Cannabis-like activity of Zornia latifolia Sm. detected in vitro on rat cortical neurons: major role of the flavone syzalterin.

Zornia latifolia is a plant suspected to possess psychoactive properties and marketed as a marijuana substitute under the name 'maconha brava'. In this study, the effects of fractions obtained from a 2-propanol extract of aerial portions of the plant were determined by multielectrode array (MEA) analyses on cultured networks of rat cortical neurons. Lipophilic (ZL_lipo, mainly containing flavonoid aglycones), and hydrophilic (ZL_hydro, mainly containing flavonoid glycosides) fractions were initially obtained from the raw extract. ZL_lipo significantly inhibited mean firing rate (MFR) and mean bursting rate (MBR) of MEA recordings, while ZL_hydro induced no inhibition. Column chromatography separation of ZL_lipo yielded five fractions (ZL1-ZL5), among which ZL1 induced the strongest MFR and MBR inhibition. NMR and HPLC-MS analyses of ZL1 revealed the prevalence of the common flavonoids genistein (1) and apigenin (2) (in about a 1:1 ratio), and the presence of the rare flavone syzalterin (6,8-dimethylapigenin) (3) as a minor compound. Exposures of MEA to apigenin and genistein standards did not induce the MFR and MBR inhibition observed with ZL1, whereas exposure to syzalterin standard or to a 1:9 mixture syzalterin-genistein induced effects similar to ZL1. These inhibitory effects were comparable to that observed with high-THC hashish, possibly accounting for the plant psychoactive properties. Data indicate that Z. latifolia, currently marketed as a free herbal product, should be subjected to measures of control. In addition, syzalterin showed distinctive pharmacological properties, opening the way to its possible exploitation as a neuroactive drug.

Bioactive Diterpenes from the Brazilian Native Plant (Moquiniastrum pulchrum) and Their Application in Weed Control.

Even today, weeds continue to be a considerable problem for agriculture. The application of synthetic herbicides produces serious environmental consequences, and crops suffer loss of their activity due to the appearance of new resistant weed biotypes. Our aim is to develop new effective natural herbicides that improve the problem of resistance and do not harm the environment. This work is focused on a bioassay-guided isolation and the characterization of natural products present in Moquiniastrum pulchrum leaves with phytotoxic activity and its preliminary application in weeds. Moquiniastrum pulchrum was selected for two reasons: it is an abundant species in the Cerrado region (the second most important ecosystem in Brazil, after the Amazon)-the explanation behind its being a dominant species is a major focus of interest-and it has traditional employment in folk medicine. Six major compounds were isolated in this plant: one flavone and five diterpenes, two of which are described for the first time in the literature. Four of the six compounds exhibited phytotoxic activity in the bioassays performed. The results confirmed the phytotoxic potential of this plant, which had not been investigated until now.

Icariside I specifically facilitates ATP or nigericin-induced NLRP3 inflammasome activation and causes idiosyncratic hepatotoxicity.

BACKGROUND: Epimedii Folium (EF) is commonly used for treating bone fractures and joint diseases, but the potential hepatotoxicity of EF limits its clinical application. Our previous study confirms that EF could lead to idiosyncratic drug-induced liver injury (IDILI) and hepatocyte apoptosis, but the mechanism remains unknown. Studies have shown that NLRP3 inflammasome plays an important role in the development of various inflammatory diseases such as IDILI. Specific stimulus-induced NLRP3 inflammasome activation may has been a key strategy for lead to liver injury. Therefore, main compounds derived from EF were chosen to test whether the ingredients in EF could activate the NLRP3 inflammasome and to induce IDILI. METHODS: Bone-marrow-derived macrophages (BMDMs) were treated with Icariside I, and then stimulated with inflammasome stimuli and assayed for the production of caspase-1 and interleukin 1ß (IL-1ß) and the release of lactate dehydrogenase (LDH). Determination of intracellular potassium, ASC oligomerization as well as reactive oxygen species (ROS) production were used to evaluate the stimulative mechanism of Icariside I on inflammasome activation. Mouse models of NLRP3 diseases were used to test whether Icariside I has hepatocyte apoptosis effects and promoted NLRP3 inflammasome activation in vivo. RESULTS: Icariside I specifically enhances NLRP3 inflammasome activation triggered by ATP or nigericin but not SiO2, poly(I:C) or cytosolic LPS. Additionally, Icariside I does not alter the activation of NLRC4 and AIM2 inflammasomes. Mechanically, Icariside I alone does not induce mitochondrial reactive oxygen species (mtROS), which is one of the critical upstream events of NLRP3 inflammasome activation; however, Icariside I increases mtROS production induced by ATP or nigericin but not SiO2. Importantly, Icariside I leads to liver injury and NLRP3 inflammasome activation in an LPS-mediated susceptibility mouse model of IDILI, but the effect of Icariside I is absent in the LPS-mediated mouse model pretreated with MCC950, which is used to mimic knockdown of NLRP3 inflammasome activation. CONCLUSIONS: Our study reveals that Icariside I specifically facilitates ATP or nigericin-induced NLRP3 inflammasome activation and causes idiosyncratic hepatotoxicity. The findings suggest that Icariside I or EF should be avoided in patients with diseases related to ATP or nigericin-induced NLRP3 inflammasome activation, which may be risk factors for IDILI. Video abstract.

Inductive and synergistic interactions between plant allelochemical flavone and Bt toxin Cry1Ac in Helicoverpa armigera.

Genetically engineered crops simultaneously produce defensive allelochemicals and Bacillus thuringiensis (Bt) toxin proteins to kill some of the world's most devastating insect pests. How the two types of toxins, when ingested sequentially or simultaneously, interact at both lethal and sublethal doses in these pests remains underexplored. Here, we examined the toxicological interactions between the Bt toxin Cry1Ac and the flavonoid allelochemical flavone in Helicoverpa armigera. Simultaneous exposure of H. armigera neonates to lethal doses (LC25 ) of Cry1Ac and flavone caused a mortality significantly higher than that of either toxin alone and their expected additive mortality. Preexposure for 24 h to a sublethal dose (LC10 ) of Cry1Ac followed by 6-d simultaneous exposure to the same dose of Cry1Ac plus a lethal dose (1.6 mg/g diets, LC50 ) of flavone resulted in a mortality significantly higher than that of the LC50 dose of flavone alone and the expected additive mortality of the LC50 dose of flavone plus the LC10 dose of Cry1Ac. One-day preexposure to the sublethal dose (LC10 ) of flavone followed by 6-d simultaneous exposure to the LC50 dose (6 ng/cm2 ) of Cry1Ac plus the LC10 dose of flavone yielded a mortality significantly higher than that of the LC50 dose of Cry1Ac but similar to the expected additive mortality of the LC50 dose of Cry1Ac plus the LC10 dose of flavone. The results suggest that Cry1Ac induces and synergizes the toxicity of flavone against H. armigera larvae.

Effect of methoxyflavones contained in Kaempferia parviflora on CRE-mediated transcription in PC12D cells.

The cAMP-response element (CRE) is critical in the formation of long-term memory. To prove the pharmacological effects of the methoxyflavones-rich residue (MRR) and its constituent methoxyflavones (1-9) extracted from the rhizomes of Kaempferia parviflora on the nervous system, we examined the effects of the MRR and methoxyflavones (1-9) on CRE-mediated transcription in PC12D cells. The MRR increased CRE-mediated transcription in PC12D cells. In addition, among methoxyflavones (1-9) isolated from MRR, compounds 1-4 increased CRE-mediated transcription. These results suggest that K. parviflora and methoxyflavone might be very useful materials for preventing and recovering from cognitive decline.

Prospects of tangeretin as a modulator of cancer targets/pathways.

To date, cancer is the second leading cause of death worldwide after cardiac arrest. A large number of synthetic drugs are available for the treatment of different types of cancer; however, a major problem associated with these drugs is its toxicity towards the normal cells. To overcome these problems, researchers explore plants derived phytochemicals because of their pleiotropic action and least toxicity towards the normal cells. Tangeretin is a polymethoxylated flavone found extensively in citrus fruits and has shown potent anti-cancer activity in different types of cancer cells. Hence, this review examines the anti-cancer activity of tangeretin via different molecular targets/pathways. Tangeretin induces apoptosis via intrinsic as well as extrinsic pathways and arrest the cell cycle. It also suppresses cell proliferation by modulating PI3K/AKT/mTOR, Notch, and MAPK signalling pathways. Besides, it induces autophagic cell death, suppresses migration, invasion, and angiogenesis. Further, the role of tangeretin in multi-drug resistance and combination therapy, different biological sources of tangeretin, its derivatives, and pharmacokinetics profile and toxicity studies are also discussed. Towards the end, the challenges associated with tangeretin usage as potential anti-cancer phytochemicals have also been discussed. Tangeretin, like a pandora's box, needs to be explored further, and more research is warranted to improve its usefulness for better human health.

An evaluation of the genotoxicity and subchronic toxicity of the peel extract of Ponkan cultivar 'Ohta ponkan' (Citrus reticulata Blanco) that is rich in nobiletin and tangeretin with anti-dementia activity.

Nobiletin and tangeretin are major components of polymethoxylated flavones in the peels of citrus fruits such as Citrus reticulata. Because nobiletin and tangeretin have attracted attention due to their beneficial health properties, citrus peel extracts, in which they are concentrated, have the potential to serve as a functional food ingredient to prevent diseases. In this study, a series of toxicological studies on the peel extract of Ponkan cultivar 'Ohta ponkan' (Citrus reticulata Blanco), was conducted. No mutagenic activity was observed in a bacterial reverse mutation test, whereas chromosomal aberrations were induced in an in vitro mammalian chromosomal aberration test. No genotoxicity was observed in an in vivo mammalian micronucleus test. In a 90-day study at daily doses of 54, 180, or 540 mg/kg body weight (bw)/day, hyaline droplet nephropathy, which specifically occurs in adult male rats, was observed in males of 540 mg/kg bw/day group. No other adverse effects were observed in the 90-day study. The no adverse effect level in the 90-day study was considered to be 540 mg/kg bw/day for female rats and less than 540 mg/kg bw/day for male rats.

Synthesis, crystal studies and biological evaluation of flavone derivatives.

Three substituted flavone derivatives have been synthesized from substituted O-hydroxy acetophenones and 4-trifluoromethyl benzaldehyde in good yield. These compounds were characterized by NMR spectroscopy and single crystal X-ray Diffraction. Compound F1 and F3 were re-crystallized from their concentrated solutions in chloroform ethyl acetate mixture while F2 was re-crystallized in ethyl acetate n-hexane mixture. Compound F1 and F3 are monoclinic (space group P21/c) with lattice parameters: [a, b, c (A) / ß (°)] = 13.332 (2), 15.616 (2) / 6.2898 (8) and 13.9716 (15), 7.1868 (7), 13.6912 (14) / 91.113(6) respectively. Compound F2 is Triclinic (space group P-1) and has lattice parameters: [a, b, c (Å) / α, ß, γ (°)] = 6.5002 (6), 8.3801 (9), 13.5989 (14) / 89.348(5), 85.141(4), 84.521(5). Antioxidant, antibacterial and cytotoxic profile was investigated. The compounds showed moderate to less activity on 1,1-diphenyl-2-picryl-hydrazyl (DPPH), Hydrogen peroxide (H/2/O/2) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) models of radical scavenging activity while promising antibacterial potentials were recorded. Furthermore, these molecules can also be used as potential candidates for new antitumor agents.

Microbial Metabolites Determine Host Health and the Status of Some Diseases.

The gastrointestinal (GI) tract is a highly complex organ composed of the intestinal epithelium layer, intestinal microbiota, and local immune system. Intestinal microbiota residing in the GI tract engages in a mutualistic relationship with the host. Different sections of the GI tract contain distinct proportions of the intestinal microbiota, resulting in the presence of unique bacterial products in each GI section. The intestinal microbiota converts ingested nutrients into metabolites that target either the intestinal microbiota population or host cells. Metabolites act as messengers of information between the intestinal microbiota and host cells. The intestinal microbiota composition and resulting metabolites thus impact host development, health, and pathogenesis. Many recent studies have focused on modulation of the gut microbiota and their metabolites to improve host health and prevent or treat diseases. In this review, we focus on the production of microbial metabolites, their biological impact on the intestinal microbiota composition and host cells, and the effect of microbial metabolites that contribute to improvements in inflammatory bowel diseases and metabolic diseases. Understanding the role of microbial metabolites in protection against disease might offer an intriguing approach to regulate disease.

Synthesis, antinociceptive activity and structure activity relationship of flavone derivatives.

Flavonoids are phenolic compounds that have always attracted pharmaceutical researchers and food manufacturers. Nature has indirectly provided us flavones in our daily diet i.e. tea, fruits, juices and vegetables. Flavones have got special position in research field of natural and synthetic organic chemistry due to their biological capabilities. Flavone derivative has been synthesized in good yield from ketone and corresponding aldehydes. The structures have been established by different spectroscopic techniques like 1H NMR, 13C NMR, IR and elemental analysis. The compounds were then screened for its acute toxicity and antinociceptive response in mice models with writhings induced by acetic acid, tail immersion and formalin-induced nociception assay procedures and structure activity relationship was established. The compounds were safe up to a maximum dose of 1200 mg/kg body weight in mice. The effects following pretreatment with naloxone were also studied to reveal the involvement of opioid receptors in the antinociceptive action. The flavone derivatives showed significant reduction in number of abdominal constrictions, increase in paw licking response time in both phases and a significant raise in latency time in nociception models. Moreover, the antinociceptive response was significantly attenuated by pretreatment with naloxone suggesting the involvement of opioid system in the antinociceptive action. The promising effects were shown by halogenated flavone. The flavone derivatives showed analgesic response in all models of nociception suggesting the involvement of opioid system in the antinociceptive action.

Novel Flavones from the Root of Phytolacca acinosa Roxb.

Two new flavones, 6,7-methylenedioxy-4-hydroxypeltogynan-7'-one (1), cochliophilin B (2), as well as two known ones, cochliophilin A (3) and 6-methoxy-7-hydroxy flavone (4), were isolated from the ethanol extract of the root of Phytolacca acinosa Roxb. Compound 1 is a flavanol framework with one δ-lactone unit, which is rather rare in nature. The structures of the new compounds were determined on the basis of extensive spectroscopic (IR, MS, 1D- and 2D-NMR) analyses, the absolute configuration of 1 was established by comparing experimental and calculated electronic circular dichroism spectra. The structures of known compounds were fixed by comparison with literatures data. Compounds 2 and 4 showed modest inhibitory activities against BEL-7402 cell line, with IC50 values of 28.22 and 39.16 µmol/L, respectively.

The flavonoid 6-methoxyflavone allays cisplatin-induced neuropathic allodynia and hypoalgesia.

Chemotherapy-induced peripheral neuropathy (CIPN) is a major dose limiting side-effect of several commonly used chemotherapeutic agents (such as cisplatin) that profoundly impairs patient quality of life. Unfortunately, neither prophylactic strategies nor symptomatic treatments have proven useful in this condition. Flavonoids are found ubiquitously in fruits and vegetables and exert a multiplicity of beneficial effects. In this study, the antinociceptive activity of 6-methoxyflavone (6-MF) was investigated and evaluated in comparison with gabapentin in a rat model of CIPN. The effect on motor balance was also assessed using the rotarod and footprint analysis paradigms. 6-MF possessed both peripheral and central antinociceptive activities against tonic and phasic nociceptive stimuli. Cisplatin administration (3.0mg/kg/week, i.p.) for four consecutive weeks generated temporal mechanical allodynia (decreased paw withdrawal threshold; PWT) and thermal hypoalgesia (increased paw thermal threshold; PTT) in the bilateral hindpaws. Daily treatment with 6-MF (25, 50 and 75mg/kg/day, i.p) for four weeks attenuated the cisplatin-induced expression of nocifensive behaviors observed as a significant increase in PWT and alleviation of PTT during the third and fourth weeks of cisplatin administration. Accordingly, daily gabapentin (75mg/kg, i.p) suppressed the expression of CIPN by normalizing the PWT and hotplate response latency. However, these antinociceptive actions were associated with motor impairment exemplified by a significant decrease in rotarod endurance latency and a deficit in the uniformity of step alternation. In contrast, 6-MF was devoid of these adverse side-effects. These findings suggested that 6-MF afforded desirable neuropathic pain alleviating effects in CIPN and it was devoid of gabapentin-like unwanted motor side-effects.

Semisynthetic Flavone-Derived Antimicrobials with Therapeutic Potential against Methicillin-Resistant Staphylococcus aureus (MRSA).

A new series of semisynthetic flavone-based small molecules mimicking antimicrobial peptides has been designed from natural icaritin to combat drug-resistant Gram-positive bacterial infections. Compound 6 containing two arginine residues exhibited excellent antibacterial activity against Gram-positive bacteria, including MRSA, and very low toxicity to mammalian cells, resulting in a high selectivity of more than 511, comparable to that of several membrane-active antibiotics in clinical trials. Our data show for the first time that icaritin derivatives effectively kill bacteria. Meanwhile, this is the first study deploying a biomimicking strategy to design potent flavone-based membrane targeting antimicrobials. 6 showed rapid bactericidal activity by disrupting the bacterial membrane and can circumvent the development of bacterial resistance. Importantly, 6 was highly efficacious in a mouse model of corneal infection caused by MRSA and Staphylococcus aureus.

Identification and structure activity relationship of novel flavone derivatives that inhibit the production of nitric oxide and PGE2 in LPS-induced RAW 264.7 cells.

In an effort to identify novel anti-inflammatory compounds, a series of flavone derivatives were synthesized and biologically evaluated for their inhibitory effects on the production of nitric oxide (NO) and prostaglandin E2 (PGE2), representative pro-inflammatory mediators, in LPS-induced RAW 264.7 cells. Their structure-activity relationship was also investigated. In particular, we found that compound 3g displayed more potent inhibitory activities on PGE2 production, similar inhibitory activities on NO production and less weak cytotoxicity than luteolin, a natural flavone known as a potent anti-inflammatory agent.

Pharmacokinetics of calycopterin and xanthmicrol, two polymethoxylated hydroxyflavones with anti-angiogenic activities from Dracocephalum kotschyi Bioss.

BACKGROUND: Recently flavonoids have attracted the attention of researchers in the fight against cancer. Calycopterin and xanthomicrol, are two polymethoxylated flavonoids found in the aerial parts of Dracocephalum kotschyi Bioss.. We have recently shown that these compounds possess antiangiogenic activity and may be of value as potential anticancer agents. In order to demonstrate putative in vivo antitumor effect of these compounds we needed preliminary information on both pharmacokinetics and toxicological properties of these two agents. METHOD: A new online SPE HPLC method for measurement of calycopterin and xanthomicrol in rat plasma was developed. Pharmacokinetic parameters of calycopterin and xanthomicrol, after i.v. administration in rats, were determined. RESULTS: The plasma half-life for both agents was around 4 h, however, the volume of distribution of calycopterin appeared to be about 8 times greater than xanthomicrol. This was probably due the greater hydrophobicity of the former which had other consequences such as much smaller maximum plasma concentration of calycopterin compared to its less methoxylated congener. Preliminary toxicological study of xanthomicrol failed to show any behavioral, histological and biochemical adverse effects after repeated administrations of high doses. Pharmacokinetics of xanthomicrol in rats.

Synthesis of novel flavone derivatives possessing substituted benzamides and their biological evaluation against human cancer cells.

Baicalein is a well-known flavone derivative that possesses diverse biological properties, such as anticancer, antioxidant and anti-inflammatory activities. Numerous baicalein derivatives, including 5,6,7-trimethoxyflavone, have been synthesized with the aim of enhancing its inherent biological activities. In the present work, new flavones, possessing an N-aroylamine-substituent on the B-ring, were synthesized to improve the cytotoxicity of baicalein and 5,6,7-trimethoxyflavone against human cancer cell lines. The majority of the flavones synthesized exhibited greater cytotoxicity than baicalein and 5,6,7-trimethoxyflavone against HepG2 and MCF-7 cells. Among them, compounds 5n, possessing a 3-methoxybenzoylamino group, exhibited great cytotoxic effects on HepG2 (GI50=7.06µM) and MCF-7 (GI50=7.67µM) cells. In contrast, N-aroylamine-substituted 5-hydroxy-6,7-dimethoxyflavone derivatives showed greater cytotoxicity against MCF-7 than HepG2 cells, indicating that the replacement of a 5-methoxy group on the A-ring with a 5-hydroxy group has a marked influence on the cytotoxicity profile.

Cytotoxic prenylated flavones from the stem and root bark of Daphne giraldii.

Three new prenylated flavones (1-3), along with three known analogues (4-6), were isolated from the stem and root bark of Daphne giraldii. Their structures were determined by comprehensive NMR and HRESIMS spectroscopic data analyses. The absolute configurations of compounds 2 and 3 were assigned by optical rotation comparison, CD and [Rh2(OCOCF3)4]-induced CD spectral methods. The in vitro cytotoxicity experiments carried out involving five cancer cell lines (U251, A549, HepG2, MCF-7 and Bcap37) showed that 2 markedly inhibited the proliferation of all tested cells with IC50 values ranging from 4.26 to 20.82µM. The preliminary structure-activity relationships of these flavones are discussed. In addition, compound 2 was found to effectively induce apoptosis in HepG2 cells according to a flow cytometry analysis.

Phytochemical analysis of hydroethanolic extract of Turnera diffusa Willd and evaluation of its effects on astrocyte cell death.

OBJECTIVE: To evaluate the phytochemical composition of hydroethanolic extracts from powdered aerial parts of Turnera diffusa Willd (Turneraceae; T. diffusa), as well as its toxicity in astrocytes. METHODS: Chemical analyses of hydroethanolic extract from powdered aerial parts ofT. diffusa were carried out using HPLC-DAD-ESI-MS/MS.In vitro assays using astrocytes culture were performed to evaluate cell death. RESULTS: Flavone-C, O-diglycosides, such as, luteolin-8-C-[6-deoxy-2-O-rhamnosyl]-xylo-hexos-3-uloside, apigenin-8-C-[6-deoxy-2-O-rhamnosyl]-xylo-hexos-3-uloside and apigenin-7-O-6"-p-coumaroylglucoside were the main compounds found in this hydroethanolic extract. Concentration time-effect demonstrated the toxicity of this extract at a concentration of 1,000µg/mL in astrocyte culture, after 6 and 24 hours of incubation. CONCLUSION: In phytochemical analyses, important antioxidants (mainly flavonoids) were observed. T. diffusa extracts presented cytotoxic effect in high concentrations, leading to increased cell death in astrocyte culture.

Phytochemical analysis of hydroethanolic extract of Turnera diffusa Willd and evaluation of its effects on astrocyte cell death / Análise fitoquímica do extrato hidroetanólico de Turnera diffusa Willd e avaliação de seus efeitos na morte de astrócitos

ABSTRACT Objective To evaluate the phytochemical composition of hydroethanolic extracts from powdered aerial parts of Turnera diffusa Willd (Turneraceae; T. diffusa), as well as its toxicity in astrocytes. Methods Chemical analyses of hydroethanolic extract from powdered aerial parts ofT. diffusa were carried out using HPLC-DAD-ESI-MS/MS.In vitro assays using astrocytes culture were performed to evaluate cell death. Results Flavone-C, O-diglycosides, such as, luteolin-8-C-[6-deoxy-2-O-rhamnosyl]-xylo-hexos-3-uloside, apigenin-8-C-[6-deoxy-2-O-rhamnosyl]-xylo-hexos-3-uloside and apigenin-7-O-6”-p-coumaroylglucoside were the main compounds found in this hydroethanolic extract. Concentration time-effect demonstrated the toxicity of this extract at a concentration of 1,000µg/mL in astrocyte culture, after 6 and 24 hours of incubation. Conclusion In phytochemical analyses, important antioxidants (mainly flavonoids) were observed. T. diffusa extracts presented cytotoxic effect in high concentrations, leading to increased cell death in astrocyte culture.

RESUMO Objetivo Avaliar a composição fitoquímica do extrato hidroetanólico das partes aéreas de Turnera diffusa Willd (Turneraceae; T. diffusa) e sua toxicidade em astrócitos. Métodos Análises químicas do extrato hidroetanólico de partes aéreas de T. diffusa foram feitas por HPLC-DAD-ESI-MS/MS. Os ensaiosin vitro utilizaram culturas de astrócitos para avaliar morte celular. Resultados Flavonas-C, O-diglicosídeos, como, luteolina-8-C-[6-deoxi-2-O-raminosil]-xilo-hexos-3-ulosideo, apigenina-8-C-[6-deoxi-2-O-raminosil]-xilo-hexos-3-ulosideo e apigenina-7-O-6”-p-cumaroilglucosídeo foram os principais constituintes encontrados neste extrato hidroetanólico. Uma curva tempo-concentração demonstrou toxicidade desse extrato na concentração de 1.000µg/mL, na cultura de astrócitos após 6 e 24 horas de incubação. Conclusão Nas análises fitoquímicas, importantes antioxidantes, sobretudo flavonoides, foram observados. Extratos de T. diffusa apresentaram efeitos citotóxicos em altas concentrações, ocasionando aumento de morte celular em cultura de astrócitos.

Identification and characterization of naturally occurring inhibitors against UDP-glucuronosyltransferase 1A1 in Fructus Psoraleae (Bu-gu-zhi).

As an edible traditional Chinese herb, Fructus psoraleae (FP) has been widely used in Asia for the treatment of vitiligo, bone fracture and osteoporosis. Several cases on markedly elevated bilirubin and acute liver injury following administration of FP and its related proprietary medicine have been reported, but the mechanism in FP-associated toxicity has not been well investigated yet. This study aimed to investigate the inhibitory effects of FP extract and its major constituents against human UDP-glucuronosyltransferase 1A1 (UGT1A1), the key enzyme responsible for metabolic elimination of bilirubin. To this end, N-(3-carboxy propyl)-4-hydroxy-1,8-naphthalimide (NCHN), a newly developed specific fluorescent probe for UGT1A1, was used to evaluate the inhibitory effects of FP extract or its fractions in human liver microsomes (HLM), while LC-UV fingerprint and UGT1A1 inhibition profile were combined to identity and characterize the naturally occurring inhibitors of UGT1A1 in FP. Our results demonstrated that both the extract of FP and five major components of FP displayed evident inhibitory effects on UGT1A1 in HLM. Among these five identified naturally occurring inhibitors, bavachin and corylifol A were found to be strong inhibitors of UGT1A1 with the inhibition kinetic parameters (Ki) values lower than 1 µM, while neobavaisoflavone, isobavachalcone, and bavachinin displayed moderate inhibitory effects against UGT1A1 in HLM, with the Ki values ranging from 1.61 to 9.86µM. These findings suggested that FP contains natural compounds with potent inhibitory effects against human UGT1A1, which may be one of the important reasons for triggering FP-associated toxicity, including elevated bilirubin levels and liver injury.