A dual functional probe for assessing human CYP450 3A5 and 3A enzymes bioactivities.

Aim: CYP3A5 plays a vital role in the drug metabolism, it displays varied expression levels among individuals and is easily influenced by genetic polymorphisms and some diseases. Methodology & results: A dual function probe isobutyryl-11-keto-ß-boswellic acid (IKBA) was developed; it possessed a high selectivity toward CYP3A5 and CYP3A enzymes for its two individual metabolites, respectively. The probe has the high accuracy and wide applicability in measuring the real activity of CYP3A5. Finally, IKBA was successfully used for the evaluation of the activity of CYP3A5 and CYP3A enzymes in various bio samples. Conclusion: IKBA could serve as a useful tool for exploring the physiology and pathology functions of CYP3A5 and give some useful guidance for the rational use of clinical drugs.

Correction to: Metabolic Profile of 3-Acetyl-11-Keto-ß-Boswellic Acid and 11-Keto-ß-Boswellic Acid in Human Preparations In Vitro, Species Differences, and Bioactivity Variation.

The authors regret that Fig. 7d for the group: LPS+M-2 (80 µM) was mistakenly uploaded.

Identification and Isolation of Glucosytransferases (GT) Expressed Fungi Using a Two-Photon Ratiometric Fluorescent Probe Activated by GT.

As is well-known, fungi are an important biocatalysis model of glucosylation and have been widely applied for bioactive compounds glucosylation mediated by the intracellular glucosytransferases (GTs). However, there is no efficient method for the real-time detection of GTs and the rapid isolation of the target fungi strains with the high expression of GTs. In the present work, we first developed a two-photon ratiometric fluorescent probe N-( n-butyl)-4-hydroxy-1,8-naphthalimide (NHN) for detecting the glucosyltransferases activity and intracellular imaging of GTs. Under UV light (365 nm), the transformed product of NHN mediated by intracellular glucosyltransferase displayed blue emission to guide the rapid isolation of fungal strains possessing overexpression of GTs from complex soil samples. Finally, by using the fluorescent probe, two target fungi were isolated and identified to be Rhizopus oryzae and Mucor circinelloides by molecular analysis, and they exhibited a robust capability for regio- and stereospecific O-glycosylation. Our results fully demonstrated that NHN may be a promising tool for guiding real-time GTs activity in fungal strains and even for developing natural fungal strains with GTs overexpression.

Highly Specific near-Infrared Fluorescent Probe for the Real-Time Detection of ß-Glucuronidase in Various Living Cells and Animals.

ß-Glucuronidase (GLU) is an important biomarker for primary cancers and intestinal metabolism of drugs or endogenous substances; however, an effective optical probe for near-infrared (NIR) monitoring in vivo is still lacking. Herein, we design an enzyme-activated off-on NIR fluorescent probe, HC-glu, based on a hemicyanine keleton, which is conjugated with a d-glucuronic acid residue via a glycosidic bond, for the fluorescent quantification and trapping of endogenous GLU activity in vitro and in vivo. The newly developed NIR probe exhibited prominent features including prominent selectivity, high sensitivity, and ultrahigh imaging resolution. It has been successfully used to detect and image endogenous GLU in various hepatoma carcinoma cells, tumor tissues, and tumor-bearing mouse models, for cancer diagnosis and therapy. Moreover, it could detect the in vivo activity of GLU in the intestinal tracts of animals including mice and zebrafish, where GLU performs a vital biological function and is mainly distributed. It could also evaluate real intestinal distribution and real-time variations of GLU in development and growth, all of which are very helpful to guide rational drug use in the clinic. Our results fully demonstrated that HC-glu may serve as a promising tool for evaluating the biological function and process of GLU in living systems.

Diterpenoids from the roots of Euphorbia ebracteolata and their inhibitory effects on human carboxylesterase 2.

A chemical investigation of the roots of Euphorbia ebracteolata identified eighteen diterpenoids and glycosides. On the basis of spectroscopic data, they were determined to be ent-kauranes, ent-atisanes, tigliane derivatives, ingenane, and ent-abietanes, among which were eleven previously undescribed diterpenoids. The inhibitory effects of the isolated compounds against human carboxylesterase 2 (hCE-2) were evaluated in vitro, which revealed moderate inhibitory effects with IC50 values < 50 µM. Next, the inhibitory kinetics were evaluated for the putative hCE-2 inhibitor 4ß,9α,16,20-tetrahydroxy-14(13 → 12)-abeo-12αH-1,6-tigliadiene-3,13-dione (IC50 3.88 µM), and results indicated competitive inhibition with Ki 4.94 µM. Additionally, none of the diterpenoids showed cytotoxic effects against five human tumor cell lines as determined by MTT assays.

Heterodimeric Diterpenoids Isolated from Euphorbia ebracteolata Roots and Their Inhibitory Effects on α-Glucosidase.

Two heterodimeric diterpenoids (1 and 2) comprising abietane lactone and nor-rosane constituent units were isolated from Euphorbia ebracteolata roots. Compound 1 exhibited a moderate inhibitory effect on α-glucosidase (IC50 = 7.94 µM), with a Ki value of 10.8 µM. In silico molecular docking has been performed to investigate the inhibition mechanism. Compound 2 inhibited the acetyl transfer activity of Mycobacterium tuberculosis GlmU (IC50 = 41.85 µM), which is a novel tuberculosis treatment target.

Catechol-O-Methyltransferase and UDP-Glucuronosyltransferases in the Metabolism of Baicalein in Different Species.

BACKGROUND: Baicalein is the major bioactive flavonoid in some herb medicines and dietary plants; however, the detailed metabolism pathway of its major metabolite oroxylin A-7-O-ß-D-glucuronide in human was not clear. It was important to illustrate the major metabolic enzymes that participate in its elimination for the clinic use of baicalein. OBJECTIVES: We first revealed a two-step metabolism profile for baicalein and illustrated the combination of catechol-O-methyltransferase (COMT) and uridine diphosphate-glucuronosyltransferases (UGTs) in drug metabolism, further evaluated its bioactivity variation during drug metabolism. METHODS: The metabolism profiles were systematically characterized in different human biology preparations; after then, the anti-inflammatory activities of metabolites were evaluated in LPS-induced RAW264.7 cell. RESULTS: The first-step metabolite of baicalein was isolated and identified as oroxylin A; soluble-bound COMT (S-COMT) was the major enzyme responsible for its biotransformation. Specially, position 108 mutation of S-COMT significantly decreases the elimination. Meantime, oroxylin A was rapidly metabolized by UGTs, UGT1A1, -1A3, -1A6, -1A7, -1A8, -1A9, and -1A10 which were involved in the glucuronidation. Considerable species differences were observed with 1060-fold K m (3.05 ± 1.86-3234 ± 475 µM) and 330-fold CLint (5.93-1973 µL/min/mg) variations for baicalein metabolism. Finally, the middle metabolite oroxylin A exhibited a potent anti-inflammatory activity with the IC50 value of 28 µM. CONCLUSION: The detailed kinetic parameters indicated that COMT provide convenience for the next glucuronidation; monkey would be a preferred animal model for the preclinical investigation of baicalein. Importantly, oroxylin A should be reconsidered in evaluating baicalein efficacy against inflammatory diseases.

Metabolic Profile of 3-Acetyl-11-Keto-ß-Boswellic Acid and 11-Keto-ß-Boswellic Acid in Human Preparations In Vitro, Species Differences, and Bioactivity Variation.

3-Acetyl-11-keto-ß-boswellic acid (AKBA) and 11-keto-ß-boswellic acid (KBA) are widely used in the clinic as anti-inflammatory drugs. However, these drugs have the poor bioavailability, which may be caused by their extensive metabolism. In this study, we systemically characterized both phase I and II metabolism of AKBA and KBA in vitro. In total, four major metabolites were firstly biosynthesized and identified using 1D and 2D NMR spectroscopy. Among them, three metabolites were novel. The kinetic parameters (K m , V max , CL int, and K i ) were also analyzed systematically in various biological samples. Finally, the deacetylation of AKBA and hydroxylation of KBA were confirmed to be the major metabolic pathways based on their large CL int and the high amounts of KBA (46.7%) and hydroxylated KBA (50.8%) along with a low amount of AKBA (2.50%) in human primary hepatocytes. Carboxylesterase 2 (CE2) selectively catalyzed the deacetylation of AKBA to form KBA. Although CYP3A4, CYP3A5, and CYP3A7 catalyzed the metabolism of KBA, CYP3A4 played a predominant role in the hydroxylation reaction of KBA in human. Notably, deacetylation and regioselective hydroxylation exhibited considerable species differences. Deacetylation was only observed in human liver microsomes and primary human hepatocytes; 21- and 20-mono-hydroxylation of KBA were primarily observed in human, monkey, and dog; and 16- and 30-mono-hydroxylation were observed in other species. More importantly, all four mono-hydroxylation metabolites exhibited a moderate anti-inflammatory activity. The 21- and 20-hydroxylation metabolites inhibited the expression of iNOS, the LPS-induced activation of IkBα and p65 phosphorylation, and suppressed p65 nuclear translocation in RAW264.7 cells.