Potential of alisols as cancer therapeutic agents: Investigating molecular mechanisms, pharmacokinetics and metabolism.

Albeit remarkable achievements in anti-cancer endeavors, the prevention and treatment of cancer remain unresolved challenges. Hence, there is an urgent need to explore new and efficacious natural compounds with potential anti-cancer therapeutic agents. One such group of compounds is alisols, tetracyclic triterpene alcohols extracted from alisma orientale. Alisols play a significant role in cancer therapy as they can suppress cancer cell proliferation and migration by regulating signaling pathways such as mTOR, Bax/Bcl-2, CHOP, caspase, NF-kB and IRE1. Pharmacokinetic studies showed that alisols can be absorbed entirely, rapidly, and evenly distributed in vivo. Moreover, alisols are low in toxicity and relatively safe to take. Remarkably, each alisol can be converted into many compounds with different pathways to their anti-cancer effects in the body. Thus, alisols are regarded as promising anti-cancer agents with minimal side effects and low drug resistance. This review will examine and discuss alisols' anti-cancer molecular mechanism, pharmacokinetics and metabolism. Based on a comprehensive analysis of nearly 20 years of research, we evaluate the therapeutic potential of alisols for various types of cancer and offer insights and strategies for developing new cancer treatments.

Therapeutic Effects of Alisma orientale and its Active Constituents on Cardiovascular Disease and Obesity.

The treatment of cardiovascular diseases and obesity, two diseases posing a major risk to human health, has been plagued by the scarcity of potent and effective medication with fewer side effects. To address this problem, numerous efforts, and some progress, have been made. Among possible treatments are some medicinal herbs; particularly promising is Alisma orientale (AO). In the last decade, an increasing amount of research has shown that AO has some desirable therapeutic effects on cardiovascular diseases and obesity. Because of its efficacy, natural origin, and minimal adverse effects, AO has aroused great attention. Based on this, this review provides an overview of the latest progress from the last decade regarding the pharmacological and therapeutic effects, molecular mechanisms, and related effective constituents of AO in the treatment of cardiovascular diseases and obesity. Results from the research currently available reveal that active constituents of AO, such as alisol B 23-acetate, alisol A 24-acetace, and alisol A, have been proven to be effective for treating cardiovascular diseases by modulating the lipid metabolism of macrophages, improving the biological behavior of vascular smooth muscle cells (VSMCs), and enhancing anti-inflammatory effects. Moreover, the active constituents of AO can also intervene in obesity by modulating abnormal glucose and lipid metabolism and fat decomposition of the body by activating the AMPK- and PPAR-related signaling pathways. In summation, based upon our research of available literature, this review reveals that AO and its active constituents have a great potential to be used as drugs for treating cardiovascular diseases and ameliorating obesity.

Engineering a Highly Regioselective Fungal Peroxygenase for the Synthesis of Hydroxy Fatty Acids.

The hydroxylation of fatty acids is an appealing reaction in synthetic chemistry, although the lack of selective catalysts hampers its industrial implementation. In this study, we have engineered a highly regioselective fungal peroxygenase for the ω-1 hydroxylation of fatty acids with quenched stepwise over-oxidation. One single mutation near the Phe catalytic tripod narrowed the heme cavity, promoting a dramatic shift toward subterminal hydroxylation with a drop in the over-oxidation activity. While crystallographic soaking experiments and molecular dynamic simulations shed light on this unique oxidation pattern, the selective biocatalyst was produced by Pichia pastoris at 0.4 g L-1 in a fed-batch bioreactor and used in the preparative synthesis of 1.4 g of (ω-1)-hydroxytetradecanoic acid with 95 % regioselectivity and 83 % ee for the S enantiomer.

Stabilisation of the Fatty Acid Decarboxylase from Chlorella variabilis by Caprylic Acid.

The fatty acid photodecarboxylase from Chlorella variabilis NC64 A (CvFAP) catalyses the light-dependent decarboxylation of fatty acids. Photoinactivation of CvFAP still represents one of the major limitations of this interesting enzyme en route to practical application. In this study we demonstrate that the photostability of CvFAP can easily be improved by the administration of medium-chain length carboxylic acids such as caprylic acid indicating that the best way of maintaining CvFAP stability is 'to keep the enzyme busy'.

An alginate-confined peroxygenase-CLEA for styrene epoxidation.

Oxyfunctionalisation reactions in neat substrate still pose a challenge for biocatalysis. Here, we report an alginate-confined peroxygenase-CLEA to catalyse the enantioselective epoxidation of cis-ß-methylstyrene in a solvent-free reaction system achieving turnover numbers of 96 000 for the biocatalyst and epoxide concentrations of 48 mM.

Intensification of Photobiocatalytic Decarboxylation of Fatty Acids for the Production of Biodiesel.

Light-driven biocatalytic processes are notoriously hampered by poor penetration of light into the turbid reaction media. In this study, wirelessly powered light-emitting diodes are found to represent an efficient and scalable approach for process intensification of the photobiosynthetic production of diesel alkanes from renewable fatty acids.

Identification two key residues at the intersection of domains of a thioether monooxygenase for improving its sulfoxidation performance.

AcCHMO, a cyclohexanone monooxygenase from Acinetobacter calcoaceticus, is a typical Type I Baeyer-Villiger monooxygenase (BVMO). We previously obtained the AcCHMOM6 mutant, which oxidizes omeprazole sulfide (OPS) to the chiral sulfoxide drug esomeprazole. To further improve the catalytic efficiency of the AcCHMOM6 mutant, a focused mutagenesis strategy was adopted at the intersections of the FAD-binding domain, NADPH-binding domain, and α-helical domain based on structural characteristics of AcCHMO. By using focused mutagenesis and subsequent global evolution two key residues (L55 and P497) at the intersections of the domains were identified. Mutant of L55Y improved catalytic efficiency significantly, whereas the P497S mutant alleviated substrate inhibition remarkably. AcCHMOM7 (L55Y/P497S) was obtained by combining the two mutations, which increased the specific activity from 18.5 (M6) to 108 U/g, and an increase in the Ki of the substrate OPS from 34 to 265 µM. The results indicate that catalytic performance can be elevated by modification of the sensitive sites at the intersection of the domains of AcCHMO. The results also provided some insights for the engineering of other Type I BVMOs or other multidomain proteins.

Storm induced estuarine turbidity maxima and controls on nutrient fluxes across river-estuary-coast continuum.

Climate change is likely to increase the frequency and intensity of tropical storms. However, the impacts of major storms on nutrient cycling processes in the river-estuary-coast continuum are poorly understood. Continuous observations were made at lower river stations and on a transect down the Jiulong River Estuary in south east China for three storms in 2013-2014. There were major increases in both dissolved nutrients and suspended particulate matter (SPM) brought down the river during storms. Strong Estuarine Turbidity Maxima (ETM) were observed during major storms and were the result of SPM brought down rivers augmented by sediment scoured within the Upper Estuary (salinity=0psu) and possibly also from behind the dikes opened for flood control. There were major increases in dissolved nutrients (nitrate, ammonium and phosphate) in the Upper Estuary particularly during major Storms C (July 2013) and D (May 2014). These increases were probably due to river inflows with surrounding runoff, pore water supply and nutrients desorbed from scoured sediment. During major Storm D there were greater nutrient fluxes through the estuary-coast interface compared to the nutrients supplied through the river-estuary interface while the opposite pattern was observed during normal flow. The increased supply of ammonium and phosphate to the coastal region caused increased chlorophyll a once the light inhibiting SPM had been removed from the water column. This is likely to increase the potential of eutrophication. Storm induced increases in N:P:Si supplied from the estuary to the coastal region increased the degree of P limitation.

Discovery of Two Native Baeyer-Villiger Monooxygenases for Asymmetric Synthesis of Bulky Chiral Sulfoxides.

Two Baeyer-Villiger monooxygenases (BVMOs), designated BoBVMO and AmBVMO, were discovered from Bradyrhizobium oligotrophicum and Aeromicrobium marinum, respectively. Both monooxygenases displayed novel features for catalyzing the asymmetric sulfoxidation of bulky and pharmaceutically relevant thioethers. Evolutionary relationship and sequence analysis revealed that the two BVMOs belong to the family of typical type I BVMOs and the subtype ethionamide monooxygenase. Both BVMOs are active toward medium- and long-chain aliphatic ketones as well as various thioether substrates but are ineffective toward cyclohexanone, aromatic ketones, and other typical BVMO substrates. BoBVMO and AmBVMO showed the highest activities (0.117 and 0.025 U/mg protein, respectively) toward thioanisole among the tested substrates. Furthermore, these BVMOs exhibited distinct activity and excellent stereoselectivity toward bulky and prochiral prazole thioethers, which is a unique feature of this family of BVMOs. No native enzyme has been reported for the asymmetric sulfoxidation of bulky prazole thioethers into chiral sulfoxides. The identification of BoBVMO and AmBVMO provides an important scaffold for discovering enzymes capable of asymmetrically oxidizing bulky thioether substrates by genome mining.IMPORTANCE Baeyer-Villiger monooxygenases (BVMOs) are valuable enzyme catalysts that are an alternative to the chemical Baeyer-Villiger oxidation reaction. Although BVMOs display broad substrate ranges, no native enzymes were reported to have activity toward the asymmetric oxidation of bulky prazole-like thioether substrates. Herein, we report the discovery of two type I BVMOs from Bradyrhizobium oligotrophicum (BoBVMO) and Aeromicrobium marinum (AmBVMO) which are able to catalyze the asymmetric sulfoxidation of bulky prazole thioethers (proton pump inhibitors [PPIs], a group of drugs whose main action is a pronounced and long-lasting reduction of gastric acid production). Efficient catalysis of omeprazole oxidation by BoBVMO was developed, indicating that this enzyme is a promising biocatalyst for the synthesis of bulky and pharmaceutically relevant chiral sulfoxide drugs. These results demonstrate that the newly identified enzymes are suitable templates for the discovery of more and better thioether-converting BVMOs.

Hydrological controls on nitrogen (ammonium versus nitrate) fluxes from river to coast in a subtropical region: Observation and modeling.

Increased anthropogenic nutrient input and losses has caused eutrophication problems in freshwater and coastal ecosystems worldwide. High-frequency observations and modeling of river fluxes in subtropical regions are required to understand nutrient cycling and predict water quality and ecological responses. In 2014, a normal hydrologic year, we carried out daily sampling of the North Jiulong River in southeast China, which drains an agricultural watershed and experiences the Asian monsoon climate. We focused on the distinct characteristics of two important inorganic nitrogen forms (ammonium and nitrate). Our results show contrasting hydrological controls on the seasonal timing and magnitude of ammonium and nitrate concentrations and loads, likely due to differing sources and transport pathways (surface runoff versus baseflow) to the river. Both nitrogen concentrations were enriched in the dry season and diluted in the wet season. Arrival of rains in the pre-wet period in March caused a "first flush" peak event with the highest concentrations of the year, during which ammonium peaked two weeks earlier than nitrate. In contrast, the majority of nitrogen transport occurred during the lower concentrations of the wet season, with seven storms inducing flood events that lasted 24% of the time, contributed 52% of the runoff, and exported 47% of the ammonium and 42% of the nitrate. We found that seasonally piecewise LOADEST models (for pre-wet, wet and post-wet periods) performed better (5-8% error) than a year-round model (12-24% error) in estimating monthly nitrogen loads. However, not all nitrogen dynamics are easily synthesized by this approach, and extreme floods might produce a greater deviation in estimating nitrogen loads. These findings represent important implications for coastal ecology and provide opportunity on improving observation and modeling.

Effective pretreatment of sugarcane bagasse with combination pretreatment and its hydrolyzates as reaction media for the biosynthesis of ethyl (S)-4-chloro-3-hydroxybutanoate by whole cells of E. coli CCZU-K14.

In this study, sugarcane bagasse (SB) was pretreated with combination pretreatment (e.g., sequential KOH extraction and ionic liquid soaking, sequential KOH extraction and Fenton soaking, or sequential KOH extraction and glycerol soaking). After the enzymatic hydrolysis of pretreated SBs, it was found that all these three concentrated hydrolyzates could be used for the asymmetric bioreduction of ethyl 4-chloro-3-oxobutanoate (COBE) into ethyl (S)-4-chloro-3-hydroxybutanoate [(S)-CHBE]. Compared with glucose, arabinose and cellobiose couldn't promote the initial reaction rate, and xylose could increase the intracellular NADH content. Moreover, it was the first report that hydrolyzates could be used for the effective biosynthesis of (S)-CHBE (∼500g/L; 98.0% yield) from 3000 COBE by whole cells of Escherichia coli CCZU-K14 in the presence of ß-CD (0.4mol ß-CD/mol COBE), l-glutamine (200mM) and glycine (500mM). In conclusion, it is a new alternative to utilize bioresource for the synthesis of key chiral intermediate (S)-CHBE.

[Sediment-water flux and processes of nutrients and gaseous nitrogen release in a China River Reservoir].

The key processes and fluxes of nutrients (N and P) and gaseous N (N2 and N2O) across the sediment-water interface in a river reservoir (Xipi) of the Jiulong River watershed in southeast China were studied. Intact core sediment incubation of nutrients exchange, in-situ observation and lab incubation of excess dissolved N2 and N2O (products of nitrification, denitrification and Anammox), and determination of physiochemical and microbe parameters were carried out in 2013 for three representative sites along the lacustrine zone of the reservoir. Results showed that ammonium and phosphate were generally released from sediment to overlying water [with averaged fluxes of N (479.8 ± 675.4) mg. (m2. d)-1 and P (4. 56 ± 0.54) mg. (m2 d) -1] , while nitrate and nitrite diffused into the sediment. Flood events in the wet season could introduce a large amount of particulate organic matter that would be trapped by the dam reservoir, resulting in the high release fluxes of ammonium and phosphate observed in the following low-flow season. No clear spatial variation of sediment nutrient release was found in the lacustrine zone of the reservoir. Gaseous N release was dominated by excess dissolved N2 (98% of total), and the N2 flux from sediment was (15.8 ± 12. 5) mg (m2. d) -1. There was a longitudinal and vertical variation of excess dissolved N2, reflecting the combined results of denitrification and Anammox occurring in anoxic sediment and fluvial transport. Nitrification mainly occurred in the lower lacustrine zone, and the enrichment of N2O was likely regulated by the ratio of ammonium to DIN in water.