Sesquilignans PD from Zanthoxylum nitidum var. tomentosum exerts antitumor effects via the ROS/MAPK pathway in liver cancer cells.

Sesquilignans PD is a natural phenylpropanoid compound that was isolated from Zanthoxylum nitidum var. tomentosum. In this study, we assessed the antitumor effect of PD on SK-Hep-1 and HepG2 cells and the underlying molecular mechanisms. The results revealed that PD markedly inhibited the proliferation and migration of both liver cancer cells. Moreover, PD induced apoptosis, autophagy, and reactive oxygen species (ROS) production in liver cancer cells. Notably, PD increased the protein levels of p-p38 MAPK and p-ERK1/2 in liver cancer cells. This is the first report on the anticancer effect of PD, which is mediated via increased ROS production and MAPK signaling activation.

A calculation approach for current density distribution evolution of secondary electrons using differential algebra method.

In this study, the concept of the current density distribution (CDD) evolution of secondary electron (SE) beam is presented, and a novel approach using the differential algebra (DA) method is proposed to calculate the CDD evolution of the SE beam. Firstly, the emitted SE beam is divided into some beamlets in polar and azimuth angle directions. For each beamlet only one reference trajectory is traced using DA method. As a result, the transfer properties for this beamlet are obtained. Using the transfer properties, the current density function at arbitrary plane for the beamlet can be derived, in which the initial angle distribution, energy distribution and emission source size are considered. And then, the current density function is integrated, resulting in the CDD of this beamlet at arbitrary plane. Finally, the CDD evolution of the whole SE beam is obtained by superposing the CDDs of all beamlets. As an example, a SE detection system for a scanning electron microscope (SEM) is calculated using the proposed approach and therefore the SE CDD evolution is obtained and analyzed. Furthermore, experiments for observing the SE image of detector are performed, and the calculated SE CDD and the corresponding simulation images well explained the experimental results, validating the proposed calculation method. The proposed approach can be potentially applied for optimizing the SE detection system and therefore improving the collection efficiency of SE.

Alkaloids from Corydalis saxicola and their antiproliferative activity against cancer cells.

Eight undescribed alkaloids named corydalisine D-K (1-7), including one isoquinoline benzopyranone alkaloid (1), one benzocyclopentanone alkaloid (2), four benzofuranone alkaloids (3, 4, and 5a/5b) and two protoberberine alkaloids (6 and 7), along with fourteen known ones, were isolated from the Corydalis saxicola. Their structures, including absolute configurations, were unambiguously identified using spectroscopic techniques, single-crystal X-ray diffraction and electron circular dichroism calculation. Compounds 2, 14 and 21 exhibit antiproliferative activity against five cancer cell lines. The aporphine alkaloid demethylsonodione (compound 14), which exhibited the best activity (IC50 = 3.68 ± 0.25 µM), was subjected to further investigation to determine its mechanism of action against the T24 cell line. The molecular mechanism was related to the arrest of cell cycle S-phase, inhibition of CDK2 expression, accumulation of reactive oxygen species (ROS), induction of cell apoptosis, inhibition of cell migration, and activation of p38 MAPK signaling pathway. The results indicated that 14 could be used as a potential candidate agent for further development of anti-bladder transitional cell carcinoma.

Single fibre cytoarchitecture in ventilator-induced diaphragm dysfunction (VIDD) assessed by quantitative morphometry second harmonic generation imaging: Positive effects of BGP-15 chaperone co-inducer and VBP-15 dissociative corticosteroid treatment.

Ventilator-induced diaphragm dysfunction (VIDD) is a common sequela of intensive care unit (ICU) treatment requiring mechanical ventilation (MV) and neuromuscular blockade (NMBA). It is characterised by diaphragm weakness, prolonged respirator weaning and adverse outcomes. Dissociative glucocorticoids (e.g., vamorolone, VBP-15) and chaperone co-inducers (e.g., BGP-15) previously showed positive effects in an ICU-rat model. In limb muscle critical illness myopathy, preferential myosin loss prevails, while myofibrillar protein post-translational modifications are more dominant in VIDD. It is not known whether the marked decline in specific force (force normalised to cross-sectional area) is a pure consequence of altered contractility signaling or whether diaphragm weakness also has a structural correlate through sterical remodeling of myofibrillar cytoarchitecture, how quickly it develops, and to which extent VBP-15 or BGP-15 may specifically recover myofibrillar geometry. To address these questions, we performed label-free multiphoton Second Harmonic Generation (SHG) imaging followed by quantitative morphometry in single diaphragm muscle fibres from healthy rats subjected to five or 10 days of MV + NMBA to simulate ICU treatment without underlying confounding pathology (like sepsis). Rats received daily treatment of either Prednisolone, VBP-15, BGP-15 or none. Myosin-II SHG signal intensities, fibre diameters (FD) as well as the parameters of myofibrillar angular parallelism (cosine angle sum, CAS) and in-register of adjacent myofibrils (Vernier density, VD) were computed from SHG images. ICU treatment caused a decline in FD at day 10 as well as a significant decline in CAS and VD from day 5. Vamorolone effectively recovered FD at day 10, while BGP-15 was more effective at day 5. BGP-15 was more effective than VBP-15 in recovering CAS at day 10 although not to control levels. In-register VD levels were restored at day 10 by both compounds. Our study is the first to provide quantitative insights into VIDD-related myofibrillar remodeling unravelled by SHG imaging, suggesting that both VBP-15 and BGP-15 can effectively ameliorate the structure-related dysfunction in VIDD.

Phytoconstituents of Selaginella effusa Alston and Their α-Glucosidase as well as Urease Inhibitory Activities.

Three new compounds (1-2, 14), as well as 22 known compounds (3-13, 15-25), were extracted for the first time from the Selaginella effusa Alston (S. effusa). For the unknown compounds, the planar configurations were determined via NMR and by high-resolution mass spectrometry, while their absolute configurations were determined by calculated electronic circular dichroism (ECD), and the configuration of the stereogenic center of biflavones 4-5 were established for the first time. The pure compounds (1-25) were tested in vitro to determine the inhibitory activity of the enzyme-catalyzed reactions. Compounds 1-9 inhibited α-glucosidase with IC50 values ranging from 0.30±0.02 to 4.65±0.04 µM and kinetic analysis of enzyme inhibition indicated that biflavones 1-3 were mixed-type α-glucosidase inhibitors. Compounds 12-13 showed excellent inhibitory activity against urease, with compound 12 (IC50 =4.38±0.31 µM) showing better inhibitory activity than the positive control drug AHA (IC50 13.52±0.61 µM). In addition, molecular docking techniques were used to simulate inhibitor-enzyme binding and to estimate the binding posture of the α-glucosidase and urease catalytic sites.

Discovery of novel 2-oximino-2-indolylacetamide derivatives as potent anticancer agents capable of inducing cell autophagy and ferroptosis.

A series of 2-oximino-2-indolylacetamide derivatives were designed, synthesized and evaluated for their antitumour effects. Among them, 4d exhibited the most potent antiproliferative effect in vitro on the tested human cancer cells. Additionally, 4d significantly induced cell apoptosis, caused mitochondrial dysfunction, promoted Bax, cleaved-PARP and p53 expression and inhibited Bcl-2 expression in 5-8F cells. Moreover, 4d remarkably promoted autophagosome formation, leading to cell apoptosis. Further investigation indicated that 4d could trigger cell death through cell ferroptosis, including increased ROS generation and lipid peroxidation and decreased glutathione peroxidase 4 (GPx4) expression and glutathione (GSH) levels. More importantly, 4d induced 5-8F cell death by activating ROS/MAPK and inhibiting the AKT/mTOR and STAT3 signalling pathways. Interestingly, 4d significantly suppressed tumour growth in a 5-8F cell xenograft model without obvious toxicity to mice. Overall, these results demonstrate that 4d may be a potential compound for cancer therapy.

Structurally diverse isobutylamides from Zanthoxylum nitidum.

Five pairs of new racemic alkamides (1a/1b and 4a/4b-7a/7b) and two new achiral derivatives (2-3), as well as five known ones (8-12), were purified from the 95% EtOH extract of Zanthoxylum nitidum. Their structures were elucidated based on spectroscopic analyses (NMR and HR-ESI-MS), electronic circular dichroism (ECD) and NMR calculations. The enantiomeric separation was successfully achieved by chiral-phase HPLC-ECD measurements. Among all the isolates, compounds 2, 3, and 10 showed inhibitory effects against five human cancer cell lines, with IC50 values in range of 18.51-48.03 µM.

Undescribed isoquinolines from Zanthoxylum nitidum and their antiproliferative effects against human cancer cell lines.

Eleven previously undescribed alkaloids, including three pairs of enantiomers nitidumalkaloids A-C, a pair of scalemic mixtures nitidumalkaloid D and three optically pure or achiral alkaloids, nitidumalkaloids E-G, along with 20 known alkaloids, were isolated from an ethanolic extract of the whole Zanthoxylum nitidum (Roxb.) DC plant. The chemical structures of the alkaloids were elucidated using a combination of comprehensive nuclear magnetic resonance (NMR) and high-resolution electro-spray ionization mass spectrometry (HR-ESI-MS) analyses. The configuration of the stereogenic centers of all undescribed compounds was precisely established based on single-crystal X-ray diffraction and electronic circular dichroism (ECD) calculations. Racemic mixtures of nitidumalkaloids A-D were purified, and their enantiomers were analyzed via chiral-phase high-performance liquid chromatography with electrochemical detection measurements (HPLC-ECD). Twelve compounds exhibited significant antiproliferative activities against a panel of cancer cell lines. Further studies were designed to investigate the underlying molecular mechanism of (1'S, 6R)-nitidumalkaloid B, which was the most active antiproliferative agent against human cancer A549 cells. G2/M cell cycle arrest, induction of apoptosis, and suppression of the Wnt/ß-catenin signaling pathway were in part associated with the antiproliferative activity of (1'S, 6R)-nitidumalkaloid B. Moreover, (1'S, 6R)-nitidumalkaloid B inhibited cell migration by downregulating the epithelial-mesenchymal transition process in A549 cells. These data suggest that the antiproliferation activity of (1'S, 6R)-nitidumalkaloid B was correlated with the stereoselectivity of the stereoisomers, and (1'S, 6R)-nitidumalkaloid B was prioritized as a potential leading compound for the management of aggressive human non-small-cell lung cancer (NSCLC) from natural products.

A prospective clinical study on the mechanisms underlying critical illness myopathy-A time-course approach.

BACKGROUND: Critical illness myopathy (CIM) is a consequence of modern critical care resulting in general muscle wasting and paralyses of all limb and trunk muscles, resulting in prolonged weaning from the ventilator, intensive care unit (ICU) treatment and rehabilitation. CIM is associated with severe morbidity/mortality and significant negative socioeconomic consequences, which has become increasingly evident during the current COVID-19 pandemic, but underlying mechanisms remain elusive. METHODS: Ten neuro-ICU patients exposed to long-term controlled mechanical ventilation were followed with repeated muscle biopsies, electrophysiology and plasma collection three times per week for up to 12 days. Single muscle fibre contractile recordings were conducted on the first and final biopsy, and a multiomics approach was taken to analyse gene and protein expression in muscle and plasma at all collection time points. RESULTS: (i) A progressive preferential myosin loss, the hallmark of CIM, was observed in all neuro-ICU patients during the observation period (myosin:actin ratio decreased from 2.0 in the first to 0.9 in the final biopsy, P < 0.001). The myosin loss was coupled to a general transcriptional downregulation of myofibrillar proteins (P < 0.05; absolute fold change >2) and activation of protein degradation pathways (false discovery rate [FDR] <0.1), resulting in significant muscle fibre atrophy and loss in force generation capacity, which declined >65% during the 12 day observation period (muscle fibre cross-sectional area [CSA] and maximum single muscle fibre force normalized to CSA [specific force] declined 30% [P < 0.007] and 50% [P < 0.0001], respectively). (ii) Membrane excitability was not affected as indicated by the maintained compound muscle action potential amplitude upon supramaximal stimulation of upper and lower extremity motor nerves. (iii) Analyses of plasma revealed early activation of inflammatory and proinflammatory pathways (FDR < 0.1), as well as a redistribution of zinc ions from plasma. CONCLUSIONS: The mechanical ventilation-induced lung injury with release of cytokines/chemokines and the complete mechanical silencing uniquely observed in immobilized ICU patients affecting skeletal muscle gene/protein expression are forwarded as the dominant factors triggering CIM.

New alkaloids and their in vitro antitumor activity of Corydalis balansae.

The chemical investigation on Corydalis balansae resulted in the isolation of three previous undescribed compounds (1, 10, and 11) and 17 known compounds. Compound 1 and 2 were obtained as two lignanamide dimers, and compound 11 had a spiro [benzofuranone-benzazepine] skeleton, which was found in Corydalis for the first time. The structures of new compound were determined by the detailed analysis of 1D/2D NMR, UV, and IR data. Absolute configurations of compounds 10 and 11 were defined by their crystal X-ray diffraction data and calculations of electronic circular dichroism (ECD). The CCK-8 method was used to assay the inhibition effect of all the compounds on the growth of Hela, MGC-803, A549, and HepG2 cancer cells. Compound 2, 13, and 14 showed moderate inhibitory activity against the tested cell lines. Compound 2 exhibited potential antitumor activity against MGC-803 cells with an IC50 value of 20.8 µM, while the positive control etoposide was 17.3 µM. Furthermore, results from the cellular-mechanism investigation indicated that compound 2 could induce S-phase cell-cycle arrest and MGC-803 cells apoptosis, which was triggered by the up-regulation of PARP1, caspase-3 and -9, Bax, and down-regulation of Bcl-2. The 2-induced strong apoptosis indicated that compound 2 had good potential as an antitumor lead compound.

Four New Sesquiterpenoids from Zanthoxylum nitidum.

Zanthoxylum nitidum (Roxb.) DC., is one of Guangxi's characteristic national medicines, and is the classic Laoban medicine of Yao people "Ru Shan Hu" and Zhuang medicine "Liang Bei Zhen". It has been used as an anti-inflammatory, analgesic and haemostatic medicine for thousands of years. In this study, four new sesquiterpenoids (1-4), along with six previously described coumarins (5-10), were isolated from 95 % EtOH extract of Zanthoxylum nitidum. Comprehensive spectroscopic analyses (NMR and HR-ESI-MS) were used to elucidate the structures of these isolates. The absolute configurations of nitidumine A-D (1-4) were established by electronic circular dichroism (ECD). Their cytotoxicity of all the isolates against five cancer cell lines (T24, HeLa, MGC-803, A549, and HepG2) was evaluated by MTT experiment and found not to be cytotoxicity.

Pentagalloylglucose suppresses the growth and migration of human nasopharyngeal cancer cells via the GSK3ß/ß-catenin pathway in vitro and in vivo.

BACKGROUND: Nasopharyngeal carcinoma (NPC) is a type of malignant squamous cell tumour originating from the nasopharynx epithelium. Pentagalloylglucose (PGG) is a natural polyphenolic compound that exerts anticancer effects in many types of tumours. However, the role and underlying mechanism of PGG in NPC cells have not been fully defined. PURPOSE: This study aimed to investigate the anticancer activity of PGG as well as the potential mechanism in NPC cells. METHODS: The effects of PGG on the proliferation, apoptosis and cell cycle distribution of CNE1 and CNE2 cells were assessed by MTT and flow cytometry assays. Cell migration was evaluated using wound healing and transwell assays. The expression of microtubule-associated protein 1 light chain 3 beta (LC3B) was observed by immunofluorescence staining. Western blotting was used to explore the levels of related proteins and signalling pathway components. Furthermore, the effects of PGG on NPC cell growth were analysed in a xenograft mouse model in vivo using cisplatin as a positive control. RESULTS: PGG dose-dependently inhibited the proliferation of CNE1 and CNE2 cells. PGG regulated the cell cycle by altering p53, cyclin D1, CDK2, and cyclin E1 protein levels. PGG induced apoptosis and autophagy in NPC cells and elevated the Bax/Bcl-2 ratio and the protein levels of LC3B. Moreover, PGG decreased NPC cell migration by increasing E-cadherin and decreasing N-cadherin, vimentin and CD44 protein levels. Mechanistically, PGG treatment downregulated p-mTOR and ß-catenin expression but upregulated p-p38 MAPK and p-GSK3ß expression. In addition, PGG significantly inhibited NPC cell tumour growth and lung metastasis in vivo. CONCLUSION: PGG may suppress cell proliferation, induce apoptosis and autophagy, and decrease the metastatic capacity of NPC cells through the p38 MAPK/mTOR and Wnt/ß-catenin pathways. The present study provides evidence for PGG as a potential therapy for NPC.

The optimized quantum dot mediated thermometry reveals isoform specific differences in efficiency of myosin extracted from muscle mini bundles.

The biophysical function of myosin in vitro has been extensively investigated in different motility assays, but the study of myosin ATPase properties at the fiber level is insufficiently investigated. In this study, quantum dot (QD) mediated thermometry measurements were optimized to measure the efficiency of myosin extracted from muscle mini bundles. A reduction in fluorescent intensity of QD reflects an increase in temperature caused by the heat released during ATP hydrolysis and denotes the efficiency of the motor protein myosin. The procedure for extracting myosin was similar to the single fiber in vitro motility assay with some small modifications, and the concentration of myosin was represented by the extracted total protein since the ratio of extracted myosin to total protein was constant. Moreover, the efficiencies of myosin extracted from preparations containing different myosin heavy chain isoforms reveal lower efficiency of slow compared to fast myosin isoforms. Specifically, more heat was released in slow myosin enzymatic reaction, resulting in faster decay of QD fluorescence intensity. Hence, the optimized QD mediated thermometry provides a novel and sensitive approach to evaluate efficiency of myosin ATPase obtained from small muscle samples, representing a significant advantage in the clinical evaluation of neuromuscular disorders.

Molten salt method synthesis of multivalent cobalt and oxygen vacancy modified Nitrogen-doped MXene as highly efficient hydrogen and oxygen Evolution reaction electrocatalysts.

Nitrogen-doped Ti3C2Ty MXene with multivalent cobalt and oxygen vacancy (Vo) modification was obtained by using molten salt method and greatly improved electrocatalytic performance. The structural properties of MXene and the valence state of cobalt were adjusted by controlling the molten salt temperature. When the molten salt treatment temperature was 377 °C, the obtained 377-CoOxN1-x-Ti3C2Ty maintained the chemical structure of MXene well, and also has high Co2+ content and Vo content. Electrochemical test results showed that 377-CoOxN1-x-Ti3C2Ty had the lowest Hydrogen Evolution Reaction (HER) overpotential of 87.73 mV and good electrocatalytic stability. X-ray Photoelectron Spectroscopy (XPS) results and Density Functional Theory (DFT) calculations showed that the introduction of polyvalent cobalt and Vo in the nitrogen-doped Ti3C2Ty structure effectively reduced the energy barrier of the electrocatalytic reaction of MXene.

The neurotrophic and antineuroinflammatory effects of phenylpropanoids from Zanthoxylum nitidum var. tomentosum (Rutaceae).

Three novel lignans (1, 5 and 6) and two novel quinic acids (16 and 17) along with 15 known phenylpropanoids were obtained from the ethanol extract of Zanthoxylum nitidum var. tomentosum (Rutaceae). Their structures were confirmed by comprehensive spectroscopic data (NMR and HRESIMS), and the absolute configurations of all novel compounds were elucidated based on electronic circular dichroism (ECD) spectroscopic data. The production of nitric oxide (NO) in BV-2 microglial cells induced through lipopolysaccharide (LPS) was used to evaluate in vitro anti-neuroinflammatory activity of compounds 1-20. Compound 2, 3, 7 and 16 showed excellent inhibition of LPS-induced NO production. The structure-activity relationships of the isolates were investigated. In addition, the mechanism of action of 2 was elucidated by RT-PCR and Western blotting analysis, which indicated that it reduced neuroinflammatory mainly through NLRP3/caspase1 signaling pathways in LPS-induced BV2 microglial cells.

Chaperone co-inducer BGP-15 mitigates early contractile dysfunction of the soleus muscle in a rat ICU model.

AIM: Critical illness myopathy (CIM) represents a common consequence of modern intensive care, negatively impacting patient health and significantly increasing health care costs; however, there is no treatment available apart from symptomatic and supportive interventions. The chaperone co-inducer BGP-15 has previously been shown to have a positive effect on the diaphragm in rats exposed to the intensive care unit (ICU) condition. In this study, we aim to explore the effects of BGP-15 on a limb muscle (soleus muscle) in response to the ICU condition. METHODS: Sprague-Dawley rats were subjected to the ICU condition for 5, 8 and 10 days and compared with untreated sham-operated controls. RESULTS: BGP-15 significantly improved soleus muscle fibre force after 5 days exposure to the ICU condition. This improvement was associated with the protection of myosin from post-translational myosin modifications, improved mitochondrial structure/biogenesis and reduced the expression of MuRF1 and Fbxo31 E3 ligases. At longer durations (8 and 10 days), BGP-15 had no protective effect when the hallmark of CIM had become manifest, that is, preferential loss of myosin. Unrelated to the effects on skeletal muscle, BGP-15 had a strong positive effect on survival compared with untreated animals. CONCLUSIONS: BGP-15 treatment improved soleus muscle fibre and motor protein function after 5 days exposure to the ICU condition, but not at longer durations (8 and 10 days) when the preferential loss of myosin was manifest. Thus, long-term CIM interventions targeting limb muscle fibre/myosin force generation capacity need to consider both the post-translational modifications and the loss of myosin.

Synthesis and discovery of asiatic acid based 1,2,3-triazole derivatives as antitumor agents blocking NF-κB activation and cell migration.

A series of asiatic acid (AA) based 1,2,3-triazole derivatives were designed, synthesized and subjected to a cell-based NF-κB inhibition screening assay. Among the tested compounds, compound 6k displayed impressive NF-κB inhibitory activity with an IC50 value in the low micromolar range. A molecular docking study was performed to reveal key interactions between 6k and NF-κB in which the 1,2,3-triazole moiety and the hydroxyl groups of the AA skeleton were important for improving the inhibitory activity. Subsequently, surface plasmon resonance analysis validated the high affinity between compound 6k and NF-κB protein with an equilibrium dissociation constant (KD) value of 0.36 µM. Further studies showed that compound 6k observably inhibited the NF-κB DNA binding, nuclear translocation and IκBα phosphorylation. Moreover, in vitro antitumor activity screening showed that compound 6k (IC50 = 2.67 ± 0.06 µM) exhibited the best anticancer activity against A549 cells, at least partly, by inhibition of the activity of NF-κB. Additionally, the treatment of A549 cells with compound 6k resulted in apoptosis induction potency and in vitro cell migration inhibition. Thus, we conclude that AA based 1,2,3-triazole derivatives may be potential NF-κB inhibitors with the ability to induce apoptosis and suppress cell migration.

Sarcopenia: Aging-Related Loss of Muscle Mass and Function.

Sarcopenia is a loss of muscle mass and function in the elderly that reduces mobility, diminishes quality of life, and can lead to fall-related injuries, which require costly hospitalization and extended rehabilitation. This review focuses on the aging-related structural changes and mechanisms at cellular and subcellular levels underlying changes in the individual motor unit: specifically, the perikaryon of the α-motoneuron, its neuromuscular junction(s), and the muscle fibers that it innervates. Loss of muscle mass with aging, which is largely due to the progressive loss of motoneurons, is associated with reduced muscle fiber number and size. Muscle function progressively declines because motoneuron loss is not adequately compensated by reinnervation of muscle fibers by the remaining motoneurons. At the intracellular level, key factors are qualitative changes in posttranslational modifications of muscle proteins and the loss of coordinated control between contractile, mitochondrial, and sarcoplasmic reticulum protein expression. Quantitative and qualitative changes in skeletal muscle during the process of aging also have been implicated in the pathogenesis of acquired and hereditary neuromuscular disorders. In experimental models, specific intervention strategies have shown encouraging results on limiting deterioration of motor unit structure and function under conditions of impaired innervation. Translated to the clinic, if these or similar interventions, by saving muscle and improving mobility, could help alleviate sarcopenia in the elderly, there would be both great humanitarian benefits and large cost savings for health care systems.

Influence of organic acids and heat treatment on ginsenoside conversion.

BACKGROUND: Heat treatments are applied to ginseng products in order to improve physiological activities through the conversion of ginsenosides, which are key bioactive components. During heat treatment, organic acids can affect ginsenoside conversion. Therefore, the influence of organic acids during heat treatment should be considered. METHODS: Raw ginseng, crude saponin, and ginsenoside Rb1 standard with different organic acids were treated at 130°C, and the chemical components, including ginsenosides and organic acids, were analyzed. RESULTS: The organic acid content in raw ginseng was 5.55%. Organic acids were not detected in crude saponin that was not subjected to heat treatment, whereas organic acids were found in crude saponin subjected to heat treatment. Major ginsenosides (Rb1, Re, and Rg1) in ginseng and crude saponin were converted to minor ginsenosides at 130°C; the ginsenoside Rb1 standard was very stable in the absence of organic acids and was converted into minor ginsenosides in the presence of organic acids at high temperatures. CONCLUSION: The major factor affecting ginsenoside conversion was organic acids in ginseng. Therefore, the organic acid content as well as ginsenoside content and processing conditions should be considered important factors affecting the quality of ginseng products.

Nanothermometry Reveals Calcium-Induced Remodeling of Myosin.

Ions greatly influence protein structure-function and are critical to health and disease. A 10, 000-fold higher calcium in the sarcoplasmic reticulum (SR) of muscle suggests elevated calcium levels near active calcium channels at the SR membrane and the impact of localized high calcium on the structure-function of the motor protein myosin. In the current study, combined quantum dot (QD)-based nanothermometry and circular dichroism (CD) spectroscopy enabled detection of previously unknown enthalpy changes and associated structural remodeling of myosin, impacting its function following exposure to elevated calcium. Cadmium telluride QDs adhere to myosin, function as thermal sensors, and reveal that exposure of myosin to calcium is exothermic, resulting in lowering of enthalpy, a decrease in alpha helical content measured using CD spectroscopy, and the consequent increase in motor efficiency. Isolated muscle fibers subjected to elevated levels of calcium further demonstrate fiber lengthening and decreased motility of actin filaments on myosin-functionalized substrates. Our results, in addition to providing new insights into our understanding of muscle structure-function, establish a novel approach to understand the enthalpy of protein-ion interactions and the accompanying structural changes that may occur within the protein molecule.