Safety evaluation of kaempferol glycosides-rich standardized roasted goji berry leaf extract.

Goji berry leaf (GL) has been used for medicinal foods for its pharmacological effects, including anti-oxidative and anti-obesity activities. Nevertheless, toxicological information on GL is limited for developing health functional ingredient. The aim of the research was to evaluate the single dose acute, 14-day repeated oral toxicity, and genotoxicity of standardized roasted GL extract (rGL) rich in kaempferol-3-O-sophoroside-7-O-glucoside. Tested rGL was found to be stable as kaempferol-3-O-sophoroside-7-O-glucoside, showing 0.7-2.1% of analytical standard variance. According to the single dose toxicity for 14 days, the lethal dose of rGL was determined to be ≥ 2000 mg/kg. Repeated doses of 0-1000 mg/kg of rGL per day for 14 days did not show any toxicity signs or gross pathological abnormalities. No genotoxic signs for the rGL treatment appeared via bacterial reverse mutation up to 5000 µg/plate. There was no significant increase in chromosomal aberration of rGL irrespective of metabolic activation by using CHO-K1 cells (p > 0.05). Regarding carcinogenic toxicity, chromosomal aberrations were not induced at 2000 mg of rGL/kg by using the in vivo bone marrow micronucleus test (p > 0.05). Results from the current study suggest that rGL could be used as a functional ingredient to provide various effects with safety assurance.

Analysis of the toxicological and pharmacokinetic profile of Kaempferol-3-O-ß-D-(6"-E-p-coumaryl) glucopyranoside - Tiliroside: in silico, in vitro and ex vivo assay / Análise do perfil toxicológico e farmacocinético de Kaempferol-3-O-ß-D- (6 "-E-p-cumaril) glucopiranosídeo - Tilirosídeo: ensaio in silico, in vitro e ex vivo

Abstract Tiliroside is a glycosidic flavonoid present in many plants species including Helicteres velutina K. Schum (Malvaceae sensu lato), commonly known in Brazil as "pitó". This molecule has been shown to have many biological activities, however no study has been carried out to investigate the toxicity of this substance. The present work aimed to evaluate the possible cellular toxicity in silico, in vitro and ex-vivo of the kaempferol-3-O-β-D-(6"-E-p-coumaroyl) glucopyranoside (tiliroside), through chemical structure analysis, toxicity assessment and predictive bioactive properties, using human samples for in vitro and ex-vivo tests. The in silico analysis suggests that tiliroside exhibited great absorption index when penetrating biological membranes. In addition, it also displayed considerable potential for cellular protection against free radicals, and anticarcinogenic, antioxidant, antineoplastic, anti-inflammatory, anti-hemorrhagic and antithrombotic activities. The assessment of the hemolytic and genotoxic effects of tiliroside showed low hemolysis rates in red blood cells and absence of cellular toxicity in the oral mucosa cells. The data obtained indicate that this molecule could be a promising therapeutic approach as a possible new drug with biotechnological potential.

Resumo O tilirosídeo é um flavonóide glicosídico presente em muitas espécies de plantas, incluindo Helicteres velutina K. Schum (Malvaceae sensu lato), conhecida no Brasil como "pitó". Esta molécula mostrou ter muitas atividades biológicas, porém nenhum estudo foi realizado para investigar a toxicidade dessa substância. O presente trabalho teve como objetivo avaliar a possível toxicidade celular in silico, in vitro e ex-vivo do kaempferol-3-O-β-D- (6 "-Ep-coumaroil) glucopiranosídeo (tilirosídeo), por meio de análises de estrutura química, toxicidade avaliação e propriedades bioativas preditivas, utilizando amostras humanas para testes in vitro e ex-vivo. A análise in silico sugere que o tilirosídeo exibe bom índice de absorção para penetrar nas membranas biológicas. Além disso, apresentou considerável potencial de proteção celular contra os radicais livres e com atividades anticarcinogênica, antioxidante, antineoplásica, antiinflamatória, anti-hemorrágica e antitrombótica. A avaliação dos efeitos hemolíticos e genotóxicos do tilirosídeo mostrou baixas taxas de hemólise nas hemácias e ausência de toxicidade em células da mucosa oral. Os dados obtidos indicam que esta molécula pode possuir uma abordagem terapêutica promissora como uma possível nova droga com potencial biotecnológico.

Analysis of the toxicological and pharmacokinetic profile of Kaempferol-3-O-ß-D-(6"-E-p-coumaryl) glucopyranoside - Tiliroside: in silico, in vitro and ex vivo assay.

Tiliroside is a glycosidic flavonoid present in many plants species including Helicteres velutina K. Schum (Malvaceae sensu lato), commonly known in Brazil as "pitó". This molecule has been shown to have many biological activities, however no study has been carried out to investigate the toxicity of this substance. The present work aimed to evaluate the possible cellular toxicity in silico, in vitro and ex-vivo of the kaempferol-3-O-ß-D-(6"-E-p-coumaroyl) glucopyranoside (tiliroside), through chemical structure analysis, toxicity assessment and predictive bioactive properties, using human samples for in vitro and ex-vivo tests. The in silico analysis suggests that tiliroside exhibited great absorption index when penetrating biological membranes. In addition, it also displayed considerable potential for cellular protection against free radicals, and anticarcinogenic, antioxidant, antineoplastic, anti-inflammatory, anti-hemorrhagic and antithrombotic activities. The assessment of the hemolytic and genotoxic effects of tiliroside showed low hemolysis rates in red blood cells and absence of cellular toxicity in the oral mucosa cells. The data obtained indicate that this molecule could be a promising therapeutic approach as a possible new drug with biotechnological potential.

A New Iridoid Dimer and Other Constituents from the Traditional Kurdish Plant Pterocephalus nestorianus Nábelek.

Accompanied by other rare compounds, a new iridoid dimer, named kurdnestorianoside (1), showing an unprecedented secologanol configuration, has been isolated for the first time from the Kurdish medicinal plant Pterocephalus nestorianus, which is used in Kurdistan for treating oral diseases and inflammation. The structure of 1 was established from 1D- and 2D-NMR spectroscopic data. Kaempferol 3-O-[3,6-di-O-(E)-p-coumaroyl]-ß-d-glucopyranoside (7) showed a remarkable antiproliferative activity against several human tumor cell lines.

Natural Compounds as Occult Ototoxins? Ginkgo biloba Flavonoids Moderately Damage Lateral Line Hair Cells.

Several drugs, including aminoglycosides and platinum-based chemotherapy agents, are well known for their ototoxic properties. However, FDA-approved drugs are not routinely tested for ototoxicity, so their potential to affect hearing often goes unrecognized. This issue is further compounded for natural products, where there is a lack of FDA oversight and the manufacturer is solely responsible for ensuring the safety of their products. Natural products such as herbal supplements are easily accessible and commonly used in the practice of traditional eastern and alternative medicine. Using the zebrafish lateral line, we screened a natural products library to identify potential ototoxins. We found that the flavonoids quercetin and kaempferol, both from the Gingko biloba plant, demonstrated significant ototoxicity, killing up to 30 % of lateral line hair cells. We then examined a third Ginkgo flavonoid, isorhamnetin, and found similar levels of ototoxicity. After flavonoid treatment, surviving hair cells demonstrated reduced uptake of the vital dye FM 1-43FX, suggesting that the health of the remaining hair cells was compromised. We then asked if these flavonoids enter hair cells through the mechanotransduction channel, which is the site of entry for many known ototoxins. High extracellular calcium or the quinoline derivative E6 berbamine significantly protected hair cells from flavonoid damage, implicating the transduction channel as a site of flavonoid uptake. Since known ototoxins activate cellular stress responses, we asked if reactive oxygen species were necessary for flavonoid ototoxicity. Co-treatment with the antioxidant D-methionine significantly protected hair cells from each flavonoid, suggesting that antioxidant therapy could prevent hair cell loss. How these products affect mammalian hair cells is still an open question and will be the target of future experiments. However, this research demonstrates the potential for ototoxic damage caused by unregulated herbal supplements and suggests that further supplement characterization is warranted.

Mechanistic evaluation of Ginkgo biloba leaf extract-induced genotoxicity in L5178Y cells.

Ginkgo biloba has been used for many thousand years as a traditional herbal remedy and its extract has been consumed for many decades as a dietary supplement. Ginkgo biloba leaf extract is a complex mixture with many constituents, including flavonol glycosides and terpene lactones. The National Toxicology Program 2-year cancer bioassay found that G. biloba leaf extract targets the liver, thyroid gland, and nose of rodents; however, the mechanism of G. biloba leaf extract-associated carcinogenicity remains unclear. In the current study, the in vitro genotoxicity of G. biloba leaf extract and its eight constituents was evaluated using the mouse lymphoma assay (MLA) and Comet assay. The underlying mechanisms of G. biloba leaf extract-associated genotoxicity were explored. Ginkgo biloba leaf extract, quercetin, and kaempferol resulted in a dose-dependent increase in the mutant frequency and DNA double-strand breaks (DSBs). Western blot analysis confirmed that G. biloba leaf extract, quercetin, and kaempferol activated the DNA damage signaling pathway with increased expression of γ-H2AX and phosphorylated Chk2 and Chk1. In addition, G. biloba leaf extract produced reactive oxygen species and decreased glutathione levels in L5178Y cells. Loss of heterozygosity analysis of mutants indicated that G. biloba leaf extract, quercetin, and kaempferol treatments resulted in extensive chromosomal damage. These results indicate that G. biloba leaf extract and its two constituents, quercetin and kaempferol, are mutagenic to the mouse L5178Y cells and induce DSBs. Quercetin and kaempferol likely are major contributors to G. biloba leaf extract-induced genotoxicity.

Kaempferol from Semen cuscutae attenuates the immune function of dendritic cells.

Dendritic cells (DCs) are the critical leukocytes in regulating immune responses. Accordingly, DCs are the major target in the development of immunomodulators. In this study, we examined the effect of Semen cuscutae (SC), an important traditional Chinese medicine, on mouse bone marrow-derived DCs. We found that the n-butanol and methanol extracts of SC significantly suppressed LPS-stimulated DC activation. Several flavonoids were verified in the extracts using HPLC, and then kaempferol was identified as the major flavonoid in the methanol fraction of SC. Kaempferol was able to reduce cytokines and chemokines produced by LPS-stimulated DCs, and this reduction was not due to its cytotoxicity on DCs. In addition, DC maturation was impaired by kaempferol. Furthermore, kaempferol abrogated the ability of LPS-stimulated DCs to promote Ag-specific T cell activation, both in vitro and in vivo. Thus, we show for the first time that SC exhibits an immunosuppressive effect on DCs and that the active ingredient kaempferol attenuates DC function, which suggests that kaempferol has potential in the treatment of chronic inflammatory and autoimmune diseases.

Podophyllin, but not the constituents quercetin or kaempferol, induced genotoxicity in vitro and in vivo through ROS production.

The genotoxic potential of podophyllin (PD) was investigated in this study. PD increased bacterial revertants and abnormal chromosomal structures in a concentration-dependent manner, both with and without metabolic activating enzymes, and increased the incidence of micronuclei in imprinted control region mouse reticulocytes. Results from three studied constituents of PD, such as podophyllotoxin, kampferol, and quercetin, suggested that the mutagenic effect of PD was not due to the presence of podophyllotoxin, kampferol, and quercetin and might be related to other components and the formation of reactive oxygen species. The detailed mutagenic mechanisms need further investigation, and the medicinal use of PD needs to be cautioned against.

Kaempferol, a mutagenic flavonol from Helichrysum simillimum.

Helichrysum simillimum is native to South Africa. It is used for the treatment of coughs, colds, fever, infections, headache, and menstrual pain. Extracts of this species showed mutagenic effects in the Salmonella/microsome assay. The aim of this study was to isolate and determine the mutagenic constituents of H. simillimum. Bioassay-guided fractionation of 90% aqueous methanol extracts, using Salmonella typhimurium TA98, led to the isolation of the flavonol kaempferol.

Bioassay-guided isolation of kaempferol-3-O-beta-D-galactoside with anti-inflammatory and antinociceptive activity from the aerial part of Calluna vulgaris L.

Calluna vulgaris L. (Ericaceae) is used for the treatment of various inflammatory ailments in traditional medicines. In order to evaluate this ethnobotanical information, its anti-inflammatory and antinociceptive activities were studied using in vivo experimental models in mice. The ethanolic extract of the plant was first fractionated into five extracts; namely, n-hexane, chloroform, ethyl acetate (EtOAc), n-butanol, and water fractions. Among them, the EtOAc Fr. was found to be the most effective and was further subjected to bioassay-guided fractionation and isolation procedures. After successive column chromatography applications, on Sephadex LH-20 and silica gel, a component, which is responsible for the above-mentioned activities of this species of Turkish origin, was isolated and its structure was elucidated as kaempferol-3-O-beta-D-galactoside, a common flavonol derivative by means of spectral techniques.

The effect of short-term kaempferol exposure on reactive oxygen levels and integrity of human (HL-60) leukaemic cells.

Flavonoids may be a principal contributor to the cancer preventative activity of fruit- and vegetable-rich diets and there is interest in their use as dietary supplements. However, there is potential conflict between the cytoprotective and cytotoxic activities of flavonoids, and their efficacy as anti-cancer agents is unresolved. Here, the integrity and survival of HL-60 promyelocytic leukaemia cells following short-term (90 min) exposure to the dietary abundant flavonoid kaempferol (1-100 microM) is reported. Supplementation initially decreased reactive oxygen levels but, paradoxically, a dose-dependent increase in single-strand DNA breakage occurred. However, there was no increase in oxidised DNA purines or membrane damage. Following a 24-h recovery period in non-kaempferol supplemented media, DNA single-strand breakage had declined and kaempferol exposed and control cultures possessed similar reactive oxygen levels. A reduction in (3)H-thymidine incorporation occurred with > or =10 microM kaempferol. One hundred micromolar kaempefrol increased the proportion of cells in G(2)-M phase, the proportion of cells with a sub-G(1) DNA content and enhanced 'active' caspase-3 expression but only induced a loss of mitochondrial membrane potential within a minority of cells. The relevance of induced DNA damage within a non-overtly oxidatively stressed environment to the disease preventative and therapeutic use of kaempferol is discussed.