The absorption, distribution, metabolism and excretion of Riccardin D in rats.

The present study was designed to investigate the pharmacokinetics following oral and intravenous administration of Riccardin D, an anticancer drug candidate isolated from Chinese liverworts Dumortiera hirsute, in Wistar rats. An HPLC-MS/MS analytical method was developed and validated. The results demonstrated that Riccardin D's bioavailability was 13.4%, 11.4%, and 9.8% after oral administration at 20 mg/kg, 40 mg/kg, and 80 mg/kg, respectively. There was no significant difference in the elimination half-time of Riccardin D at these doses, suggesting that Riccardin D may have linear pharmacokinetic characteristics in rats. The metabolite of Riccardin D in rat was identified as the glucuronide of Riccardin D. Riccardin D showed a wide distribution in various tissues followed by a rapid elimination from most of the tissues tested. Riccardin D was found to distribute widely in the tissues 0.5 h after oral and intravenous administration. The tissue concentrations were markedly decreased 8 h and 6 h after oral and intravenous dosing, respectively. Both Riccardin D and its conjugated metabolite were detected in urine and bile samples while only Riccardin D was detected in feces. Taken together, the study provided valuable pharmacokinetic data for further drug development of Riccardin D.

Cloning and expression analysis of squalene synthase, a key enzyme involved in antifungal steroidal glycoalkaloids biosynthesis from Solanum nigrum.

Steroidal glycoalkaloids (SGAs) are a family of nitrogenous secondary metabolites produced in solanaceous plants. In our present study, γ-solamargine and its aglycone solasodine from Solanum nigrum were found to inhibit hyphae formation of Fusarium oxysporum. As phytoalexins, the formation of SGAs was significantly increased in the plants when infected with the spore of F. oxysporum. In order to understand this inducible defense mechanism, the rate-limiting enzyme squalene synthase in the biosynthesis process of SGAs was investigated well. A full-length cDNA encoding squalene synthase was isolated from S. nigrum (the squalene synthase in S. nigrum was designated as SnSS). The full-length cDNA of SnSS was 1,765 bp and contained a 1,236 bp open reading frame (ORF) encoding a polypeptide of 411 amino acids. Bioinformatic analysis revealed that the deduced SnSS protein had a high similarity with other plant squalene synthases. Real-time RT-PCR analysis showed that SnSS was expressed constitutively in all tested tissues, with the highest expression in stems. After treatment with the spore of F. oxysporum, the mRNA level of SnSS was significantly increased in the infected plants in accordance with the change of SGAs.

Synthesis of solasodine glycoside derivatives and evaluation of their cytotoxic effects on human cancer cells.

Solasodine glycosides, such as solamargine, have been proved to be very important anti-cancer agents. In order to discover more potent cytotoxic agents and explore the preliminary structure activity relationship, a new series of solasodine glycosides 2-9 were synthesized via a transglycosylation strategy, and their cytotoxic activity against a panel of human cancer cell lines (MCF-7, KB, K562, and PC3 cells) were evaluated by MTT assays. The results indicated that compounds 2, 8, and 9 with the substitute moiety of rhamnose, 2-hydroxyethoxymethyl, and 1,3-dihydroxypropan-2-yloxy-methyl, respectively, exhibited quite strong anticancer activity. The underlying mechanism tests demonstrated that these compounds could induce apoptosis detected by DAPI staining, and Annexin V and propidium iodide binding. Cell cycle analysis indicated that the cancer cells were predominantly arrested at the G2/M phase when exposure to these compounds was examined by flow cytometry. These compounds may serve as lead candidates in the development of novel chemotherapeutics for cancer treatment.

Synergistic mechanisms of retigeric acid B and azoles against Candida albicans.

AIMS: To clarify the underlying synergistic antifungal mechanisms of retigeric acid B (RAB) in combination with azoles against Candida albicans. METHODS AND RESULTS: Increased accumulation of rhodamine 123 in C. albicans was measured by both spectrophotometric method and flow cytometry. The inhibitory properties to the drug efflux of C. albicans were determined spectrophotometrically. The decreased cellular ergosterol synthesis was measured using its unique spectrophotometric absorbance profile, and the downregulation expression levels of CDR1 and ERG11 were detected by real-time reverse transcription polymerase chain reaction. Transmission electron microscopy investigation found the wrinkled cell membrane and the impaired cell wall. CONCLUSIONS: RAB synergizes the antifungal effect of azoles against C. albicans by inhibiting efflux pump activity, targeting the ergosterol biosynthesis pathway and increasing the fluidity for the resulted ergosterol depletion. SIGNIFICANCE AND IMPACT OF THE STUDY: Investigating the mechanism of the synergy between RAB and azoles against C. albicans will help us to uncover the antifungal roles of this lichen-derived triterpene acid and find its possible clinical applications in overcoming fungal resistance.

Significant impact of gene polymorphisms on tacrolimus but not cyclosporine dosing in Asian renal transplant recipients.

Calcineurin inhibitors (CNI) are metabolized by cytochrome-P4503A (CYP3A) enzymes and extruded into the intestinal lumen by the drug efflux pump, P-glycoprotein (P-gp). The impact of single nucleotide polymorphisms (SNPs) of genes encoding CYP3A5 and P-gp on CNI dosing was examined among Asian renal transplant recipients. Frequencies of CYP3A5*1 versus *3 and MDR1-C3435T were correlated with tacrolimus (TAC) and cyclosporine (CSA) concentration-to-dose (C/D) ratios. Among 82 recipients (49% male; 88% Chinese), the majority were CYP3A5 expressors (*1*1 and *1*3, 11% and 40%, respectively) and 49% were nonexpressors (*3/*3). The prevalence of MDR-1-C3435T variants was 3435CC (41%), 3435CT (46%), and 3435TT (13%). Among 18 TAC-treated recipients, all receiving Diltiazem (DTZ), the median C/D ratio was lower for CYP3A5 *1/*1 versus *1/*3 versus *3/*3 (1.9, 4.6, and 13.5 ng/mL per 0.1 mg/kg/d, respectively; P = .001). The median C/D ratio was higher for TAC-treated patients with MDR-1-3435CC (14.1, 7.3, and 2.2 ng/mL per 0.1 mg/kg/d for CC, CT, and TT, respectively; P = .023). Neither CYP3A5 nor MDR-1-C3435T variants had an impact on CSA C/D ratios. Thus, CYP3A5 SNP has a significant impact on TAC dosing in Asian renal transplant recipients, which was likely to facilitate TAC metabolism. Although MDR-1-3435CC with higher P-gp expression should experience more TAC efflux and, therefore, lower TAC C/D ratios, all MDR-1-3435CC carriers were CYP3A5 nonexpressors; the latter ultimately contributed to the observed higher TAC C/D ratios in this population. This study advocates starting with a higher TAC dose for CYP3A5 expressors. Coadministration of DTZ may further optimize the TAC level through preferential P-gp binding and CYP3A4 inhibition.

Plagiochin E, a botanic-derived phenolic compound, reverses fungal resistance to fluconazole relating to the efflux pump.

AIM: In this study, we investigated the effect of plagiochin E (PLE), a botanic-derived phenolic natural product, on reversal of fungal resistance to fluconazole (FLC) in vitro and the related mechanism. METHODS AND RESULTS: A synergistic action of PLE and FLC was observed in the FLC-resistant Candida albicans strains and was evaluated using the fractional inhibited concentration index. The effect of PLE on FLC intracellular uptake was investigated in FLC-resistant C. albicans cells by liquid chromatography-tandem mass spectrometry, and the effect on efflux drug pump was assessed by measuring the efflux of Rhodamine 123 (Rh123). PLE significantly inhibited the efflux, but not the absorption, of Rh123 in FLC-resistant strains in phosphate-buffered saline with 5% glucose. Overexpression of the multidrug-resistance gene CDR1 in FLC-resistant C. albicans isolates was detected, and the introduction of PLE to the cells showed a significant reduction of the CDR1 expression in those FLC-resistant isolates. CONCLUSIONS: These findings indicate that PLE could reverse the fungal resistant to FLC by inhibiting the efflux of FLC from C. albicans, and this effect may be related to the efflux pump. SIGNIFICANCE AND IMPACT OF THE STUDY: These results indicate that the combination of PLE and FLC may provide an approach for the clinical therapy of fungus infection induced by FLC-resistant strains.

Dynamic of modernizing traditional Chinese medicine and the standards system for its development.

This article reviewed the process of Traditional Chinese Medicine's modernization on a global scale. This process is motivated by the potential need for traditional medicine as a result of health transitions and increasing drug R&D based on know-how from TCM. The established standards system for modern medicine serves as a basic model yet has limitations in terms of comprehensively evaluating TCM. Spurred by policy committments, research to provide supplements suited to TCM's features and principles is underway. Advanced and interdisciplinary technology and methodology is expected to play an essential role in TCM development.

GMP implementation in China: A double-edged sword for the pharmaceutical industry.

China's Good Manufacturing Practice (GMP) standards that mainly parallel WHO standards were made compulsory in 2004. However, GMP implementation had both positive as well as negative impacts on the pharmaceutical industry, with negatives including pharmaceutical companies suffering economic hardships, poor execution of GMP standards, and sequent health scares. This report briefly describes the problems with GMP implementation in China.

Conversion from mycophenolate mofetil to azathioprine in high-risk renal allograft recipients on cyclosporine-based immunosuppression.

OBJECTIVE: In a randomized control trial of mycophenolate mofetil (MMF) versus azathioprine (AZA) with cyclosporine and steroids, we demonstrated that MMF reduced acute rejection (AR) among renal allograft recipients (RTX) who were of low to moderate risk. However, 10% had AR when converted from MMF to AZA at 6 months, postrenal transplantation (RT). Two clinical markers, abnormal serum creatinine (SCr) and proteinuria at 6 months, post-RT, were associated with AR postconversion. The present study examined the safety of such conversion in selected high-risk RTX at 1 year of MMF therapy. METHODS: Thirteen high-risk RTX receiving MMF for either high panel reactive antibody (n = 9) or following AR (n = 4), with normal SCr and no proteinuria at 1 year, were selected for conversion. The incidence of AR, adverse events, and renal parameters (SCr, creatinine clearance, proteinuria) at 6 months postconversion was evaluated. Eight high-risk RTX who did not meet these selection criteria were retrospectively reviewed and used as controls. RESULTS: Renal parameters (SCr 123 +/- 26 vs 129 +/- 27 mumol/L; pre- vs postconversion) were not significantly different; no episodes of AR or proteinuria were documented. Azathioprine was discontinued in two patients due to leukopenia. In the control group, one patient had graft loss from chronic rejection, whereas one developed posttransplant lymphoproliferative disease necessitating MMF withdrawal. CONCLUSION: These results suggest that selective conversion from MMF to AZA after 1 year is safe, even in high-risk RTX. Normal SCr and absence of proteinuria are good screening parameters to identify patients at low risk for AR following such conversion.

Stereoselective metabolism of silybin diastereoisomers in the glucuronidation process.

A separation method for the hepatoprotective drug silybin and its metabolites by RP-HPLC was described. Based on this separation, the stereoselectivity of the metabolism of silybin was investigated by incubation of the drug and its two diastereoisomers with bovine liver microsomes. Information about the structures of these metabolites was obtained, using UV, HPLC/MS and NMR spectra. Four major metabolites (M(1), M(4) of silybin A and M(2), M(5) of silybin B), were prepared by preparative HPLC, and their configurations were accomplished by NMR spectra. A HPLC method was used to quantify the metabolites. The results showed that silybin was extensively metabolized and the major sites for glucuronidation were the C-20, C-7, at phenolic OH groups. Furthermore, the results obtained reveal that there was significant stereoselectivity in the glucuronidation process of silybin. Silybin B was glucuronidated at a more efficient rate than its diastereoisomer, and glucuronidation of silybin B was much preferred at the 20 position, while that of silybin A was similar at both 7 and 20 position.

[New monoterpenoids from Cynanchum hancockianum].

Five monoterpenoids have been isolated from the roots of Cynanchum hancockianum (Maxim) AI. Iljinski. Their structures were determined on the basis of spectral evidence. The three new compounds are: 4-p-menthane-1,7,8-triol (III), neohancoside A (IV), neohancoside B (V), and the two knowns: 4-p-menthene-1-8, 9-diol (I), and 4-p-menthane-1,8, 9-triol (II). Compound V was purified by acetylation.

[C21 steroidal constituents from Cynanchum hancockianum].

Two new compounds hancogenin B (V) and hancoside A (VI) and four known compounds glucogenin C (I), cynatratoside A (II), glaucogenin A (III) and anhydrohirundigenin (IV) were isolated from the roots of Cynanchum hancockianum (Maxim) Al. Iljinski. Their structures were identified on the basis of spectral evidence. The fragmentation ways of 13:14, 14:15-secopregnenes in EIMS were outlined and the antitumor activity of II and the antiendotoxic activity of VI were also preliminarily tested in vitro.

[Novel triterpenoids from Cynanchum hancockianum].

Four new triterpenoids have been isolated from the petroleum ether extract of Cyananchum hancockianum (Maxim) Al. Iljinski (Asclepiadaceae). On the basis of spectral data (1HNMR, 13CNMR, 1H-1H COSY, 1H-13C COSY, longrange 1H-13C COSY, MS, X-Ray analysis) and chemical connections, they were identified as hancockinol (Ia), hancolupenol (IIa), hancolupenone (IIc), and hancolupenol octacosanate (IId). They are of new skeletons with B/C cis, C/D trans, D/E cis junctures for Ia and with A/B trans, C/D trans, D/E cis junctures for IIa, IIc and IId.