Acid Hydrolysis Research Articles

Simultaneous extraction of five heavy metal ions from root vegetables via dual-frequency ultrasound-assisted enzymatic digestion

The dual-frequency ultrasound-assisted enzymatic digestion (DUED) technique was developed for synchronous green extraction of five heavy metal ions in root vegetables. The combination of α-amylase, cellulase, and papain showed significant advantageous in extracting heavy metal ions. Under optimized dual-frequency ultrasonic conditions, the extraction rates of Cr, As, Cd, Pb, and Hg in carrots reached 99.04%, 105.88%, 104.65%, 104.10%, and 103.13% respectively. And the extraction process is highly efficient, completing in just 15 min. Compared to conventional microwave-assisted acid hydrolysis method, this technique eliminates the need for high-temperature concentrated acid, enhancing its environmental sustainability while maintaining mild reaction conditions, making it ideal for biosensors application. Additionally, simultaneous extraction and detection of four heavy metals in lotus roots were successfully achieved by using DUED and a fluorescent paper-based microfluidic chip. The obtained results are consistent with those obtained using conventional methods.

A novel bio-based water reducer for concrete application: Facile process and techno-economic analysis of xylonate bioproduction from lignocellulosic residues

The xylonate was bioproduced directly from lignocellulosic residues, and the application properties of crude xylonate powder were investigated with a promising potential as a bio-based concrete water reducer. The overall integrated process was evaluated on the view of mass balance and techno-economic analysis using Aspen Plus modeling. 56 g/L of calcium xylonate (XA-Ca) can be obtained within 8 h from acidic corncob hydrolysate (ACH) at a 100 % yield with the whole-cell catalysis of Gluconobacter oxydans. At the addition of 0.2 wt% in the dry concrete content, XA-Ca powder and sodium xylonate powder prepared from pure xylose and ACH could reduce water used in concrete by 15 %, 14 %, 13 %, and 13 %, respectively. XA-Ca from ACH led to a 33% increase in concrete compressive strength and a 24% increase in concrete flexural strength at day 7 compared to the blank group. The techno-economic analysis showed the minimum XA-Ca powder price to be $ 0.806/kg which can be economically feasible. This study provides a practical and economical process prototype for the industrial concrete water reducer application of novel bio-based xylonate produced from lignocellulosic residues.

The Effect of Acid Hydrolysis on the Pickering Emulsifying Capacity of Tartary Buckwheat Flour.

The effect of sulfuric acid hydrolysis on the Pickering emulsifying capacity of Tartary buckwheat flour (TBF) rich in starch was evaluated for the first time. The results indicate that the sulfuric acid concentration and hydrolysis time had a significant impact on the Pickering emulsifying capacity of acid-hydrolyzed Tartary buckwheat flour (HTBF). A low sulfuric acid concentration (1-2 mol/L) could reduce the particle size of HTBF, but it also decreased the Pickering emulsifying ability. At a sulfuric acid concentration of 3 mol/L, appropriate treatment time (2 and 3 days) led to particle aggregation but significantly improved wettability, thereby resulting in a rapid enhancement in emulsifying capacity. Under these conditions, the obtained HTBF (HTBF-D2-C3 and HTBF-D3-C3) could stabilize medium-chain triglyceride (MCT)-based Pickering high-internal-phase emulsions (HIPEs) with an oil-phase volume fraction of 80% at the addition amounts (c) of ≥1.0% and ≥1.5%, respectively. Its performance was significantly superior to that of TBF (c ≥ 2.0%). Furthermore, at the same addition amount, the droplet size of HIPEs constructed by HTBF-D3-C3 was smaller than that of HTBF-D2-C3, and its gel strength and microrheological performance were also superior to those of HTBF-D2-C3, which was attributed to the higher wettability of HTBF-D3-C3. The findings of this study can facilitate the in-depth application of Tartary buckwheat and provide references for the development of novel Pickering emulsifiers.

Synergistic Inhibitions of Gram-Negative Bacteria by Combination Treatment with Ciprofloxacin and a Novel Glucolipid.

Psychrophilic fungus Pseudogymnoascus sp. OUCMDZ-4032 derived from Antarctica was cultivated under 16 °C to produce a new glucolipid compound (1). Its structure was elucidated by analysis of detailed spectroscopic data, acid hydrolysis and 1-phenyl-3-methyl-5-pyrazolone precolumn derivatization, and 13C NMR quantum chemical calculations. Though compound 1 did not show inhibitory activity against bacteria, it can reduce the minimum inhibitory concentration (MIC) of ciprofloxacin against Gram-negative bacteria Pseudomonas aeruginosa, Escherichia coli, and Salmonella paratyphi by 1024, 256 and 256-fold. Compound 1 showed potential as a synergistically inhibiting adjuvant in co-administration with antibiotic to enhance antibacterial activities.

Nervogenic Acid Derivatives and Phenanthrenes from Liparis nervosa and Their Antimicrobial and Immunosuppressive Activities.

Two new nervogenic acid derivatives liparisnervosides Q (1) and R (5), as well as five known nervogenic acid derivatives (2-4, 6, 7) and four phenanthrenes (8-11) were isolated from the whole plant of Liparis nervosa (Thunb. ex A. Murray) Lindl.. Their structures were detremined using extensive spectroscopic techniques, including 1D, 2D NMR, and HR-ESI-MS, and acid hydrolysis. Furthermore, their antimicrobial and immunosuppressive activities were evaluated. Nervosine VII (3) exhibited antimicrobial activity against Staphylococcus aureus with an MIC of 62.5 μg/mL and inhibited the proliferation of human T cells with an IC50 value of 9.67±0.96 μM. These findings contribute to our understanding of the potential pharmacological properties of these compounds.

Quantification of Arbutin and its degradation products, hydroquinone and p-Benzoquinone, in hyperpigmentation topical formulation: Effect of extraction procedure and interference assessment

The utilization of Hydroquinone (HQ) in over-the-counter skincare items is subject to restrictions. Consequently, Arbutin (AR) serves as a reliable alternative for addressing hyperpigmentation in non-prescription topical formulations. Nevertheless, AR undergoes decomposition into HQ and p-Benzoquinone (BZ) when exposed to temperature stress, ultraviolet light, or dilution in an acidic environment, all of which can induce skin toxicity. The intention of this paper is to investigate the effect of extraction procedure on the conversion of AR to HQ and or BZ and to evaluate kinetics of AR hydrolysis to HQ. Meanwhile this study aims to evaluate AR and BZ interference with the United States Pharmacopoeia (USP) identification and assessment method for HQ Hydrolytic stress during extraction conditions underwent optimization through systematic screening tests. Subsequent assessment of the residual drug and its degradation products were achieved by HPLC method. The resulting data were meticulously fitted to various kinetic models. To analyze the potential interference of AR in HQ measurement using USP method, the standard concentrations of AR and HQ were analyzed through UV–VIS spectrophotometry. For enhanced certainty, a validated HPLC method analysis was also conducted. Notably, the acid hydrolysis of AR exhibited independence from its initial concentration. So, the hydrolytic degradation of AR exhibited a Zero-order kinetic profile. Furthermore, the proven interference of AR in the UV–VIS spectrophotometry method was identified within the context of the USP method. This study successfully utilized an adopted HPLC method for the concurrent quantification of AR, HQ, and BZ. The potential interference of AR in the UV–VIS spectrophotometric assay for HQ may lead to false results especially for regulatory purposes.

Assessing β-Sitosterol Levels in Dietary Supplements for Benign Prostatic Hyperplasia: Implications for Therapeutic Efficacy.

Introduction Benign prostatic hyperplasia (BPH) is a prevalent condition among aging men that affects their life quality due to urinary symptoms. Current pharmacologic treatments, often lead to sexual dysfunction, so dietary supplements (DS) containing plant-based compounds such as β-sitosterol (SIT) are preferred. DSare highly accessible and widely used, but poorly regulated, so oftenpatients are victims of fraud. The use of DS to treat BPH symptoms is questionable, and this may be due not to the efficacity of the active compound but to the quality of commonly available DS. Aim This study aimed to assess the concentration of SIT in DS available on the market and evaluate whether the concentration of the active compound at the recommended dosage is sufficient to elicit beneficial effects in BPH. Method An HPLC-UV method based on direct saponification and acid hydrolysis was developed for the quantification of free and conjugated SIT in DS. The concentration of SIT in various DS was determined and compared with the one declared on the label. Results The chromatographic analysis confirmed the presence of SIT in all the DS but also showed a considerable variability of SIT content among DS, with only one product meeting the necessary concentration to bring potential benefits in BPH. Conclusion The study highlights inconsistencies in SIT content among DS and the importance of DS containing a standardized extract of SIT. Quality control measures are imperative to ensure that consumers receive effective and safe SIT-based DS to manage BPH symptoms. Further research is needed to establish standardized dosages and to evaluate their long-term efficacy and safety.

Cellulose Nanocrystals and Lignin Nanoparticles Extraction from Lemna minor L.: Acid Hydrolysis of Bleached and Ionic Liquid-Treated Biomass.

Using biomass to develop and obtain environmentally friendly and industrially applicable biomaterials is increasingly attracting global interest. Herein, cellulose nanocrystals (CNCs) and lignin nanoparticles (LNPs) were extracted from Lemna minor L., a freshwater free-floating aquatic species commonly called duckweed. To obtain CNCs and LNPs, two different procedures and biomass treatment processes based on bleaching or on the use of an ionic liquid composed of triethylammonium and sulfuric acid ([TEA][HSO4]), followed by acid hydrolysis, were carried out. Then, the effects of these treatments in terms of the thermal, morphological, and chemical properties of the CNCs and LNPs were assessed. The resulting nanostructured materials were characterized by using Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) spectroscopy, thermo-gravimetric analysis (TGA), and scanning electron microscopy (SEM). The results showed that the two methodologies applied resulted in both CNCs and LNPs. However, the bleaching-based treatment produced CNCs with a rod-like shape, length of 100-300 nm and width in the range of 10-30 nm, and higher purity than those obtained with ILs that were spherical in shape. In contrast, regarding lignin, IL made it possible to obtain spherical nanoparticles, as in the case of the other treatment, but they were characterized by higher purity and thermal stability. In conclusion, this research highlights the possibility of obtaining nanostructured biopolymers from an invasive aquatic species that is largely available in nature and how it is possible, by modifying experimental procedures, to obtain nanomaterials with different morphological, purity, and thermal resistance characteristics.

Comparison of lactic and propionic acid hydrolysis for production of xylo-oligosaccharides and ethanol from polysaccharides in Toona sinensis branch

Xylan-type hemicellulose hydrolysis by an organic acid solution for the production of xylo-oligosaccharides (XOS) is efficient and eco-friendly, but the effects of different organic acids on XOS production from Toona sinensis branch (TB) biomass is limited. In this work, under the conditions of 170 °C for 60 min, 33.1 % and 38.7 % XOS yields were obtained from polysaccharides present in TB by 2 % lactic acid (LA) and 6 % propionic acid (PA), respectively. Then 77 % of the lignin was removed by hydrogen peroxide−acetic acid pretreatment system, and 39.5 % and 44.7 % XOS yield were obtained from polysaccharides in delignification TB by 2 % LA and 6 % PA, respectively. It was found that PA hydrolysis, especially from delignified TB, resulted in higher XOS yield and purity compared to LA hydrolysis. Moreover, the content of byproducts (xylose, hydroxymethyl-furfural and furfural) in PA hydrolysate was lower. Following the hydrolysis process, the simultaneous saccharification and fermentation of the TB solid residue achieved an ethanol yield of 71.5 %. This work proposed an integrated process to preferentially convert the TB hemicellulose into valuable XOS and then convert the cellulose into ethanol. This process had the advantages of eliminating the need for isolation and purification of xylan, and the potential to obtain multiple products from the same raw material.

Sago Starch Modification by Combination of Lactic Acid Hydrolysis and Oxidation of Hydrogen Peroxide Under Ultraviolet Rotary Dryer Irradiation

Sago Starch Modification by Combination of Lactic Acid Hydrolysis and Oxidation of Hydrogen Peroxide Under Ultraviolet Rotary Dryer Irradiation

Bioethanol from Arthrospira platensis biomass using a combined pretreatment

With the aim to reduce the reliance on gasoline by supporting efficient bioethanol production to meet the biofuel goal of 46 % in the transportation sector by 2050, the present study proposes a combined pretreatment of microwave-assisted acid hydrolysis for bioethanol production, which was applied to commercially-produced microalgal biomass of Arthrospira platensis. The Separated Hydrolysis and Fermentation (SHF) method was applied to prevent sugar loss and produce a higher bioethanol yield. After examining the effect of acid concentrations (0, 0.1, 0.2, and 0.3 M) and hydrolysis duration (30, 60, 90, 120, and 180 min) on the fermentable sugars, it was discovered that both operation parameters had a major impact on the synthesis of monosaccharides. With a 0.3 M H2SO4 concentration and a 90-minute hydrolysis time at 100 °C, the maximum concentration of fermentable sugars of 11.60 g/L was obtained. Regarding the fermentable sugar yield, the suggested combined pretreatment (78.4 %) outperforms the literature-reported single pretreatment of acid hydrolysis (55 %), under comparable operating settings. After 96 h of anaerobic fermentation with Saccharomyces cerevisiae, the hydrolysate of the fermentable sugars produced 0.06 g ethanol/g biomass, corresponding to 0.35 g ethanol/g total carbohydrates in Arthrospira platensis.

ISOLATION, PURIFICATION AND PHYTOCHEMICAL SCREENING OF POLYSACCHARIDE FRACTIONS FROM APIUM GRAVEOLENS’ L. BOTANICAL FORMS

The study of natural polysaccharides is an important area of research due to their pharmacological effects, including antiviral activity and the ability to regulate metabolic disorders. In addition, these polymeric structures realize several properties (sorption, shaping, transport (and delivery systems), which increases the interest of scientists in their isolation and analysis. This study aims to comparatively investigate the polysaccharide fractions in different botanical forms of celery odouriferous. The objectives of the study include the isolation of polysaccharide fractions, their purification by the Sevag method, estimation of monomeric composition of the fractions after acid hydrolysis by the HPTLC method, and determination of structural characteristics of the molecules by IR spectroscopy. Alcohol-soluble polysaccharides (ASPS), water-soluble polysaccharides (WSPS), and pectin substances (PS) were isolated from leaf, petiole, and root botanical forms of celery. After purification, the obtained substances were amorphous powders of light brown or light beige colour and odourless. The root botanical form of celery showed the highest yield of the target compounds (total (13.54±1.07)% after purification), while the petiole form (total (5.51±0.04)% after purification) showed the lowest yield. The monomeric composition of pectins and WSPS showed a predominance of galactose and arabinose, whereas the alcoholic ones showed a predominance of fructose and glucose. The interpretation of IR spectra showed the presence of absorption bands characteristic of free and bound carboxyl groups, C-O-C valence vibrations, α-configuration of the glycosidic bond, and C1-α-conformation of galacturonic acid in different polysaccharide fractions, which allows us to draw some conclusions regarding the structure of the substances. A comparative study of polysaccharide fractions of different botanical forms of odorous celery was carried out for the first time. Based on the results obtained, it is possible to single out WSPS and PS of celery root crops as the most promising phytosubstances for further development of products of functional, specialized nutrition and potential medicines on their basis. The methods of analysis used in the study can be proposed as part of the regulatory documentation for the control of these products.

New Flavonoids from the leaves and stems of Sedum formosanum (Crassulaceae)

As a series of the phytochemical research of the family Crassulaceae, the flavonoids of Sedum formosanum from two Taiwanese and one Japanese sites were isolated and characterized by UV spectra, HR-MS, LC-MS, acid hydrolysis, NMR, and HPLC and TLC comparisons with authentic samples. Eight new flavonoids (21, 22, 24-26 and 28-30) including two flavones and six isoflavones were isolated from the leaves and stems, together with 24 known compounds (1-20, 23, 27, 31 and 32), and identified as chrysoeriol 7-O-[6´´-(3-hydroxy-3-methylglutaroyl)glucoside] (21), chrysoeriol 7-O-[6´´-(5´´´-methoxy-3-hydroxy-3-methyglutaroyl)glucoside] (22), 3´-O-methylorobol 7-O-rutinoside (24), 3´-O-methylorobol 7-O-arabinosyl-(1→2)-glucoside (25), 3´-O-methylorobol 7-O-arabinosyl-(1→6)-glucoside (26), orobol 3´,4´-dimethyl ether 7-O-rutinoside (28), orobol 3´,4´-dimethyl ether 7-O-sophoroside (29) and orobol 3´,4´-dimethyl ether 7-O-arabinosyl-(1→6)-glucoside (30). The samples were collected in three sites of Taiwan and Japan, and geographic chemical variation was observed among their sites.

A versatile bilayer smart packaging based on konjac glucomannan/alginate for maintaining and monitoring seafood freshness

This study introduces a novel multi-functional double-layer intelligent packaging. It focuses on developing a dual-function system capable of real-time monitoring and freshness preservation. Specifically, cellulose nanocrystalline (CNC) was obtained through acid hydrolysis, and then CNC/soybean protein isolate (CNC/SPI) complex colloid particles were prepared via antisolvent method. These particles served as stabilizers to prepare oil-in-water (O/W) cinnamon essential oil Pickering emulsion (CSCEO). The CSCEO was then integrated into the emulsified hydrophobic layer of a konjac glucomannan (Kgm) matrix through intermolecular hydrogen bonding. Finally, alginate (Alg) matrix containing alizarin (Al) as an indicator was added to construct the bilayer structure using a layer-by-layer casting strategy. The inner layer Alg/Al was the pH/NH3-responsive indicator layer, while the outer layer Kgm/CSCEO acted as the high-barrier bacteriostatic layer. The obtained dual-function, double-layer film (Alg/Al-Kgm/CSCEO), which possesses a sensitive, reversible and rapid response towards pH/NH3, shows exceptional antibacterial and antioxidant properties, as well as excellent mechanical property, light-blocking capability and hydrophobicity. For monitoring and maintaining the actual freshness of shrimp, such a bilayer packaging displays smallest change of ∆E and TVB-N (18.65 mg/100 g) even after 72 h, which further highlighting its potential in enhancing food safety and extending shelf life.

Discovery of Potent Glycosidases Enables Quantification of Smoke-Derived Phenolic Glycosides through Enzymatic Hydrolysis.

When grapes are exposed to wildfire smoke, certain smoke-related volatile phenols (VPs) can be absorbed into the fruit, where they can be then converted into volatile-phenol (VP) glycosides through glycosylation. These volatile-phenol glycosides can be particularly problematic from a winemaking standpoint as they can be hydrolyzed, releasing volatile phenols, which can contribute to smoke-related off-flavors. Current methods for quantitating these volatile-phenol glycosides present several challenges, including the requirement of expensive capital equipment, limited accuracy due to the molecular complexity of the glycosides, and the utilization of harsh reagents. To address these challenges, we proposed an enzymatic hydrolysis method enabled by a tailored enzyme cocktail of novel glycosidases discovered through genome mining, and the generated VPs from VP glycosides can be quantitated by gas chromatography-mass spectrometry (GC-MS). The enzyme cocktails displayed high activities and a broad substrate scope when using commercially available VP glycosides as the substrates for testing. When evaluated in an industrially relevant matrix of Cabernet Sauvignon wine and grapes, this enzymatic cocktail consistently achieved a comparable efficacy of acid hydrolysis. The proposed method offers a simple, safe, and affordable option for smoke taint analysis.

Enhanced Production of Clean Fermentable Sugars by Acid Pretreatment and Enzymatic Saccharification of Sugarcane Bagasse

Sugarcane bagasse (SCB), an agro-industrial byproduct generated by a sugar mill, holds a substantial carbohydrate content of around 70 wt.%, comprising cellulose and hemicellulose. Saccharification plays a pivotal role in the conversion of SCB into second-generation (2G)-ethanol and valuable compounds, which is significantly aided by thermochemical pretreatments. In this study, SCB underwent diluted sulfuric acid pretreatment (2% H2SO4, 80 rpm, 200 °C, 20 min), resulting in the removal of 77.3% of the xylan. The hemicellulosic hydrolysate was analyzed to identify the sugars and degraded products acting as microbial inhibitors. The acid hydrolysate showed a xylose yield of 68.0% (16.4 g/L) and a yield of 3.8 g/L of acetic acid. Afterward, the hemicellulosic hydrolysate was concentrated 2.37 times to obtain a xylose-rich stream (39.87 g/L). The sequential detoxification, employing calcium oxide and activated carbon, removed the inhibitory compounds, including acetic acid, while preserving the xylose at 38.10 g/L. The enzymatic saccharification of cellulignin at 5% and 10% of the total solids (TSs) yielded comparable reducing sugar (RS) yields of 47.3% (15.2 g/L) and 47.4% (30.4 g/L), respectively, after 96 h, employing a 10 FPU/g enzyme loading of Cellic® CTec3 (Novozymes Inc. Parana, Brazil). In summary, these findings outline an integrated green chemistry approach aimed at addressing the key challenges associated with pretreatment, concentration, detoxification, and enzymatic hydrolysis to produce fermentable sugars.

Berkeleylactones S–T, novel 16-membered macrolides isolated from the endophytic fungus Penicillium egyptiacum

The fungus Penicillium egyptacum has been reported as a producer of the 16-membered macrolide antibiotic A26771B. In this study, two new berkeleylactone analogues, berkeleylactones S–T (1–2), were isolated from P. egyptiacum. Their structures were determined by the analyses of 1D- and 2D-NMR data, HRESIMS, and chemical derivatization. 1 is the first example of berkeleylactone analogue possessing a glucose moiety, whose absolute configuration was elucidated by acid hydrolysis followed by derivatization and LC-MS analysis. No antibacterial activity against Bacillus subtilis and Streptococcus salivarius was found within the range of 0–100 μM for compounds 1–2.

Influence of acid hydrolysis on the degree of polymerization of cellulose from colored cotton substrates

This study investigated the influence of sulfuric acid hydrolysis on the cellulosic fibers and films’ degree of polymerization (DP). Cotton textile residues (dyed and white) and hydrophilic cotton were used as the raw material. The films were formed by the dissolution of fibers in ionic liquid and regeneration in water. Results showed that dyed cotton residues required hydrolysis at 0.5 M sulfuric acid for 30 min to achieve complete dissolution during viscosimetry assay. Due to different dyeing processes and chemical compositions, the color of the fibers influences the DP. Undyed samples submitted to hydrolysis had DP around 60% lower than samples without pretreatment. This effect was not observed when comparing films with and without hydrolysis, because the depolymerization occurs in the dissolution and regeneration step. This study expands the applicability of viscometry to colored substrates, serving as a starting point for future research on the impact of process parameters and dyes on cellulose polymerization.

Multiple effects of relative humidity on heterogeneous ozonolysis of cooking organic aerosol proxies from heated peanut oil emissions

The exposure to cooking organic aerosols (COA) is closely related to people's daily lives. Despite extensive investigations into COA's model compounds like oleic acid, the intricacies of heterogeneous ozonolysis of real COA and the effects of ambient conditions like humidity remain elusive. In this work, the ozonolysis of COA proxies from heated peanut oil emissions was investigated using diffuse reflectance infrared Fourier transform (DRIFTS) spectroscopy, and proton transfer reaction time-of-flight mass spectrometer (PTR-ToF-MS). We found that humidity hinders the reaction between ozone and CC double bonds due to the competitive adsorption of water and ozone on COA. Although visible light has little influence on the ozonolysis of COA in the absence of humidity, the ozonolytic CO production is significantly promoted by visible light in the presence of humidity. It may be attributed to the formation of water-derived reactive oxygen species (ROS, mainly HO•) from the photosensitization of polycyclic aromatic hydrocarbons (PAHs) in COA. We also found that humidity can enhance the depolymerization of carboxylic acid dimers and hydrolysis of intrinsic acetals in the COA. Moreover, humidity promotes the release of VOCs during both the dark and light ozonolysis of COA. This work reveals the important roles of humidity-responsive and photo-responsive components in COA during its ozonolysis, and the change in VOC release may guide the control of human VOC exposure in indoor air.

L-PTMI-co-L-PEI copolymers obtained through copolymerization of cyclic imino ethers and their chain modification: Antibacterial properties and cytotoxicity

Polymeric antimicrobial agents are intensively investigated as potential novel antibiotics. In this work we use copolymerization of 2-propyl-2-oxazine (PrOzi) and 2-methyl-2-oxazoline (MeOx) combined with hydrolysis of the polymer side chains as a tool to obtain various linear polymeric derivatives of polytrimethylenimines (L-PTMI) and polyethylenimine (L-PEI). To obtain well-defined polymers, initially we determined copolymerization rates, and subsequently, we investigated the hydrolytic rates of various repeating units, namely PrOzi, MeOx, and 2-methyl-2-oxazine (MeOzi) in both homo- and copolymers. We observed that the structure of the polymeric main chain significantly influences the rate of acidic hydrolysis. In particular, the protonated L–PEI repeating unit (r.u.) accelerates the hydrolytic cleavage of the amide bond more than the protonated L-PTMI r.u., due to the shorter distance between amine centers.The biological activity of the polymers was assessed against three model microorganisms, namely Escherichia coli, Staphylococcus aureus and Candida albicans, and benchmarked in toxicity test against human lung fibroblast cell line. The antibacterial activity of L-PTMI-co-L–PEI increases monotonically with the increasing content of PTMI r.u., indicating an additive effect of covalently bonded L-PTMI and L-PEI. The antimicrobial activity of the copolymers is almost identical to that of the tested polymer blends in the corresponding ratios.The introduction of up to 40 % of PrOzi r.u. into the polyamine structure of PTMI (PPrOzi–co-L-PTMI copolymer) does not decrease the antimicrobial activity, compared to L–PTMI. The molecule remains active, particularly against Staphylococcus aureus (MIC = 4 μg/mL). At the same time, the presence of amide r.u. reduces toxicity. The highest observable selectivity index can reach values as high as 20 (PPrOzi40%–co-L-PTMI60%).