Concentration Of Guaiacol Research Articles

Characterization of aroma profiles of kokuto-shochu prepared from three different cultivars of sugarcane

Kokuto-shochu is a traditional Japanese spirit prepared from kokuto, obtained by evaporating water from sugarcane (Saccharum officinarum L.) juice. To clarify the effects of sugarcane cultivars on the sensory quality of kokuto-shochu, we investigated the flavor characteristics and composition of volatiles in kokuto-shochu prepared from kokuto using three different sugarcane cultivars, NiF8, Ni15, and RK97-14. Furthermore, experiments were conducted by using the cultivars collected between 2018 and 2020 to observe annual variations in their properties. The amino acid content of the three kokuto varieties did not differ significantly, but the amino acid content of NiF8 was two to five times higher than that of RK97-14, which was the same for all samples collected in the selected years. The browning degrees of kokuto were also higher in NiF8, and they were positively correlated to the amino acid contents of kokuto. The kokuto-like aroma of shochu made from Ni15 was stronger than that of shochu made from RK97-14. The concentration of ethyl lactate in shochu made from Ni15 was higher, however, the concentration of guaiacol was the lowest in the three cultivars' products. Shochu made from NiF8 had the highest levels of Maillard reaction products (MRPs; pyrazines and furans), β-damascenone, and guaiacol amounts. In contrast, shochu made from RK97-14 tended to have a fruity flavor, and lower MRP levels than those made from NiF8. Thus, it was shown that sugarcane cultivars affect the sensory characteristics and volatiles in kokuto-shochu.

Guaiacol augments quorum quenching potential of ciprofloxacin against Pseudomonas aeruginosa.

The present study aims to investigate the antimicrobial as well as antivirulence potential and the principle mechanism of action of guaiacol against Pseudomonas aeruginosa. Quorum sensing inhibition and membrane disruption studies were performed to check the effect of guaiacol on the virulence of P. aeruginosa. Production of various virulence factors and biofilm formation was studied at a sub-MIC concentration of guaiacol alone (1/8 MIC) and in combination with ciprofloxacin (1/2 FIC). Guaiacol exhibited synergistic interactions with ciprofloxacin and further reduced the production of all virulence factors and biofilm formation. Using crystal violet (CV) assay and quantification of exopolysaccharide, we observed weak biofilm formation, together with reduced motilities at sub-MIC, which was further visualized by confocal laser microscopy and Field Emission Scanning Electron Microscopy. The antibacterial activity of guaiacol against P. aeruginosa upon 2 × MIC exposure coincided with enhanced membrane permeability leading to disruption and release of cellular material as quantified by CV uptake assay and sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). The results demonstrated that sub-MICs of guaiacol in combination with ciprofloxacin can act as a potent alternate compound for attenuation of quorum sensing in P. aeruginosa. The study reports that guaiacol in combination with ciprofloxacin at 1/2 FIC significantly compromised the bacterial growth and motilities alongside inducing quorum quenching potential. This was accompanied by inhibition of biofilm which subsequently decreased EPS production at sub-MIC concentration. Furthermore, guaiacol in combination displayed a severe detrimental effect on bacterial membrane disruption, thereby enhancing cellular material release. For the first time, the potential of guaiacol in combination with ciprofloxacin in attenuation of virulence factors, and biofilm formation in Pseudomonas aeruginosa was described. Results corroborate how plant bioactive in synergism with antibiotics can act as an alternate treatment regime to tackle the menace of drug resistance.

Guaiacol as a natural melanin biosynthesis inhibitor to control northern corn leaf blight

The natural 1,8-dihydroxynaphthalene (DHN) melanin biosynthesis inhibitors (MBIs) are one of the promising approaches to the integrated management of plant diseases but have received scarce attention until now. Herein, to explore the natural DHN MBIs used in the control of northern corn leaf blight (NCLB), a library of 53 essential oil compounds was used to screen the MBIs against Exserohilum turcicum, the causal pathogen of NCLB, using tricyclazole as a reference compound. The results of morphological change in the colony, thermogravimetric analysis, ultraviolet-visible spectroscopy, and transmission electron microscopy confirmed that guaiacol could effectively inhibit the melanin production at 50 μg/mL under in vitro conditions. The in vitro bioassay results indicated that this inhibition effect was concentration-dependent and the minimum inhibition concentration of guaiacol was 50 μg/mL. The in vivo experimental results demonstrated that guaiacol significantly inhibited appressorium formation and penetration on corn leaf sheaths at the concentration of 500 μg/mL. The pot experiment results revealed that there were no differences between guaiacol (500 μg/mL) and tricyclazole (100 μg/mL) in control efficacy. The enzymatic assay suggested that guaiacol might exert the activity through inhibiting DHN polymerization to form melanins, which was distinct from tricyclazole. Taken together, this study screened out guaiacol as a natural MBI from 53 essential oil compounds and verified its effectiveness in the control of NCLB at 500 μg/mL. Above all, this research opened an avenue for exploring natural DHN MBIs in the integrated management of plant diseases. © 2022 Society of Chemical Industry.

Novel use of activated carbon fabric to mitigate smoke taint in grapes and wine

Background and Aims Grapegrowers and winemakers, around the world, are searching for strategies to mitigate the compositional and sensory consequences of grapevine exposure to smoke from wildfires. This study evaluated the use of activated carbon fabrics as protective coverings to mitigate the uptake of smoke-derived volatile phenols by grapes, and accordingly, the intensity of smoky, ashy characters in wine. Methods and Results Smoke was applied to Mataro grapes, with and without individual bunches being enclosed in bags made from three activated carbon fabrics (felt, light cloth and heavy cloth). Wine made from smoke-exposed grapes had an elevated concentration of volatile phenols, but the composition of wines made from grapes protected by activated carbon fabric was comparable to that of the Control wine; the difference in concentration of guaiacol, o- and m-cresol and/or syringol was only 1 μg/L. Wine made from smoke-exposed grapes had diminished fruit and prominent smoke characters, whereas the sensory profile of the wines corresponding to activated carbon fabric treatments could not be differentiated from that of the Control wine. Analysis by GC/MS of the activated carbon fabrics following repeated smoke exposure confirmed their adsorption of smoke volatiles. Conclusions The activated carbon fabrics successfully protected Mataro grapes and wine from being tainted by smoke exposure. Significance of the Study This study demonstrates a promising new technology for overcoming smoke taint, an issue of major concern for grape and wine producers worldwide.

Understanding Smoke Exposure Results: Pinot noir Baseline Concentrations of Smoke Impact Markers across Five Vintages

<h3>Summary</h3> <h3>Goals:</h3> With increased wildfires in recent years, winemakers must be able to interpret analyses of smoke-related marker compounds to determine whether smoke intrusion has affected their wines. The goal of this study was to examine naturally-occurring, baseline levels of smoke exposure marker compounds in un-oaked Pinot noir to enable winemakers to better understand smoke exposure results. This study also sought to understand how baseline concentrations of smoke marker compounds change from year to year. <h3>Key Findings:</h3> Pinot noir wines from California and Oregon had detectable baseline levels of free and bound marker compounds, including guaiacol, 4-methylguaiacol, 4-ethylphenol, and <i>m</i>-, <i>p</i>-, and <i>o</i>-cresol. In 2019, the baseline free guaiacol concentration ranged from 1.2 to 2.3 µg/L, while total (free and bound) guaiacol ranged from 6.4 to 12.0 µg/L. The concentration of free guaiacol was greater in older vintages, while total guaiacol did not change much from year to year. The ratio of free to total guaiacol approached 1:2 after five years, suggesting baseline guaiacol may approach an equal ratio of free to bound over time. <h3>Impact and Significance:</h3> While baseline levels identified here were low, winemakers should become familiar with the baseline concentrations in their wines to better understand risk during smoke-impacted vintages. With increased analysis of non-smoke-impacted, baseline samples, it may be possible to create a variety-specific risk matrix for smoke exposure. Additionally, as wines age, free volatile smoke marker compounds may increase due to normal changes to baseline compounds and may not always represent smoke-related glycosides releasing free volatiles.

Coupling effect of condensing temperature and residence time on bio-oil component enrichment during the condensation of biomass pyrolysis vapors

Walnut shell pyrolysis condensation experiments were conducted at different condensing temperatures (323 K, 333 K, 343 K, 353 K and 363 K) and residence times (2.3 s, 2.6 s, 3.0 s, 3.5 s and 4.1 s) to analyze the coupling effect of these variables on the separation and enrichment of bio-oil components. The content of guaiacol and its derivatives increased by 150% at the expense of the considerable reductions in condensing efficiency and bio-oil moisture when the condensing effect of pyrolysis vapors was substantially inhibited. With decreasing residence time, the contents of acetic acid and furfural increased by 20% at 333 K but decreased by 50% at 363 K. The equivalent relationships between condensing temperature and residence time were established to separate target components and prevent high condensing temperatures. Considering condensing efficiency and component distribution, the efficient condition for dewatering was 343 K condensing temperature and 2.6 s residence time. The optimal conditions for acetic acid enrichment and separation were 323 K and 3.0 s and 363 K and 4.1 s, respectively. The condensing condition of 363 K and 3.0 s could be applied to the concentration of guaiacol and its derivatives.

Sensory descriptive and comprehensive GC-MS as suitable tools to characterize the effects of alternative winemaking procedures on wine aroma. Part II: BRS Rúbea and BRS Cora

The present manuscript assessed the volatile and sensory profiles of BRS Rúbea and BRS Cora wines elaborated from traditional, grape pre-drying and submerged cap winemaking. The wines contained a higher concentration of acetates (257 mg L−1 to 547 mg L−1) and ethyl and methyl esters (183 mg L−1 to 456 mg L−1) in comparison with Vitis vinifera wines. PCA was applied (explaining 68.43% of the total variance), and the higher concentration of ethyl decanoate and ethyl octanoate, diethyl succinate, hydroxylinalool, and 2-phenyl ethanol was responsible for describing the BRS Rúbea wines as fruity/foxy. They also presented an intense jam note, probably due to their higher concentration of syringol and guaiacol. BRS Cora wines exhibited a vegetal note, possibly due to their higher concentration of 1-hexanol and cis-3-hexenol. Wines from pre-dried grapes presented higher concentration of furfural, assuming a bitter/burned almond aroma. Alternative winemaking accounted for suitable changes in wine aroma, enhancing wine quality.

Evaluation of Aroma Compounds in the Process of Wine Ageing with Oak Chips.

Many modern alcoholic beverages are subjected to ageing processes during which compounds extracted from wood contribute decisively to the overall beverage character. Wines represent a perfect example of beverage in which ageing is a crucial technological manufacturing step. During winemaking, producers accelerate chemical changes in wine composition by traditional and alternative methods, such as the use of oak wood barrels and/or oak wood chips. Our research aimed to investigate the overall volatile composition and sensory quality of red wines aged for two timeframes, namely, 1.5 and 3 months, and with two technological variants, i.e., American and French oak wood chips. Red grapes from the Fetească neagră (Vitis vinifera) variety were harvested from a vineyard in the North-East region of Romania. Stir bar sorptive extraction and gas chromatography coupled with mass spectrometry (SBSE–GC–MS) was used to extract minor aromas present in wine samples. The results showed clear differences between wines treated with American and French oak chips. Furthermore, ageing for 3 months increased the concentration of cis-whiskey lactone and guaiacol in American oak-treated wine samples. For wines aged with French oak chips, we observed higher concentrations of furfural, 5-methylfurfural, 4-vinylguaiacol, and trans-whiskey lactone. The increased presence of chemical compounds in wine aged with French oak chips generated prominent smoky, licorice, and toasty aromas, whereas in wines aged with American oak chips, notes of vanilla, toasty, and cacao aromas were noticed. Moreover, red wines aged with American and French oak chips were discriminated by chemometric analysis, which confirmed the evolution of aroma compounds.

Conversion of guaiacol in supercritical water gasification: Detailed effect of feedstock concentration

The effect of feedstock concentration on the gasification characteristics of guaiacol, a model compound for lignin, in supercritical water was investigated using a laboratory-scale continuous-flow reactor. The reaction temperature, pressure, and residence time used were 600 °C, 25 MPa, and 94 s, respectively. A reaction model was developed and kinetic parameters were determined so that experimental results could be reproduced. The carbon gasification efficiency (CGE) and TOC yield were not affected by the initial concentration of guaiacol. Solid yields increased with feedstock concentration, reflecting an order of reaction greater than one for solid production. A reaction model was developed and the reaction rate constants were determined successfully to reproduce experimental results. The decomposition rate constant was determined as 0.0718 ± 0.0403 /s and was found to be in good agreement with the previous study. The reaction order for the solid production was determined to be 1.25.

Advantages of an Electrochemical Method Compared to the Spectrophotometric Kinetic Study of Peroxidase Inhibition by Boroxine Derivative.

In this study, boroxine derivative (K2[B3O3F4OH]) was tested as an inhibitor of horseradish peroxidase (HRP) by spectrophotometric and electrochemical methods. The activity of horseradish peroxidase was first studied under steady-state kinetic conditions by a spectrophotometric method which required the use of guaiacol as a second substrate to measure guaiacol peroxidation. The results of this method have shown that, by changing the concentration of guaiacol as the literature suggests, a different type of inhibition is observed than when changing the concentration of hydrogen peroxide as the substrate. This suggests that guaiacol interferes with the reaction in some way. The electrochemical method involves direct electron transfer of HRP immobilized in Nafion nanocomposite films on a glassy carbon (GC) electrode, creating a sensor with an electro-catalytic response to the reduction of hydrogen peroxide. The electrochemical method simplifies kinetic assays by removing the requirement of reducing substrates.

Analysis of Volatile Phenolic Compounds Responsible for 4-vinylguaiacol-like Odor Characteristics of Sake

Sake samples having characteristics of 4-vinylguaiacol (4-VG)-like odor were analyzed by GC-MS and organoleptic methods. The quantified levels of 4-VG, 4-vinylphenol, 4-ethylguaiacol, and 4-ethylphenol of 15 sake samples, including 7 samples presenting 4-VG-like odor characteristics by multiple assessors, did not show a clear relation with the perception rate of 4-VG-like odor characteristics. Hence, we screened for other compound(s) responsible for the 4-VG-like odor characteristics, and found that odorous sake samples contain 2-methoxy phenol (guaiacol), 2,6-dimethoxyphenol (syringol), and 3-methyphenol at higher levels than the odor-less sample. The quantified level of guaiacol well matched the perception rate of 4-VG-like odor characteristics. The recognition threshold value of guaiacol in the sake and of 4-VG in the model sake solution was estimated as 14.6 µg/L and 141 µg/L, respectively. The concentration of guaiacol in the most odorous sake samples was higher than the estimated recognition threshold.

Detection of medicinal off-flavor in apple juice with artificial sensing system and comparison with test panel evaluation and GC–MS

Guaiacol, a potent volatile compound, has proven to be responsible for the distinct medicinal off-flavor in spoiled apple juice produced by Alicyclobacillus acidoterrestris. In this study, the artificial sensing system electronic nose (e-nose) was employed to detect this off-flavor compound in apple juice, using GC–MS and test panel evaluation as reference, as well as water as a comparative medium. Principle component analysis and linear discriminant analysis were employed to evaluate the capacity of e-nose for guaiacol detection in both media. A loadings analysis was used to examine the sensors' chemometric discrimination. Multiple regression analysis was applied to investigate the potential relationship between the concentration of guaiacol and the e-nose response. The detection limit based on e-nose for guaiacol in apple juice was 0.25–0.5 mg/L. For comparison, a 12-member test panel evaluation found an aroma detection threshold of 1.50 mg/L in apple juice, and the GC–MS detection limit for guaiacol in apple juice was determined to be 0.4 μg/L. In summary, the e-nose was capable of detecting guaiacol in apple juice, with significantly higher sensitivity than the test panel evaluation. This information should be useful for developing instrumental sensory detection techniques for rapid scanning of potential medicinal off-flavor in Alicyclobacillus-spoiled apple juice prior to consumer perception.

Effect of bioconversion conditions on vanillin production by Amycolatopsis sp. ATCC 39116 through an analysis of competing by-product formation

This study investigated the effects of transformation conditions such as initial pH, the initial concentration of glucose and yeast extract in the medium, and the separate addition of ferulic acid and vanillic acid, on the production of vanillin through an analysis of competing by-product formation by Amycolatopsis sp. ATCC 39116. The extent and nature of by-product formation and vanillin yield were affected by initial pH and different initial concentrations of glucose and yeast extract in the medium, with a high yield of vanillin and high cell density obtained at pH 8.0, 10 g/l glucose, and 8 g/l yeast extract. High concentrations of ferulic acid were found to negatively affect cell density. Additional supplementation of 100 mg/l vanillic acid, a metabolically linked by-product, was found to result in a high concentration of vanillin and guaiacol, an intermediate of vanillin. Via an analysis of the effect of these transformation conditions on competing by-product formation, high concentrations of ferulic acid were transformed with a molar yield to vanillin of 96.1 and 95.2 %, by Amycolatopsis sp. ATCC 39116 and Streptomyces V1, respectively, together with a minor accumulation of by-products. These are among the highest performance values reported in the literature to date for Streptomyces in batch cultures.

Effect of pH on lignin analysis by Raman spectroscopy

Abstract Ultraviolet resonance Raman (UVRR) spectroscopy is a powerful tool for structural lignin analysis in situ: modification or isolation of lignin from biomass is not necessary. UVRR spectroscopy is equally applicable for samples with high lignin content and those with very low lignin content. Monomeric phenolic lignin model compounds and wood pulp samples have been studied at neutral and alkaline pH with UVRR spectroscopy. Concentration of guaiacol correlated well with the relative Raman band intensity, which indicates that lignin-containing solutions can be quantitatively measured with UVRR spectroscopy. A change in pH induced a recordable shift in the aromatic band position in the spectra, which was 25–35 cm-1 with phenolic model compounds without para substitution, 8–12 cm-1 with phenolic model compounds with para substitution, and about 2–7 cm-1 with pulp samples. No shift was detected with a non-phenolic model compound. Increasing the amount of phenolic hydroxyl groups increased the UVRR band shift in pulp samples. Additionally, increasing the pH enhanced the relative aromatic band intensity in the UVRR spectra in solution of the phenolic model compound. Accordingly, pH adjustment is relevant prior to any lignin analysis with Raman spectroscopy.

Comparison of methods for the analysis of smoke related phenols and their conjugates in grapes and wine

Background and Aims: Australian grape growers and winemakers have typically relied on guaiacol and 4-methylguaiacol measurements to determine smoke exposure of grapes following bushfires or prescribed burns. However, the guaiacol and 4-methylguaiacol content of grapes does not always correlate with the extent of taint in resultant wines. This study compared several methods for the analysis of smoke related phenols and their conjugates in grapes and wine, to determine their capacity as diagnostic assays for smoke exposure. Methods and Results: Smoke-affected grapes were sourced from commercial vineyards exposed to bushfire smoke and from experimental field trials involving the application of smoke to grapevines, and small-scale wines were made from a number of these samples. Several analytical methods were applied to grapes and wine to determine the concentration of smoke related phenols and their conjugates. Strong correlations were observed between the glycoconjugate content of smoke-affected grapes and the concentration of guaiacol and 4-methylguaiacol released following acid hydrolysis of juice. Conclusions: Where smoke-affected grapes contain low or non-detectable levels of guaiacol and 4-methylguaiacol, analytical methods that quantify their glycoconjugate forms (either directly or indirectly) provide a better indication of the extent of smoke exposure. Significance of the Study: This is the first study to compare different methods for assessing smoke exposure in grapes and wine, through analysis of free and bound guaiacol and 4-methylguaiacol. These methods will allow grape growers and winemakers to more reliably assess smoke exposure of grapes, enabling better informed decisions to be made with regards to harvesting and processing smoke-affected grapes.

Physiochemical properties of bio-oil produced at various temperatures from pine wood using an auger reactor

A fast pyrolysis process produces a high yield of liquid (a.k.a. bio-oil) and has gained a lot of interest among various stakeholders. Nonetheless, some of the properties inherent by the bio-oil create significant challenges for its wider applications. Quality of the bio-oil and its yield are highly dependent on process parameters, such as temperature, feedstock, moisture content and residence time. In this study, the effect of temperature on bio-oil quality and its yield were examined using pine wood, an abundant biomass source in the southeastern part of the United States. Physical properties of bio-oil such as pH, water content, higher heating value, solid content and ash were analyzed and compared with a recently published ASTM standard. Bio-oil produced from pine wood using an auger reactor met specifications suggested by the ASTM standard. Thirty-two chemical compounds were analyzed. The study found that the concentration of phenol and its derivatives increased with the increase in pyrolysis temperature whereas the concentration of guaiacol and its derivatives decreased as the temperature increased. Concentration of acetic and other acids remained almost constant or increased with the increase in temperature although the pH value of the bio-oil decreased with the increase in temperature.

Formation of guaiacol from vanillin by Alicyclobacillus acidoterrestris in apple juice: a model study

In this study, the formation of guaiacol from vanillin by Alicyclobacillus acidoterrestris in apple juice was investigated. Apple juices spiked with 10 and 100 mg/L of vanillin were inoculated with 1×103 CFU/mL and 1×105 CFU/mL spores of A. acidoterrestris and incubated at 25 and 46 °C. A. acidoterrestris started to form guaiacol from vanillin when the spore count exceeded the critical level of 1×104 CFU/mL. Increasing the vanillin concentration also increased the concentration of guaiacol formed, especially at 46 °C. The growth of A. acidoterrestris was not favorable at 25 °C. Thus, the formation of guaiacol is strongly limited at room temperature.

The effects of sample preparation and gas chromatograph injection techniques on the accuracy of measuring guaiacol, 4-methylguaiacol and other volatile oak compounds in oak extracts by stable isotope dilution analyses.

The deuterium-labeled standards [(2)H(3)]-guaiacol and [(2)H(3)]-4-methylguaiacol were synthesized and utilized in a method employing gas chromatography-mass spectrometry to determine the concentration of guaiacol and 4-methylguaiacol in wine or extracts of oak shavings. The method was combined with previously published methods for 4-ethylphenol, 4-ethylguaiacol, cis- and trans-oak lactone and vanillin, so that all these compounds could be quantified in a single analysis. The method can employ either liquid-liquid extraction or headspace solid-phase microextraction (SPME) and is rapid, robust, precise, and accurate. Under certain conditions, there was artifactual generation, to varying degrees, of guaiacol, 4-methylguaiacol, cis-oak lactone, and vanillin during the analysis of oak extracts, especially when diethyl ether extraction and injector block temperatures at or above 225 degrees C were employed. The most substantial effects were observed for guaiacol, in which results could be exaggerated by over 10 times. These artifacts could be avoided by using headspace SPME or by preparing liquid-liquid extracts with pentane or pentane/diethyl ether (2:1) injected at 200 degrees C providing spot checks using headspace SPME were performed. Data obtained for previously published quantitative determination of guaiacol in oak extracts should be reexamined carefully, with special attention paid to their respective methods of sample preparation and analysis.

Extraction-Chromatographic Separation and Concentration of Phenol and Guaiacol with the Use of Organic Solvent Mixtures as Stationary Phases

Extraction-chromatographic concentration and separation of phenol and guaiacol was studied as influenced by the composition of binary tributyl phosphate-pentyl acetate, tributyl phosphate-dinonyl phthalate, tributyl phosphate-didecyl sebacate, and ternary tributyl phosphate-dicyclohexano-18-crown-6-toluene and tributyl phosphate-dicyclohexano-18-crown-6-chloroform stationary phases.

グアヤコール・ホルムアルデヒド・レジン(GF レジン)の化学的組成, 消毒作用ならびに毒性に関する研究

Guaiacol formaldehyde resin (GF-resin) is a polycondensation product of guaiacol and formaldehyde and a solution of 40% GF-resin in organic solvents has been put to use as a medicament for root canal treatment. Its details such as chemical formula and molecular weights, however, are not yet known. High performance liquid chromatography therefore was applied to the estimation of molecular weights of GF-resin and to the quantitative analysis of guaiacol and formaldehyde in GF-resin. Furthermore four biological studies were made to determine the antimicrobial effect and the toxicities of GF-resin and of FR liquid, a solution of 40% GF-resin in organic solvents. Formalin guaiacol (FG), guaiacol, and formalin were included in the test samples to make a comparative study. In the first biological study the antimicrobial effect was tested on five kinds of strains by the paper disc method. Liquefied phenol (liq. phenol) was used as a positive control. In the second study the inflammatory potential was examined by Evan's blue test. A paper disc soaked with 30μl of a sample was stuck on the shaved dorsal skin of rabbits. The minimal inflammatory dose for skin reactions was also obtained. In the third study the cytotoxic effect on L cell tissue culture system was tested, and 50% inhibitory concentration for cell growth was examined. In the fourth study oral acute toxicity in mice was examined. Each LD_<50> with confidence limits was calculated with use of Litchfield-Wilcoxon's method. The results obtained from the above were as follows : 1. Four polycondensation products of guaiacol and formaldehyde were detected in GF-resin, and molecular weight of each was 205, 390, 450 and 720 in terms of the polystyrene. These polycondensation products have a slight antimicrobial effect and cytotoxicity. Inflammatory potential and acute toxicity however were not detected in these tests. Consequently, it is estimated that the polycondensation products have very slight toxicities. 2. The concentration of guaiacol in GF-resin is 27.75% and that of formaldehyde in GF-resin is 0.15%. Guaiacol produces the antimicrobial effect, the inflammatory potential and the cytotoxicity of GF-resin. Formaldehyde content is so small that it makes little contribution to the pharmacological effects of GF-resin. 3. Inhibitory potency ratio on the area of inhibitory zone to liq. phenol is 1.4-10 for formalin, 1.1-10 for FG, 0.6-0.9 for guaiacol, and 0.2-0.6 for GF-resin. GF-resin shows the antimicrobial effect on each strain of microbes tested. 4. The intensity of Evan's blue response of GF-resin corresponds to 1 : 16 dilutions of formalin and to 1 : 4 dilutions of FG and liq. phenol respectively, but it is milder than that of guaiacol. 5. On the basis of 50% L cells inhibitory concentration, the comparative intensity of cytotoxicity is 14 times for formalin, 6 times for FG and 1.3 times for guaiacol, as compared with GF-resin. 6. Mice didn't die from the administration of 10.0g/kg GF-resin which was the maximum that can be administered orally to mice. Oral LD_<50> therefore is over 10.0g/kg for GF-resin. In summary, antimicrobial and cytotoxic effects of GF-resin are brought about not only by guaiacol in it but also by polycondensation products, though inflammatory potential and acute toxicity are brought about by guaiacol alone.