively, after 4 days. Conclusions Production of trans-cinnamic acid, unlike that of p-coumaric acid, is not limited by the protein level of heterologously expressed PAL in Synechocystis. High density cultivation led to higher titres of both products, while knocking out slr1573 did not have a positive effect on production. This work contributes to capability of exploiting the primary metabolism of cyanobacteria for sustainable production of plant phenylpropanoids.

Co-Ingestion of Natal Plums (Carissa macrocarpa) and Marula Nuts (Sclerocarya birrea) in a Snack Bar and Its Effect on Phenolic Compounds and Bioactivities

This study investigated the effect of co-ingesting Natal plums (Carissa macrocarpa) and Marula nuts (Sclerocarya birrea) on the bioaccessibility and uptake of anthocyanins, antioxidant capacity, and the ability to inhibit α-glucosidase. A Natal plum–Marula nut bar was made by mixing the raw nuts and the fruit pulp in a ratio 1:1 (v/v). The cyanidin-3-O-sambubioside (Cy-3-Sa) and cyanidin-3-O-glucoside content (Cy-3-G) were quantified using the ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UHPLC/Q-TOF-MS). Inclusion of Natal plum in the Marula nut bar increased the Cy-3-Sa, Cy-3-G content, antioxidants capacity and α-glucosidase inhibition compared to ingesting Marula nut separately at the internal phase. Adding Natal plum to the Marula nut bar increased bioaccessibility of Cy-3-Sa, Cy-3-G, quercetin, coumaric acid, syringic acid and ferulic acid to 80.2% and 71.9%, 98.7%, 95.2%, 51.9% and 89.3%, respectively, compared to ingesting the Natal plum fruit or nut separately.

Allelopathy and allelochemical quantitative analysis in Pinto peanut (Arachis pintoi)

Pinto peanut (Arachis pintoi) considered as a perennial legume animal fed plant with good soil fertility improvement was uesed for its allelopathy that had been reported on the germination of Ageratum conyzoides L, Comnyza canadensis L. Cronq., Bidens pilosa L., Solanum lycopersicum and Capsicum annum. through the solutions extracted from different parts of pinto peanut on mustard greens (Brassica juncea), barnyardgrass (Echinochloa crus-galli) and junglerice (Echinochloa colonum). Consideration of the growth of hypocotyls and rootlets at 48 hours after incubation with pinto peanut extracts, results showed that 1.0 g/ml of the methanolic pinto peanut stem extract greatly inhibited 100% mustard greens growth, 77.7% and 93.5% the hypocotyls and rootlets growth of barnyardgrass, 57.2% and 92.7% the hypocotyls and rootlets growth of junglerice, respectively. The allelopathic activity after liquid-liquid extraction of the ethyl acetate phase greater than the aqueous phase. Allelopathic extract loading from C18 chromatographic column was purified by HPLC to obtain 6 phenolic compounds with the contents in 1 g fresh pinto peanut weight were 0.214 μg (cinamic acid), 0.8344 μg (caffeic acid), 7.7676 μg (coumaric acid), 2.2354 μg (ferullic acid), 0.045 μg (2-4 dimehydroxy benzoic) and 32.1162 μg (salicylic acid). These results should be accordingly considered in the production of biological herbicides.

Synthesis of hydroxycinnamoyl shikimates and their role in monolignol biosynthesis

Hydroxycinnamoyl shikimates were reported in 2005 to be intermediates in monolignol biosynthesis. 3-Hydroxylation of p-coumarate, originally thought to occur via coumarate 3-hydroxylase (C3H) from p-coumaric acid or its CoA thioester, was revealed to be via the action of coumaroyl shikimate 3′-hydroxylase (C3′H) utilizing p-coumaroyl shikimate as the substrate, itself derived from p-coumaroyl-CoA via hydroxycinnamoyl-CoA: shikimate hydroxycinnamoyltransferase (HCT). The same HCT was conjectured to convert the product, caffeoyl shikimate, to caffeoyl-CoA to continue on the pathway starting with its 3-O-methylation. At least in some plants, however, a more recently discovered caffeoyl shikimate esterase (CSE) enzyme hydrolyzes caffeoyl shikimate to caffeic acid from which it must again produce its CoA thioester to continue on the monolignol biosynthetic pathway. HCT and CSE are therefore monolignol biosynthetic pathway enzymes that have provided new opportunities to misregulate lignification. To facilitate studies into the action and substrate specificity of C3H/C3′H, HCT, and CSE enzymes, as well as for metabolite authentication and for enzyme characterization, including kinetics, a source of authentic substrates and products was required. A synthetic scheme starting from commercially available shikimic acid and the four key hydroxycinnamic acids (p-coumaric, caffeic, ferulic, and sinapic acid) has been developed to provide this set of hydroxycinnamoyl shikimates for researchers.

Analysis of Phenolic Compounds for the Determination of Grafts (in) Compatibility Using In Vitro Callus Cultures of Sato-Zakura Cherries

The aim of this study was to prove that under in vitro conditions, the adhesiveness of the callus between rootstock and scion, the development of callus cells at the points of fusion, and the presence of phenolic components are closely related to the level of (in) compatibility of the grafting combinations between Sato-zakura cherry cultivars (‘Amanogawa’, ‘Kanzan’, and ‘Kiku-shidare-zakura’) and commercial rootstocks. Prunus avium, Prunus ‘Colt’, Prunus mahaleb and Prunus serrulata were used as compatible and Prunus serotina and Pyrus communis ‘Pyrodwarf’ were used as two potentially incompatible rootstocks. The results indicated the significant manifestations of the early signs of the incompatibility on the callus junction. Phenols, as well as tissue senescence, were very precisely localized by toluidine blue and alcian blue as well as safranin staining, which can indicate the early signs of the callus incompatibility in some grafting unions. In the callus unions of Prunus avium with ‘Amanogawa’ and ‘Kiku-shidare-zakura’ the results of chemical analyses indicated that the existence of several flavonols, flavones and phenol acids could be involved in the incompatibility process in grafted combination. The detection of flavonol astragalin in the unions can be a biomarker of compatibility between scion and the rootstock, while some polyphenols, such as neochlorogenic acid, sinapic acid, ellagic acid, caffeic acid, baicalein, naringenin, apigenin and luteolin can be used as the indicators of graft incompatibility. p-coumaric acid and ferulic acid could be used for detection of delayed incompatibility.

Experimental and Computational Analysis of Para-Hydroxy Methylcinnamate Following Photoexcitation

Para-hydroxy methylcinnamate is part of the cinnamate family of molecules. Experimental and computational studies have suggested conflicting non-radiative decay routes after photoexcitation to its S1(ππ*) state. One non-radiative decay route involves intersystem crossing mediated by an optically dark singlet state, whilst the other involves direct intersystem crossing to a triplet state. Furthermore, irrespective of the decay mechanism, the lifetime of the initially populated S1(ππ*) state is yet to be accurately measured. In this study, we use time-resolved ion-yield and photoelectron spectroscopies to precisely determine the S1(ππ*) lifetime for the s-cis conformer of para-hydroxy methylcinnamate, combined with time-dependent density functional theory to determine the major non-radiative decay route. We find the S1(ππ*) state lifetime of s-cis para-hydroxy methylcinnamate to be ∼2.5 picoseconds, and the major non-radiative decay route to follow the [1ππ*→1nπ*→3ππ*→S0] pathway. These results also concur with previous photodynamical studies on structurally similar molecules, such as para-coumaric acid and methylcinnamate.

Darkfield and Fluorescence Macrovision of a Series of Large Images to Assess Anatomical and Chemical Tissue Variability in Whole Cross-Sections of Maize Stems

The proportion and composition of plant tissues in maize stems vary with genotype and agroclimatic factors and may impact the final biomass use. In this manuscript, we propose a quantitative histology approach without any section labelling to estimate the proportion of different tissues in maize stem sections as well as their chemical characteristics. Macroscopic imaging was chosen to observe the entire section of a stem. Darkfield illumination was retained to visualise the whole stem cellular structure. Multispectral autofluorescence images were acquired to detect cell wall phenolic compounds after UV and visible excitations. Image analysis was implemented to extract morphological features and autofluorescence pseudospectra. By assimilating the internode to a cylinder, the relative proportions of tissues in the internode were estimated from their relative areas in the sections. The approach was applied to study a series of 14 maize inbred lines. Considerable variability was revealed among the 14 inbred lines for both anatomical and chemical traits. The most discriminant morphological descriptors were the relative amount of rind and parenchyma tissues together with the density and size of the individual bundles, the area of stem and the parenchyma cell diameter. The rind, as the most lignified tissue, showed strong visible-induced fluorescence which was line-dependant. The relative amount of para-coumaric acid was associated with the UV-induced fluorescence intensity in the rind and in the parenchyma near the rind, while ferulic acid amount was significantly correlated mainly with the parenchyma near the rind. The correlation between lignin and the tissue pseudospectra showed that a global higher amount of lignin resulted in a higher level of lignin fluorescence whatever the tissues. We demonstrated here the potential of darkfield and autofluorescence imaging coupled with image analysis to quantify histology of maize stem and highlight variability between different lines.