Effect of arginine on microorganisms involved in dental caries: a systematic literature review of in vitro studies

Abstract

This systematic review aimed to discuss the effects of arginine on caries-related microorganisms in different in vitro biofilm models. The eligibility criteria were in vitro studies that evaluated the effect of arginine at different concentrations on caries-related microorganisms using biofilm models. Eighteen studies published between 2012 and 2019 were included. Different bacterial species were studied. Seventeen studies (94.4%) achieved a low risk of bias and only one showed a medium risk of bias. The studies showed that arginine is a promising approach for the ecological management of dental caries. The focus of this review was to evaluate the effects of arginine on microorganisms involved in the mechanism of dental caries.     

Effect of prostaglandins E2 and F2α on in vitro development and hatching of caprine blastocysts

Prostaglandin E₂ has been shown to increase the ovine embryo hatching rate, and PGF_2α to reduce the development of rabbit, bovine, and rat embryos. The objective was to determine the effects of PGE₂ and PGF_2α on development of caprine embryos. Estrus was synchronized in does (n = 25) with medroxyprogesterone acetate (MAP) intravaginal sponges for 12 days, and superovulated with 20 units of FSH. On day 6 following estrus, embryos were flushed (n = 128) and incubated individually per well in 25 μl droplets of TCM-199 and BSA (8 mg/ml) for 6 days at 38.5 °C in a 5% CO₂: air with one of the following treatments: (1) control (0.0002% EtOH), (2) PGE₂ (7 ng/ml), (3) PGF_2α (7 ng/ml), (4) low PGE₂:high PGF_2α (3.5 ng/ml:14 ng/ml), (5) balanced PGE₂:PGF_2α (7 ng/ml:7 ng/ml), or (6) high PGE₂:low PGF_2α (14 ng/ml:3.5 ng/ml). Treatment with PGE₂ alone reduced (P < 0.05) the hatching rate (1/15; 7%). The hatching rate of embryos treated with PGF_2α alone (9/18; 50%), low PGE₂:high PGF_2α (8/16; 50%), and balanced PGE₂:PGF_2α (11/16; 69%) were similar to control (6/18; 33%). In contrast, the hatching rate was non-significantly increased (13/18; 72%) with the high PGE₂:low PGF_2α treatment. None of the treatments affected development from the morula to blastocyst stage. From the current data, it can be concluded that PGE₂ alone reduced hatching rate, and PGF_2α alone had no effect on the development of caprine embryos. High concentrations of PGE₂ with PGF_2α improved the hatching rates. Thus, uterine concentrations of PGE₂ may need to reach a threshold level to improve embryo hatching, as previously reported, while increased uterine concentrations of PGF_2α during early pregnancy would not affect development of the embryo.     

In vivo and in vitro development of mouse pancreatic β-cells in organotypic slices

Taking tissue slices of the embryonic and newborn pancreas is a novel approach for the study of the perinatal development of this gland. The aim of this study was to describe the morphology and physiology of in vivo and in vitro developing -cells. In addition, we wanted to lay a foundation for the functional analysis of other pancreatic cells, either alone or as part of an integrative pancreatic physiology approach. We used cytochemistry and light microscopy to detect specific markers and the whole-cell patch-clamp to assess the function of single -cells. The insulin signal in the embryonic -cells was condensed to a subcellular compartment and redistributed throughout the cytosol during the first 2 days after birth. The hormone distribution correlated well with the development of membrane excitability and hormone release competence in -cells. Endocrine cells survived in the organotypic tissue culture and maintained their physiological properties for weeks. We conclude that our preparation fulfills the criteria for a method of choice to characterize the function of developing pancreas in wild-type and genetically modified mice that die at birth. We suggest organotypic culture for in vitro studies of the development and regeneration of -cells.This work was supported by the European Commission (grant QLG1-CT-2001-02233 to TMR, AR and MR), the DFG Research Center for Molecular Physiology of the Brain (CMPB) and the Max-Planck Society (MR)     

Evaluation of oxygen dependence on in vitro and in vivo cytotoxicity of photoimmunotherapy using IR-700–antibody conjugates

Photoimmunotherapy (PIT) using the near-infrared-absorbing photosensitizing phthalocyanine dye, IRDye 700DX (IR-700), conjugated with a tumor-targeting antibody such as panitumumab (Pan) has shown efficacy in in vitro studies and several preclinical models in mice with promise for clinical translation. PIT results in rapid necrotic cell death in vitro and tumor shrinkage in vivo. Photochemical studies with the Pan-IR-700 conjugate showed that this agent can support generation of singlet oxygen and also generate reactive oxygen species after exposure to near-infrared (NIR) light. Moreover, in vitro studies using A431 cells, singlet oxygen scavengers abrogated the efficacy of PIT with Pan-IR-700, while oxygen depletion to undetectable levels in the exposure chamber almost completely inhibited the cellular cytotoxicity of PIT. Survival of tumor bearing mice was prolonged in PIT-treated animals but mice whose tumors were made transiently hypoxic prior to PIT had no benefit from the treatment. The results from this study support a central role for molecular oxygen-derived species in cell death caused by PIT.     

Composition and in vitro antimicrobial activity of Populus buds and poplar-type propolis

The antibacterial activity of propolis has been widely investigated. Since reports dealing with antimicrobial activity of the origin of propolis are not available, this study was carried out aiming to analyse the in vitro antimicrobial activity of the methanol extracts of poplar type propolis and Populus (Populus nigra, P. alba, P. tremuloides) buds as its sources against standard strains of a panel of microorganisms by determining the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The concentrations of the “poplar” phenolics were relatively high (4.5%) and some compounds typical for P. nigra such as pinobanksin and 4,3 acetyloxycaffeate were found in the propolis sample by GC-MS. The poplar type propolis and Populus bud exudates were found to inhibit most clinically important microorganisms in a wide spectrum including pathogenic yeasts but not Gram-negative bacteria.     

In vitro and in vivo efficacy of rosmarinic acid on quorum sensing mediated biofilm formation and virulence factor production in Aeromonas hydrophila

Rosmarinic acid (RA) was assessed for its quorum sensing inhibitory (QSI) potential against Aeromonas hydrophila strains AH 1, AH 12 and MTCC 1739. The pathogenic strains of A. hydrophila were isolated from infected zebrafish and identified through biochemical analysis and amplification of a species-specific gene (rpsL). The biofilm inhibitory concentration (BIC) of RA against A. hydrophila strains was found to be 750 μg ml^?1. At this concentration, RA reduced the QS mediated hemolysin, lipase and elastase production in A. hydrophila. In FT-IR analysis, RA treated A. hydrophila cells showed a reduction in cellular components. Gene expression analysis confirmed the down-regulation of virulence genes such as ahh1, aerA, lip and ahyB. A. hydrophila infected zebrafish upon treatment with RA showed increased survival rates. Thus, the present study demonstrates the use of RA as a plausible phytotherapeutic compound to control QS mediated biofilm formation and virulence factor production in A. hydrophila.     

Effects of Schisandrin B and α-tocopherol on lipid peroxidation, in vitro and in vivo

Effects of Schisandrin B (Sch B) and -tocopherol (-TOC) on ferric chloride (Fe³⁺) induced oxidation of erythrocyte membrane lipids in vitro and carbon tetrachloride (CCl₄) induced lipid peroxidation in vivo were examined. While -TOC could produce prooxidant and antioxidant effect on Fe³⁺-induced lipid peroxidation, Sch B only inhibited the peroxidation reaction. Pretreatment with -TOC (3 mmol/kg/day × 3) did not protect against CCl₄-induced lipid peroxidation and hepatocellular damage in mice, whereas Sch B pretreatment (0.3 mmol/3.0 mmol/kg/day × 3) produced a dose-dependent protective effect on the CCl₄-induced hepatotoxicity. The ensemble of results suggests that the ability of Sch B to inhibit lipid peroxidation, while in the absence of pro-oxidant activity, may at least in part contribute to its hepatoprotective action.Abbreviations ALT alanine aminotransferase - CCl₄ carbon tetrachloride - Fe³⁺ ferric chloride - MDA malondialdehyde - Sch B Schisandrin B - TBA 2-thiobarbituric acid - TBARS thiobarbituric acid reactive substances - -TOC dl--tocopherol     

The effects of salicylate on the activity of rat liver tyrosine–2-oxoglutarate aminotransferase in vitro and in vivo

1. Salicylate, in concentrations of 0.25mm and above, enhances the basal activity of tyrosine–2-oxoglutarate aminotransferase in homogenates of rat liver incubated in the absence of added pyridoxal 5′-phosphate (endogenous activity). The effect is decreased by increasing the concentration of the cofactor. 2. The intraperitoneal administration of sodium salicylate enhances the activity of rat liver tyrosine aminotransferase; the major effect during the first hour being on the enzyme in the absence of added pyridoxal phosphate. Actinomycin D prevents the induction of the enzyme by cortisol and tryptophan. Induction by pyridoxine or salicylate is 50% inhibited by actinomycin D. The effects of the injections of various combinations of cortisol, pyridoxine and salicylate were also studied in the absence or presence of actinomycin D. 3. It is suggested that salicylate induces rat liver tyrosine aminotransferase by displacing its protein-bound cofactor and that a cofactor-type induction of the hepatic enzyme occurs in pyridoxine-treated rats.     

Combined anti-tumor effects of IFN-α and sorafenib on hepatocellular carcinoma in vitro and in vivo

Hepatocellular carcinoma (HCC) is among the most common and aggressive cancers worldwide, and novel therapeutic strategies are urgently required to improve clinical outcome. Interferon-alpha (IFN-α) and sorafenib are widely used as anti-tumor agents against various malignancies. In this study, we investigated the combined effects of IFN-α and sorafenib against HCC. We demonstrated that the combination therapy synergistically suppressed HCC cellular viability, arrested cell cycle propagation and induced apoptosis in HCC cells. Further research revealed that IFN-α and sorafenib collaboratively regulated the expression levels of cell cycle-related proteins Cyclin A and Cyclin B as well as the pro-survival Bcl-2 family proteins Mcl-1, Bcl-2 and Bcl-X(L). Moreover, sorafenib inhibited IFN-α induced oncogenic signaling of STAT3, AKT and ERK but not the activation of the tumor suppressor STAT1. Xenograft experiments also confirmed the combined effects of IFN-α and sorafenib on tumor growth inhibition and apoptosis induction in vivo. In conclusion, these results provide rationale for the clinical application of IFN-α and sorafenib combination therapy in HCC treatment.     

Time to flowering of temperate pulses in vivo and generation turnover in vivo–in vitro of narrow-leaf lupin accelerated by low red to far-red ratio and high intensity in the far-red region

Understanding the role light quality plays on floral initiation is key to a range of pre-breeding tools, such as accelerated single-seed-descent. We have elucidated the effect of light quality on early flowering onset in cool-season grain legumes and developed predictive models for time to flowering under the optimised light conditions. Early and late flowering genotypes of pea, chickpea, faba bean, lentil and lupin were grown in controlled environments under different light spectra (blue and far red-enriched LED lights and metal halide). All species and genotypes showed a positive response to a decreasing red to far-red ratio (R:FR). In general, ratios above 3.5 resulted in the longest time to flowering. In environments with R:FR below 3.5, light with the highest intensity in the FR region was the most inductive. We demonstrate the importance of considering both relative (R:FR) and absolute (FR photons) light values for flower induction in grain legumes. Greater response to light spectra was observed in the later flowering genotypes, enabling a drastic compression of time to flowering between phenologically diverse genotypes. A novel protocol for robust in vitro germination of immature seeds was developed for lupin, a species known for its recalcitrance to in vitro manipulation. We show how combining this protocol with growth under conditions optimized for early flowering drastically speeds generation turnover. The improved understanding of the effect of light on flowering regulation and the development of robust in vitro culture protocols will assist the development and exploitation of biotechnological tools for legume breeding.     

Microenvironmental influences of apoptosis in vivo and in vitro

The apoptosis program of physiological cell death elicits a range of non-phlogistic homeostatic mechanisms—“recognition, response and removal”—that regulate the microenvironments of normal and diseased tissues via multiple modalities operating over short and long distances. The molecular mechanisms mediate intercellular signaling through direct contact with neighboring cells, release of soluble factors and production of membrane-delimited fragments (apoptotic bodies, blebs and microparticles) that allow for interaction with host cells over long distances. These processes effect the selective recruitment of mononuclear phagocytes and the specific activation of both phagocytic and non-phagocytic cells. While much evidence is available concerning the mechanisms underlying the recognition and responses of phagocytes that culminate in the engulfment and removal of apoptotic cell bodies, relatively little is yet known about the non-phagocytic cellular responses to the apoptosis program. These responses regulate inflammatory and immune cell activation as well as cell fate decisions of proliferation, differentiation and death. Here, we review current knowledge of these processes, considering especially how apoptotic cells condition the microenvironments of normal and malignant tissues. We also discuss how apoptotic cells that persist in the absence of phagocytic clearance exert inhibitory effects over their viable neighbors, paying particular attention to the specific case of cell cultures and highlighting how new cell-corpse-clearance devices—Dead-Cert^® Nanoparticles—can significantly improve the efficacy of cell cultures through effective removal of non-viable cells in the absence of phagocytes in vitro.     

Effect of metalaxyl,fosetyl‐al,dimethomorph, cymoxanil on development and control Phytophthora on peach tree in vitro

Four fungicides were evaluated for their effectiveness against Phytophthora diseases of peach trees and their ability to absorbed and translocated by roots of peach tree in laboratory. Meta‐laxyl suppressed the development of P. cactorum and P. citwphthora on segments. Fosetyl‐Al showed variable fungicidal activity against P. cactorum and P. citwphthora. Both dimetho‐morph and cyraoxanil were not effective to inhibit the growth of fungi on segments. Section of tree trunks in 2‐yr‐old GF 677 trees were painted with one of the test fungicides. Strips of bark were removed 10 and 20 days after painting within treated area and inoculated with P. cactorum and P. citwphthora. Generally, the results agree with them obtained with excised stem and excised twig methods. Exception is the dimethomorph that reduced the development of P. cartorum and P. citrophthora. This study indicated that application with metalaxyl to the peach tree appears to be an effective procedure to control Phytophthora diseases on peach trees.     

Effect of glucose on Listeria monocytogenes biofilm formation,and assessment of the biofilm’s sanitation tolerance

Listeria monocytogenes is an important cause of human foodborne infections and its ability to form biofilms is a serious concern to the food industry. To reveal the effect of glucose conditions on biofilm formation of L. monocytogenes, 20 strains were investigated under three glucose conditions (0.1, 1.0, and 2.0% w v^–1) by quantifying the number of cells in the biofilm and observing the biofilm structure after incubation for 24, 72, and 168 h. In addition, the biofilms were examined for their sensitivity to sodium hypochlorite. It was found that high concentrations of glucose reduced the number of viable cells in the biofilms and increased extracellular polymeric substance production. Moreover, biofilms formed at a glucose concentration of 1.0 or 2.0% were more resistant to sodium hypochlorite than those formed at a glucose concentration of 0.1%. This knowledge can be used to help design the most appropriate sanitation strategy.     

Functional significance of glutamate–cysteine ligase modifier for erythrocyte survival in vitro and in vivo

Erythrocytes endure constant exposure to oxidative stress. The major oxidative stress scavenger in erythrocytes is glutathione. The rate-limiting enzyme for glutathione synthesis is glutamate–cysteine ligase, which consists of a catalytic subunit (GCLC) and a modifier subunit (GCLM). Here, we examined erythrocyte survival in GCLM-deficient (gclm^−/−) mice. Erythrocytes from gclm^−/− mice showed greatly reduced intracellular glutathione. Prolonged incubation resulted in complete lysis of gclm^−/− erythrocytes, which could be reversed by exogenous delivery of the antioxidant Trolox. To test the importance of GCLM in vivo, mice were treated with phenylhydrazine (PHZ; 0.07 mg/g b.w.) to induce oxidative stress. Gclm^−/− mice showed dramatically increased hemolysis compared with gclm^+/+ controls. In addition, PHZ-treated gclm^−/− mice displayed markedly larger accumulations of injured erythrocytes in the spleen than gclm^+/+ mice within 24 h of treatment. Iron staining indicated precipitations of the erythrocyte-derived pigment hemosiderin in kidney tubules of gclm^−/− mice and none in gclm^+/+ controls. In fact, 24 h after treatment, kidney function began to diminish in gclm^−/− mice as evident from increased serum creatinine and urea. Consequently, while all PHZ-treated gclm^+/+ mice survived, 90% of PHZ-treated gclm^−/− mice died within 5 days of treatment. In vitro, upon incubation in the absence or presence of additional oxidative stress, gclm^−/− erythrocytes exposed significantly more phosphatidylserine, a cell death marker, than gclm^+/+ erythrocytes, an effect at least partially due to increased cytosolic Ca²⁺ concentration. Under resting conditions, gclm^−/− mice exhibited reticulocytosis, indicating that the enhanced erythrocyte death was offset by accelerated erythrocyte generation. GCLM is thus indispensable for erythrocyte survival, in vitro and in vivo, during oxidative stress.     

Receptor-Mediated Transfer of DNA–Galactosylated Poly-L-lysine Complexes into Mammalian Cells in vitro and in vivo

With the goal of developing non-viral techniques for exogenous gene delivery into mammalian cells, we have studied receptor-mediated gene transfer using complexes of plasmid DNA and galactosylated poly-L-lysine, poly(L-Lys)Gal. To evaluate the optimal parameters for efficient gene transfer into human hepatoma HepG2 cells by the DNA–poly(L-Lys)Gal complexes, the bacterial reporter genes lacZ and cat were used. Examination of the reporter gene expression level showed that the efficiency of DNA delivery into the cells depends on the structure of DNA–poly(L-Lys)Gal complexes formed at various ionic strength values. The efficiency of DNA transfer into the cells also depends on DNA/poly(L-Lys)Gal molar ratio in the complexes. Plasmid vector carrying human apolipoprotein A-I (apoA-I) gene was injected as its complex with poly(L-Lys)Gal into rat tail vein. Some level of ApoA-I was detected in the serum of the injected rats. Also, the human apoA-I-containing plasmid was found to be captured specifically by the rat liver cells and transported into the cell nuclei, where it can persist as an episome-like structure for at least a week. After repeated injections of DNA–poly(L-Lys)Gal complexes, the level of human ApoA-I in rat serum increases, probably, due to accumulation of functional human apoA-I gene in the liver cell nuclei. The data seem to be useful for the development of non-viral approaches to gene therapy of cardiovascular diseases.     

Synthesis,characterization, and in vitro and in vivo evaluation of a novel pectin–adriamycin conjugate

Adriamycin (ADM) has been widely used in the treatment of many types of solid malignant tumor. However, cardiotoxicity, multidrug resistance and a short half-life in vivo are significant problems that limit its clinical application. To resolve these problems, a novel pectin–adriamycin conjugate (PAC) was synthesized by attaching ADM to low-methoxylated pectin via an amide linkage. The ADM content and weight-average molecular weight (Mw) of PAC were greater than 25% (w/w) and 50,360 g/mol, respectively. PAC was highly stable in plasma, but 33.2% of ADM was released from PAC after incubation for 30 h with lysosomes derived from rat liver. PAC was distributed uniformly in the cytoplasm of most A549 cells and accumulated in the nucleus of a few A549 cells after incubation for 30 h. At concentrations equivalent to 0.125–1.000 μg of ADM/mL, PAC did not inhibit the growth of either A594 or B16 cells to the same extent as free ADM or a mixture of ADM and pectin. Interestingly, at all concentrations, PAC inhibited the growth of 2780cp cells in vitro significantly more effectively than ADM or the mixture of ADM and pectin. The anticancer effect of PAC in vivo was evaluated with C57BL/6 mice bearing pulmonary metastases of B16 cells. Compared with ADM and the mixture of ADM and pectin, PAC suppressed tumor growth significantly and prolonged the mean survival time of the B16-inoculated mice. PAC has great potential for development as a tumor targeting polymer-drug.     

Effect of basal lamina on progesterone production by chicken granulosa cells in vitro — influence of follicular development

Experiments were conducted in vitro to study the regulation of progesterone production in chicken granulosa cells by homologous basal lamina isolated from preovulatory follicles of chicken ovary. The majority of components of the basal lamina (90–95% by weight) were solubilized with guanidine-HCl (and designated fraction 1); the remaining components were solubilized with β-mercaptoethanol containing guanidine-HCl (and designated fraction 2). The ability of fraction 1 to regulate progesterone production in granulosa cells obtained from the largest (F₁, mature), third largest (F₃, growing), fifth to seventh largest (F_5–7, growing) follicles and a pool of small yellow follicles (SYF, immature) of chicken ovary was assessed. Granulosa cells isolated from SYF follicles were in the least differentiated (undifferentiated) and those obtained from F₁ follicles were in the most differentiated state. The ability of fraction 1 to regulate progesterone production by chicken granulosa cells was influenced both by the state of cell differentiation and the form of the matrix material (whether solid or liquid). When fraction 1 was added as liquid to the incubation mixture, it promoted progesterone production by granulosa cells at all stages of differentiation; however, it caused a greater relative increase in the amount of progesterone produced by undifferentiated (SYF) and differentiating (F₃) granulosa cells than by differentiated (F₁) ones. In the presence of the liquid-form of fraction 1, luteinizing hormone (LH) stimulated progesterone production in differentiated (F₁) and differentiating (F_5–7) granulosa cells. Similarly, follicle-stimulating hormone (FSH) stimulated progesterone production by differentiating (F₃) and undifferentiated (SYF) granulosa cells in the presence of the liquid-form of fraction 1 protein. In culture wells that had been pre-coated with fraction 1 (solid-form), progesterone production by less differentiated (SYF, F_5–7) granulosa cells was enhanced, whereas progesterone production by differentiated (F₁) cells was reduced. The solid-form of fraction 1 augmented LH-stimulated progesterone production by less differentiated (F_5–7) granulosa cells however, it attenuated LH-induced progesterone production in differentiated (F₁) cells. FSH-promoted progesterone production in granulosa cells from immature follicles (SYF) was augmented by solid-form of fraction 1 whereas the effect of FSH on cells obtained from older follicle (F₃) was suppressed by solid-form of fraction 1. In experiments in which gonadotropin action was attenuated by solid-form of fraction 1, the amount of progesterone produced in the presence of maximally inhibiting concentrations of fraction 1 protein was greater than control values (no fraction 1, no gonadotropin). These results show that basal lamina of the ovarian follicle can regulate progesterone production by granulosa cells. The data demonstrate that the interactions between the components of basal lamina and LH or FSH on granulosa cell function were dependent on the stage of follicular development and were influenced by the form of the matrix material. It is concluded that the basal lamina of the chicken ovarian follicle is biologically active and regulates granulosa cell function.     

In vitro–in vivo study on the effects of plant compounds on rumen fermentation,microbial abundances and methane emissions in goats

Two in vitro and one in vivo experiments were conducted to investigate the effects of a selection of plant compounds on rumen fermentation, microbial concentration and methane emissions in goats. Treatments were: control (no additive), carvacrol (CAR), cinnamaldehyde (CIN), eugenol (EUG), propyl propane thiosulfinate (PTS), propyl propane thiosulfonate (PTSO), diallyl disulfide (DDS), a mixture (40 : 60) of PTS and PTSO (PTS+PTSO), and bromochloromethane (BCM) as positive control with proven antimethanogenic effectiveness. Four doses (40, 80, 160 and 320 µl/l) of the different compounds were incubated in vitro for 24 h in diluted rumen fluid from goats using two diets differing in starch and protein source within the concentrate (Experiment 1).The total gas production was linearly decreased (P<0.012) by all compounds, with the exception of EUG and PTS+PTSO (P⩾0.366). Total volatile fatty-acid (VFA) concentration decreased (P⩽0.018) only with PTS, PTSO and CAR, whereas the acetate:propionate ratio decreased (P⩽0.002) with PTS, PTSO and BCM, and a tendency (P=0.064) was observed for DDS. On the basis of results from Experiment 1, two doses of PTS, CAR, CIN, BCM (160 and 320 µl/l), PTSO (40 and 160 µl/l) and DDS (80 and 320 µl/l) were further tested in vitro for 72 h (Experiment 2). The gas production kinetics were affected (P⩽0.045) by all compounds, and digested NDF (DNDF) after 72 h of incubation was only linearly decreased (P⩽0.004) by CAR and PTS. The addition of all compounds linearly decreased (P⩽0.009) methane production, although the greatest reductions were observed for PTS (up to 96%), DDS (62%) and BCM (95%). No diet–dose interaction was observed. To further test the results obtained in vitro, two groups of 16 adult non-pregnant goats were used to study in vivo the effect of adding PTS (50, 100 and 200 mg/l rumen content per day) and BCM (50, 100 and 160 mg/l rumen content per day) during the 9 days on methane emissions (Experiment 3). The addition of PTS and BCM resulted in linear reductions (33% and 64%, respectively, P⩽0.002) of methane production per unit of dry matter intake, which were lower than the maximum inhibition observed in vitro (87% and 96%, respectively). We conclude that applying the same doses in vivo as in vitro resulted in a proportional lower extent of methane decrease, and that PTS at 200 mg/l rumen content per day has the potential to reduce methane emissions in goats. Whether the reduction in methane emission observed in vivo persists over longer periods of treatments and improves feed conversion efficiency requires further research.