Degradation Of Substances Research Articles

Three new, UV spectrum filtration protocols for the synchronous quantification of ciprofloxacin HCl and ornidazole in the existence of ciprofloxacin-induced degradation compound

Three new spectrum filtration protocols have been developed and adapted to overcome some difficulties in dealing with highly overlapping triple drug mixtures by proposing new smart mathematical techniques that facilitate the resolution of the ternary mixture and the recovery of a filtrated zero-order spectrum (D0 spectrum) of each component without any overlapping from the accompanying components. The three established spectrophotometric protocols were conducted on the combination of ciprofloxacin hydrochloride and ornidazole as a green alternative to the usual chromatographic technique: the first protocol is ratio difference-isosbestic points coupled with ratio difference-areas under the curve (RD-ISO/RD-AUC); the second protocol is ratio difference-isosbestic points coupled with dual-wavelength equation (RD-ISO/DWE); and the third protocol is signal retrieval by zero-crossing point (SRZ). All three developed protocols have the power to recover a filtrated zero-order spectrum of each ornidazole and ciprofloxacin hydrochloride without any involvement from the ciprofloxacin-induced degradation substance through processing their spectral data either in the zero-order spectrum, ratio spectrum, or derivative spectrum. The correctness of the spectral filtration process for each protocol was checked by involving the spectral print recognition index to ensure the drug's purity and freeness from impurities or degradation products. The validation process was performed as per the directions of ICH, which confirmed the effectiveness of the elaborated protocols and their usability as daily analysis methods with a linearity range of (3.5–15 μg/ml) for ciprofloxacin in (RD-ISO/RD-AUC) and (RD-AUC/DWE) protocols and (1.5–15 μg/ml) in (SRZ) protocol; and a linearity range of (3–20 μg/ml) for ornidazole in (RD-ISO/RD-AUC) and (SRZ) protocols and (3–15 μg/ml) in (RD-ISO/DWE) protocol. A statistical comparison and greenness evaluation utilizing NEMI, AGREE, GAPI, and CALIFICAMET-HEXAGON tools were made with the reference approach, confirming no statistical variations and a better greenness profile for the newly established protocols.

Forced Degradation Studies for Glycopyrrolate, Formoterol & Budesonide By UPLC

Forced degradation studies include the degradation of new drug substance and drug product at conditions more severe than accelerated conditions. These studies illustrate the chemical stability of the molecule which further facilitates the development of stable formulation with suitable storage conditions. ICH guidelines demonstrate certain degradation conditions like light, oxidation, dry heat, acidic, basic, hydrolysis etc.

Study on the correlation between the dominant microflora and the main flavor substances in the fermentation process of cigar tobacco leaves

The flavor of cigar tobacco leaf determines the quality of finished cigar tobacco, and the enhancement of flavor generally relies on microbial fermentation. In this paper, the correlation between the dominant microorganisms and the main flavor substances of cigar tobacco leaves during fermentation and the correlation between the two were investigated to reveal the correlation between microorganisms and flavor and the metabolic pathways of microorganisms affecting the flavor substances. During the fermentation process, the main flavors of cigar tobacco leaves were sweet, light and grassy, with hexanal, 2,6-dimethylpyridine, nonanal, phenylacetaldehyde, naphthalene, and methyl benzoate as the main constituents, and the key microorganisms Haloferax mediterranei, Haloterrigena limicola, Candidatus Thorarchaeota archaeon SMTZ-45, the genera Methyloversatilis, Sphingomonas, Thauera, Pseudomonas, Penicillium, and Aspergillus. Correlation analysis revealed that fungi were negatively correlated with the main aroma and inhibited the main flavor substances, while bacteria were positively correlated with Benzoic acid, methyl ester in the main flavor substances, which was conducive to the accumulation of green aroma. Functional analysis revealed that the dominant bacterial population was producing aroma by metabolizing glycoside hydrolases and glycosyltransferases, performing amino acid metabolism, carbohydrate metabolism and film transport metabolism. The present study showed that the bacterial and fungal dominant microorganisms during the fermentation of cigar tobacco were influencing the production and degradation of the main flavor substances through the enzyme metabolism by the occurrence of the Merad reaction.

Multivariate and multiscale investigation of ammonia production and emission mechanisms during membrane-covered cattle manure/wheat straw aerobic composting

Ammonia (NH3) emissions accompanying aerobic composting cause significant atmospheric pollution and nitrogen losses. Understanding the mechanisms of NH3 production and emission can help optimize composting strategies. Here, environmental parameters, microbial communities, microbial metabolism, and organic component degradation were characterized at the pile and particle scales during atmospheric aerobic composting and in two membrane-covered aerobic composting (MCAC) systems. Pile-scale results showed that NH3 emission was concentrated in the thermophilic phase; MCAC significantly increased the relative abundances of aerobic lignocellulose-degrading bacteria, carbohydrate-degrading enzymes, and deaminases (P < 0.05); MCAC increased microbial ammonification and carbon source use. The degradation and distribution of organic components in compost particles were visualized for the first time by Fourier transform infrared microspectroscopy: MCAC increased the degradation of polysaccharide-like substances and glycoside-like substances in the particles, and accelerated the degradation of proteins to amide-like substances within the outer layer ∼ 25 μm of particles. We speculated that the micro-positive pressure (∼500 Pa) created by MCAC enhanced the dissolution–diffusion of oxygen into compost particles, thereby facilitating aerobic degradation of organic components. Taken together, micro-positive pressure in the MCAC systems promoted the co-degradation of carbon and nitrogen substrates, which probably increased NH3 production potential, while the water films attached to the inside and outside of the semi-permeable membrane in MCAC were effective in reducing NH3 release by 7.11 %–12.42 %. These findings provide new insights for MCAC improvement.

Retracing the Rapid Evolution of an Herbicide-Degrading Enzyme by Protein Engineering.

The mechanisms underlying the rapid evolution of novel enzymatic activities from promiscuous side activities are poorly understood. Recently emerged enzymes catalyzing the catabolic degradation of xenobiotic substances that have been spread out into the environment during the last decades provide an exquisite opportunity to study these mechanisms. A prominent example is the herbicide atrazine (2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine), which is degraded through a number of enzymatic reactions constituting the Atz pathway. Here, we analyzed the evolution of the hydroxyatrazine ethylaminohydrolase AtzB, a Zn(II)-dependent metalloenzyme that adopts the amidohydrolase fold and catalyzes the second step of the Atz pathway. We searched for promiscuous side activities of AtzB, which might point to the identity of its progenitor. These investigations revealed that AtzB has low promiscuous guanine deaminase activity. Furthermore, we found that the two closest AtzB homologues, which have not been functionally annotated up to now, are guanine deaminases with modest promiscuous hydroxyatrazine hydrolase activity. Based on sequence comparisons with the closest AtzB homologues, the guanine deaminase activity of AtzB could be increased by three orders of magnitude through the introduction of only four active site mutations. Interestingly, introducing the inverse four mutations into the AtzB homologues significantly enhanced their hydroxyatrazine hydrolase activity, and in one case is even equivalent to that of wild-type AtzB. Molecular dynamics simulations elucidated the structural and molecular basis for the mutation-induced activity changes. The example of AtzB highlights how novel enzymes with high catalytic proficiency can evolve from low promiscuous side activities by only few mutational events within a short period of time.

Green synthesis of carbon nitride by NaNO3/NaCl eutectic molten salt and study on its versatile photocatalytic performance

The green synthesis of carbon nitride by NaNO3/NaCl eutectic molten salt was successfully realized in this study. Based on this envisaging, the heat treatment temperature has been successfully lowered to 340 °C to modulate and optimize the carbon nitride structure. The prepared target photocatalysts were characterized by using various characterization methods (SEM, BET, XRD, XPS, UV–Vis DRS, FT-IR, PL and transient photocurrents), which confirmed the practicability of the proposed strategy. The incorporation of doped Na+ ions and introduced cyano groups into the main structure can enhance the separation and migration capability of photo-induced electrons and holes, thereby inhibiting their recombination. Consequently, the much-enhanced photocatalytic activity of the obtained target catalyst was achieved and demonstrated through comprehensive tests such as photocatalytic degradation of organic dyes, photocatalytic degradation of organic pesticides, photocatalytic degradation of organic flotation reagent, and photocatalytic hydrogen evolution. Among them, g-CN-A-T-NaNO3/NaCl exhibited the highest photocatalytic activity and the highest repeated usage stability compared with the original sample. Additionally, the active species yielded in the system and possible mechanism for photocatalytic degradation of organic substances and photocatalytic H2 production was achieved based on systematically trapping experiments and electron spin resonance analysis.

Investigating the effect of polarity reversal of the applied current on electrochemical degradation of per-and polyfluoroalkyl substances

Advanced electrochemical oxidation methods have demonstrated significant potential in degrading per- and polyfluoroalkyl substances (PFAS). However, the widespread application of these techniques is impeded by the long term performance and the limited service life of electrodes. This study introduces a novel approach by investigating the impact of polarity reversal (PR) of the applied current on the electrochemical degradation of perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS), 6:2 fluorotelomer sulfonate (6:2 F TS), and aqueous film-forming foam (AFFF) samples. A laboratory-scale electrochemical cell equipped with two titanium sub-oxide (Ti4O7) electrodes is used for the experimental investigation. The results indicate 6-h direct current (DC) operation causes fouling and ageing of the electrode (anode) such as the formation of titanium oxide (TiO2). The application of PR effectively mitigates fouling and aging, leading to an enhanced mass transfer and an improved long-term defluorination of PFOA, PFOS, 6:2 FTS, and AFFF samples. The investigation also suggests that PR can help to reduce the energy consumption by ∼13%. Overall, the application of PR emerges as a promising and practical strategy to augment the electrochemical degradation of PFAS, addressing critical issues related to electrode stability and longevity.

Investigate the effect of ZnO/Bi2O3 nanocomposite: A synergistic versatile approach for biomedical and environmental applications

The escalating increase in the presence of organic and pharmaceuticals residues in the water bodies poses a serious environmental challenge, demanding the efficient photocatalyst for the remediation of microbial and hazardous contaminates. In this context the study addresses the synthesis of ZnO/Bi2O3 composites as an efficient degradation and microbial agents. The hydrothermal prepared nano-structures with (1 %, 3 %, 5 %, 7 %) Bismuth oxide (Bi2O3) concentration delves into an array of characterizations. The X-ray Diffraction (XRD) and Scanning Electron Microscopes (SEM) demonstrate structural and morphological analysis of nano composites. Brunauer Emmett Teller analysis (BET) showcased the surface area while Zeta potential analyzes the electrical conductivity of sample. Additionally, Ultraviolet Visible Spectroscopy (UV) and Photoluminescence Spectroscopy (PL) describe the optical properties of fabricated composites. The results reveal the synergistic effect that leads the effective dual applications of ZnO/Bi2O3 against the environmental concern. Our study finds out the efficient degradation of organic substances (MB dye and pharmaceutical Tetracycline) and strong reduction of pathogenic bacteria under exposes of 5 % ZnO/Bi2O3 composites (optimal sample).

Application of Methionine Increases the Germination Rate of Maize Seeds by Triggering Multiple Phenylpropanoid Biosynthetic Genes at Transcript Levels.

Methionine is an essential amino acid that initiates protein synthesis and serves as a substrate for various chemical reactions. Methionine metabolism plays an important role in Arabidopsis seed germination, but how methionine works in seed germination of maize has not been elucidated. We compared the changes in germination rate, the contents of methionine and folates, and transcriptional levels using transcriptome analysis under water or exogenous methionine treatment. The results indicate that the application of methionine increases seed germination rate (95% versus 70%), leading to significant differences in the content of methionine at 36 h, which brought the rapid increase forward by 12 h in the embryo and endosperm. Transcriptome analysis shows that methionine mainly affects the proliferation and differentiation of cells in the embryo, and the degradation of storage substances and signal transduction in the endosperm. In particular, multiple phenylpropanoid biosynthetic genes were triggered upon methionine treatment during germination. These results provide a theoretical foundation for promoting maize seed germination and serve as a valuable theoretical resource for seed priming strategies.

Parabens and Methylisotiazolinone (MIT): Preservatives with Different Behaviors When Subjected to Ozone and Ultraviolet Light Treatments

The influence that contaminants exert on the degradation of other substances commonly found in the same water bodies drives this study, which aims to investigate the simultaneous degradation of preservatives such as parabens and methylisothiazolinone (MIT). Mixtures of five parabens, MIT solutions, and mixtures of all five parabens plus MIT (each at 5 mg/L) were treated using 254 nm UV light, ozone treatments, and simultaneous ozone and UV light treatments at three different pH levels (3, 5, and 9). Regardless of pH, UV light is inefficient in degrading parabens, whereas MIT is efficiently degraded under this radiation. On the other hand, ozone treatments rapidly degrade the paraben mixture at any pH, with a basic pH resulting in faster degradation due to the predominance of the indirect mechanism. MIT, due to its structural characteristics, reacts minimally with ozone, and the process is enhanced at basic pH when hydroxyl radicals are involved. The simultaneous treatment with ozone and UV light proves to be the fastest method for eliminating both parabens and MIT at any pH. However, when treating joint mixtures of parabens and MIT, behaviors change notably, particularly for processes involving UV light due to the interfering effect of MIT. Both parabens and MIT require more time to degrade, except at an acidic pH. Only MIT reduces its ozone treatment time when treated alongside parabens due to the distinct degradation mechanisms that each type of contaminant has in the presence of ozone.

Factors of Degradation, Transformation, and Distribution of Medicinal Substances in the Water–Bottom Sediment System

English-language scientific publications on the natural degradation and transformation of medicinal substances in the aquatic environment under the effect of various factors are reviewed. The medicines that are most common in water are listed. The main source of pollution is shown to be poorly treated municipal sewage. The factors that affect the fate of substances in the medium and are considered in the article are the dilution or concentration due to changes in the hydrological regime or the conditions of the use of medicines, water pH, wind-wave roiling, photodegradation, bioaccumulation, etc. The analysis of foreign studies of drug contamination was used to make conclusions about the prospects of the development of these areas for use in Russian studies.

Plant-Derived Vesicles: A New Era for Anti-Cancer Drug Delivery and Cancer Treatment.

Lipid-structured vesicles have been applied for drug delivery system for over 50 years. Based on their origin, lipid-structured vesicles are divided into two main categories, namely synthetic lipid vesicles (SLNVEs) and vesicles of mammalian origin (MDVEs). Although SLNVEs can stably transport anti-cancer drugs, their biocompatibility is poor and degradation of exogenous substances is a potential risk. Unlike SLNVEs, MDVEs have excellent biocompatibility but are limited by a lack of stability and a risk of contamination by dangerous pathogens from donor cells. Since the first discovery of plant-derived vesicles (PDVEs) in carrot cell supernatants in 1967, emerging evidence has shown that PDVEs integrate the advantages of both SLNVEs and MDVEs. Notably, 55 years of dedicated research has indicated that PDVEs are an ideal candidate vesicle for drug preparation, transport, and disease treatment. The current review systematically focuses on the role of PDVEs in cancer therapy and in particular compares the properties of PDVEs with those of conventional lipid vesicles, summarizes the preparation methods and quality control of PDVEs, and discusses the application of PDVEs in delivering anti-cancer drugs and their underlying molecular mechanisms for cancer therapy. Finally, the challenges and future perspectives of PDVEs for the development of novel therapeutic strategies against cancer are discussed.

Application of Fe-MOFs in Photodegradation and Removal of Air and Water Pollutants: A Review.

Photocatalytic technology has received increasing attention in recent years. A pivotal facet of photocatalytic technology lies in the development of photocatalysts. Porous metal-organic framework (MOF) materials, distinguished by their unique properties and structural characteristics, have emerged as a focal point of research in the field, finding widespread application in the photo-treatment and conversion of various substances. Fe-based MOFs have attained particular prominence. This review explores recent advances in the photocatalytic degradation of aqueous and gaseous substances. Furthermore, it delves into the interaction between the active sites of Fe-MOFs and pollutants, offering deeper insights into their mechanism of action. Fe-MOFs, as photocatalysts, predominantly facilitate pollutant removal through redox processes, interaction with acid sites, the formation of complexes with composite metal elements, binding to unsaturated metal ligands (CUSs), and hydrogen bonding to modulate their respiratory behavior. This review also highlights the focal points of future research, elucidating the challenges and opportunities that lie ahead in harnessing the characteristics and advantages of Fe-MOF composite catalysts. In essence, this review provides a comprehensive summary of research progress on Fe-MOF-based catalysts, aiming to serve as a guiding reference for other catalytic processes.

Cold Plasma for Green Advanced Reduction/Oxidation Processes (AROPs) of Organic Pollutants in Water.

Cold plasma is gaining increasing attention as a novel tool to activate energy demanding chemical processes, including advanced reduction/oxidation processes (AROPs) of organic pollutants in water. The very complex milieu generated by discharges at the water/plasma interface comprises photons, strong oxidants and strong reductants which can be exploited for achieving the degradation of most any kind of pollutants. Despite the complexity of these systems, the powerful arsenal of mechanistic tools and chemical probes of physical organic chemists can be usefully applied to understand and develop plasma chemistry. Specifically, the added value of air plasma generated by in situ discharge with respect to ozonation (ex situ discharge) is demonstrated using phenol and various phenol derivatives and mechanistic evidence for the prevailing role of hydroxyl radicals in the initial attack is presented. On the reduction front, the impressive performance of cold plasma in inducing the degradation of recalcitrant perfluoroalkyl substances, which do not react with OH radicals but are attacked by electrons, is reported and discussed. The widely different reactivities of perfluorooctanoic acid (PFOA) and of perfluorobutanoic acid (PFBA) underline the crucial role played in these processes by the interface between plasma and solution and the surfactant properties of the treated pollutants.

Soil macroporosity modulates the extent of negative microbial associations during organic substance decomposition

Microbial species interactions are expected to influence the community-level properties, such as the production of extracellular enzymes and the degradation of organic substances. This work examined how microbial diversity, composition and the overall sign of microbial associations were altered with soil texture and structure following the amendment of organic substances. Two sets of microcosms (1:100 and 1:1) of a 4 × 3 factorial design were constructed, with four artificial textural classes (a sandy loam, two loams, and a (silty) clay loam) and three organics (TSB, tryptic soy broth; CA, a mixture of cellulose and humic/fulvic acids; BS, barley straw). As the ‘microbial inoculant’, an agricultural soil was added to the 1:100 and 1:1 microcosms at 1% and 50%, respectively. A few of microbial taxa were specifically enriched after soil addition of TSB, CA, or BS, but distributions across textural classes were inconsistent between microcosms or between organic amendments. Regardless, top abundant bacterial and fungal OTUs were overall negatively associated, suggesting that microbial competition for the shared resource dominated the decomposition of both simple and complex organics. Microbial associations were also modified by soil pore size distribution (PSD), being fewer negative (or more positive) in soils of greater macroporosity than in soils of lower macroporosity. The PSD-based differences in microbial associations were coordinated with PSD-based differences in the activities of exoglucanase and β-glucosidase in TSB-amended soils or soil respiration characteristics in CA-amended soils. Our results provide new insight into how soil structure regulates microbial interactions and, accordingly, the degradation of organic matter.

Hepatotoxicity evaluation and possible mechanisms of decabrominated diphenyl ethers (BDE-209) in broilers: Oxidative stress, inflammatory, and transcriptomics

Decabrominated diphenyl ether (BDE-209), a persistent organic pollutant, is linked to a great number of health problems, the most severe of which impact the liver due to its role in the elimination and degradation of exogenous harmful substances. Though the hepatotoxicity of BDE-209 has been observed, its underlying mechanism is yet unknown. The purpose of this study is to thoroughly investigate the hepatotoxicity of BDE-209 and its molecular processes in broilers by subjecting 120 male broilers to varied concentrations of BDE-209 for 42 days. We observed that the bioaccumulation of BDE-209 in the liver in a dose-dependent manner, and that BDE-209 exposure can raise the concentrations of ALT, AST, and GGT, accompanied by hepatocyte fatty degeneration and inflammatory foci. In the hepatic homogenates, oxidative stress was evidenced by elevated levels of MDA and ROS and decreased activies of SOD and CAT. Additionally, pro-inflammatory cytokines including IL-1, IL-1β, TNF-α, IL-8 levels were increased, whereas anti-inflammatory cytokine IL-4 level was declined. Furthermore, RNA sequencing revealed that genes involved in inflammation were considerably dysregulated, and real-time PCR verified the expressed alterations of numerous genes related to the MAPK and WNT signaling pathways. The protein concentrations of NF-κB, β-catenin, and WNT5A, and the phosphorylation levels of JNK and ERK were all dramatically enhanced. The current study indicates that BDE-209 exposure can cause hepatotoxicity in broilers via bioaccumulation and oxidative stress, which then activates the MAPK and WNT signaling pathways, subsequently generating inflammation and hepatic injury.

Pharmaceutical Forced Degradation (Stress Testing) Endpoints: A Scientific Rationale and Industry Perspective

Forced degradation (i.e., stress testing) of small molecule drug substances and products is a critical part of the drug development process, providing insight into the intrinsic stability of a drug that is foundational to the development and validation of stability-indicating analytical methods. There is a lack of clarity in the scientific literature and regulatory guidance as to what constitutes an “appropriate” endpoint to a set of stress experiments. That is, there is no clear agreement regarding how to determine if a sample has been sufficiently stressed. Notably, it is unclear what represents a suitable justification for declaring a drug substance (DS) or drug product (DP) “stable” to a specific forced degradation condition. To address these concerns and to ensure all pharmaceutically-relevant, potential degradation pathways have been suitably evaluated, we introduce a two-endpoint classification designation supported by experimental data. These two endpoints are 1) a % total degradation target outcome (e.g., for “reactive” drugs) or, 2) a specified amount of stress, even in the absence of any degradation (e.g., for “stable” drugs). These recommended endpoints are based on a review of the scientific literature, regulatory guidance, and a forced degradation data set from ten global pharmaceutical companies. The experimental data set, derived from the Campbell et al. (2022) benchmarking study,1 provides justification for the recommendations. Herein we provide a single source reference for small molecule DS and DP forced degradation stress conditions and endpoint best practices to support regulatory submissions (e.g., marketing applications). Application of these forced degradation conditions and endpoints, as part of a well-designed, comprehensive and a sufficiently rigorous study plan that includes both the DS and DP, provides comprehensive coverage of pharmaceutically-relevant degradation and avoids unreasonably extreme stress conditions and drastic endpoint recommendations sometimes found in the literature.

Study of the effectiveness of a ZnO–TiO2 formulation in the degradation of humic substances in mature leachate by solar photocatalysis Brazil

Treatment of landfill leachate is an important environmental issue, especially in developing countries such as Brazil. Advanced oxidation processes (AOPs) have been considered interesting treatment alternatives. In this study, ZnO–TiO2 mixtures were incorporated into a paint polymer matrix and fixed onto supports. Paints were applied by overlapping coat layers on plates, resulting in high film thickness (600 ± 80 µm). Treatment of mature leachate by an AOP was conducted in a plug flow reactor connected to a stirred tank under solar irradiation. The objective was to evaluate the degradation of humic acid (HA) and fulvic acid + humins (FAH). The highest HA and FAH removal efficiencies were 62% ± 4.9% and 16% ± 4.2%, respectively. The kinetic model provided a coefficient of determination (R2) of 0.974. Rate constants for HA and FAH removal were 2.96 and 1.03 × 10−3 min−1, respectively. Statistical models for HA and FAH degradation had R2 values of 0.96 and 0.99, respectively. Both approaches indicated that HA degradation is greater at acidic pH and higher TiO2 concentrations. FAH degradation was favored by acidic pH and higher ZnO concentrations. Statistical models showed the same mean difference in conversion between replicate runs of HA and FAH, suggesting a uniform diffusion of fractions through catalysts.&#x0D; Keywords: heterogeneous photocatalysis, humic and fulvic acid, landfill leachate treatment, titanium dioxide, zinc oxide.

Effects of fermentation chamber temperature on microbes and quality of cigar wrapper tobacco leaves.

The natural fermentation of cigar tobacco leaves usually utilizes natural temperature and humidity for fermentation. Cigars produced in China are often fermented in winter, and the low environmental temperatures can lead to slow heating of the tobacco stack, affecting the cigar tobacco leaves quality. This study aimed to determine the minimum chamber temperature required to initiate the process of fermentation for cigar tobacco leaves and to explore the impact of temperature on the microbial community of tobacco leaves. Here, the cigar variety "Dexue 1" were subjected to stacking fermentation under three temperature parameters (20 ℃, 27 ℃, 34 ℃). With an increase in environmental temperature, the temperature inside the stack of cigar leaves increased significantly, the protein, total sugar, starch, and total alkaloid content in fermented tobacco leaves decreased, and the aroma components and amino acid content increased. Microbial richness and community diversity associated with fermented tobacco were highest at chamber temperatures of above 27 ℃. The relative abundance of Chryseobacterium and Rhodococcus was significantly negatively correlated with protein, alkaloids, total sugar, and starch, and positively correlated with amino acids and aroma components. Chryseobacterium and Rhodococcus may be responsible for the degradation of macromolecular substances and the conversion of favorable aromatic substances, thus improving the tobacco leaves quality. This study demonstrated that increasing the fermentation chamber temperature above 27 ℃ was conductive to raising the inner-stack temperature, increased microbial diversity and aromatic quality, reduced the strength and irritation, and extremely enhanced the overall quality of fermented cigar tobacco leaves. KEY POINTS: • The environmental temperature of the fermentation chamber has a significant impact on the quality of tobacco • Temperature > 27 ℃ can initiate the process of cigar tobacco leaves fermentation and increase inner-stack temperature and microbial diversity and abundance • Chryseobacterium and Rhodococcus may be related to the degradation of macromolecular substances and the transformation of aromatic substances, thereby improving the quality of tobacco leaves.

Degradation study of Doxycycline in bulk and formulation by UV-Visible spectrophotometry

Introduction: Forced degradation is a process that involves degradation of drug products and drug substances at condition more severe than accelerated conditions and thus generates degradation products that can be studied to determine the stability of the molecule. Aim and objective: To investigate the forced degradation study for the determination of degradation of Doxycycline by UV-Visible spectrophotometric method. Methods: Doxycycline sample and standard were exposed to different stress conditions (hydrolytic and oxidative degradation). Both standard drug and marketed formulations were used for the degradation study. The amount of percentage degradation of each standard and samples were calculated by taking absorbances at their λmax with the help of UV-Visible spectrophotometer. Forced degradation of drug substance was done by exposing to acidic, basic and to medium of hydrogen peroxide. The degradation results of each condition were compared with that of standard. This method can be used successfully for studying the stress degradation factors. Because this method is less time consuming and simple and cost effective also. Results: Forced degradation of selected drugs performed using HCl, NaOH and H2O2. Degraded sample were quantified by UV visible spectroscopy. In all the methods used in degradation study, sample undergoes greater degradation compared with that of standard. Among the degradation conditions used in the study it is found that NaOH produce more degradation.