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The Influence of Environmental Conditions on Secondary Metabolites in Medicinal Plants: A Literature Review.
Pant, P, Pandey, S, Dall'Acqua, S
Chemistry & biodiversity. 2021;(11):e2100345
Abstract
Medicinal plants, a source of different phytochemical compounds, are now subjected to a variety of environmental stresses during their growth and development. Different ecologically limiting factors including temperature, carbon dioxide, lighting, ozone, soil water, soil salinity and soil fertility has significant impact on medicinal plants' physiological and biochemical responses, as well as the secondary metabolic process. Secondary metabolites (SMs) are useful for assessing the quality of therapeutic ingredients and nowadays, these are used as important natural derived drugs such as immune suppressant, antibiotics, anti-diabetic, and anti-cancer. Plants have the ability to synthesize a variety of secondary metabolites to cope with the negative effects of stress. Here, we focus on how individual environmental variables influence the accumulation of plant secondary metabolites. A total of 48 articles were found to be relevant to the review topic during our systematic review. The review showed the influence of different environmental variables on SMs production and accumulation is complex suggesting the relationship are not only species-specific but also related to increases and decline in SMs by up to 50 %. Therefore, this review improves our understanding of plant SMs ability to adapt to key environmental factors. This can aid in the efficient and long-term optimization of cultivation techniques under ambient environmental conditions in order to maximize the quality and quantity of SMs in plants.
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Metal (Mo, W, Ti) Carbide Catalysts: Synthesis and Application as Alternative Catalysts for Dry Reforming of Hydrocarbons-A Review.
Czaplicka, N, Rogala, A, Wysocka, I
International journal of molecular sciences. 2021;(22)
Abstract
Dry reforming of hydrocarbons (DRH) is a pro-environmental method for syngas production. It owes its pro-environmental character to the use of carbon dioxide, which is one of the main greenhouse gases. Currently used nickel catalysts on oxide supports suffer from rapid deactivation due to sintering of active metal particles or the deposition of carbon deposits blocking the flow of gases through the reaction tube. In this view, new alternative catalysts are highly sought after. Transition metal carbides (TMCs) can potentially replace traditional nickel catalysts due to their stability and activity in DR processes. The catalytic activity of carbides results from the synthesis-dependent structural properties of carbides. In this respect, this review presents the most important methods of titanium, molybdenum, and tungsten carbide synthesis and the influence of their properties on activity in catalyzing the reaction of methane with carbon dioxide.
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Synthetic Enzyme-Catalyzed CO2 Fixation Reactions.
Aleku, GA, Roberts, GW, Titchiner, GR, Leys, D
ChemSusChem. 2021;(8):1781-1804
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Abstract
In recent years, (de)carboxylases that catalyze reversible (de)carboxylation have been targeted for application as carboxylation catalysts. This has led to the development of proof-of-concept (bio)synthetic CO2 fixation routes for chemical production. However, further progress towards industrial application has been hampered by the thermodynamic constraint that accompanies fixing CO2 to organic molecules. In this Review, biocatalytic carboxylation methods are discussed with emphases on the diverse strategies devised to alleviate the inherent thermodynamic constraints and their application in synthetic CO2 -fixation cascades.
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Novel technologies for emission reduction complement conservation agriculture to achieve negative emissions from row-crop production.
Northrup, DL, Basso, B, Wang, MQ, Morgan, CLS, Benfey, PN
Proceedings of the National Academy of Sciences of the United States of America. 2021;(28)
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Abstract
Plants remove carbon dioxide from the atmosphere through photosynthesis. Because agriculture's productivity is based on this process, a combination of technologies to reduce emissions and enhance soil carbon storage can allow this sector to achieve net negative emissions while maintaining high productivity. Unfortunately, current row-crop agricultural practice generates about 5% of greenhouse gas emissions in the United States and European Union. To reduce these emissions, significant effort has been focused on changing farm management practices to maximize soil carbon. In contrast, the potential to reduce emissions has largely been neglected. Through a combination of innovations in digital agriculture, crop and microbial genetics, and electrification, we estimate that a 71% (1,744 kg CO2e/ha) reduction in greenhouse gas emissions from row crop agriculture is possible within the next 15 y. Importantly, emission reduction can lower the barrier to broad adoption by proceeding through multiple stages with meaningful improvements that gradually facilitate the transition to net negative practices. Emerging voluntary and regulatory ecosystems services markets will incentivize progress along this transition pathway and guide public and private investments toward technology development. In the difficult quest for net negative emissions, all tools, including emission reduction and soil carbon storage, must be developed to allow agriculture to maintain its critical societal function of provisioning society while, at the same time, generating environmental benefits.
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Alkali Therapy for Respiratory Acidosis: A Medical Controversy.
Adrogué, HJ, Madias, NE
American journal of kidney diseases : the official journal of the National Kidney Foundation. 2020;(2):265-271
Abstract
Alkali therapy for certain organic acidoses remains a topic of ongoing controversy, but little attention has been given to a related medical controversy, namely the prescription of alkali for respiratory acidosis. We first describe the determinants of carbon dioxide retention in the 2 types of respiratory failure; hypercapnic respiratory failure and hypoxemic respiratory failure with coexisting hypercapnia. We then highlight the deleterious consequences of severe acidemia for several organ systems, particularly the cardiovascular and central nervous systems. We argue that alkali therapy is not indicated for respiratory acidosis as a simple acid-base disturbance. Notwithstanding, we recommend prescription of alkali for severe acidemia caused by mixed acidosis (ie, combined respiratory and metabolic acidosis) or permissive hypercapnia. We examine the utility of alkali therapy in various clinical scenarios incorporating respiratory acidosis. We conclude that controlled studies will be required to test the impact of alkali therapy on clinical outcomes of these clinical settings. Such studies should also examine the optimal mode of administering alkali (amount, rate, and tonicity) and the blood pH to be targeted. The development of new buffers should be explored, especially systems that do not generate carbon dioxide or even consume it.
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Comparing Molecular Mechanisms in Solar NH3 Production and Relations with CO2 Reduction.
Mallamace, D, Papanikolaou, G, Perathoner, S, Centi, G, Lanzafame, P
International journal of molecular sciences. 2020;(1)
Abstract
Molecular mechanisms for N2 fixation (solar NH3) and CO2 conversion to C2+ products in enzymatic conversion (nitrogenase), electrocatalysis, metal complexes and plasma catalysis are analyzed and compared. It is evidenced that differently from what is present in thermal and plasma catalysis, the electrocatalytic path requires not only the direct coordination and hydrogenation of undissociated N2 molecules, but it is necessary to realize features present in the nitrogenase mechanism. There is the need for (i) a multi-electron and -proton simultaneous transfer, not as sequential steps, (ii) forming bridging metal hydride species, (iii) generating intermediates stabilized by bridging multiple metal atoms and (iv) the capability of the same sites to be effective both in N2 fixation and in COx reduction to C2+ products. Only iron oxide/hydroxide stabilized at defective sites of nanocarbons was found to have these features. This comparison of the molecular mechanisms in solar NH3 production and CO2 reduction is proposed to be a source of inspiration to develop the next generation electrocatalysts to address the challenging transition to future sustainable energy and chemistry beyond fossil fuels.
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Toward Sustainable Hydroxymethylfurfural Production Using Seaweeds.
Heo, JB, Lee, YS, Chung, CH
Trends in biotechnology. 2020;(5):487-496
Abstract
Chemical manufacturing involves carbon sources releasing CO2 into the atmosphere. By contrast, seaweeds are carbon sinks that can absorb released CO2 and therefore have great potential for use as feedstocks in sustainable chemical manufacturing. In particular, seaweeds could contribute to mitigating vast amounts of global CO2 emissions. Accordingly, seaweeds could be an excellent candidate biomaterial for sustainable production of hydroxymethylfurfural (HMF), called a 'sleeping giant' platform chemical due to its wide versatility in chemical manufacturing. HMF is produced through sugar dehydration mechanisms, and seaweed storage glucans comprised of glucose can be appropriate feeding substrates for its production. This opinion article introduces a new opportunity for sustainable production of HMF using storage glucan-rich seaweeds.
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Constraining estimates of terrestrial carbon uptake: new opportunities using long-term satellite observations and data assimilation.
Smith, WK, Fox, AM, MacBean, N, Moore, DJP, Parazoo, NC
The New phytologist. 2020;(1):105-112
Abstract
The response of terrestrial carbon uptake to increasing atmospheric [CO2 ], that is the CO2 fertilization effect (CFE), remains a key area of uncertainty in carbon cycle science. Here we provide a perspective on how satellite observations could be better used to understand and constrain CFE. We then highlight data assimilation (DA) as an effective way to reconcile different satellite datasets and systematically constrain carbon uptake trends in Earth System Models. As a proof-of-concept, we show that joint DA of multiple independent satellite datasets reduced model ensemble error by better constraining unobservable processes and variables, including those directly impacted by CFE. DA of multiple satellite datasets offers a powerful technique that could improve understanding of CFE and enable more accurate forecasts of terrestrial carbon uptake.
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The influence of grafting on crops' photosynthetic performance.
Fullana-Pericàs, M, Conesa, MÀ, Pérez-Alfocea, F, Galmés, J
Plant science : an international journal of experimental plant biology. 2020;:110250
Abstract
In a near scenario of climate change where stress-derived limitations on crops' yield by affecting plant gas-exchange are expected, grafting may become a cheap and easy technique to improve crops photosynthetic performance and water-use efficiency. Inconsistent data of the effect of rootstocks over gas-exchange can be found in literature, being necessary an integrative analysis of the effect of grafting over photosynthetic parameters. With this aim, we present a compilation of the effect of graft on the net CO2 assimilation rate (AN) and other photosynthetic parameters across different species with agronomic interest. No differences were observed in any photosynthetic parameter between non-grafted and self-grafted plants under non-stress conditions. However, differences were found depending on the used rootstock, particularly for the intrinsic water-use efficiency (WUEi). We observed that variations in AN induced by rootstocks were related to changes in both diffusive and biochemical parameters. Under drought or salt stress, different photosynthetic performances were observed depending on the rootstock, although the high variability among studies promted to remarkable results. Overall, we observed that grafting can be a useful technique to improve plant photosynthetic performance, and therefore, crop yield and WUE, and that the rootstock selection for a target environment is determinant for the variations in photosynthesis.
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Characterization of Carbonic Anhydrase In Vivo Using Magnetic Resonance Spectroscopy.
Tomar, JS, Shen, J
International journal of molecular sciences. 2020;(7)
Abstract
Carbonic anhydrase is a ubiquitous metalloenzyme that catalyzes the reversible interconversion of CO2/HCO3-. Equilibrium of these species is maintained by the action of carbonic anhydrase. Recent advances in magnetic resonance spectroscopy have allowed, for the first time, in vivo characterization of carbonic anhydrase in the human brain. In this article, we review the theories and techniques of in vivo 13C magnetization (saturation) transfer magnetic resonance spectroscopy as they are applied to measuring the rate of exchange between CO2 and HCO3- catalyzed by carbonic anhydrase. Inhibitors of carbonic anhydrase have a wide range of therapeutic applications. Role of carbonic anhydrases and their inhibitors in many diseases are also reviewed to illustrate future applications of in vivo carbonic anhydrase assessment by magnetic resonance spectroscopy.