Three types of enzymes complete the furanocoumarins core skeleton biosynthesis in Angelica sinensis.

Furanocoumarins (FCs) are widely distributed secondary metabolites found in higher plants, including Apiaceae, Rutaceae, Moraceae, and Fabaceae. They play a crucial role in the physiological functions of plants and are well-known for their diverse pharmacological activities. As a representative plant of the Apiaceae family, Angelica sinensis is highly valued for its medicinal properties and FCs are one of the main ingredients of A. sinensis. However, the biosynthetic mechanism of FCs in A. sinensis remains poorly understood. In this study, we successfully cloned and verified three types of enzymes using genome analysis and in vitro functional verification, which complete the biosynthesis of the FCs core skeleton in A. sinensis. It includes a p-coumaroyl CoA 2'-hydroxylase (AsC2'H) responsible for umbelliferone formation, two UbiA prenyltransferases (AsPT1 and AsPT2) that convert umbelliferone to demethylsuberosin (DMS) and osthenol, respectively, and two CYP736 subfamily cyclases (AsDC and AsOD) that catalyze the formation of FCs core skeleton. Interestingly, AsOD was demonstrated to be a bifunctional cyclase and could catalyze both DMS and osthenol, but had a higher affinity to osthenol. The characterization of these enzymes elucidates the molecular mechanism of FCs biosynthesis, providing new insights and technologies for understanding the diverse origins of FCs biosynthesis.

Semisynthesis and anti-cancer properties of novel honokiol derivatives in human nasopharyngeal carcinoma CNE-2Z cells.

In this study, 21 new honokiol derivatives were synthesised, and their anti-cancer properties were investigated. Among these, compound 1g exhibited the most potent cytotoxic activity against human nasopharyngeal carcinoma CNE-2Z cells, human gastric cancer SGC7901 cells, human breast cancer MCF-7 cells, and mouse leydig testicular cancer I-10 lines with IC50 values of 6.04, 7.17, 6.83, and 5.30 µM, respectively. Compared to the parental compound, 1g displayed up to 5.18-fold enhancement of the cytotoxic effect on CNE-2Z cells. We further demonstrated that 1g inhibited cell growth, suppressed migration and invasion, and induced apoptosis of CNE-2Z cells by down-regulating HIF-1α, MMP-2, MMP-9, Bcl-2, Akt and up-regulating Bax protein levels. Transfection of CNE-2Z cells with HIF-1α siRNA reduced cell migration and invasion. In addition, in vivo experiments confirmed that 1g inhibited tumour growth in CNE-2Z cell-xenografted nude mice with low toxicity. Thus, our data suggested that 1g was a potent and safe lead compound for nasopharyngeal carcinoma therapy.

The chemical profiling of Salvia plebeia during different growth periods and the biosynthesis of its main flavonoids ingredients.

Salvia plebeia (Lamiaceae) is a valuable medicinal plant widely distributed across Asia and Oceania. However, the composition and accumulation patterns of its active ingredients in different organs during the growth and their biosynthetic mechanism remain unknown. Therefore, we conducted metabolite profiling, transcriptomic analysis, and biological functional verification to explore the distribution, accumulation, and biosynthesis mechanisms of flavonoids in S. plebeia. We identified 70 metabolites including 46 flavonoids, 16 phenolic acids, seven terpenoids, and one organic acid, of which 21 were previously unreported in S. plebeia. Combining metabolomic-transcriptomic analysis and biological functional verification, we identified the key genes involved in biosynthesis of its main active ingredients, hispidulin and homoplantaginin, including SpPAL, SpC4H, Sp4CL2, Sp4CL5, SpCHS1, SpCHI, SpFNS, SpF6H1, SpF6OMT1, SpF6OMT2, SpUGT1, SpUGT2, and SpUGT3. Using the identified genes, we reconstructed the hispidulin and homoplantaginin biosynthesis pathways in Escherichia coli, and obtained a yield of 5.33 and 3.86 mg/L for hispidulin and homoplantaginin, respectively. Our findings provide valuable insights into the changes in chemical components in different organs of S. plebeia during different growth and harvest stages and establishes a foundation for identifying and synthesizing its active components.

Isobavachalcone Induces Multiple Cell Death in Human Triple-Negative Breast Cancer MDA-MB-231 Cells.

Standardized treatment guidelines and effective drugs are not available for human triple-negative breast cancer (TNBC). Many efforts have recently been exerted to investigate the efficacy of natural compounds as anticancer agents owing to their low toxicity. However, no study has examined the effects of isobavachalcone (IBC) on the programmed cell death (PCD) of human triple-negative breast MDA-MB-231 cancer cells. In this study, IBC substantially inhibited the proliferation of MDA-MB-231 cells in concentration- and time-dependent manners. In addition, we found that IBC induced multiple cell death processes, such as apoptosis, necroptosis, and autophagy in MDA-MB-231 cells. The initial mechanism of IBC-mediated cell death in MDA-MB-231 cells involves the downregulation of Akt and p-Akt-473, an increase in the Bax/Bcl-2 ratio, and cleaved caspases-3 induced apoptosis; the upregulation of RIP3, p-RIP3 and MLKL induced necroptosis; as well as a simultaneous increase in LC3-II/I ratio induced autophagy. In addition, we observed that IBC induced mitochondrial dysfunction, thereby decreasing cellular ATP levels and increasing reactive oxygen species accumulation to induce PCD. These results suggest that IBC is a promising lead compound with anti-TNBC activity.

Anti-Cancer Properties of Ginkgolic Acids in Human Nasopharyngeal Carcinoma CNE-2Z Cells via Inhibition of Heat Shock Protein 90.

Ginkgo biloba L. has been used in traditional Chinese medicine (TCM) for thousands of years. However, the anti-cancer properties of ginkgolic acids (GAS) isolated from G. biloba have not been investigated in human nasopharyngeal carcinoma cells. In this study, GAS exhibited an inhibitory effect on the ATPase activity of heat shock protein 90 (Hsp90) and anti-proliferative activities against four human cancer cell lines, with IC50 values ranging from 14.91 to 23.81 µg·mL-1. In vivo experiments confirmed that GAS inhibited tumor growth in CNE-2Z cell-xenografted nude mice with low hepatotoxicity. We further demonstrated that GAS suppressed migration and invasion and induced the apoptosis of CNE-2Z cells by inducing the degradation of Hsp90 client proteins (MMP-2, MMP-9, Her-2, c-Raf, Akt, and Bcl-2). Together, GAS are new Hsp90 inhibitors by binding to Hsp90 (hydrogen bond and hydrophobic interaction). Thus, GAS from G. biloba might represent promising Hsp90 inhibitors for the development of anti-nasopharyngeal carcinoma agents.

Semi-Synthesis and In Vitro Anti-Cancer Evaluation of Magnolol Derivatives.

Magnolol (MAG), a biphenolic neolignan, has various biological activities including antitumor effects. In this study, 15 MAG derivatives were semi-synthesized and evaluated for their in vitro anticancer activities. From these derivatives, compound 6a exhibited the best cytotoxic activity against four human cancer cell lines, with IC50 values ranging from 20.43 to 28.27 µM. Wound-healing and transwell assays showed that compound 6a significantly inhibited the migration and invasion of MDA-MB-231 cells. In addition, Western blotting experiments, performed using various concentrations of 6a, demonstrated that it downregulates the expression of HIF-1α, MMP-2, and MMP-9 in a concentration-dependent manner. Overall, these results suggest that substituting a benzyl group having F atoms substituted at the C2 position on MAG is a viable strategy for the structural optimization of MAG derivatives as anticancer agents.

The Effect of Hispidulin, a Flavonoid from Salvia plebeia, on Human Nasopharyngeal Carcinoma CNE-2Z Cell Proliferation, Migration, Invasion, and Apoptosis.

Nasopharyngeal carcinoma (NPC) is a common malignant head and neck tumor. Drug resistance and distant metastasis are the predominant cause of treatment failure in NPC patients. Hispidulin is a flavonoid extracted from the bioassay-guided separation of the EtOH extract of Salvia plebeia with strong anti-proliferative activity in nasopharyngeal carcinoma cells (CNE-2Z). In this study, the effects of hispidulin on proliferation, invasion, migration, and apoptosis were investigated in CNE-2Z cells. The [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] (MTT) assay and the colony formation assay revealed that hispidulin could inhibit CNE-2Z cell proliferation. Hispidulin (25, 50, 100 µM) also induced apoptosis in a dose-dependent manner in CNE-2Z cells. The expression of Akt was reduced, and the expression of the ratio of Bax/Bcl-2 was increased. In addition, scratch wound and transwell assays proved that hispidulin (6.25, 12.5, 25 µM) could inhibited the migration and invasion in CNE-2Z cells. The expressions of HIF-1α, MMP-9, and MMP-2 were decreased, while the MMPs inhibitor TIMP1 was enhanced by hispidulin. Moreover, hispidulin exhibited potent suppression tumor growth and low toxicity in CNE-2Z cancer-bearing mice at a dosage of 20 mg/kg/day. Thus, hispidulin appears to be a potentially effective agent for NPC treatment.

Anti-cancer effects of methanol-ethyl acetate partitioned fraction from Magnolia grandiflora in human non-small cell lung cancer H1975 cells.

Non-small cell lung cancer (NSCLC) constitutes nearly 85% of all cases of lung cancer. Drug resistance, dose-limiting toxicity, and metastasis in NSCLC eventually reduce the efficacy of chemotherapeutics. In this study, we have shown that the methanol-ethyl acetate partitioned fraction from Magnolia grandiflora L. seeds (MEM) exhibit potential anti-cancer activities against NSCLC H1975 cells in vivo and in vitro. MEM significantly inhibited the proliferation of H1975 cells in a concentration- and time-dependent manner. Further, MEM exhibited potent anti-tumor efficacy and low toxicity in nude mice bearing H1975 tumors. Our study also showed that MEM could induce cellular apoptosis in H1975 cells by down-regulating the protein expression levels of Akt and p-Akt-473, and by increasing the ratio of Bax/Bcl-2. Also, MEM significantly inhibited metastasis-related cell invasion and migration of H1975 cells, which associated with the down-regulation of HIF-1α, MMP-2, and MMP-9 protein expression levels. Thus, our data shows that MEM may be an effective fraction of M. grandiflora in NSCLC treatment.

Bishonokiol A Induces Multiple Cell Death in Human Breast Cancer MCF-7 Cells.

OBJECTIVE: A dimeric neolignan, bishonokiol A (BHNKA) isolated from Magnolia grandiflora, significantly inhibits the proliferation of human breast cancer cells. However, the exact mechanism of BHNKA induced breast cancer cell death is unknown. In this study, we investigated the pharmacological mechanism underlying BHNKA induced MCF-7 cell death. METHODS: Cell viability measurement was performed by the MTT assay. Flow cytometry with PI staining, DAPI staining, and electron microscopy were used to analyze cellular death modes. In addition, western blotting, siRNA transfection, ATP assay, and fluorescence microscopy were used to determine the mechanism of BHNKA induced MCF-7 cell death. RESULTS: BHNKA induced cell death by apoptosis, necroptosis and autophagy at the same concentration and time in MCF-7 cells, and electron microscopy confirmed these results. The mechanism of BHNKA triggered apoptosis and autophagy in MCF-7 cells was primarily due to an increase in the Bax/Bcl-2 ratio and simultaneous up-regulation of LC3-II protein expression, respectively. BHNKA induced necroptosis by activation of the RIP1-RIP3-MLKL necroptosis cascade, up-regulation of cyclophilin D (CypD) protein expression to stimulate ROS generation. We further demonstrated that siRNA-mediated down-regulation of CypD protected against BHNKA induced cell death. CONCLUSIONS: These results suggest that BHNKA may be a potential lead compound for development as an anti-breast cancer agent for induction of multiple cell death pathways.

Synthesis and in vitro antitumor evaluation of honokiol derivatives.

Honokiol is a natural bioactive neolignan and has been widely researched and structural modified as an anticancer agent. In this paper, 18 honokiol derivatives were synthesized and investigated for their antitumor activity. Among these, the promising compound 5a exhibited much higher anti-proliferative activity with IC50 value of 10.41 µM. Transwell assays showed that 5a could significantly inhibit the invasion and migration of I-10 cells at 2.5 µM, which was further confirmed by the western blotting experiments with down-regulation of the HIF-1α and its associated downstream proteins MMP-2 and MMP-9. Overall, these results provided useful suggestion for further structural optimization of honokiol derivatives.

Biosynthesis of Novel Shikonin Glucosides by Enzymatic Glycosylation.

Shikonin, a natural naphthoquinone, has attracted much attention due to its various biological activities. Two shikonin glucosides, shikonin-1',8-di-O-ß-D-glucopyranoside (1) and shikonin-1'-O-ß-D-glucopyranoside (2), were biosynthesized through in vitro enzymatic glycosylation and their structures were elucidated using spectroscopic techniques. The water-solubility and stability of compounds 1 and 2 were significantly higher than those of the parent compound. Furthermore, compound 2 showed moderate cytotoxicity against six cancer cell lines, with IC50 values ranging from 36.10 to 67.47 µM. This research indicated that in vitro enzymatic glycosylation of shikonin is an effective strategy to improve it water solubility and chemical stability.

Bishonokiol A inhibits breast cancer cell invasion and migration by suppressing hypoxia inducible factor-1α.

Hypoxia inducible factor-1α (HIF-1α) plays a central role in cell survival, invasion, metastasis and angiogenesis, and also is emerging as an important target in anti-cancer drug discovery. In the present study, bishonokiol A, a dimeric neolignan isolated from Magnolia grandiflora, was identified as a novel HIF-1α inhibitor. We here demonstrated that in a dose-dependent manner, bishonokiol A inhibited metastasis-related cell invasion and migration of cobalt chloride (CoCl2)-induced MCF-7 and MDA-MB-231 cells, associating with the reduction in HIF-1α levels. Transfection of MDA-MB-231 cells with HIF-1α small interfering ribonucleic acid (siRNA) resulted in a reduction in cell invasion and migration. Furthermore, we found that bishonokiol A not only inhibited the synthesis of HIF-1α protein and protein kinase B (AKT-473) phosphorylation without affecting the expression of HIF-1α mRNA or ubiquitination degradation, but also inhibited the expression of matrix metalloproteinase-9 (MMP-9) and promoter activity. Nude mice bearing MDA-MB-231 cells incubation were treated with bishonokiol A and results showed that bishonokiol A exhibited potent antitumor activity and low toxicity. Therefore, we suggest that bishonokiol A may be a potential inhibitor of HIF-1α and effective antitumor agent for breast cancer.

Synthesis and Evaluation of Bakuchiol Derivatives as Potential Anticancer Agents.

A series of bakuchiol derivatives were synthesized and evaluated for their anti-proliferative and the inhibitory activities on SMMC7721 cell line migration using PX-478 as a positive control. The results showed (S,E)-4-(7-methoxy-3,7-dimethyl-3-vinyloct-1-en-1-yl)phenol (10) to have the best activity among the tested compounds, which included PX-478. In addition, compound 10 showed greater inhibitory activity than that of bakuchiol in the transwell migration and invasion assays at every dose. In western blotting tests, compound 10 showed a promising ability to downregulate the expression of HIF-1α and its associated downstream proteins MMP-2 and MMP-9. Moreover, this effect was dose-dependent and could represent a possible mechanism of action for the anticancer activity of compound 10.

Enzymatic synthesis of novel corylifol A glucosides via a UDP-glycosyltransferase.

Corylifol A, a member of the isoflavone subclass of isoflavonoids, has long been considered to have various biological activities. Here, we sought to synthesize corylifol A glucosides by the in vitro glucosylation reaction using the UDP-glycosyltransferase YjiC from Bacillus licheniformis DSM 13, and obtained two novel glucosides: corylifol A-4',7-di-O-beta-d-glucopyranoside (1) and corylifol A-4'-O-beta-d-glucopyranoside (2). To improve the yield of the products, the reaction time, concentration of UDP-glucose, and pH of the buffer were optimized. The Michaelis constant (Km) was calculated to be 2.88 mM, and the maximal velocity (Vmax) was calculated to be 77.32 nmol/min/mg for UDP-glycosyltransferase. Meanwhile, the water-solubility of compounds 1 and 2 was approximately 27.03 and 15.13 times higher, respectively, than that of their parent compound corylifol A. Additionally, the corylifol A glycosylated products exhibited the highest stability at pH 9.6 and better temperature stability than corylifol A at 40, 60, 80 and 100 °C. In addition, cytotoxicity activity assays against three human tumor cell lines, only corylifol A showed moderate anti-proliferative activity. Overall, this work demonstrates that glycosylation can enhance the water solubility and stability of promising compounds, with potential for further development and application.

Enzymatic biosynthesis of novel neobavaisoflavone glucosides via Bacillus UDP-glycosyltransferase.

The present study was designed to perform structural modifications of of neobavaisoflavone (NBIF), using an in vitro enzymatic glycosylation reaction, in order to improve its water-solubility. Two novel glucosides of NBIF were obtained from an enzymatic glycosylation by UDP-glycosyltransferase. The glycosylated products were elucidated by LC-MS, HR-ESI-MS, and NMR analysis. The HPLC peaks were integrated and the concentrations in sample solutions were calculated. The MTT assay was used to detect the cytotoxic activity of compounds in cancer cell lines. Based on the spectroscopic analyses, the two novel glucosides were identified as neobavaisoflavone-4'-O-ß-D-glucopyranoside (1) and neobavaisoflavone-4', 7-di-O-ß-D-glucopyranoside (2). Additionally, the water-solubilities of compounds 1 and 2 were approximately 175.1- and 4 031.9-fold higher than that of the substrate, respectively. Among the test compounds, only NBIF exhibited weak cytotoxicity against four human cancer cell lines, with IC50 values ranging from 63.47 to 72.81 µmol·L-1. These results suggest that in vitro enzymatic glycosylation is a powerful approach to structural modification, improving water-solubility.

[Biosynthesis of a new psoralidin glucoside by enzymatic glycosylation].

OBJECTIVE: To modify the structure of psoralidin using in vitro enzymatic glycosylation to improve its water solubility and stability. METHODS: A new psoralidin glucoside (1) was obtained by enzymatic glycosylation using a UDP- glycosyltransferase. The chemical structure of compound 1 was elucidated by HR-ESI-MS and nuclear magnetic resonance (NMR) analysis. The high-performance liquid chromatography (HPLC) peaks were integrated and sample solution concentrations were calculated. MTT assay was used to detect the cytotoxicity of the compounds against 3 cancer cell lines in vitro. Results Based on the spectroscopic data, the new psoralidin glucoside was identified as psoralidin-6',7-di-O-ß-D- glucopyranoside (1), whose water solubility was 32.6-fold higher than that of the substrate. Analyses of pH and temperature stability demonstrated that compound 1 was more stable than psoralidin at pH 8.8 and at high temperatures. Only psoralidin exhibited a moderate cytotoxicity against 3 human cancer cell lines. Conclusion In vitro enzymatic glycosylation is a powerful approach for structural modification and improving water solubility and stability of compounds.

Biosynthesis of Novel Glucosides Geldanamycin Analogs by Enzymatic Synthesis.

Two new glucosides (1 and 2) of geldanamycin (GA) analogs were obtained from in vitro glycosylation by UDP-glycosyltransferase (YjiC). Based on spectroscopic (HR-ESI-MS, 1D, and 2D-NMR) analyses, the glucosides were elucidated as 4,5-dihydro-7-O-descarbamoyl-7- hydroxyl GA-7-O-ß-D-glucoside (1) and ACDL3172-18-O-ß-D-glucoside (2). Furthermore, the water solubility of compounds 1 and 2 was about 215.2 and 90.7 times higher respectively, than that of the substrates. Among compounds 1-4, only 3 showed weak antiproliferative activity against four human tumor cell lines: MDA-MB-231, SMMC7721, HepG2, and SW480 (IC50: 13.6, 15.1, 31.8, and 22.7 micrometer, respectively).

Chemical Constituents of Pyrrosia calvata.

A novel flavanone glycoside, 3',5',5,7-tetrahydroxy-6-C-ß-D-glucopyranosyl-flavanone (1), along with 16 known compounds, (R/S)-eriodictyol-8-C-ß-D-glucopyranoside (2), quercetin-3-O-α-L-rhamnosyl (1''' --> 3''')-ß-D-glucopyranoside (3), hemipholin (4), 4ß-carboxymethyl-(-)-epicatechin methyl ester (5), kaempferol (6), quercetin (7), mangiferin (8), chlorogenic acid (9), 1,5-O-dicaffeoylquinic acid (10), 3,5-O-dicaffeoylquinic acid (11), 3-O-caffeoylquinic acid methyl ester (12), 1-O-caffeoyl glycoside (13), 4-O-ß-D-glucopyranosyl-caffeic acid (14), 3'-O-methyleplcatechin-7-O-ß-D-glucopyranoside (15), hop-22(29)-en-30-ol (16) and diploptene (17), were isolated from the whole plant of Pyrrosia calvata (Backer) Ching. Among them, compounds 2, 3, 4, 10, 11, 13 and 14 were isolated from the family Polypodiaceae for the first time, and compound 5 has not been recorded previously from the genus Pyrrosia.

Four new eudesmane-type sesquiterpenes from the basal leaves of Salvia plebeia R. Br.

Four new eudesmane-type sesquiterpenes, named plebeiolide A-C (1-3) and plebeiafuran (4), together with a known eudesmanolide (5), were isolated from the basal leaves of Salvia plebeia R. Br. Their structures were elucidated by extensive spectroscopic analysis including 1D and 2D NMR, HR-ESI-MS spectra. The absolute configuration of compound 1 was confirmed by single-crystal X-ray analysis and CD spectra. The inhibitory activity of isolated compounds toward NO production in lipopolysaccharide-induced RAW264.7 cells was evaluated and compounds 3 and 4 showed moderate inhibitory activity. In addition, the sesquiterpene lactones in Lamiaceae plants may possess some chemosystematic implications at intergeneric and intrageneric levels.

A facile one-pot synthesis of layered protonated titanate nanosheets loaded with silver nanoparticles with enhanced visible-light photocatalytic performance.

Layered protonated titanate nanosheets (LPTNs) loaded with silver nanoparticles are prepared by a simple one-pot hydrothermal route in silver-ammonia solution. The as-synthesized Ag-loaded LPTNs possess large specific surface area. The Ag nanoparticles are highly dispersed on the surface of the LPTNs. They have negligible effects on the crystal structure, crystallinity, and surface area of the LPTNs but result in considerable enhancement of visible-light absorption and in a red-shift of the band gap for the LPTNs. The Ag-loaded LPTNs show enhanced photocatalytic activity for both liquid- and gas-phase reactions under visible-light irradiation. Moreover, the photocatalytic activity first increases gradually with increasing Ag loading content, and then decreases after maximizing at an optimal Ag content. At the Ag loading content of 2.87 mol% and 1.57 mol%, the Ag-loaded LPTNs exhibit the highest visible-light photocatalytic activity for degradation of rhodamine B in water and mineralization of benzene in air, respectively. An alternative possible mechanism for the enhancement of the visible-light photocatalytic activity is also proposed.