In-depth phenolic characterization of iron gall inks by deconstructing representative Iberian recipes

Elemental imaging approach to comparative analysis of historical inks. Proof of concept based on non-invasive examinations of the Chopin manuscript as a case study

This work presents an indirect method of investigating the elemental diversity of historical inks. The manuscript of Fryderyk Chopin's Impromptu in A flat major, Op. 29 was examined as an example of the proposed approach for testing documents containing different inks. Preliminary in situ X-ray fluorescence (XRF) measurements carried out it the museum storage room provided qualitative reference data for the object. Then, selected areas on the item were examined with indicator papers soaked in 4,7-diphenyl-1,10-phenanthroline (Bphen). The reaction with the ligand enabled the immediate colorimetric detection of Fe(II) in the form of magenta Fe(Bphen)₃ complex. The overall condition of the manuscript with regard to the risk of ink corrosion was assessed in this way. More chemical information were obtained by the proposed elemental imaging-based approach to evaluate chemical heterogeneity of the used indicator paper samples using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The recorded data were visualised in the form of elemental distribution maps. The Fe enriched areas indicated Regions of Interest (ROIs) to approximate composition of the inks from the manuscript. All calculations were done solely for the data mathematically singled out from these areas. The varying proportions of AI, Mn, Co and Cu relative to Fe correlated with the ROIs of the composer's handwriting, editor's notes and stave lines, demonstrating the applicability of the proposed approach for comparative studies.

Fractal algorithms and RGB image processing in scribal and ink identification on an 1819 secret initiation manuscript to the "Philike Hetaereia"

Historical texts incorporate important characteristics that need to be assessed including genre, text structure and content. Often overlooked are characteristics of handwritten manuscripts commonly divided into legibility, readability and aesthetics. To determine the scientific feasibility of classification of handwritten texts an objective approach is developed to describe twenty handwritten pages of an 1819 Greek manuscript, that refers to the initiation to the Greek secret "friendly society" (Philike Hetaereia) organization, established as part of the Greek independence against the Ottoman Turks. It is investigated through a fractal and RGB image analysis approach. Fractal Minkowski Dimension was applied on the handwritten text and the RGB color analysis on the ink and paper and both were used as a non-invasive manner and revealed interesting results. The novel RGB image analysis and the fractal analysis of the manuscript identified respectively, five iron gall inks and four scribes from the ink content and handwritten styles, of the compact five lines text and whole text pages. The novel approach was verified with another old manuscript of known ink pigments, as well as with thirteen known handwritten texts of that period and four prints representing modern and similar period texts substantiating the findings of the novel methods.

A Model Iron Gall Ink: An In-Depth Study of Ageing Processes Involving Gallic Acid

Iron gall inks have been among the most used writing materials after carbon black, thus representing an important element of the historical and artistic heritage of our society. Crucially, the preservation of manuscripts and drawings is influenced by the presence of these inks, leading to conservation issues related to paper degradation and text fading. Besides all the advances obtained in paper conservation, the study of iron gall ink's behaviour and ageing is still an important topic, which requires investigation through an accurate molecular characterisation to produce reliable models. In the present work a micro-destructive method based on liquid chromatography techniques (HPLC-DAD and HPLC-ESI-Q-ToF) has been optimised starting from a model gallic acid-based ink. An in-depth study of the behaviour of the ink in time was performed by natural and artificial ageing tests, monitored by colorimetry, showing the autoxidation of gallic acid to ellagic acid in the prepared mock-ups. The effect of relative humidity on ageing processes was also evaluated, allowing us to determine different intermediates depending on the environmental conditions. Finally, the analytical method developed was then successfully applied for investigating 19th-20th century historical ink samples, where one of the identified ageing markers was detected, besides the expected gallic and ellagic acids.

Valorization of Pimenta racemosa Essential Oils and Extracts: GC-MS and LC-MS Phytochemical Profiling and Evaluation of Helicobacter pylori Inhibitory Activity

Pimenta racemosa is a commonly known spice used in traditional medicine to treat several ailments. In this study, comprehensive phytochemical profiling of the essential oils and methanol extracts of P. racemosa leaves and stems was performed, alongside assessing their potential Helicobacter pylori inhibitory activity in vitro and in silico. The essential oils were chemically profiled via GC-MS. Moreover, the methanol extracts were profiled using HPLC-PDA-ESI-MS/MS. The antibacterial activity of the essential oils and methanol extracts against H. pylori was determined by adopting the micro-well dilution method. GC-MS analysis unveiled the presence of 21 constituents, where eugenol represented the major component (57.84%) and (59.76%) in both leaves and stems of essential oils, respectively. A total of 61 compounds were annotated in both leaves and stems of P. racemosa methanolic extracts displaying richness in phenolic compounds identified as (epi)catechin and (epi)gallocatechin monomers and proanthocyanidins, hydrolyzable tannin derivatives (gallotannins), flavonoids, and phenolic acids. The stem essential oil showed the most promising inhibitory effects on H. pylori, exhibiting an MIC value of 3.9 µg/mL, comparable to clarithromycin with an MIC value of 1.95 µg/mL. Additionally, in silico molecular modeling studies revealed that decanal, eugenol, terpineol, delta-cadinene, and amyl vinyl showed potential inhibitory activity on H. pylori urease as demonstrated by high-fitting scores indicating good binding to the active sites. These findings indicate that P. racemosa comprises valuable phytochemical constituents with promising therapeutic effects, particularly the stem, an economic agro-industrial waste.

Use of hyphenated analytical techniques to identify the bioactive constituents of Gunnera perpensa L., a South African medicinal plant, which potently inhibit SARS-CoV-2 spike glycoprotein-host ACE2 binding

SARS-CoV-2, the causative agent of COVID-19, continues to cause global morbidity and mortality despite the increasing availability of vaccines. Alongside vaccines, antivirals are urgently needed to combat SARS-CoV-2 infection and spread, particularly in resource-limited regions which lack access to existing therapeutics. Small molecules isolated from medicinal plants may be able to block cellular entry by SARS-CoV-2 by antagonising the interaction of the viral spike glycoprotein receptor-binding domain (RBD) with the host angiotensin-converting enzyme II (ACE2) receptor. As the medicinal plant Gunnera perpensa L. is being used by some South African traditional healers for SARS-CoV-2/COVID-19 management, we hypothesised that it may contain chemical constituents that inhibit the RBD-ACE2 interaction. Using a previously described AlphaScreen-based protein interaction assay, we show here that the DCM:MeOH extract of G. perpensa readily disrupts RBD (USA-WA1/2020)-ACE2 interactions with a half-maximal inhibition concentration (IC₅₀) of < 0.001 µg/mL, compared to an IC₅₀ of 0.025 µg/mL for the control neutralising antibody REGN10987. Employing hyphenated analytical techniques like UPLC-IMS-HRMS (method developed and validated as per the International Conference on Harmonization guidelines), we identified two ellagitannins, punicalin (2.12% w/w) and punicalagin (1.51% w/w), as plant constituents in the DCM:MeOH extract of G. perpensa which antagonised RBD-ACE2 binding with respective IC₅₀s of 9 and 29 nM. This good potency makes both compounds promising leads for development of future entry-based SARS-CoV-2 antivirals. The results also highlight the advantages of combining reverse pharmacology (based on medicinal plant use) with hyphenated analytical techniques to expedite identification of urgently needed antivirals.