Enantiomeric composition of natural pericosine A derived from Periconia byssoides and α-glycosidase inhibitory activity of (-)-enantiomer.

Chiral high-performance liquid chromatography (HPLC) analysis of natural pericosine A, which appeared in literature first in 1977, from Periconia byssoides was conducted using a column CHIRALPAK® AD-H to determine the enantiomeric composition of the original mixture which was found to be 68: 32 mixtures of (+)- and (-)-enantiomer, respectively. Furthermore, two independently isolated samples of pericosine A from the same fungus were also analyzed to show the two peaks in the HPLC charts at approximate 1:1 ratio. These results concluded that pericosine A derived from Periconia byssoides was indeed an enantiomeric mixture. Synthesized enantiomers were subjected to evaluation of antitumor activity against three kinds of tumor cells (p388, L1210, HL-60), indicating moderate cytotoxicity against all three kinds of tumor cell lines, but significant difference in potency between the enantiomers was not observed. In contrast, when both the enantiomers of pericosine A were evaluated against five kinds of glycosidases-inhibitory activities (α- and ß-glucosidases, α- and ß-galactosidases, and α-mannosidase), an apparent difference on anti-glycosidase assay was found between the enantiomers: (-)-pericosine A inhibited α-glucosidase at IC50 : 2.25 mM, and ß-galactosidase at IC50 : 5.38 mM, albeit the (+)-enantiomer showed inactivity against these five enzymes.

Engineering Yarrowia lipolytica for Enhanced Production of Arbutin.

Arbutin, a glycoside, is derived from the leaves of several plants, including wheat, pear, and bearberry plants, and has a significant role in the treatment of melanoma, cystitis, and cough. Here, we aimed to modify Yarrowia lipolytica to produce arbutin. To construct the arbutin synthetic pathway in Y. lipolytica, three genes (chorismate pyruvate-lyase (UbiC), 4-hydroxybenzoate 1-hydroxylase (MNX1), and hydroquinone glucosyltransferase (AS)) were codon-optimized and heterologously expressed. To maximize arbutin production, seven arbutin-biosynthesis molecular targets were overexpressed, and we found that the individual strengthening of DHS1 and DHS2 led to an 8.9- and 7.8-fold improvement in arbutin yield, respectively. Through optimization, a maximum arbutin titer of 8.6 ± 0.7 g/L was achieved using the finally engineered strain, po1f-At09. Overall, this is the first report of heterologous arbutin synthesis in Y. lipolytica at a high titer. Furthermore, this work opens a possibility for the overproduction of shikimate pathway derivatives in Y. lipolytica.

Functional Characteristics of Caffeoyl Shikimate Esterase in Larix Kaempferi and Monolignol Biosynthesis in Gymnosperms.

Caffeoyl shikimate esterase (CSE) has been reported to be involved in lignin biosynthesis; however, studies of CSE in gymnosperms are lacking. In this study, CSE was successfully cloned from Larix kaempferi (LkCSE) based on Larix laricina transcriptome screening. LkCSE was likely to have catalytic activity based on homologous sequence alignment and phylogenetic analyses of CSEs from different species. In vitro assays with the recombinant enzyme validated the catalytic activity of LkCSE, indicating its function in converting caffeoyl shikimate into caffeate and shikimate. Additionally, the optimum reaction pH and temperature of LkCSE were determined to be 6.0 and 30 °C, respectively. The values of Km and Vmax of CSE for caffeoyl shikimate were 98.11 µM and 14.44 nM min-1, respectively. Moreover, LkCSE was observed to have tissue expression specificity and was abundantly expressed in stems and leaves, especially stems, which was 50 times higher than the expression levels of roots. Lastly, translational fusion assays using LkCSE fused with green fluorescent proteins (GFP) in tobacco leaves indicated that LkCSE was localized in the plasma membrane and endoplasmic reticulum (ER). These results revealed that CSE clearly functions in gymnosperms and it is possible for LkCSE to interact with other ER-resident proteins and regulate mass flux in the monolignol biosynthesis pathway.

Shikimic acid promotes estrogen receptor(ER)-positive breast cancer cells proliferation via activation of NF-κB signaling.

Shikimic acid (SA), a widely-known hydroaromatic compound enriched in Bracken fern and Illicium verum (also known as Chinese star anise), increases the risk of gastric and esophageal carcinoma, nevertheless, the influence of SA on breast cancer remains indistinct. Herein we found that, with models in vitro, SA significantly promoted estrogen receptor(ER) positive cells proliferation and NF-κB activation was involved in it. Moreover, our data showed that IκBα, a critically endogenous inhibitor of NF-κB, was repressed. Subsequently, we found increase of miR-300 by SA treatment sand miR-300 could target IκBα mRNA. Additionally, inhibition of miR-300 abrogated the repression of IκBα by SA. As a result, miR-300 was also involved in NF-κB activation and breast cancer cells proliferation promotion due to SA exposure. Taken together, with ER-positive breast cancer cell models in vitro, MCF-7 and T47D, our results implied that SA promoted breast cancer cells proliferation via a miR-300-induced NF-κB dependent pathway controlling cell cycle proteins.

Potential Mechanisms of 3, 4-Oxo-Isopropylidene-Shikimic Acid in Ameliorating 2, 4, 6-Trinitrobenzenesulfonic Acid-Induced Colitis in Rats.

Previously, we reported that 3, 4-oxo-isopropylidene-shikimic acid (ISA) has therapeutic potential in experimental colitis in rats. This study aimed to elucidate the potential mechanisms of ISA on the inflammatory response in rats with 2, 4, 6-trinitrobenzenesulfonic acid-induced colitis. After the induction of colitis, rats were orally administered ISA for 12 days. Then, the expression levels of inflammatory cytokines, cell adhesion molecules, and matrix metalloproteinase (MMP) in the blood and colon tissues, and the protein level of nuclear factor kappa B (NF-κB) p65 in cytoplasm and nucleus of colon tissues were evaluated. As a result, an enhanced inflammatory response was observed in rats with experimental colitis. However, the treatment with ISA significantly ameliorated the inflammatory response, which was manifested as a significant decrease in the levels of tumor necrosis factor (TNF)-α, interleukin (IL)-1ß, interferon (IFN)-γ, IL-8, TNF-α mRNA, P-selectin, E-selectin, intercellular cell adhesion molecule-1, MMP9 and MMP9 mRNA in rat blood and colon tissues, respectively, and a significant decrease in the levels of IFN-γ/IL-4, and the NF-κBp65 activity coefficient. Therefore, the therapeutic effect of ISA on experimental colitis may be related to its inhibitory effect on the expression of cytokines, adhesion molecules, and MMP9, which may be involved in the inhibition of the activation and nuclear translocation of NF-κBp65.

(-)-Shikimic Acid as a Chiral Building Block for the Synthesis of New Cytotoxic 6-Aza-Analogues of Angucyclinones.

We describe the syntheses of nine new angucyclinone 6-aza-analogues, achieved through a hetero Diels-Alder reaction between the shikimic acid derivative-azadiene 13, with different naphthoquinones. The cytotoxic activity of the new synthesized compounds and five angucyclinones, previously reported, was evaluated in vitro against three cancer cell lines: PC-3 (prostate cancer), HT-29 (colon cancer), MCF-7 (breast cancer), and one non-tumoral cell line, human colon epithelial cells (CCD841 CoN). Our results showed that most 6-azadiene derivatives exhibited significant cytotoxic activities, which was demonstrated by their IC50 values (less than 10 µM), especially for the most sensitive cells, PC-3 and HT-29. From a chemical point of view, depending on the protected group of ring A and the pattern of substitution on ring D, cytotoxicity elicited these compounds, in terms of their potency and selectivity. Therefore, according to these chemical features, the most promising agents for every cancer cell line were 7a, 17, and 19c for PC-3 cells; 7a, 17, and 20 for HT-29 cells, and 19a for MCF-7 cells.

An Overview of Compounds Derived from the Shikimate and Phenylpropanoid Pathways and Their Medicinal Importance.

OBJECTIVE: There has been a massive increase in the number of reports about the medicinal benefits of the consumption of phenylpropanoids derived from the plastidic shikimate pathway. These benefits include anti-retroviral, anti-hypertensive, anti-inflammatory, anti-aging and insulin-sensitizing activities, the reduction of the risk of a range of chronic diseases including cardiovascular disease, cancer and osteoporosis as well as inhibition of LDL (low-density lipoprotein) oxidation. In addition, chorismate-derived salicylate which was originally isolated from plants, albeit now under chemical production, is massively used for pain relief in the form of acetylsalycilic acid, namely aspirin. Chorismate also acts as precursor in the biosynthesis of folate and phylloquinone, i.e., vitamins B9 and K1, respectively. RESULTS: Cumulative evidence suggests that deficiencies of either of these vitamins in the diet can result in a wide range of diseases. In parallel to our enhanced comprehension of the dietary importance of shikimate-derived compounds, the advent of metabolomics and the development of next-generation sequencing technologies have dramatically accelerated advances in our understanding of the biosynthetic, decorative and degradation pathways underlying their metabolism. Furthermore, forward and reverse genetic approaches have begun to facilitate the metabolic engineering of plants for biofortification of these compounds. CONCLUSION: Here we review data about the bioactivities of these compounds and provide an overview of our current understanding of biosynthesis, molecular function and their in planta occurrence. Finally we discuss the future perspectives and the importance of further development of cross-disciplinary research efforts in this rapidly expanding research field.

Exhaustive Qualitative LC-DAD-MSn Analysis of Arabica Green Coffee Beans: Cinnamoyl-glycosides and Cinnamoylshikimic Acids as New Polyphenols in Green Coffee.

Coffee is one of the most consumed beverages in the world, due to its unique aroma and stimulant properties. Although its health effects are controversial, moderate intake seems to be beneficial. The present work deals with the characterization and quantification of polyphenols and methylxanthines in four Arabica green coffee beans from different geographical origins. The antioxidant activity was also evaluated. Forty-three polyphenols (cinnamic acid, cinnamoyl-amide, 5 cinammoyl-glycosides, and 36 cinnamate esters) were identified using LC-MSn. Among these, cinnamate esters of six different chemical groups (including two dimethoxycinnamoylquinic acid isomers, three caffeoyl-feruloylquinic acid isomers, caffeoyl-sinapoylquinic acid, p-coumaroyl-feruloylquinic acid, two caffeoylshikimic acid isomers, and trimethoxycinnamoylshikimic acid) in addition to five isomers of cinnamoyl-glycosides called caffeoyl-2,7-anhydro-3-deoxy-2-octulopyranosic acid (CDOA) are described for the first time in Arabica green coffee beans. Moreover, 38 polyphenols (6-7% w/w) and 2 methylxanthines (1.3% w/w) were quantified by HPLC-DAD. Caffeoylquinic was the most abundant group of compounds (up to 85.5%) followed by dicaffeoylquinic and feruloylquinic acids (up to 8 and 7%, respectively) and the newly identified cinnamoyl-glycosides (CDOA) (up to 2.5%). Caffeine was the main methylxanthine (99.8%), with minimal amounts of theobromine (0.2%). African coffees (from Kenya and Ethiopia) showed higher polyphenolic content than American beans (from Brazil and Colombia), whereas methylxanthine contents varied randomly. Both phenols and methylxanthines contributed to the antioxidant capacity associated with green coffee, with a higher contribution of polyphenols. We conclude that green coffee represents an important source of polyphenols and methylxanthines, with high antioxidant capacity.

An essential role of caffeoyl shikimate esterase in monolignol biosynthesis in Medicago truncatula.

Biochemical and genetic analyses have previously identified caffeoyl shikimate esterase (CSE) as an enzyme in the monolignol biosynthesis pathway in Arabidopsis thaliana, although the generality of this finding has been questioned. Here we show the presence of CSE genes and associated enzyme activity in barrel medic (Medicago truncatula, dicot, Leguminosae), poplar (Populus deltoides, dicot, Salicaceae), and switchgrass (Panicum virgatum, monocot, Poaceae). Loss of function of CSE in transposon insertion lines of M. truncatula results in severe dwarfing, altered development, reduction in lignin content, and preferential accumulation of hydroxyphenyl units in lignin, indicating that the CSE enzyme is critical for normal lignification in this species. However, the model grass Brachypodium distachyon and corn (Zea mays) do not possess orthologs of the currently characterized CSE genes, and crude protein extracts from stems of these species exhibit only a weak esterase activity with caffeoyl shikimate. Our results suggest that the reaction catalyzed by CSE may not be essential for lignification in all plant species.

Antithrombosis activity of protocatechuic and shikimic acids from functional plant Pinus densiflora Sieb. et Zucc needles.

Pine needle extract (PE) and fermented pine needle extract (FPE) have been reported to show various biological and pharmacological activities such as antioxidant, anti-inflammatory, anti-bacterial, anti-cholesterol, gastrointestinal motility control, and fibrinolytic effect. The aims of our research were to isolate fibrinolytic compounds from PE and FPE and evaluate their antithrombotic activity in vitro and in vivo. Protocatechuic (1) and shikimic (2) acids were isolated and identified from FPE. 1 and 2 not only have fibrinolysis activity but also inhibit fibrin formation similar to aspirin. Lysis of fibrin clots by 1 and 2 occurred completely at pH 2-4. Results of SDS-PAGE showed that fibrin polypeptide chains (Aα, Bß, γ) lysed by 1 and 2 were intact. The antithrombotic effects of 1 and 2 were confirmed by models of carrageenan-induced tail thrombosis, collagen and epinephrine-induced pulmonary thromboembolism in mice, and FeCl3-induced carotid arterial thrombus. Moreover, 1 and 2 did not induce hemorrhage in the tail veins of mice, unlike common antithrombotic compounds. We also measured changes in the quantities of 1 and 2 obtained from FPE. As fermentation progressed, we demonstrated that the quantity of 1 steadily increased, while the quantity of 2 did not significantly change. We therefore demonstrated that FPE is an excellent resource for 1 and 2 and can be produced inexpensively in sufficient quantities for industrial-scale extraction.

Synthesis and biological evaluation of oseltamivir analogues from shikimic acid.

New oseltamivir analogues were designed and synthesized, starting from shikimic acid. Biological evaluation against three human cancer cell lines (KB, MCF7 and Lu-1) showed that many of them exhibited cytotoxic activity. Azides 5 are more active than the corresponding amines 6. Thus, the reduction of the azide group into amine led to the loss of cytotoxicity. The compounds with a cyclohexanemethyloxy group at C-3 were more active than the other investigated compounds belonging to the same series. This cyclohexanemethyloxy group seems to be critical for the cytotoxic activity of this class of compounds. The synthetic oseltamivir analogues 6a-e had no inhibition activity, even at the concentration of 50 microM when they were evaluated for their in vitro influenza A neuraminidase inhibitory activity by an enzymatic assay.

5-O-caffeoylshikimic acid from Solanum somalense leaves: advantage of centrifugal partition chromatography over conventional column chromatography.

Solanum somalense leaves, used in Djibouti for their medicinal properties, were extracted by MeOH. Because of the high polyphenol and flavonoid contents of the extract, respectively, determined at 80.80 ± 2.13 mg gallic acid equivalent/g dry weight and 24.4 ± 1.01 mg quercetin equivalent/g dry weight, the isolation and purification of the main polyphenols were carried out by silica gel column chromatography and centrifugal partition chromatography. Column chromatography led to 11 enriched fractions requiring further purification, while centrifugal partition chromatography allowed the easy recovery of the main compound of the extract. In a solvent system composed of CHCl3/MeOH/H2O (9.5:10:5), 21.8 mg of this compound at 97% purity was obtained leading to a yield of 2.63%. Its structure was established as 5-O-caffeoylshikimic acid by mass spectrometry and NMR spectroscopy. This work shows that S. somalense leaves contain very high level of 5-O-caffeoylshikimic acid (0.74% dry weight), making it a potential source of production of this secondary metabolite that is not commonly found in nature but could be partly responsible of the medicinal properties of S. somalense leaves.

Crowdsourcing natural products discovery to access uncharted dimensions of fungal metabolite diversity.

A fundamental component for success in drug discovery is the ability to assemble and screen compounds that encompass a broad swath of biologically relevant chemical-diversity space. Achieving this goal in a natural-products-based setting requires access to a wide range of biologically diverse specimens. For this reason, we introduced a crowdsourcing program in which citizen scientists furnish soil samples from which new microbial isolates are procured. Illustrating the strength of this approach, we obtained a unique fungal metabolite, maximiscin, from a crowdsourced Alaskan soil sample. Maximiscin, which exhibits a putative combination of polyketide synthase (PKS), non-ribosomal peptide synthetase (NRPS), and shikimate pathway components, was identified as an inhibitor of UACC-62 melanoma cells (LC50=0.93 µM). The metabolite also exhibited efficacy in a xenograft mouse model. These results underscore the value of building cooperative relationships between research teams and citizen scientists to enrich drug discovery efforts.

Mycobacterium tuberculosis shikimate kinase inhibitors: design and simulation studies of the catalytic turnover.

Shikimate kinase (SK) is an essential enzyme in several pathogenic bacteria and does not have any counterpart in human cells, thus making it an attractive target for the development of new antibiotics. The key interactions of the substrate and product binding and the enzyme movements that are essential for catalytic turnover of the Mycobacterium tuberculosis shikimate kinase enzyme (Mt-SK) have been investigated by structural and computational studies. Based on these studies several substrate analogs were designed and assayed. The crystal structure of Mt-SK in complex with ADP and one of the most potent inhibitors has been solved at 2.15 Å. These studies reveal that the fixation of the diaxial conformation of the C4 and C5 hydroxyl groups recognized by the enzyme or the replacement of the C3 hydroxyl group in the natural substrate by an amino group is a promising strategy for inhibition because it causes a dramatic reduction of the flexibility of the LID and shikimic acid binding domains. Molecular dynamics simulation studies showed that the product is expelled from the active site by three arginines (Arg117, Arg136, and Arg58). This finding represents a previously unknown key role of these conserved residues. These studies highlight the key role of the shikimic acid binding domain in the catalysis and provide guidance for future inhibitor designs.

The mode of action of recombinant Mycobacterium tuberculosis shikimate kinase: kinetics and thermodynamics analyses.

Tuberculosis remains as one of the main cause of mortality worldwide due to a single infectious agent, Mycobacterium tuberculosis. The aroK-encoded M. tuberculosis Shikimate Kinase (MtSK), shown to be essential for survival of bacilli, catalyzes the phosphoryl transfer from ATP to the carbon-3 hydroxyl group of shikimate (SKH), yielding shikimate-3-phosphate and ADP. Here we present purification to homogeneity, and oligomeric state determination of recombinant MtSK. Biochemical and biophysical data suggest that the chemical reaction catalyzed by monomeric MtSK follows a rapid-equilibrium random order of substrate binding, and ordered product release. Isothermal titration calorimetry (ITC) for binding of ligands to MtSK provided thermodynamic signatures of non-covalent interactions to each process. A comparison of steady-state kinetics parameters and equilibrium dissociation constant value determined by ITC showed that ATP binding does not increase the affinity of MtSK for SKH. We suggest that MtSK would more appropriately be described as an aroL-encoded type II shikimate kinase. Our manuscript also gives thermodynamic description of SKH binding to MtSK and data for the number of protons exchanged during this bimolecular interaction. The negative value for the change in constant pressure heat capacity (ΔCp) and molecular homology model building suggest a pronounced contribution of desolvation of non-polar groups upon binary complex formation. Thermodynamic parameters were deconvoluted into hydrophobic and vibrational contributions upon MtSK:SKH binary complex formation. Data for the number of protons exchanged during this bimolecular interaction are interpreted in light of a structural model to try to propose the likely amino acid side chains that are the proton donors to bulk solvent following MtSK:SKH complex formation.

Macrophage biospecific extraction and HPLC-ESI-MSn analysis for screening immunological active components in Smilacis Glabrae Rhizoma.

A cell-permeable membrane, as typified by Transwell insert Permeable Supports, permit accurate repeatable invasion assays, has been developed as a tool for screening immunological active components in Smilacis Glabrae Rhizoma (SGR). In this research, components in the water extract of SGR (ESGR) might conjugate with the receptors or other targets on macrophages which invaded Transwell inserts, and then the eluate which contained components biospecific binding to macrophages was identified by HPLC-ESI-MS(n) analysis. Six compounds, which could interact with macrophages, were detected and identified. Among these compounds, taxifolin (2) and astilbin (4) were identified by comparing with the chromatography of standards, while the four others including 5-O-caffeoylshikimic acid (1), neoastilbin (3), neoisoastilbin (5) and isoastilbin (6), were elucidated by their structure clearage characterizations of tandem mass spectrometry. Then compound 1 was isolated and purified from SGR, along with 2 and 4, was applied to the macrophage migration and adhesion assay in HUVEC (Human Umbilical Vein Endothelial Cells) -macrophages co-incultured Transwell system for immunological activity assessment. The results showed that compounds 1, 2 and 4 with concentration of 5µM (H), 500nM (M) and 50nM (L) could remarkably inhibit the macrophage migration and adhesion (Vs AGEs (Advanced Glycation End Produces) group, 1-L, 2-H and 4-L groups: p<0.05; other groups: p<0.01). Moreover, 1 and 4 showed satisfactory dose-effect relationship. In conclusion, the application of macrophage biospecific extraction coupled with HPLC-ESI-MS(n) analysis is a rapid, simple and reliable method for screening immunological active components from Traditional Chinese Medicine.

Transition state analysis of acid-catalyzed hydrolysis of an enol ether, enolpyruvylshikimate 3-phosphate (EPSP).

Proton transfer to carbon represents a significant catalytic challenge because of the large intrinsic energetic barrier and the frequently unfavorable thermodynamics. Multiple kinetic isotope effects (KIEs) were measured for acid-catalyzed hydrolysis of the enol ether functionality of enolpyruvylshikimate 3-phosphate (EPSP) as a nonenzymatic analog of the EPSP synthase (AroA) reaction. The large solvent deuterium KIE demonstrated that protonating C3 was the rate-limiting step, and the lack of solvent hydron exchange into EPSP demonstrated that protonation was irreversible. The reaction mechanism was stepwise, with C3, the methylene carbon, being protonated to form a discrete oxacarbenium ion intermediate before water attack at the cationic center, that is, an AH(‡)*AN (or AH(‡) + AN) mechanism. The calculated 3-(14)C and 3,3-(2)H2 KIEs varied as a function of the extent of proton transfer at the transition state, as reflected in the C3-H(+) bond order, nC3-H+. The calculated 3-(14)C KIE was a function primarily of C3 coupling with the movement of the transferring proton, as reflected in the reaction coordinate contribution ((light)ν(‡)/(heavy)ν(‡)), rather than of changes in bonding. Coupling was strongest in early and late transition states, where the reaction coordinate frequency was lower. The other calculated (14)C and (18)O KIEs were more sensitive to interactions with counterions and solvation in the model structures than nC3-H+. The KIEs revealed a moderately late transition state with significant oxacarbenium ion character and with a C3-H(+) bond order ≈0.6.

Characterization of hydroxycinnamoyltransferase from rice and its application for biological synthesis of hydroxycinnamoyl glycerols.

Hydroxycinnamoyltransferases (HCTs) catalyze the transfer of the cinnamoyl moiety from hydroxycinnamoyl-CoA to various acceptors such as shikimic acid, quinic acid, hydroxylated acid, and glycerol. Four rice HCT homologues (OsHCT1-4) to tobacco HST were cloned, and OsHCT4 was expressed in Escherichia coli as a glutathione S-transferase fusion protein. Using the purified recombinant protein and biotransformation techniques, whether OsHCT4 shows hydroxycinnamoyltransferase activity with a variety of acyl group acceptors was investigated. The results of high performance liquid chromatography (HPLC) and mass spectrometry (MS) established that OsHCT4 mediated the trans-esterification of glycerol as well as shikimic acid in the presence of hydroxycinnamoyl-CoA. The structure of the reaction product was determined using nuclear magnetic resonance spectroscopy (NMR). E. coli cells co-expressing 4CL (4-coumarate:coenzyme A ligase) and OsHCT4 converted p-coumaric acid, ferulic acid, and caffeic acid into the corresponding glycerides. While this conversion is very efficient in vitro, the physiological significant in rice is currently unknown.

Labdane diterpenoids and shikimic acid derivatives from Araucaria cunninghamii.

Four new (1-4) and two known compounds (5, 6) were isolated from the aerial parts of Araucaria cunninghamii. By analysis of UV, IR, MS, and NMR, the new compounds were identified as ENT-19-(Z)-coumaroyloxylabda-8(17),13(16),14-triene (1), ENT-19-( E)-coumaroyloxylabda-8(17),13(16),14-triene (2), shikimic acid N-butyl ester (3), and 5-(Z)-coumaroyloxyquinic acid N-butyl ester (4). Compounds 1 and 6 exhibited inhibitory activity against Escherichia coli, and compound 1 also exhibited moderate activity against human leukemia cells (HL-60) and human hepatoma cells (SMMC-7721) with IC50 values of 8.90 and 11.53 µM, respectively.