Identification of 20(S)-protopanaxadiol metabolites in human liver microsomes and human hepatocytes

A Novel Dipterocarpol Derivative That Targets Alpha-Glucosidase and NLRP3 Inflammasome Activity for Treatment of Diabetes Mellitus

Type 2 diabetes mellitus is a chronic metabolic disorder characterized by persistent hyperglycemia, chronic inflammation, impaired insulin secretion, and/or peripheral insulin resistance. Current α-glucosidase inhibitors approved for clinical use exhibit limited efficacy compared to other glucose-lowering agents. In this study, a series of mono- and bis-benzylidene derivatives were synthesized via aldol condensation of 3-oxo-dammarane triterpenoids with terephthalic aldehyde. The target mono- and bis-benzylidene derivatives, based on the dammarane triterpenoids hollongdione 1, (20S)-23,24-epoxy-25,26,27-trinordammar-3,24-dione 2, and 24(R,S)-20(S)-epoxy-25-hydroxy-dammar-3-one 3, were successfully synthesized. Several of these inhibitors demonstrated significantly greater efficacy than the reference drug acarbose. Notably, compound 4 inhibited S. cerevisiae α-glucosidase with an IC50 of 2.67 μM. Furthermore, the target compounds effectively inhibited NLRP3 inflammasome activation, reducing IL-1β production in LPS+ATP-stimulated murine peritoneal macrophages without detectable cytotoxicity. Compound 8, which exhibited dual activity, was further characterized as an inhibitor of NLRP3 activation in peripheral blood mononuclear cells, leading to the prevention of pyroptosis and IL-1β release. Additionally, compound 8 was shown to promote neuronal survival in LPS+ATP-treated rat hippocampal slices, highlighting its potential as a promising antidiabetic agent that targets both postprandial hyperglycemia and metaflammation.

Novel pyxinol amide derivatives bearing an aliphatic heterocycle as P-glycoprotein modulators for overcoming multidrug resistance

P-glycoprotein (Pgp) modulators are promising agents for overcoming multidrug resistance (MDR) in cancer chemotherapy. In this study, via structural optimization of our lead compound S54 (nonsubstrate allosteric inhibitor of Pgp), 29 novel pyxinol amide derivatives bearing an aliphatic heterocycle were designed, synthesized, and screened for MDR reversal activity in KBV cells. Unlike S54, these active derivatives were shown to transport substrates of Pgp. The most potent derivative 4c exhibited promising MDR reversal activity (IC50 of paclitaxel = 8.80 ± 0.56 nM, reversal fold = 211.8), which was slightly better than that of third-generation Pgp modulator tariquidar (IC50 of paclitaxel = 9.02 ± 0.35 nM, reversal fold = 206.6). Moreover, the cytotoxicity of this derivative was 8-fold lower than that of tariquidar in human normal HK-2 cells. Furthermore, 4c blocked the efflux function of Pgp and displayed high selectivity for Pgp but had no effect on its expression and distribution. Molecular docking revealed that 4c bound preferentially to the drug-binding domain of Pgp. Overall, 4c is a promising lead compound for developing Pgp modulators.

Synthesis, Anti-Inflammatory Activities, and Molecular Docking Study of Novel Pyxinol Derivatives as Inhibitors of NF-κB Activation

Pyxinol, an active metabolite of ginsenosides in human hepatocytes, exhibits various pharmacological activities. Here, a series of C-3 modified pyxinol derivatives was designed and virtually screened by molecular docking with the key inflammation-related proteins of the nuclear factor kappa B (NF-κB) pathway. Some of the novel derivatives were synthesized to assess their effects in inhibiting the production of nitric oxide (NO) and mitochondrial reactive oxygen species (MtROS) in lipopolysaccharide-triggered RAW264.7 cells. Derivative 2c exhibited the highest NO and MtROS inhibitory activities with low cytotoxicity. Furthermore, 2c decreased the protein levels of interleukin 1β, tumor necrosis factor α, inducible nitric oxide synthase, and cyclooxygenase 2 and suppressed the activation of NF-κB signaling. Cellular thermal shift assays indicated that 2c could directly bind with p65 and p50 in situ. Molecular docking revealed that 2c's binding to the p65-p50 heterodimer and p50 homodimer was close to their DNA binding sites. In summary, pyxinol derivatives possess potential for development as NF-κB inhibitors.

Safety and efficacy of a feed additive consisting of a tincture derived from the roots of Panax ginseng C.A.Mey. (ginseng tincture) for horses, dogs and cats (FEFANA asbl)

Following a request from the European Commission, EFSA was asked to deliver a scientific opinion on the safety and efficacy of a tincture from the roots of Panax ginseng C.A.Mey. (ginseng tincture), when used as a sensory additive in feed for horses, dogs and cats. The product is a water/ethanol (40:60 v/v) solution, with a dry matter content of no more than 6% and a content of 0.01%-0.5% (w/w) for the sum of the two triterpene saponins ginsenoside Rb1 and ginsenoside Rg1. The Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) concluded that the tincture is safe for horses, dogs and cats at the maximum proposed use level of 48.6, 228.7 and 162 mg/kg complete feed, respectively. The Panel also concluded that the additive is considered safe for consumers when used at the proposed conditions of use in feed for horses. Ginseng tincture should be considered as an irritant to skin and eyes, and as a dermal and respiratory sensitiser. The use of the ginseng tincture as a flavour in feed for horses was not expected to pose a risk for the environment. Since the roots of P. ginseng and its preparations were recognised to flavour food and their function in feed would be essentially the same, no demonstration of efficacy was considered necessary.

Pharmacokinetics and pharmacodynamics of Rh2 and aPPD ginsenosides in prostate cancer: a drug interaction perspective

Ginsenoside Rh2 and its aglycon (aPPD) are one of the major metabolites from Panax ginseng. Preclinical studies suggest that Rh2 and aPPD have antitumor effects in prostate cancer (PCa). Our aims in this review are (1) to describe the pharmacokinetic (PK) properties of Rh2 and aPPD ginsenosides; 2) to provide an overview of the preclinical findings on the use of Rh2 and aPPD in the treatment of PCa; and (3) to highlight the mechanisms of its PK and pharmacodynamic (PD) drug interactions. Increasing evidence points to the potential efficacy of Rh2 or aPPD for PCa treatment. Based on the laboratory studies, Rh2 or aPPD combinations revealed an additive or synergistic interaction or enhanced sensitivity of anticancer drugs toward PCa. This review reveals that enhanced anticancer activities were demonstrated in preclinical studies through interactions of Rh2 and/or aPPD with the proteins related to PK (e.g., cytochrome P450 enzymes, transporters) or PD of the other anticancer drugs or PCa signaling pathways. In conclusion, combining Rh2 or aPPD with anti-prostate cancer drugs leads to PK or PD interactions which could facilitate either therapeutically beneficial or toxic effects.

Protective effects of ginseng and ginsenosides in the development of osteoarthritis (Review)

Osteoarthritis (OA) is a chronic inflammatory joint disease. Traditional chinese medicine provides a resource for drug screening for OA treatment. Ginseng and the associated bioactive compound, ginsenosides, may reduce inflammation, which is considered a risk factor for the development of OA. Specifically, ginsenosides may exhibit anti-inflammatory and anti-oxidative stress activities, and inhibit extracellular matrix degradation by suppressing the NF-κB and MAPK signaling pathways. Notably, specific ginsenosides, such as compound K and Rk1, may physically interact with IκB kinase and inhibit the associated phosphorylation. Thus, ginsenosides exhibit potential as therapeutic candidates in the management of OA. However, the low water solubility limits the clinical applications of ginsenosides. Numerous effective strategies have been explored to improve bioavailability; however, further investigations are still required.

Discovery of Pyxinol Amide Derivatives Bearing Amino Acid Residues as Nonsubstrate Allosteric Inhibitors of P-Glycoprotein-Mediated Multidrug Resistance

Nonsubstrate allosteric inhibitors of P-glycoprotein (Pgp), which are considered promising modulators for overcoming multidrug resistance (MDR), are relatively unknown. Herein, we designed and synthesized amino acids bearing amide derivatives of pyxinol, the main ginsenoside metabolite produced by the human liver, and examined their MDR reversal abilities. A potential nonsubstrate inhibitor (7a) was identified to undergo high-affinity binding to the putative allosteric site of Pgp at the nucleotide-binding domains. Subsequent assays confirmed that 7a (25 μM) was able to suppress both basal and verapamil-stimulated Pgp-ATPase activities (inhibition rates of 87 and 60%, respectively) and could not be pumped out by Pgp, indicating that it was a rare nonsubstrate allosteric inhibitor. Moreover, 7a interfered with Pgp-mediated Rhodamine123 efflux while exhibiting high selectivity for Pgp. Notably, 7a also markedly enhanced the therapeutic efficacy of paclitaxel, with a tumor inhibition ratio of 58.1%, when used to treat nude mice bearing KBV xenograft tumors.

Protopanaxadiol ameliorates NAFLD by regulating hepatocyte lipid metabolism through AMPK/SIRT1 signaling pathway

Non-alcoholic fatty liver disease (NAFLD) has become one of the main chronic liver diseases worldwide. Protopanaxadiol (PPD), an active compound derived from Gynostemma pentaphyllum, has been found able to improve free fatty acid-induced lipid accumulation in hepatocytes. However, the efficacy of PPD on NAFLD and the underlying mechanism remains unknown. In this study, the mice were fed with a high-fat diet for 22 weeks to induce the NAFLD model, and then were treated with PPD by gavage for 8 weeks. Moreover, AML12 and HepG2 cells induced by free fatty acids for 24 h, were treated with different doses of PPD and/or AMPK or SIRT1 inhibitor to explore the pharmacological mechanism of PPD. The results showed that mice with PPD treatment had significantly reduced liver weight and serum aminotransferase levels, less severe hepatosteatosis, and inflammatory cell infiltration in liver tissues when compared with the model mice. PPD also reversed the down-regulated activation of AMPK and SIRT1 expression as well as the change of lipid metabolism-related molecules in the mice liver tissues. Consistently, the in vitro experiments showed the effect of PPD in ameliorating lipid accumulation in hepatocytes. The inhibitor of AMPK or SIRT1 suppressed the AMPK and SIRT1 signaling and markedly diminished the anti-steatosis effect of PPD. In conclusion, our results prove the ameliorating impact of PPD on NAFLD and also reveal the involvement of regulation of AMPK/SIRT1 signaling pathway-mediated lipid metabolism in the underlying mechanism, suggesting PPD as a potential natural compound for the treatment of NAFLD.

Fusion of Michael-acceptors enhances the anti-inflammatory activity of ginsenosides as potential modulators of the NLRP3 signaling pathway

Ginsenosides are a promising group of secondary metabolites for developing anti-inflammatory agents. In this study, Michael acceptor was fused into the aglycone A-ring of protopanoxadiol (PPD)-type ginsenosides (MAAG), the main pharmacophore of ginseng, and its liver metabolites to produce novel derivatives and assess their anti-inflammatory activity in vitro. The structure-activity relationship of MAAG derivatives was assessed based on their NO-inhibition activities. Of these, a 4-nitrobenzylidene derivative of PPD (2a) was the most effective and dose-dependently inhibited the release of proinflammatory cytokines. Further studies indicated that 2a-induced downregulation on lipopolysaccharide (LPS)-induced iNOS protein expression and cytokine release may be related to its inhibitory effect on MAPK and NF-κB signaling pathways. Importantly, 2a almost completely inhibited LPS-induced production of mitochondrial reactive oxygen species (mtROS) and LPS-induced NLRP3 upregulation. This inhibition was higher than that by hydrocortisone sodium succinate, a glucocorticoid drug. Overall, the fusion of Michael acceptors into the aglycone of ginsenosides greatly enhanced the anti-inflammatory activities of the derivatives, and 2a alleviated inflammation considerably. These findings could be attributed to the inhibition of LPS-induced mtROS to block abnormal activation of the NLRP3 pathway.

Design, Synthesis, and Anti-Inflammatory Activities of 12-Dehydropyxinol Derivatives

Pyxinol skeleton is a promising framework of anti-inflammatory agents formed in the human liver from 20S-protopanaxadiol, the main active aglycone of ginsenosides. In the present study, a new series of amino acid-containing derivatives were produced from 12-dehydropyxinol, a pyxinol oxidation metabolite, and its anti-inflammatory activity was assessed using an NO inhibition assay. Interestingly, the dehydrogenation at C-12 of pyxinol derivatives improved their potency greatly. Furthermore, half of the derivatives exhibited better NO inhibitory activity than hydrocortisone sodium succinate, a glucocorticoid drug. The structure-activity relationship analysis indicated that the kinds of amino acid residues and their hydrophilicity influenced the activity to a great extent, as did R/S stereochemistry at C-24. Of the various derivatives, 5c with an N-Boc-protected phenylalanine residue showed the highest NO inhibitory activity and relatively low cytotoxicity. Moreover, derivative 5c could dose-dependently suppress iNOS, IL-1β, and TNF-α via the MAPK and NF-κB pathways, but not the GR pathway. Overall, pyxinol derivatives hold potential for application as anti-inflammatory agents.

In vitro modulatory effects of ginsenoside compound K, 20(S)-protopanaxadiol and 20(S)-protopanaxatriol on uridine 5'-diphospho-glucuronosyltransferase activity and expression

We explored the inhibitory effect of ginsenoside compound K (CK), 20(S)-protopanaxadiol (PPD), and 20(S)-protopanaxatriol (PPT) on six uridine 5'-diphospho-glucuronosyltransferase (UGT) enzyme (UGT1A1, 1A3, 1A4, 1A6, 1A9, and 2B7) activities in human liver microsomes (HLMs) and 10 UGT enzyme (UGT1A1, 1A3, 1A4, 1A6, 1A9, 2B4, 2B7, 2B10, 2B15, and 2B17) activities in recombinant UGT isoforms.PPD was a potent inhibitor of UGT1A3 activity with half-maximal inhibitory concentration values of 5.62 and 3.38 μM in HLMs and recombinant UGT1A3, respectively. UGT1A3 inhibition by CK and PPD was competitive with inhibitory constant (K_i) values of 17.4 and 1.21 μM, respectively, and inhibition by PPT was non-competitive with a K_i value of 8.07 μM in HLMs. PPD exhibited more than 3.4-fold selectivity for UGT1A3 inhibition compared with other UGT isoforms inhibition, while CK and PPT showed more than 2.16- and 2.21-fold selectivity, respectively.PPD did not significantly increase the mRNA expression of UGT1A1, 1A3, 1A4, 1A9, and 2B7 in hepatocytes.Given the low plasma concentrations of PPD in healthy human subjects and the absence of induction potential on UGT isoforms, we conclude that PPD cause no pharmacokinetic interactions with other co-administered drugs metabolised by UGT1A3.

Phytochemistry of ginsenosides: Recent advancements and emerging roles

Ginsenosides, a group of tetracyclic saponins, accounts for the nutraceutical and pharmaceutical relevance of the ginseng (Panax sp.) herb. Owing to the associated therapeutic potential of ginsenosides, their demand has been increased significantly in the last two decades. However, a slow growth cycle, low seed production, and long generation time of ginseng have created a gap between the demand and supply of ginsenosides. The biosynthesis of ginsenosides involves an intricate network of pathways with multiple oxidation and glycosylation reactions. However, the exact functions of some of the associated genes/proteins are still not completely deciphered. Moreover, ginsenoside estimation and extraction using analytical techniques are not feasible with high efficiency. The present review is a step forward in recapitulating the comprehensive aspects of ginsenosides including their distribution, structural diversity, biotransformation, and functional attributes in both plants and animals including humans. Moreover, ginsenoside biosynthesis in the potential plant sources and their metabolism in the human body along with major regulators and stimulators affecting ginsenoside biosynthesis have also been discussed. Furthermore, this review consolidates biotechnological interventions to enhance the biosynthesis of ginsenosides in their potential sources and advancements in the development of synthetic biosystems for efficient ginsenoside biosynthesis to meet their rising industrial demands.

Pyxinol bearing amino acid residues: Easily achievable and promising modulators of P-glycoprotein-mediated multidrug resistance

The P-glycoprotein (Pgp) is a major transporter involved in multidrug resistance (MDR) of cancer cells leading to chemotherapy failure. In our previous study, we demonstrated that the amide derivatives of pyxinol are promising modulators against Pgp-mediated MDR in cancer. In the present study, we designed and synthesized novel pyxinol derivatives linked to amino acid residues. We evaluated MDR (paclitaxel (Ptx) resistance) reversal potency of forty pyxinol derivatives in KBV cells and analyzed their structure-activity relationships. Half of our derivatives sensitized KBV cells to Ptx at non-toxic concentrations, among which the pyxinol compound bearing a methionine residue (3c) exhibited the best activity in MDR reversal. Compound 3c was found to possess high selectivity toward Pgp and sensitize the KBV cells to Pgp substrates by blocking the efflux function of Pgp. This manifestation may be attributed to its high binding affinity with Pgp, as suggested by docking studies. Overall, the biological profile and ease of synthesizing these pyxinol derivatives render them promising lead compounds for further development for Pgp-mediated MDR.

Synthesis and Anti-Hepatocarcinoma Effect of Amino Acid Derivatives of Pyxinol and Ocotillol

Aiming at seeking an effective anti-hepatocarcinoma drug with low toxicity, a total of 24 amino acid derivatives (20 new along with 4 known derivatives) of two active ocotillol-type sapogenins (pyxinol and ocotillol) were synthesized. Both in vitro and in vivo anti-hepatocarcinoma effects of derivatives were evaluated. At first, the HepG2 human cancer cell was employed to evaluate the anti-cancer activity. Most of the derivatives showed obvious enhanced activity compared with pyxinol or ocotillol. Among them, compound 2e displayed the most excellent activity with an IC₅₀ value of 11.26 ± 0.43 µM. Next, H22 hepatoma-bearing mice were used to further evaluate the anti-liver cancer activity of compound 2e. It was revealed that the growth of H22 transplanted tumor was significantly inhibited when treated with compound 2e or compound 2e combined with cyclophosphamide (CTX) (p < 0.05, p < 0.01), and the inhibition rates of tumor growth were 35.32% and 55.30%, respectively. More importantly, compound 2e caused limited damage to liver and kidney in contrast with CTX causing significant toxicity. Finally, the latent mechanism of compound 2e was explored by serum and liver metabolomics based on ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS) technology. A total of 21 potential metabolites involved in 8 pathways were identified. These results suggest that compound 2e is a promising agent for anti-hepato-carcinoma, and that it also could be used in combination with CTX to increase efficiency and to reduce toxicity.

Design, synthesis and biological evaluation of novel pyxinol derivatives with anti-heart failure activity

Heart failure (HF) is an important and leading cause of substantial morbidity and mortality globally. The angiotensin-converting enzymatic (ACE) is the causative source for congestive heart failure. Natural products and its derivatives play a vital role in drug discovery and development owing to their efficacy and low toxicity. Pyxinol is a potent natural agent for cardiovascular disease. Thus we investigated the effect on ACE and HF of pyxinol derivatives. We designed and synthesized 32 novel fatty acid ester derivatives of pyxinol via esterification. Among them, compounds 2e (IC₅₀=105 nM) and 3b (IC₅₀=114 nM) displayed excellent ACE inhibitory activity in vitro, and exhibited non-toxic to H9c2 cells. The interactions between ACE and compounds were predicted by molecular docking respectively. In verapamil-induced zebrafish HF model, the activity assay showed that these two derivatives could improve cardiovascular physiological indexes including heart beats, venous congestion, heart dilation, cardiac output, ejection fraction and fractional shortening in a dose-dependent manner. A UPLC-QTOF-MS-based serum metabolomics approach was applied to explore the latent mechanism. A total of 25 differentiated metabolites and 8 perturbed metabolic pathways were identified. These results indicated that pyxinol fatty acid ester derivatives 2e and 3b might be considered as potent drug candidates against heart failure and deserved further research and development.

Assessment of a New Ginsenoside Rh2 Nanoniosomal Formulation for Enhanced Antitumor Efficacy on Prostate Cancer: An in vitro Study

Introduction

Ginsenoside Rh2, purified from the Panax ginseng root, has been demonstrated to possess anticancer properties against various cancerous cells including colorectal, breast, skin, ovarian, prostate, and liver cancerous cells. However, the poor bioavailability, low stability on gastrointestinal systems, and fast plasma elimination limit further clinical applications of Ginsenoside Rh2 for cancer treatments. In this study, a novel formulation of niosomal Ginsenoside Rh2 was prepared using the thin film hydration technique.

Methods

The niosomal formulation contained Span 60 and cholesterol, and cationic lipid DOTAP was evaluated by determining particle size distribution, encapsulation efficiency, the polydispersity index (PDI), and surface morphology. The cytotoxic effects of free Ginsenoside Rh2 and Ginsenoside Rh2-loaded niosomes were determined using the MTT method in the PC3 prostate cancer cell line. For the investigation of the in vitro cellular uptake of Ginsenoside Rh2-loaded niosome, two formulations were prepared: the Ginsenoside Rh2-loaded niosomal formula containing 5% DOTAP and the Ginsenoside Rh2-loaded niosomal formula without DOTAP.

Results

The mean size, DPI, zeta potential, and encapsulation efficiency of the Ginsenoside Rh2-loaded nanoniosomal formulation containing DOTAP were 93.5±2.1 nm, 0.203±0.01, +4.65±0.65, and 98.32% ±2.4, respectively. The niosomal vesicles were found to be round and have a smooth surface. The release profile of Ginsenoside Rh2 from niosome was biphasic. Furthermore, a two-fold reduction in the Ginsenoside Rh2 concentration was measured when Ginsenoside Rh2 was administered in a nanoniosomal form compared to free Ginsenoside Rh2 solutions in the PC3 prostate cancer cell line. After storage for 90 days, the encapsulation efficiency, vesicle size, PDI, and zeta potential of the optimized formulation did not significantly change compared to the freshly prepared samples. The cellular uptake experiments of the niosomal formulation demonstrated that by adding DOTAP to the niosomal formulation, the cellular uptake was enhanced.

Discussion

The enhanced cellular uptake and cytotoxic activity of the Ginsenoside Rh2 nanoniosomal formulation on the PC3 cell make it an attractive candidate for application as a nano-sized delivery vehicle to transfer Ginsenoside Rh2 to cancer cells.

Design, synthesis and anti-inflammatory activity of 3-amino acid derivatives of ocotillol-type sapogenins

Ocotillol-type sapogenins (OTS) are major ginsenoside metabolites in human hepatic tissue. In order to better utilize OTS and derivatives thereof as anti-inflammatory compounds, present study produced multiple novel 3-amino acid OTS derivatives and evaluated their anti-inflammatory activity in vitro. The nitric oxide (NO) inhibitory activity of these compounds was used for OTS structure-activity relationship (SAR) evaluations, revealing that both R/S stereochemistry at C-24 and the amino acid type at C-3 influence such NO inhibitory activity. This activity was highest for an N-Boc-protected neutral aliphatic amino acid derivative of 24R-OTS (5a), which performed better than even hydrocortisone sodium succinate in vitro. Compound 5a was also able to markedly suppress the LPS-induced upregulation of TNF-α, IL-6, iNOS, and COX-2 via the NF-κB and MAPK pathways. This suggests that OTS derivatives may be valuable anti-inflammatory compounds worthy of further preclinical evaluation.

The metabolites and biotransformation pathways in vivo after oral administration of ocotillol, RT5 , and PF11

Ocotillol, pseudo-ginsenoside RT5 (RT₅ ), and pseudo-ginsenoside F₁₁ (PF₁₁ ) are ocotillol-type saponins that have the same aglycone structure but with different numbers of glucose at the C-6 position. In this study, the metabolites of ocotillol, RT₅ , and PF₁₁ in rat plasma, stomach, intestine, urine, and feces after oral administration were investigated by ultra-performance liquid chromatography coupled with time-of-flight mass spectrometry. The results showed that RT₅ was easily biotransformed into metabolites in vivo, whereas PF₁₁ and RT₅ were difficult to be biotransformed. Hydrogenation, dehydrogenation, dehydration, deglycosylation, deoxygenation, hydration, phosphorylation, deoxidation, glucuronidation, and reactions combining amino acid were speculated to be involved in the biotransformation of ocotillol, RT₅ , and PF₁₁ . Based on the structural analysis of metabolites, it was deduced that hydrogenation, dehydration, deoxidation, and reactions combining amino acid occurred on the aglycone structure, whereas deglycosylation, hydration, and phosphorylation occurred on the glycosyl chain. Further, metabolites in plasma, urine, feces, and tissues were different: First, glucuronidation products were found in urine, stomach, intestine, and feces, but not in plasma. Second, the ocotillol prototype was not identified in urine samples. Third, the RT₅ prototype was found in stomach, intestine, feces, and urine, but not in plasma.

Synthesis and Structure-Activity Relationship of Pyxinol Derivatives as Novel Anti-Inflammatory Agents

Pyxinol, the main metabolite of 20S-protopanaxadiol in human liver, was chosen as a novel skeleton for the development of anti-inflammatory agents. Pyxinol derivatives modified at C-3, C-12, or C-25 and selected stereoisomers were designed, prepared, and investigated for in vitro anti-inflammatory activities. Structure-activity relationship (SAR), focused on skeleton, was analyzed based on their ability to inhibit lipopolysaccharide (LPS)-induced nitric oxide (NO) synthesis. The preliminary SAR results signified that the biological activity of the pyxinol derivatives is largely dependent on the R/S stereochemistry of pyxinol skeleton and the hydroxy at C-3 is a modifiable position. Among the tested compounds, the 3-oximinopyxinol (4a) exhibited the most potent NO-inhibitory activity and was even comparable to the steroid drug. Furthermore, compound 4a also significantly decreased LPS-induced TNF-α and IL-6 synthesis and iNOS and COX-2 expressions via the NF-κB pathway. This study proves that pyxinol is an interesting skeleton for anti-inflammatory drug discovery.

Herbal Medicine of the 21st Century: A Focus on the Chemistry, Pharmacokinetics and Toxicity of Five Widely Advocated Phytotherapies

Widely advocated for their health benefits worldwide, herbal medicines (HMs) have evolved into a billion dollar generating industry. Much is known regarding their wellness inducing properties, prophylactic and therapeutic benefits for the relief of both minor to chronic ailment conditions given their long-standing use among various cultures worldwide. On the other hand, their equally meaningful chemistry, pharmacokinetic profile in humans, interaction and toxicity profile have been poorly researched and documented. Consequently, this review is an attempt to highlight the health benefits, pharmacokinetics, interaction, and toxicity profile of five globally famous HMs. A systematic literature search was conducted by browsing major scientific databases such as Bentham Science, SciFinder, ScienceDirect, PubMed, Google Scholar and EBSCO to include 196 articles. In general, ginsenosides, glycyrrhizin and curcumin demonstrate low bioavailability when orally administered. Ginkgo biloba L. induces both CYP3A4 and CYP2C9 and alters the AUC and Cmax of conventional medications including midazolam, tolbutamide, lopinavir and nifedipine. Ginsenosides Re stimulates CYP2C9, decreasing the anticoagulant activity of warfarin. Camellia sinensis (L.) Kuntze increases the bioavailability of buspirone and is rich in vitamin K thereby inhibiting the activity of anticoagulant agents. Glycyrrhiza glabra L. displaces serum bound cardiovascular drugs such as diltiazem, nifedipine and verapamil. Herbal medicine can directly affect hepatocytes leading to hepatoxicity based on both intrinsic and extrinsic factors. The potentiation of the activity of concurrently administered conventional agents is potentially lethal especially if the drugs bear dangerous side effects and have a low therapeutic window.

Ginsenosides: potential therapeutic source for fibrosis-associated human diseases

Tissue fibrosis is an eventual pathologic change of numerous chronic illnesses, which is characterized by resident fibroblasts differentiation into myofibroblasts during inflammation, coupled with excessive extracellular matrix deposition in tissues, ultimately leading to failure of normal organ function. Now, there are many mechanistic insights into the pathogenesis of tissue fibrosis, which facilitate the discovery of effective antifibrotic drugs. Moreover, many chronic diseases remain a significant clinical unmet need. For the past five years, many research works have undoubtedly addressed the functional dependency of ginsenosides in different types of fibrosis and the successful remission in various animal models treated with ginsenosides. Caveolin-1, interleukin, thrombospondin-1 (TSP-1), liver X receptors (LXRs), Nrf2, microRNA-27b, PPARδ-STAT3, liver kinase B1 (LKB1)-AMPK, and TGF-β1/Smads are potential therapy targeting using ginsenosides. Ginsenosides can play a targeting role and suppress chronic inflammatory response, collagen deposition, and epithelial-mesenchymal transition (EMT), as well as myofibroblast activation to attenuate fibrosis. In this report, our aim was to focus on the therapeutic prospects of ginsenosides in fibrosis-related human diseases making use of results acquired from various animal models. These findings should provide important therapeutic clues and strategies for the exploration of new drugs for fibrosis treatment.

Ginseng and heme oxygenase-1: The link between an old herb and a new protective system

Ginseng is an ancient herb, belonging to Asian traditional medicine, that has been considered as a restorative to enhance vitality for centuries. It has been demonstrated that the antioxidant action of ginseng may be mediated through activation of different cellular signaling pathways involving the heme oxygenase (HO) system. Several compounds derived from ginseng have been studied for their potential role in brain, heart and liver protection, and the Nrf2 pathway seems to be the most affected by these natural molecules to exert this effect. Ginseng is also popularly used in cancer patients therapy for the demonstrated capability to defend tissues from chemotherapy-induced damage. Reported results suggest that the effect of ginseng is primarily associated with ROS scavenging, mainly exerted through the activation of Nrf2 pathway, and the consequent induction of HO-1 levels. This review aims to discuss the connection between the antioxidant properties of ginseng and the activation of the HO system, as well as to outline novel therapeutic applications of this medicinal plant to human health.

Tentative identification of 20(S)-protopanaxadiol metabolites in human plasma and urine using ultra-performance liquid chromatography coupled with triple quadrupole time-of-flight mass spectrometry

BACKGROUND

20(S)-Protopanaxadiol (PPD), the aglycone part of 20(S)-protopanaxadiol ginsenosides, possesses antidepressant activity among many other pharmacological activities. It is currently undergoing clinical trial in China as an antidepressant.

METHODS

In this study, an ultra-performance liquid chromatography coupled with triple quadrupole time-of-flight mass tandem mass spectrometry method was established to identify the metabolites of PPD in human plasma and urine following oral administration in phase IIa clinical trial.

RESULTS

A total of 40 metabolites in human plasma and urine were identified using this method. Four metabolites identified were isolated from rat feces, and two of them were analyzed by NMR to elucidate the exact structures. The structures of isolated compounds were confirmed as (20S,24S)-epoxydammarane-12,23,25-triol-3-one and (20S,24S)-epoxydammarane-3,12,23,25-tetrol. Both compounds were found as metabolites in human for the first time. Upon comparing our findings with the findings of the in vitro study of PPD metabolism in human liver microsomes and human hepatocytes, metabolites with m/z 475.3783 and phase II metabolites were not found in our study whereas metabolites with m/z 505.3530, 523.3641, and 525.3788 were exclusively detected in our experiments.

CONCLUSION

The metabolites identified using ultra-performance liquid chromatography coupled with triple quadrupole time-of-flight mass spectrometry in our study were mostly hydroxylated metabolites. This indicated that PPD was metabolized in human body mainly through phase I hepatic metabolism. The main metabolites are in 20,24-oxide form with multiple hydroxylation sites. Finally, the metabolic pathways of PPD in vivo (human) were proposed based on structural analysis.

Non-clinical pharmacokinetic behavior of ginsenosides

Ginsenosides, the major active ingredients of ginseng and other plants of the genus Panax, have been used as natural medicines in the East for a long time; in addition, their popularity in the West has increased owing to their various beneficial pharmacological effects. There is therefore a wealth of literature regarding the pharmacological effects of ginsenosides. In contrast, there are few comprehensive studies that investigate their pharmacokinetic behaviors. This is because ginseng contains the complicated mixture of herbal materials as well as thousands of constituents with complex chemical properties, and ginsenosides undergo multiple biotransformation processes after administration. This is a significant issue as pharmacokinetic studies provide crucial data regarding the efficacy and safety of compounds. Moreover, there have been many difficulties in the development of the optimal dosage regimens of ginsenosides and the evaluation of their interactions with other drugs. Therefore, this review details the pharmacokinetic properties and profiles of ginsenosides determined in various animal models administered through different routes of administration. Such information is valuable for designing specialized delivery systems and determining optimal dosing strategies for ginsenosides.

Design and synthesis of acetaminophen probe APAP-P1 for identification of the toxicity targets thioredoxin reductase-1 in HepaRG cells

Drug-induced liver injury is one of the main causes of drug non-approval and drug withdrawal by the Food and Drug Administration (FDA). Acetaminophen (APAP) is a widely used non-steroidal anti-inflammatory drug for treating fever and headache. APAP is considered safe at therapeutic doses; however, there have been reports of acute liver injury following the administration of APAP. To explore APAP hepatotoxicity and its mechanisms, we designed and synthesized a new click chemistry probe, APAP-P1, in our current study. We introduced the PEG-azide probe linker into the acetyl group of acetaminophen. First, we evaluated the probe toxicity in HepaRG cells and found that it still retained hepatotoxicity. We also found that this probe APAP-P1 can be metabolized by HepaRG cells. This demonstrated that the APAP-P1 probe still kept its metabolism characteristics. Using this probe, we pulled down its potential targets in vivo and in vitro. APAP can directly target TrxR1; thus, we tested for this interaction by Western blotting of pull-down proteins. The results showed that APAP-P1 can pull down TrxR1 in vivo and in vitro.

Stepwise targeted matching strategy from in vitro to in vivo based on ultra-high performance liquid chromatography tandem mass spectrometry technology to quickly identify and screen pharmacodynamic constituents

The study of in vivo pharmacodynamic constituents (PCs) of traditional Chinese medicine (TCM) is important for providing new clues for TCM applications in clinical therapies in modern medicine. However, detecting and identifying PCs from complex biological samples remain a challenge. In this study, a practical and novel stepwise targeted matching and longitudinal analysis strategy from in vitro to in vivo was developed. This strategy combined with ultra-high performance liquid chromatography tandem mass spectrometry was applied to quickly discover PCs in TCM. This approach was developed based on a core perception that all drugs taken orally might be transformed progressively and orderly from the intestinal tract, liver, and blood to the target organ. Based on this core perception, stepwise targeted matching was orderly and efficiently accomplished by multiple screening processes that were based on a stepwise enriched in-house library. Ginseng (Panax ginseng) was set as the example of herbal medicine for validating the reliability and availability of this approach. By applying this novel strategy to the stepwise screening of metabolites, we successfully identified 113 metabolites, among which 59 compounds were defined as prototypes. Based on the in vivo metabolites, network pharmacology analysis was applied to screen the PCs of ginseng and clarified the action mechanism of ginseng for the treatment of Alzheimer's disease (AD). A total of 27 herbal constituents and 64 related targets shared commonly by compounds and AD were integrated via target network pharmacology analysis. These results demonstrated that this original approach will greatly improve high-throughput screening of metabolites and PCs on AD. It also can explicate the mechanism of action of TCM. Furthermore, this strategy is practicable to identify metabolites and screen PCs in other herbal medicines.

Design, synthesis, and discovery of ocotillol-type amide derivatives as orally available modulators of P-glycoprotein-mediated multidrug resistance

Multidrug resistance (MDR) is a major cause of failure in cancer treatment, in which the overexpression of P-glycoprotein (Pgp) plays a crucial role. Herein, a novel class of ocotillol-type amide derivatives has been designed, synthesized, and evaluated for their ability to reverse MDR. The structure-activity relationship of the reversal activity was analyzed. Ten compounds showed promising chemo-reversal ability, among which the 24R-ocotillol-type amide derivative 6c with an N-Boc-hexanoyl unit exhibited the most potency in reversing paclitaxel resistance in KBV cells. Compound 6c could inhibit Pgp-mediated rhodamine123 efflux function via stimulating Pgp-ATPase activity and exhibited high binding affinity with Pgp in molecular docking studies. Importantly, compound 6c enhanced the efficacy of paclitaxel against KBV cancer cell-derived xenograft tumors in nude mice after oral administration. These results indicate that ocotillol-type amide derivatives are promising lead compounds for overcoming MDR in cancer.

A 20(S)-protopanaxadiol derivative PPD12 reverses ABCB1-mediated multidrug resistance with oral bioavailability and low toxicity

The ATP-binding cassette subfamily B member 1 (ABCB1) is a transporter that mediates multidrug resistance (MDR) against chemotherapy, which leads to decreased patient survival. To inhibit ABCB1 activity in MDR cancer cells, the authors previously designed and synthesized a derivative from 20(S)-protopanaxadiol (PPD) PPD12 and verified its efficacy in ABCB1-overexpressing cancer cells. In the present study, the reversal effect of PPD12 on MDR was further evaluated and its pharmacokinetics and toxicity in vitro and in vivo were investigated. Incubation with PPD12 may significantly ameliorate the drug resistance of KB/VCR cells in a short time and maintain its reversed MDR ability for increasing time periods. In assays on a series of CYP450 activities, PPD12 demonstrated slight inhibition effects on the majority of enzymes. The bioavailability of PPD12 was nearly 100% by oral administration in a mouse model. Single PPD12 oral gavage at either high doses or subchronic low doses, was well tolerated by the mice. In addition, PPD12 at the therapeutic dosage did not significantly increase the toxicity of the chemotherapeutic agent Adriamycin when mice received a combination of the two compounds. In conclusion, PPD12 represents a novel type of ABCB1 inhibitor that has significant bioactivity in terms of MDR, high oral bioavailability and low toxicity.

Targeted Screening Approach to Systematically Identify the Absorbed Effect Substances of Poria cocos in Vivo Using Ultrahigh Performance Liquid Chromatography Tandem Mass Spectrometry

Poria cocos are extensively used as nutritious food, dietary supplements, and oriental medicine in Asia. However, the effect substances are still not very clear. In this study, a targeted screening approach was developed to systematically identify absorbed constituents of Poria cocos in vivo using ultrahigh performance liquid chromatography tandem mass spectrometry combined with UNIFI software. First, incubation reactions in vitro with rat intestinal microflora and rat liver microsomes were conducted to sum up metabolic rules of main constituents. Second, the absorbed constituents in vivo were picked out and identified based on the results of metabolic study in vitro. Finally, the absorbed active constituents in the treatment of Alzheimer's disease were screened by targeted network pharmacology analysis. A total of 62 absorbed prototypes and 59 metabolites were identified and characterized in dosed plasma. Thirty potential active constituents were screened, and 86 drug-targets shared by absorbed constituents and Alzheimer's disease were discovered by targeted network pharmacology analysis. In general, this proposed targeted strategy comprehensively provides new insight for active ingredients of Poria cocos.

Micro-/nano-sized delivery systems of ginsenosides for improved systemic bioavailability

Ginsenosides, dammarane-type triterpene saponins obtained from ginseng, have been used as a natural medicine for many years in the Orient due to their various pharmacological activities. However, the therapeutic potential of ginsenosides has been largely limited by the low bioavailability of the natural products caused mainly by low aqueous solubility, poor biomembrane permeability, instability in the gastrointestinal tract, and extensive metabolism in the body. To enhance the bioavailability of ginsenosides, diverse micro-/nano-sized delivery systems such as emulsions, polymeric particles, and vesicular systems have been investigated. The delivery systems improved the bioavailability of ginsenosides by enhancing solubility, permeability, and stability of the natural products. This mini-review aims to provide comprehensive information on the micro-/nano-sized delivery systems for increasing the bioavailability of ginsenosides, which may be helpful for designing better delivery systems to maximize the versatile therapeutic potential of ginsenosides.

Simultaneous determination of 20(S)-protopanaxadiol and its three metabolites in rat plasma by LC-MS/MS: application to their pharmacokinetic studies

The aim of this study was to develop an LC-MS/MS method for simultaneous determination of 20(S) protopanaxadiol (PPD) and its three metabolites, PPD-glucuronide (M1), (20S,24S)-epoxy-dammarane-3,12,25-triol (M2) and (20S,24R)-epoxydammarane-3,12,25-triol (M3), in rat plasma. Precipitation with acetonitrile was employed for sample preparation and chromatographic separations were achieved on a C₁₈ column. The sample was detected using triple quadrupole tandem mass spectrometer with selected reaction monitoring mode. The monitored precursor-to-product ion transitions were m/z 459.4 → 375.3 for PPD, m/z 635.4 → 113.0 for M1, m/z 477.4 → 441.4 for M2 and M3 and m/z 475.4 → 391.3 for IS. The developed assay was validated according to the guidelines of the US Food and Drug Administration. The calibration curves showed good linearity over the tested concentration ranges (r > 0.9993), with the LLOQ being 1 ng/mL for all analytes. The intra- and inter-day precisions (RSD) were < 9.51% while the accuracy (RE) ranged from -8.91 to 12.84%. The extraction recovery was >80% and no obvious matrix effect was detected. The analytes were stable in rat plasma with the RE ranging from -12.34 to 9.77%. The validated assay has been successfully applied to the pharmacokinetic study of PPD as well as its metabolites in rat plasma. According to the pharmacokinetic parameters, the in vivo exposures of M1, M2 and M3 were 11.91, 47.95 and 22.62% of that of PPD, respectively.

"Nano-Ginseng" for Enhanced Cytotoxicity AGAINST Cancer Cells

Panax ginseng has high medicinal and health values. However, the various and complex components of ginseng may interact with each other, thus reducing and even reversing therapeutic effects. In this study, we designed and fabricated a novel "nano-ginseng" with definite ingredients, ginsenoside Rb1/protopanaxadiol nanoparticles (Rb1/PPD NPs), completely based on the protopanaxadiol-type extracts. The optimized nano-formulations demonstrated an appropriate size (~110 nm), high drug loading efficiency (~96.8%) and capacity (~27.9 wt %), long half-time in systemic circulation (nine-fold longer than free PPD), better antitumor effects in vitro and in vivo, higher accumulation at the tumor site and reduced damage to normal tissues. Importantly, this process of "nano-ginseng" production is a simple, scalable, green economy process.

Discovery, semisynthesis, biological activities, and metabolism of ocotillol-type saponins

Ocotillol-type saponins are one kind of tetracyclic triterpenoids, sharing a tetrahydrofuran ring. Natural ocotillol-type saponins have been discovered in Panax quinquefolius L., Panax japonicus, Hana mina, and Vietnamese ginseng. In recent years, the semisynthesis of 20(S/R)-ocotillol-type saponins has been reported. The biological activities of ocotillol-type saponins include neuroprotective effect, antimyocardial ischemia, antiinflammatory, antibacterial, and antitumor activities. Owing to their chemical structure, pharmacological actions, and the stereoselective activity on antimyocardial ischemia, ocotillol-type saponins are subjected to extensive consideration. In this review, we sum up the discovery, semisynthesis, biological activities, and metabolism of ocotillol-type saponins.

Synthesis and Crystal Structure of Ocotillol-Type Metabolites Derived from (20R)-Protopanaxadiol

Four ocotillol-type (20R)-protopanaxadiol metabolites, (20R,24S)-20,24-epoxy-12β,25-dihydroxdammaran-3-one (M3), and (20R,24R)-20,24-epoxy-12β,25-dihydroxydammarane-3-one (M4), (20R,24S)-20,24-epoxy-3β,25-dihydroxydammaran-12-one (M9) and (20R,24R)-20,24-epoxy-3β,25-dihydroxydammaran-12-one (M10) are synthesised from (20R)-protopanaxadiol. Their structures are confirmed by HRMS, 1H NMR and 13C NMR. Moreover, the absolute configurations of M3 and M4 are confirmed by the X-ray single crystal diffraction.

Characterization, Molecular Docking, and In Vitro Dissolution Studies of Solid Dispersions of 20(S)-Protopanaxadiol

In this study, we prepared solid dispersions (SDs) of 20(S)-protopanaxadiol (PPD) using a melting-solvent method with different polymers, in order to improve the solubility and dissolution performance of drugs with poor water solubility. The SDs were characterized via differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), and molecular docking and dynamics study. DSC and PXRD results indicated that PPD crystallinity in SDs was significantly reduced, and that the majority of PPD is amorphous. No interaction was observed between PPD and polymers on FTIR and NMR spectra. Molecular docking and dynamic calculations indicated that the PPD molecule localized to the interpolated charged surface, rather than within the amorphous polymer chain network, which might help prevent PPD crystallization, consequently enhancing the PPD dispersion in polymers. An in vitro dissolution study revealed that the SDs considerably improved the PPD dissolution performance in distilled water containing 0.35% Tween-80 (T-80). Furthermore, among three PPD-SDs formulations, Poloxamer188 (F68) was the most effective in improving the PPD solubility and was even superior to the mixed polymers. Therefore, the SD prepared with F68 as a hydrophilic polymer carrier might be a promising strategy for improving solubility and in vitro dissolution performance. F68-based SD, containing PPD with a melting-solvent preparation method, can be used as a promising, nontoxic, quick-release, and effective intermediate for other pharmaceutical formulations, in order to achieve a more effective drug delivery.

Semi-synthetic ocotillol analogues as selective ABCB1-mediated drug resistance reversal agents

Overexpression of ATP-Binding Cassette transporters leads to multidrug resistance in cancer cells and results in the failure of chemotherapy. In this in-vitro study, we investigated whether or not (20S, 24R/S)-epoxy-12β, 25-dihydroxy-dommarane-3β-amine (ORA and OSA), a pair of semi-synthetic ocotillol analogue epimers, could inhibit the ABCB1 transporter. ORA (1 μM and 3 μM) significantly reversed the resistance to paclitaxel and vincristine in ABCB1-overexpressing SW620/Ad300 and HEK/ABCB1 cells, whereas OSA had no significant effects. In addition, ORA (3 μM) significantly increased the intracellular accumulation of [3H]-paclitaxel by suppressing the efflux function of ABCB1. Meanwhile, both ORA (3 μM) and OSA (3 μM) did not significantly alter the expression level or the subcellular location of ABCB1 protein. Moreover, the ABCB1 ATPase study suggested that ORA had a stronger stimulatory effect on the ATPase activity than OSA. ORA also exhibited a higher docking score as compared with OSA inside transmembrane domain of ABCB1. Overall, we concluded that ORA reverse ABCB1-mediated MDR by competitively inhibiting the ABCB1 drug efflux function.

Identification of Human UDP-Glucuronosyltransferase 1A4 as the Major Isozyme Responsible for the Glucuronidation of 20(S)-Protopanaxadiol in Human Liver Microsomes

20(S)-protopanaxadiol (PPD), one of the representative aglycones of ginsenosides, has a broad spectrum of pharmacological activities. Although phase I metabolism has been investigated extensively, information regarding phase II metabolism of this compound remains to be elucidated. Here, a glucuronidated metabolite of PPD in human liver microsomes (HLMs) and rat liver microsomes (RLMs) was unambiguously identified as PPD-3-O-β-d-glucuronide by nuclear magnetic resonance spectroscopy and high resolution mass spectrometry. The chemical inhibition and recombinant human UDP-Glucuronosyltransferase (UGT) isoforms assay showed that the PPD glucuronidation was mainly catalyzed by UGT1A4 in HLM, whereas UGT1A3 showed weak catalytic activity. In conclusion, PPD-3-O-β-d-glucuronide was first identified as the principal glucuronidation metabolite of PPD in HLMs, which was catalyzed by UGT1A4.

In vitro and in vivo metabolism and inhibitory activities of vasicine, a potent acetylcholinesterase and butyrylcholinesterase inhibitor

Vasicine (VAS), a potential natural cholinesterase inhibitor, exhibited promising anticholinesterase activity in preclinical models and has been in development for treatment of Alzheimer’s disease. This study systematically investigated the in vitro and in vivo metabolism of VAS in rat using ultra performance liquid chromatography combined with electrospray ionization quadrupole time-of-flight mass spectrometry. A total of 72 metabolites were found based on a detailed analysis of their ¹H- NMR and ¹³C NMR data. Six key metabolites were isolated from rat urine and elucidated as vasicinone, vasicinol, vasicinolone, 1,2,3,9-tetrahydropyrrolo [2,1-b] quinazolin-3-yl hydrogen sulfate, 9-oxo-1,2,3,9-tetrahydropyrrolo [2,1-b] quinazolin-3-yl hydrogen sulfate, and 1,2,3,9-tetrahydropyrrolo [2,1-b] quinazolin-3-β-D-glucuronide. The metabolic pathway of VAS in vivo and in vitro mainly involved monohydroxylation, dihydroxylation, trihydroxylation, oxidation, desaturation, sulfation, and glucuronidation. The main metabolic soft spots in the chemical structure of VAS were the 3-hydroxyl group and the C-9 site. All 72 metabolites were found in the urine sample, and 15, 25, 45, 18, and 11 metabolites were identified from rat feces, plasma, bile, rat liver microsomes, and rat primary hepatocyte incubations, respectively. Results indicated that renal clearance was the major excretion pathway of VAS. The acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory activities of VAS and its main metabolites were also evaluated. The results indicated that although most metabolites maintained potential inhibitory activity against AChE and BChE, but weaker than that of VAS. VAS undergoes metabolic inactivation process in vivo in respect to cholinesterase inhibitory activity.

Characterization of oxygenated metabolites of ginsenoside Rb1 in plasma and urine of rat

Oxygenated metabolites have been suggested as the major circulating metabolites of ginsenosides. In the current study, 10 oxygenated metabolites of ginsenoside Rb1 in plasma and urine of rat following iv dose were characterized by comparison with chemically synthesized authentic compounds as quinquenoside L16 (M1 and M2), notoginsenoside A (M3), ginsenoside V (M4 and M7), epoxyginsenoside Rb1 (M5 and M9), notoginsenoside K (M6), and notoginsenoside C (M8 and M10), 9 of which were detected as in vivo metabolites for the first time. After oral administration of ginsenoside Rb1, M3, M4, and M7 were observed as major circulating metabolites and presented in the bloodstream of rat for 24 h. Characterization of the exact chemical structures of these circulating metabolites could contribute greatly to our understanding of chemical exposure of ginsenosides after consumption of ginseng products and provide valuable information for explaining multiple bioactivities of ginseng products.

Structural identification of neopanaxadiol metabolites in rats by ultraperformance liquid chromatography/quadrupole-time-of-flight mass spectrometry

RATIONALE

Neopanaxadiol (NPD) is one of the major ginsenosides in Panax ginseng C. A. Meyer (Araliaceae) that has been suggested to be a drug candidate against Alzheimer's disease. However, few data are available regarding its metabolism in rats.

METHODS

In this study, a method of ultraperformance liquid chromatography/quadrupole-time-of-flight mass spectrometry (UPLC/QTOFMS) was developed to identify major metabolites of NPD in the stomach, intestine, urine and feces of rats, with the aim of determining the main metabolic pathways of NPD in rats after oral administration.

RESULTS

UPLC/QTOFMS revealed two metabolites in the stomach of rats, one metabolite in the intestine and two metabolites in feces. One metabolite, named M2, was isolated and purified from rats feces, which was identified as (20S,22S)-dammar-22,25-epoxy-3β,12β,20-triol based on extensive NMR spectroscopy and mass spectrometry data. The main metabolites of NPD in rats were the products of epoxidation, dehydrogenation and hydroxylation. NPD was predominantly metabolized by 20,22-double-bond epoxidation and rearrangement to yield an expoxidation product (M2).

CONCLUSIONS

Based on the profiles of the metabolites, possible metabolic pathways of NPD in rats were proposed for the first time. This study provides new and available information on the metabolism of NPD, which is indispensable for further research on metabolic pathways of dammarane ginsengenins in vivo.

A nanoparticulate drug-delivery system for 20(S)-protopanaxadiol: formulation, characterization, increased oral bioavailability and anti-tumor efficacy

As with many other hydrophobic anticancer agents, 20(S)-protopanaxadiol (PPD) has a very low oral bioavailability. In this study, a precipitation-combined ultrasonication technique was used to prepare PPD nanosuspensions. The mean particle size of the nanosuspensions was approximately 222 ± 12 nm, the drug payload achieved 50% after lyophilization and the maximum PPD concentration can reach 100 mg/ml, which is over 30 000 times the solubility of PPD in aqueous solution (3 μg/ml). After oral administration, the C_max and AUC_last values of PPD nanosuspensions were approximately 3.66-fold and 3.48-fold as those of PPD coarse suspensions, respectively. In contrast to the free drug solution, PPD nanosuspensions showed higher in vitro anti-tumor activity against HepG-2 cells (an IC₅₀ value of 1.40 versus 5.83 μg/ml at 24 h, p < 0.01). The in vivo study in H22-tumor-bearing mice demonstrated that PPD nanosuspensions showed good anti-tumor efficacy with an inhibition rate of 79.47% at 100 mg/kg, while 50 mg/kg of cyclophosphamide was displayed as positive control, and the inhibition rate was 87.81%. Considering the highest drug payload, oral bioavailability reported so far, significant anti-tumor efficacy and excellent safety of encapsulated drugs, PPD nanosuspensions could be used in potential effective strategies for anticancer therapy; further investigation is ongoing.