Development of a bispecific nanobody conjugate broadly neutralizes diverse SARS-CoV-2 variants and structural basis for its broad neutralization.

The continuous emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants with increased transmissibility and profound immune-escape capacity makes it an urgent need to develop broad-spectrum therapeutics. Nanobodies have recently attracted extensive attentions due to their excellent biochemical and binding properties. Here, we report two high-affinity nanobodies (Nb-015 and Nb-021) that target non-overlapping epitopes in SARS-CoV-2 S-RBD. Both nanobodies could efficiently neutralize diverse viruses of SARS-CoV-2. The neutralizing mechanisms for the two nanobodies are further delineated by high-resolution nanobody/S-RBD complex structures. In addition, an Fc-based tetravalent nanobody format is constructed by combining Nb-015 and Nb-021. The resultant nanobody conjugate, designated as Nb-X2-Fc, exhibits significantly enhanced breadth and potency against all-tested SARS-CoV-2 variants, including Omicron sub-lineages. These data demonstrate that Nb-X2-Fc could serve as an effective drug candidate for the treatment of SARS-CoV-2 infection, deserving further in-vivo evaluations in the future.

Metabolic profiling in liver microsomes and mice of E28, a potent FLT3 inhibitor.

The objective of this study was to clarify the species differences of metabolic stability of E28 in liver microsomes, and to study metabolic phenotypes of E28 in human liver microsomes by chemical inhibition method.The metabolites in plasma, urine, and faeces samples from mice received caudal vein intravenous were detected and identified by UHPLC-HRMS, and the tissue distribution was studied after oral administration.E28 was metabolised rapidly in liver microsomes of each species with a short half-live T1/2 and a moderate clearance, except for rats. The metabolic properties of E28 were similar in human and mouse liver microsomes. Data from metabolic phenotype studies indicated that CYP2D6, CYP3A4 and CYP2C9 were the main metabolic enzymes participating in the metabolism of E28.The main metabolic pathways implicated include oxidation, methylation, amide hydrolysis, acetylation, glucuronide conjugation.Tissue distribution studies showed that E28 could be detected in all organs and tissues after oral administration, with the highest level in the stomach and the lowest in the brain. In bone marrow cells, the concentration of E28 in all sample points were consistently higher than its half inhibitory concentration against MV4-11 tumour cells.

Cleavage of the N≡N Triple Bond and Unpredicted Formation of the Cyclic 1,3-Diaza-2,4-Diborete (FB)2 N2 from N2 and Fluoroborylene BF.

A complete cleavage of the triple bond of N2 by fluoroborylene (:BF) was achieved in a low-temperature N2 matrix by the formation of the four-membered heterocycle FB(µ-N)2 BF, which lacks a trans-annular N-N bond. Additionally, the linear complex FB=N-N=BF and cyclic FB(η2 -N2 ) were formed. These novel species were characterized by their matrix infrared spectra and quantum-chemical calculations. The puckered four-membered-ring B2 N2 complex shows a delocalized aromatic two-electron π-system in conjugation with the exo-cyclic fluorine π lone pairs. This work may contribute to a rational design of catalysts based on borylene for artificial dinitrogen activation.

Reversible binding of the anticancer drug KXO1 (tirbanibulin) to the colchicine-binding site of ß-tubulin explains KXO1's low clinical toxicity.

KXO1 (tirbanibulin or KX2-391) is as a non-ATP-competitive inhibitor of SRC proto-oncogene nonreceptor tyrosine kinase (SRC) and is being clinically investigated for the management of various cancers and actinic keratosis. Recently, KXO1 has also been shown to strongly inhibit tubulin. Interestingly, unlike conventional tubulin-targeting drugs, KXO1 has exhibited low toxicity in preclinical and clinical studies, but the reason for this remains elusive, as are the KXO1-binding site and other details of the interaction of KXO1 with tubulin. Here, cell-based experiments revealed that KXO1 induces tubulin depolymerization and G2/M phase cell cycle arrest at low nanomolar concentrations, similar to colchicine, used as a positive control. Results from biochemical experiments, including an N,N-ethylenebis(iodoacetamide) competition assay, disclosed that KXO1 binds to the colchicine-binding site on ß-tubulin, further confirmed by the crystal structure of the tubulin-KXO1 complex at 2.5-Å resolution. A high-quality electron density map of the crystallographic data enabled us to unambiguously determine the position and orientation of KXO1 in the colchicine-binding site, revealing the detailed interactions between KXO1 and tubulin. We also found that KXO1 binds reversibly to purified tubulin, induces a totally reversible cellular effect (G2/M cell cycle arrest), and possesses no cellular toxicity 5 days after drug washout, explaining KXO1's low toxicity. In summary, we show that KXO1 binds to the colchicine-binding site of tubulin and resolved the crystal structure of the tubulin-KXO1 complex. Importantly, KXO1's reversible binding to tubulin explains its clinically low toxicity, an insight that could guide further clinical applications of KXO1.

Covalent modification of Cys-239 in ß-tubulin by small molecules as a strategy to promote tubulin heterodimer degradation.

Clinical microtubule-targeting drugs are functionally divided into microtubule-destabilizing and microtubule-stabilizing agents. Drugs from both classes achieve microtubule inhibition by binding different sites on tubulin and inhibiting or promoting polymerization with no concomitant effects on the protein levels of tubulin heterodimers. Here, we have identified a series of small molecules with diverse structures potentially representing a third class of novel tubulin inhibitors that promote degradation by covalent binding to Cys-239 of ß-tubulin. The small molecules highlighted in this study include T0070907 (a peroxisome proliferator-activated receptor γ inhibitor), T007-1 (a T0070907 derivative), T138067, N,N'-ethylene-bis(iodoacetamide) (EBI), and allyl isothiocyanate (AITC). Label-free quantitative proteomic analysis revealed that T007-1 promotes tubulin degradation with high selectivity. Mass spectrometry findings showed covalent binding of both T0070907 and T007-01 to Cys-239 of ß-tubulin. Furthermore, T007-1 exerted a degradative effect on tubulin isoforms possessing Cys-239 (ß2, ß4, and ß5(ß)) but not those containing Ser-239 (ß3, ß6) or mutant ß-tubulin with a C239S substitution. Three small molecules (T138067, EBI, and AITC) also reported to bind covalently to Cys-239 of ß-tubulin similarly induced tubulin degradation. Our results strongly suggest that covalent modification of Cys-239 of ß-tubulin by small molecules could serve as a novel strategy to promote tubulin heterodimer degradation. We propose that these small molecules represent a third novel class of tubulin inhibitor agents that exert their effects through degradation activity.

F2BMF (M = V, Nb, and Ta) and FBMF2 (M = Nb and Ta): A Combined Matrix Isolation Infrared Spectroscopic and Quantum Chemical Investigation.

Through matrix isolation infrared spectrometry and quantum chemical calculations, the reactions of laser ablated V, Nb, and Ta with boron trifluoride were investigated in excess solid neon at 4 K. The possible reaction products FBMF2, F2BMF, and BMF3 (M = V, Nb, and Ta) were calculated at the B3LYP, BPW91, and CCSD(T) levels of theory. The B-M bond strength in FBMF2 molecules is confirmed by energy decomposition analysis-natural orbitals for chemical valence calculations, CASSCF calculation, and natural bond orbital analysis, which favors one σ bond and two half π bonds.

Flavonoids with Inhibitory Effects on NLRP3 Inflammasome Activation from Millettia velutina.

Eight new flavonoids, including two ß-hydroxy/methoxychalcones, velutones A and B (1 and 2), two 1,3-diarylpropan-1-ols, velutols C and D (3 and 4), a dihydroxychalcone, velutone E (5), a chalcone, velutone F (6), a furanoflavanone, velutone G (7), and a furanoflavonol, velutone H (8), and 14 known compounds were isolated from Millettia velutina. Their structures were determined by high-resolution electrospray ionisation mass spectrometry (HR-ESIMS) and spectroscopic data analyses and time-dependent density functional theory electronic circular dichroism (TD-DFT-ECD) calculations. Among the isolated constituents, compound 6 exhibited the most potent inhibitory effect (IC50: 1.3 µM) against nigericin-induced IL-1ß release in THP-1 cells. The initial mechanism of action study revealed that compound 6 suppressed NLRP3 inflammasome activation via blocking ASC oligomerization without affecting the priming step, which subsequently inhibited caspase-1 activation and IL-1ß secretion. Most importantly, compound 6 exerted potent protective effects in the LPS-induced septic shock mice model by improving the survival rate of mice and suppressing serum IL-1ß release. These results demonstrated that compound 6 had the potential to be developed as a broad-spectrum NLRP3 inflammasome inhibitor for the treatment of NLRP3-related disease.

Modulation of LPS-induced inflammation in RAW264.7 murine cells by novel isoflavonoids from Millettia pulchra.

Millettia pulchra is a renowned anti-inflammatory herbal medicine in southeast provinces of China. However, the underlying anti-inflammation mechanism remained incompletely understood. Herein, four new isoflavones, pulvones A-D and eleven reported constituents were isolated from the stems of Millettia pulchra with their structures being elucidated by HRMS and NMR analysis. The anti-inflammatory activities of pulvones A and C were further evaluated due to the better inhibitory activity on nitric oxide production in LPS-stimulated RAW264.7 cells and no obvious cytotoxicity to RAW264.7 cells. Western blot showed that pulvones A significantly decreased the levels of iNOS and COX-2 proteins and pulvones C only decreased the level of iNOS protein. ELISA analysis demonstrated that pulvones A inhibited the production of both interleukin-6 (IL-6) and IL-1ß while pulvones C showed better suppression effect on IL-1ß production in LPS-stimulated RAW264.7 cells. Then, their potential inhibitory effects on NF-κB pathway were tested in LPS-stimulated RAW264.7 cells. Immunofluorescence and western blot assay showed that pulvones A and C reduced the nuclear translocation of NF-κB(p65) and interrupted IκB phosphorylation. The ADP-Glo™ kinase assay showed pulvones A and C could directedly inhibit the IKKß kinase activity with the inhibitory rate of 40%, which were also verified by docking study. Collectively, these results suggested that pulvones A and C's anti-inflammatory effects were relevant to the interruption of NF-κB activation by inhibiting IKKß kinase.

The Natural Compound Withaferin A Covalently Binds to Cys239 of ß-Tubulin to Promote Tubulin Degradation.

Withaferin A (WIT) is a natural product possessing a wide range of pharmacologic activities. Previous studies have reported covalent binding of WIT to tubulin and down-of tubulin protein levels although the underlying mechanisms remain to be established. In the current investigation, we showed that WIT induces down-regulation of tubulin in a post-transcriptional manner, suggestive of direct and potent activity in tubulin degradation. The N,N'-ethylene bis(iodoacetamide) assay and competitive binding experiments with four colchicine site-targeted tubulin inhibitors further revealed that WIT interacts with the colchicine site of tubulin to promote degradation. WIT irreversibly inhibited tubulin polymerization, and mass spectrometry results disclosed binding to cysteine at position 239 (Cys239) and Cys303 sites of ß-tubulin. Interestingly, WIT promoted degradation of the ß-tubulin isoforms containing Cys239 [ß2, ß4, and ß5(ß)] but had no effect on those containing Ser239 (ß3 and ß6). Moreover, a C239S but not C303S mutation in ß-tubulin completely abolished the degradation effect of WIT, suggesting that the Cys239-WIT covalent bond accounts for this activity. Our collective results clearly demonstrate that covalent interactions between WIT and Cys239 of ß-tubulin promote tubulin degradation, supporting its potential utility as a therapeutic compound. SIGNIFICANCE STATEMENT: Withaferin A, a natural product possessing a wide range of pharmacologic activities, covalently binds to Cys239 of ß-tubulin near the colchicine site, and the WIT-Cys239 covalent bond accounts for WIT-induced tubulin degradation, fully clarifying the underlying mechanisms and supporting its potential utility a therapeutic compound.

The compound millepachine and its derivatives inhibit tubulin polymerization by irreversibly binding to the colchicine-binding site in ß-tubulin.

Inhibitors that bind to the paclitaxel- or vinblastine-binding sites of tubulin have been part of the pharmacopoeia of anticancer therapy for decades. However, tubulin inhibitors that bind to the colchicine-binding site are not used in clinical cancer therapy, because of their low therapeutic index. To address multidrug resistance to many conventional tubulin-binding agents, numerous efforts have attempted to clinically develop inhibitors that bind the colchicine-binding site. Previously, we have found that millepachine (MIL), a natural chalcone-type small molecule extracted from the plant Millettia pachycarpa, and its two derivatives (MDs) SKLB028 and SKLB050 have potential antitumor activities both in vitro and in vivo However, their cellular targets and mechanisms are unclear. Here, biochemical and cellular experiments revealed that the MDs directly and irreversibly bind ß-tubulin. X-ray crystallography of the tubulin-MD structures disclosed that the MDs bind at the tubulin intradimer interface and to the same site as colchicine and that their binding mode is similar to that of colchicine. Of note, MDs inhibited tubulin polymerization and caused G2/M cell-cycle arrest. Comprehensive analysis further revealed that free MIL exhibits an s-cis conformation, whereas MIL in the colchicine-binding site in tubulin adopts an s-trans conformation. Moreover, introducing an α-methyl to MDs to increase the proportion of s-trans conformations augmented MDs' tubulin inhibition activity. Our study uncovers a new class of chalcone-type tubulin inhibitors that bind the colchicine-binding site in ß-tubulin and suggests that the s-trans conformation of these compounds may make them more active anticancer agents.

Anti-inflammatory Ellagitannins from Cleidion brevipetiolatum for the Treatment of Rheumatoid Arthritis.

Six new ellagitannins, brevipetins B-G (5 and 7-11), and a new phenolic glucoside, brevipetin A (4), along with six known compounds were isolated from the traditional Chinese medicinal plant Cleidion brevipetiolatum. Their structures and absolute configurations were determined by spectroscopic analyses, chemical methods, and TD-DFT-ECD calculations. Compounds 5-11 exhibited NO inhibitory effects with IC50 values of 1.9-8.2 µM, and 9 showed the most potent inhibitory effect (IC50: 1.9 µM). An in vivo anti-inflammatory assessment of 9 showed that it exerts therapeutic effects in both the carrageenan-induced rat paw edema and collagen-induced arthritis (CIA) models at 50 mg/kg oral administration. The enhanced protein and mRNA expression levels of iNOS (inducible nitric oxide synthase) and COX-2 (cyclooxygenase-2) in LPS-stimulated RAW 264.7 cells were dose-dependently suppressed by 9. An anti-inflammatory mechanistic study revealed that 9 suppressed NF-κB activity by inhibiting IκBα phosphorylation and blocking translocation of p65 from the cytosol to the nucleus. Therefore, 9 might have the potential to be developed as a lead compound for relieving rheumatoid arthritis.

SKLB060 Reversibly Binds to Colchicine Site of Tubulin and Possesses Efficacy in Multidrug-Resistant Cell Lines.

BACKGROUND/AIMS: Many tubulin inhibitors are in clinical use as anti-cancer drugs. In our previous study, a novel series of 4-substituted coumarins derivatives were identified as novel tubulin inhibitors. Here, we report the anti-cancer activity and underlying mechanism of one of the 4-substituted coumarins derivatives (SKLB060). METHODS: The anti-cancer activity of SKLB060 was tested on 13 different cancer cell lines and four xenograft cancer models. Immunofluorescence staining, cell cycle analysis, and tubulin polymerization assay were employed to study the inhibition of tubulin. N, N '-Ethylenebis(iodoacetamide) assay was used to measure binding to the colchicine site. Wound-healing migration and tube formation assays were performed on human umbilical vascular endothelial cells to study anti-vascular activity (the ability to inhibit blood vessel growth). Mitotic block reversibility and structural biology assays were used to investigate the SKLB060-tubulin bound model. RESULTS: SKLB060 inhibited tubulin polymerization and subsequently induced G2/M cell cycle arrest and apoptosis in cancer cells. SKLB060 bound to the colchicine site of ß-tubulin and showed antivascular activity in vitro. Moreover, SKLB060 induced reversible cell cycle arrest and reversible inhibition of tubulin polymerization. A mitotic block reversibility assay showed that the effects of SKLB060 have greater reversibility than those of colcemid (a reversible tubulin inhibitor), indicating that SKLB060 binds to tubulin in a totally reversible manner. The crystal structures of SKLB060-tubulin complexes confirmed that SKLB060 binds to the colchicine site, and the natural coumarin ring in SKLB060 enables reversible binding. CONCLUSIONS: These results reveal that SKLB060 is a powerful and reversible microtubule inhibitor that binds to the colchicine site and is effective in multidrug-resistant cell lines.

The effect and mechanism of millepachine-disrupted spindle assembly in tumor cells.

Millepachine (MIL) is a bioactive natural product that shows great potential for cancer treatment. Previous studies showed that MIL was a novel cancer drug candidate with a special structure. To provide reference for the research and development of MIL, we further investigated the mechanism of MIL inducing G2/M arrest and found MIL disrupted spindle assembly in tumor cells. In this study, we investigated the disrupting spindle assembly effects of MIL with a focus on its potential mechanism of action. First, we indicated that MIL did not inhibit microtubule polymerization from the results of in-vivo microtubule nucleation assay and microtubule polymerization in-vitro assay but delayed this process by inhibiting the production of ATP in tumor cells. Thereafter, we investigated the effect of MIL on the mitotic spindle. We found that MIL induced multipolar spindles by inhibiting the activity of Eg5 and inhibited mitotic spindle formation and chromatin condensation by the activation of the spindle assembly checkpoint (SAC) in tumor cells. These results established a novel function of MIL in regulating the assembly of mitotic spindle. As Eg5 and SAC are antitumor targets, effect of MIL on the Eg5 protein and SAC activation hinted that MIL has novel application in the development of antitumor drugs.

Design, synthesis and antibacterial evaluation of honokiol derivatives.

Staphylococcus aureus is a major and dangerous human pathogen that causes a range of clinical manifestations of varying severity, and is the most commonly isolated pathogen in the setting of skin and soft tissue infections, pneumonia, suppurative arthritis, endovascular infections, foreign-body associated infections, septicemia, osteomyelitis, and toxic shocksyndrome. Honokiol, a pharmacologically active natural compound derived from the bark of Magnolia officinalis, has antibacterial activity against Staphylococcus aureus which provides a great inspiration for the discovery of potential antibacterial agents. Herein, honokiol derivatives were designed, synthesized and evaluated for their antibacterial activity by determining the minimum inhibitory concentration (MIC) against S. aureus ATCC25923 and Escherichia coli ATCC25922 in vitro. 7c exhibited better antibacterial activity than other derivatives and honokiol. The structure-activity relationships indicated piperidine ring with amino group is helpful to improve antibacterial activity. Further more, 7c showed broad spectrum antibacterial efficiency against various bacterial strains including eleven gram-positive and seven gram-negative species. Time-kill kinetics against S. aureus ATCC25923 in vitro revealed that 7c displayed a concentration-dependent effect and more rapid bactericidal kinetics better than linezolid and vancomycin with the same concentration. Gram staining assays of S. aureus ATCC25923 suggested that 7c could destroy the cell walls of bacteria at 1×MIC and 4×MIC.

Millepachine showed novel antitumor effects in cisplatin-resistant human ovarian cancer through inhibiting drug efflux function of ATP-binding cassette transporters.

Millepachine (MIL), a bioactive natural chalcone from Chinese herbal medicine Millettia pachycarpa Benth, exhibits strong antitumor effects against many human cancer cells both in vitro and in vivo. In this study, we found that MIL significantly inhibited the proliferation of cisplatin-resistant A2780CP cells via inducing obvious G2/M arrest and apoptosis and down-regulating the activity of topoisomerase II protein. We further found that the mechanism by which MIL showed good antitumor effects in cisplatin-resistant human ovarian cancer was associated with inhibiting the expression of ATP-binding cassette transporters in cisplatin-resistant A2780CP cells. Importantly, MIL did not only significantly inhibit the tumor growth in cisplatin-sensitive A2780S xenograft model, with an inhibitory rate of 73.21%, but also inhibited the tumor growth in the cisplatin-resistant A2780CP xenograft model, with an inhibitory rate of 65.68% (p < 0.001 vs. control; p < 0.001 vs. DDP). In addition, MIL did not induce acquired drug resistance in A2780S tumor-bearing mice with an inhibitory rate of 60.03%. The promising in vitro and in vivo performance indicated that MIL exhibited potential significance for drug research and development.

Barbigerone reverses multidrug resistance in breast MCF-7/ADR cells.

Development of agents to overcome multidrug resistance (MDR) is one of the important strategies in cancer chemotherapy, and P-glycoprotein (P-gp) correlates with the degree of resistance. As a naturally occurring isoflavone, whether barbigerone (BA) could reverse MDR, is unknown. In this paper, we evaluated effects of BA on reversing P-gp mediated MDR of adriamycin (ADR)-resistant human breast carcinoma (MCF-7/ADR) cells. BA (0.5 µM) treatment showed strong potency to increase ADR cytotoxicity toward MCF-7/ADR cells. It was also demonstrated that BA time- and dose-dependently increased accumulations of ADR and reduced the efflux in MCF-7/ADR cells, pretreatment of these cells with BA might relocalized ADR to the nuclei. Furthermore, the results also revealed that BA did not affect P-gp, but alter P-gp ATPase activity. Intravenous administration of BA significantly increased anticancer efficacy of ADR to MCF-7/ADR xenograft model in nude mice. These results revealed that BA might reverse P-gp mediated MDR through inhibition of ATPase activity, which indicated a novel use of BA as a potent candidate for cancer chemotherapy.

Separation of caffeoylquinic acids and flavonoids from Asteris souliei by high-performance counter-current chromatography and their anti-inflammatory activity in vitro.

Eleven compounds were successfully separated from Asteris souliei by using a two-step high-performance counter-current chromatography method. The first step involved a reversed phase isocratic counter-current chromatography separation using hexane/ethyl acetate/methanol/water (1:0.8:1:1 v/v/v/v), which produced three fractions, the first two of which were mixtures. The second step used step-gradient reversed-phase counter-current chromatography with hexane/butanol/ethyl acetate/methanol/water (1:0.5:3.5:1:4 v/v/v/v/v) initially followed by hexane/ethyl acetate/methanol/water (1:2:1:2 v/v/v/v) to separate Fraction 1 into seven compounds; and hexane/ethyl acetate/methanol/water (1:1:1:1.2 v/v/v/v) to separate Fraction 2 into three further compounds. The chemical structures of the separated compounds were identified by ESI-MS and NMR spectroscopy (1 H and 13 C). Baicalin (5), eriodictyol (7), apigenin-7-glycoside (8), quercetin (9), luteolin (10), and apigenin (11) showed obvious inhibitory effects on lipopolysaccharide-induced nitric oxide production in RAW264.7 cells at a concentration of 10 µg/mL.

Flavonoids and biphenylneolignans with anti-inflammatory activity from the stems of Millettia griffithii.

Five new flavonoids, griffinones A-E (1-5), a new biphenylneolignan, griffilignan A (6) and ten known compounds were isolated from the n-hexane and EtOAc extracts of Millettia griffithii. The structures of the new compounds were determined by 1D and 2D NMR, and by HRMS. The anti-inflammatory activity of the isolated compounds was evaluated on lipopolysaccharide (LPS)-induced nitric oxide (NO) production in RAW 264.7 cells. Among the isolated compounds, compounds 1, 2 and 14 showed significant anti-inflammatory activity with IC50 values of 20.4, 2.1 and 35.7µM, respectively and no obvious toxicities were observed at 100µM. Western blot and PCR assay further showed that inhibition of nitric oxide production by compound 2 was associated with suppression of iNOS expression. Modeling studies suggested that the amino group, phenyl ring as well as the isopentenyl tails of compound 2 could help bind to iNOs.

[In vitro metabolism of anti-tumor compound E7 in different species of liver microsomes].

To investigate the metabolic stability of E7 in liver microsomes of human, Beagle dog, Cynomolgus monkey and SD rats, and compare the metabolic differences between different species. Selective chemical inhibitors were used to determine the effects of different inhibitors on E7 metabolic rate, and predict the main enzymes involved in E7 metabolism in rat liver microsomes. The experimental results showed that the in vitro half-lives (T1/2) of E7 in liver microsomes of human, dog, monkey and rats were 57.75, 69.30, 16.90,30.13 min respectively. Their intrinsic clearance rate was 0.004 8, 0.004 0, 0.016 4 and 0.009 2 mL•min⁻¹â€¢mg⁻¹ respectively. Hence, it could be speculated that the metabolic rate of E7 was similarly slow in human and dog liver microsomes; while it was similarly fast in monkey and rat liver microsomes. There was significant difference in metabolic rate of E7 between different species. The results showed that CYP2E1, CYP2A6, CYP1A2 and CYP2D6 might participate in metabolism of E7, while the contribution of polymorphic CYP3A4 was small.

Separation of flavonoids from Millettia griffithii with high-performance counter-current chromatography guided by anti-inflammatory activity.

Millettia griffithii is a unique Chinese plant located in the southern part of Yunnan Province. Up to now, there is no report about its phytochemical or related bioactivity research. In our previous study, the n-hexane crude extract of Millettia griffithii revealed significant anti-inflammatory activity at 100 µg/mL, inspiring us to explore the anti-inflammatory constituents. Four fractions (I, II, III, and A) were fractionated from n-hexane crude extract by high-performance counter-current chromatography with solvent system composed of n-hexane/ethyl acetate/methanol/water (8:9:8:9, v/v) and then were investigated for the potent anti-inflammatory activity. Fraction A, with the most potent inhibitory activity was further separated to give another four fractions (IV, V, VI, and B) with solvent system composed of n-hexane/ethyl acetate/methanol/water (8:4:8:4, v/v). Compound V and fraction B exhibited remarkable anti-inflammatory activity with nitric oxide inhibitory rate of 80 and 65%, which was worth further fractionation. Then, three fractions (VII, VIII, and IX) were separated from fraction B with a solvent system composed of n-hexane/ethyl acetate/methanol/water (8:1:8:1, v/v), with compound VIII demonstrating the most potent inhibitory activity (80%). Finally, the IC50 values of compound V and VIII were tested as 38.2 and 14.9 µM. The structures were identified by electrospray ionization mass spectrometry and(1)H and (13)C NMR spectroscopy.