Characteristics and Kinetics Study of Glycerolabietate from Glycerol and Abietic Acid from Rosin

Rosin is a natural resin from the coniferous tree sap, which separated from its oil content (terpenes). Rosin is brittle. Therefore modifications are needed to improve its mechanical properties. The main content of rosin is abietic acid which has a carboxylic group, so it can form an ester group when reacted with polyhydric alcohol (polyalcohol) such as glycerol. The research aimed to study the kinetics of the esterification reaction between the hydroxyl group in glycerol and the carboxylic group in abietic acid from rosin at various reaction temperatures and reactant compositions. This reaction is carried out in a three-neck flask at atmospheric pressure without a catalyst. The reaction temperatures used were 180˚C, 200˚C, and 220˚C, and the ratio of rosin and glycerol was 1:1, 1:3, and 1:5. The reaction kinetics calculations were analyzed with acid number data over the reaction time using three different models. The calculations showed that this reaction involves positioning a hydroxyl group on glycerol, which the primary and secondary hydroxyl groups contribute to forming a rosin ester (glycerolabietate). The rate of reaction constants of primary hydroxyl of glycerol and abietic acid were in the range 6.25x10-4 - 3.90x10-3 g/(mgeq.min), while reaction rate constants of secondary hydroxyl and abietic acid were in the range 1.06x10-5 - 1.15x10-4 g/(mgeq.min). FTIR analysis showed a change in the hydroxyl, carboxylate, and ester groups which were assigned by a shift of wavenumber and a difference of intensity at 3200-3570 cm-1, 1697.36 cm-1, and 1273.02 cm-1.

Fluorescence Lifetime Phasor Analysis and Raman Spectroscopy of Pigmented Organic Binders and Coatings Used in Artworks

Fluorescence analysis of materials used as binders and coatings in artworks is often hampered by numerous factors, leading to uncertainties in data interpretation. Fluorescence lifetime (FL) measurements enable improvement of the specificity with respect to steady-state measurements by resolving the decay dynamics of the fluorophore emissions. In this work, layers of natural resin, oil, and wax—in pure form, pigmented, in mixtures, and spread on different substrates—were analyzed using a compact, portable, fiber-based FL instrument. FL data were processed via the phasor method and integrated with Raman spectroscopy to obtain complementary chemical information on the different substances. It was observed that the τ-phase of the mixtures is affected by both the pigments and the dispersing medium, and that the presence of the metal substrate contributes to changes in the FL of mixtures. The results obtained with our portable FL system combined with Raman spectroscopy pave the way for a systematic study of a larger number of materials for future in situ applications on works of art.

Is sulfur the responsible for color of yellow Chiapas Amber?

Amber is a fossilized natural resin found in specific areas of the world; its geographical origin is associated to a characteristic color. Amber all over the world share basic characteristics due to a common polymeric matrix; however, its color is associated to the environment where it was formed. In this work, based on a compositional analysis, it is proposed that yellow color of Mexican amber is originated from the sulfur physical and chemical interaction within its polymeric matrix. The effect of sulfur present in yellow Mexican amber is studied by employing X-ray photoelectron and UV-Vis spectroscopies. Results show that sulfur is incorporated inside the polymer matrix with two different chemical environments; one related with sulfur-carbon bonds and the other with sulfur-sulfur bonds. The optical transmission spectrum simulated considering amber as a composite material reproduce the scattering contribution observed experimentally.

A PROPOLIS AS A HEALING AGENT FOR PULP INJURIES

As one of the natural resin materials produced by bees, propolis has been used as a traditional medicine for various diseases because of its biological and pharmacological activities. The purpose of this study was to analyze the potential of propolis as a healing agent for pulp injuries. A total of 35 journals from PubMed, Ebsco, ResearchGate, Wiley Online Library, and other international journal databases were analyzed. Propolis is very rich in active components such as flavonoids that have biological functions such as anti-inflammatory, antibacterial, antifungal and antioxidant which can act as a potential healing agent

Experimental induction of resins as a tool to understand variability in ambers

Amber is chiefly known as a preservational medium of biological inclusions, but it is itself a chemofossil, comprised of fossilised plant resin. The chemistry of today's resins has been long investigated as a means of understanding the botanical sources of ambers. However, little is known about the chemical variability of resins and consequently about that of the ambers that are derived from particular resins. We undertook experimental resin production in Araucariacean plants to clarify how much natural resin variability is present in two species, Agathis australis and Wollemia nobilis, and whether different resin exudation stimuli types can be chemically identified and differentiated. The latter were tested on the plants, and the resin exudates were collected and investigated with Fourier-transform infrared attenuated total reflection (FTIR-ATR) spectroscopy to give an overview of their chemistry for comparisons, including multivariate analyses. The Araucariacean resins tested did not show distinct chemical signatures linked to a particular resin-inducing treatment. Nonetheless, we did detect two separate groupings of the treatments for Agathis, in which the branch removal treatment and mimicked insect-boring treatment-derived resin spectra were more different from the resin spectra derived from other treatments. This appears linked to the lower resin viscosities observed in the branch- and insect-treatment-derived resins. However the resins, no matter the treatment, could be distinguished from both species. The effect of genetic variation was also considered using the same stimuli on both the seed-grown A. australis derived from wild-collected populations and on clonally derived W. nobilis plants with natural minimal genetic diversity. The variability in the resin chemistries collected did reflect the genetic variability of the source plant. We suggest that this natural variability needs to be taken into account when testing resin and amber chemistries in the future.

A multi-analytical approach for the identification of the natural resin from the Ming tomb in Shaanxi, China

Several well-preserved polychrome lacquered coffins were found in Zhang Dong family’s tombs in Shaanxi, China, rare in the history of archaeological excavation. In the lacquered coffins, a large amount of dark solid of suspected natural resin was unearthed with mysterious compositions and uses, exerting a tremendous fascination on archaeologists. In this work, a new method was explored for the identification of the suspected natural resin, mainly based on thermogravimetry (TG), elemental analysis (EA), scanning electron microscopy-energy dispersive spectrometry (SEM-EDS), matrix-assisted laser desorption ionisation time-of-flight mass spectrometry (MALDI-TOF-MS) and Fourier transform infrared spectrometry (FT-IR). The results suggested that the sample was mainly composed of organics with a content of 81.66% and little inorganics with a content of 2.21% by water excluded. Rosin with the main component of abietic acid (molecular formula C20H30O2) was identified as the principal component of the sample. Dehydrogenated abietic acid (DHA) and other oxides were also tested out. FT-IR confirmed the identification results. SEM revealed the rough surfaces evenly covered with holes of similar sizes. The use of this method directly obtained integral quasi-molecular ion fragments and molecular components of the sample. As a result, intricate multi-stage mass spectrometry is avoidable, which dramatically simplifies the analysis procedure. This approach is simple and effective for the identification of precious relic samples, requires no references, and has potential for the analysis of these kinds of unknown samples. Especially, for the first time, EA is used to identify natural resins from archaeological sites.

Enhancement of Antimicrobial and Antiproliferative Activities of Standardized Frankincense Extract Using Optimized Self-Nanoemulsifying Delivery System

Boswellic acids (BAs) are the main bioactive compounds of frankincense, a natural resin obtained from the genus Boswellia. This study aimed to develop a self-nanoemulsifying delivery system (SNEDS) to improve the antimicrobial and antiproliferative activities of standardized frankincense extract (Fr-extract). Fr-extract was standardized, and BA content was quantified using the developed HPLC-UV method. Screening studies of excipients followed by formula optimization using a mixture simplex lattice design was employed. The optimized Fr-SENDS formulation was characterized. Furthermore, microbiological and antiproliferative assessments of the standardized Fr-extract and Fr-SNEDS were evaluated. Quantification demonstrated that the major constituent is 11-keto-boswellic acid (KBA) (16.25%) among BA content (44.96%). The optimized Fr-SENDS (composed of 5% CapryolTM 90, 48.7% Gelucire® 44/14 and 46.3% ethanol) showed spherical nanosized dispersions with DS, PDI, and zeta potential of 17.9 nm, 0.2, and −14.5 mV, respectively. Fr-SNEDS exhibited lower MIC and MBC values compared with Fr-extract against pathogens conjugated with lung cancer and was comparable to reference antimicrobials. Fr-SNEDS showed superior antiproliferative activity over Fr-extract, with IC50 values of 20.49 and 109.5 μg mL−1, respectively. In conclusion, the optimized Fr-SNEDS could be easily developed and manufactured at a low cost and the in vitro results support its use as a potential adjuvant oral therapy for lung cancer. Further in vivo studies could be continued to assess the therapeutic efficiency of the prepared system.

Statistical Study of the Influence of Fiber Content, Fiber Length and Critical Length in the Mechanical Behavior of Polymeric Composites Reinforced with Carica Papaya Fibers (CPFs)

Vegetable fibers are excellent substitutes for manmade fibers because are biodegradables, resistant and sustentables. This article studied the potencial application of Carica Papaya Fibers (CPF) in polymerics composites of natural resin. A simple model of micromechanical analysis was used for prediction of breaking stress, strain and Young’s modulus in composites with short fibers of Carica Papaya with matrix of polyurethane resin obtained from Ricinus Communis vegetable. The fiber content used between 10–35% and fiber length between 3–6%. The analyzes were performed using analysis of variance (ANOVA) to assess the influence of variables on the mechanical properties of each composite produced. The results obtained show that increased in fiber length promoted increase in stress values, while the increase in fiber content favored the increased in the stiffness of the composite.

Same useful fixative from resin in Vietnam

Today, fixatives from natural raw materials are gradually replacing fixatives synthesized from chemicals. The arm of this research is the study of same useful resin in Vietnam for fixative substance in blending fragrance. We obtained Benzoin resin from Styrax tonkenensis Pierre plant in Ha Giang province, Canarium resin from Canarium Album L. in Dak Nong district, Dak Lak province, and Agarwood pulp of Aquilaria crassna plant in Binh Thuan province Vietnam. The material used in the experiment for the natural fragrance was taken from the project of Vietnam essential oils and related natural products. The method of this process is resin extraction by volatile solvents. The resin is dissolved in alcohol 96% and the distilled alcohol is removed to obtain absolute. The method of assessment of product quality in this study is using the olfactory to assess the odour of samples over time. Benzoin resin, Canarium resin, and Agarwood resin of Vietnam are useful fixatives in blending fragrance. The fixative ability of Benzoin resin absolute is not equal to the ability of Agarwood resin absolute but better than the ability of Canarium resin absolute. Through research and experiment, we can see Benzoin resin, Canarium resin and Agarwood resin are precious. They can be used as a good fixative in aromatherapy. This is a natural resin, a kind of resource available in Vietnam. Therefore, it is recommended for further research, exploitation, and effective use of this resource.