Isolation of quinic acid from dropped Citrus reticulata Blanco fruits: its derivatization, antibacterial potential, docking studies, and ADMET profiling

Citrus reticulata dropped fruits are generally discarded as waste, causing environmental pollution and losses to farmers. In the present study, column chromatography has been used to isolate quinic acid (1,3,4,5-tetrahydroxycyclohexane-1-carboxylic acid) from the ethyl acetate fraction of a methanol extract of citrus fruits dropped in April. Quinic acid is a ubiquitous plant metabolite found in various plants and microorganisms. It is an important precursor in the biosynthesis of aromatic natural compounds. It was further derivatized into 3,4-o-isopropylidenequinic acid 1,5-lactone (QA1), 1,3,4,5-tetraacetoxycyclohexylaceticanhydride (QA2), and cyclohexane-1,2,3,5-tetraone (QA3). These compounds were further tested for their antibacterial potential against the foodborne pathogens Staphylococcus aureus, Bacillus spp., Yersinia enterocolitica, and Escherichia coli. QA1 exhibited maximum antibacterial potential (minimum inhibitory concentration; 80-120 μg/mL). QA1 revealed synergistic behavior with streptomycin against all the tested bacterial strains having a fractional inhibitory concentration index ranging from 0.29 to 0.37. It also caused a significant increase in cell constituent release in all the tested bacteria compared to the control, along with prominent biofilm reduction. The results obtained were further checked with computational studies that revealed the best docking score of QA1 (-6.30 kcal/mol, -5.8 kcal/mol, and -4.70 kcal/mol) against β-lactamase, DNA gyrase, and transpeptidase, respectively. The absorption, distribution, metabolism, excretion, and toxicity (ADMET) analysis revealed that the drug-like properties of QA1 had an ideal toxicity profile, making it a suitable candidate for the development of antimicrobial drugs.

Guanidinium–amino acid hydrogen-bonding interactions in protein crystal structures: implications for guanidinium-induced protein denaturation

Structural analysis of guanidinium–amino acid interaction pairs in protein crystal structures is coupled with an effective scheme for classifying the optimized pairs, to gain understanding of the guanidinium:protein hydrogen bonding modes.

A83 BEST PRACTICES FOR THE PROVISION OF VIRTUAL CARE IN IBD AND BEYOND: A SYSTEMATIC REVIEW OF CURRENT GUIDELINES

Background

Telemedicine has emerged as a feasible adjunct to in-person care in multiple clinical contexts, including inflammatory bowel disease (IBD), and its role has expanded in the context of the COVID-19 pandemic. However, there exists a general paucity of information surrounding best practice recommendations for conducting specialty or disease-specific virtual care.

Aims

The purpose of this study was to systematically review existing best practice guidelines for conducting telemedicine encounters, both in general and specific to patients with IBD.

Methods

A systematic review of MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials (CENTRAL) of existing guidelines for the provision of virtual care was performed. Data was synthesized using the Synthesis Without Meta-Analysis (SWiM) guideline, and the AGREE II tool was used to evaluate quality of evidence

Results

A total of 60 studies providing guidance for virtual care encounters were included; 52% of these were published during the COVID-19 pandemic. No gastroenterology-specific guidelines were found. The majority (95%) of provider guidelines specified a type of virtual encounter to which their guidelines applied. Of included studies, 65% provided guidance regarding confidentiality/security, 58% discussed technology/setup, and 56% commented on patient consent. 31 studies also provided guidance to patients or caregivers. Overall guideline quality was poor.

Conclusions

General best practices for successful telemedicine encounters include ensuring confidentiality and consent, preparation prior to a visit, and clear patient communication. Future studies should aim to objectively assess the efficacy of existing clinician practices in order to further optimize the provision of virtual care for specific populations, such as patients with IBD.

Funding Agencies

None

Exploring the Nature of Hydrogen Bonding between RNA and Proteins: A Comprehensive Analysis of RNA : Protein Complexes

A nonredundant dataset of ∼300 high (up to 2.5 Å) resolution X-ray structures of RNA:protein complexes were analyzed for hydrogen bonds between amino-acid residues and canonical ribonucleotides (rNs). The identified 17100 contacts were classified based on the identity (rA, rC, rG or rU) and interacting fragment (base, sugar, or ribose) of the rN, the nature (polar or nonpolar) and interacting moiety (main chain or side chain) of the amino-acid residue, as well as the rN and amino-acid atoms participating in the hydrogen bonding. 80 possible hydrogen-bonding combinations (4 (rNs) X 20 (amino acids)) involve a wide variety of RNA and protein types and are present in multiple occurrences in almost all PDB files. Comparison with the analogously-selected DNA:protein complexes reveals that the absence of 2'-OH group in DNA mainly accounts for the differences in DNA:protein and RNA:protein hydrogen bonding. Search for intrinsically-stable base:amino acid pairs containing single or multiple hydrogen bonds reveals 37 unique pairs, which may act as well-defined RNA:protein interaction motifs. Overall, our work collectively analyzes the largest set of nucleic acid-protein hydrogen bonds to date, and therefore highlights several trends that may help frame structural rules governing the physiochemical characteristics of RNA:protein recognition.

Duplicated antagonistic EPF peptides optimize grass stomatal initiation

Peptide signaling has emerged as a key component of plant growth and development, including stomatal patterning, which is crucial for plant productivity and survival. Although exciting progress has been made in understanding EPIDERMAL PATTERNING FACTOR (EPF) signaling in Arabidopsis, the mechanisms by which EPF peptides control different stomatal patterns and morphologies in grasses are poorly understood. Here, by examining expression patterns, overexpression transgenics and cross-species complementation, the antagonistic stomatal ligands orthologous to Arabidopsis AtEPF2 and AtSTOMAGEN/AtEPFL9 peptides were identified in Triticum aestivum (wheat) and the grass model organism Brachypodium distachyon. Application of bioactive BdEPF2 peptides inhibited stomatal initiation, but not the progression or differentiation of stomatal precursors in Brachypodium. Additionally, the inhibitory roles of these EPF peptides during grass stomatal development were suppressed by the contrasting positive action of the BdSTOMAGEN peptide in a dose-dependent manner. These results not only demonstrate how conserved EPF peptides that control different stomatal patterns exist in nature, but also suggest new strategies to improve crop yield through the use of plant-derived antagonistic peptides that optimize stomatal density on the plant epidermis.

MKP1 acts as a key modulator of stomatal development

The MAPK signaling cascade is universal among eukaryotes and mediates a variety of environmental and developmental responses. Two Arabidopsis MAPKs, MPK3 and MPK6, have been shown to be activated by various stimuli and suggested as a convergence point of different signaling pathways. It is known that these MAPKs, MPK3/MPK6, control the discrete stages of stomatal development in Arabidopsis, but how they are regulated and how the same MAPK components can achieve signaling specificity is largely unknown. We recently demonstrated that MAP Kinase Phosphatase 1 (MKP1) promotes stomatal differentiation by suppressing activation of MPK3/MPK6 in the stomatal lineage. By expressing MKP1 in discrete stomatal precursor cell types, we further identified that MKP1 plays an important role at the early stage of stomatal development for the cell fate transition leading to stomatal differentiation. While MKP1 was previously known as a key regulator of environmental stress responses, our data illustrate a novel role of MKP1 in plant development: it acts as one of the specificity-determining regulators of MAPK signaling to enforce proper stomatal development in Arabidopsis.

MAP KINASE PHOSPHATASE1 Controls Cell Fate Transition during Stomatal Development

Stomata on the plant epidermis control gas and water exchange and are formed by MAPK-dependent processes. Although the contribution of MAP KINASE3 (MPK3) and MPK6 (MPK3/MPK6) to the control of stomatal patterning and differentiation in Arabidopsis (Arabidopsis thaliana) has been examined extensively, how they are inactivated and regulate distinct stages of stomatal development is unknown. Here, we identify a dual-specificity phosphatase, MAP KINASE PHOSPHATASE1 (MKP1), which promotes stomatal cell fate transition by controlling MAPK activation at the early stage of stomatal development. Loss of function of MKP1 creates clusters of small cells that fail to differentiate into stomata, resulting in the formation of patches of pavement cells. We show that MKP1 acts downstream of YODA (a MAPK kinase kinase) but upstream of MPK3/MPK6 in the stomatal signaling pathway and that MKP1 deficiency causes stomatal signal-induced MAPK hyperactivation in vivo. By expressing MKP1 in the three discrete cell types of stomatal lineage, we further identified that MKP1-mediated deactivation of MAPKs in early stomatal precursor cells directs cell fate transition leading to stomatal differentiation. Together, our data reveal the important role of MKP1 in controlling MAPK signaling specificity and cell fate decision during stomatal development.