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1.  Phyto-SERM Constitutes from Flemingia macrophylla 
The methanolic extract of Flemingia macrophylla roots exhibited significant estrogenic activity in the transgenic plant assay system which was comparable to the activity of soybean extract. Utilizing estrogenic activity-guided fractionation, one new compound, fleminigin, together with 23 known compounds were isolated from F. macrophylla roots’ methanolic extract. The structure of the new compound was identified based on intensive spectroscopic analysis and the full spectral data for one of the isolated compounds, flemichin E, was introduced for the first time in the current investigation. The estrogenic and anti-estrogenic activities of the isolated compounds were evaluated revealing that the isolated isoflavonoids may act as partial estrogen agonists, as well as antagonists. Additionally, the anti-inflammatory and the cytotoxic activities of the isolated compounds were studied. These results suggested the potential applications of F. macrophylla extract and its isolated compounds as selective estrogen receptor modulators (SERMs).
PMCID: PMC3759874  PMID: 23896592
Flemingia macrophylla; menopausal; phytoestrogen; fleminigin; flemichin E; pER8:GUS
2.  Marine algal natural products with anti-oxidative, anti-inflammatory, and anti-cancer properties 
For their various bioactivities, biomaterials derived from marine algae are important ingredients in many products, such as cosmetics and drugs for treating cancer and other diseases. This mini-review comprehensively compares the bioactivities and biological functions of biomaterials from red, green, brown, and blue-green algae. The anti-oxidative effects and bioactivities of several different crude extracts of algae have been evaluated both in vitro and in vivo. Natural products derived from marine algae protect cells by modulating the effects of oxidative stress. Because oxidative stress plays important roles in inflammatory reactions and in carcinogenesis, marine algal natural products have potential for use in anti-cancer and anti-inflammatory drugs.
PMCID: PMC3674937  PMID: 23724847
Algae; ROS; Antioxidant; Inflammation; Antinociceptive; Anti-cancer
3.  Active Constituents from Liriope platyphylla Root against Cancer Growth In Vitro 
Liriope spicata is a well-known herb in traditional Chinese medicine, and its root has been clinically demonstrated to be effective in the treatment of metabolic and neural disorders. The constituents isolated from Liriope have also recently been shown to possess anticancer activity, although the mechanism of which remains largely unknown. Here, we illustrate the anticancer activity of LPRP-9, one of the active fractions we fractionated from the Liriope platyphylla root part (LPRP) extract. Treatment with LPRP-9 significantly inhibited proliferation of cancer cell lines MCF-7 and Huh-7 and down-regulated the phosphorylation of AKT. LPRP-9 also activates the stress-activated MPAK, JNK, p38 pathways, the p53 cell-cycle checkpoint pathway, and a series of caspase cascades while downregulating expression of antiapoptotic factors Bcl-2, Bcl-XL, and survivin. Such activities strongly suggest a role for LPRP-9 in apoptosis and autophagy. We further purified and identified the compound (−)-Liriopein B from LPRP-9, which is capable of inhibiting AKT phosphorylation at low concentration. The overall result highlights the anticancer property of LPRP-9, suggests its mechanism for inhibition of proliferation and promotion of cell death for cancer cells via regulation of multitarget pathways, and denotes the importance of purifying components of fraction LPRP-9 to aid cancer therapy.
PMCID: PMC3670517  PMID: 23762164
4.  Aqueous Extract of the Edible Gracilaria tenuistipitata Inhibits Hepatitis C Viral Replication via Cyclooxygenase-2 Suppression and Reduces Virus-Induced Inflammation 
PLoS ONE  2013;8(2):e57704.
Hepatitis C virus (HCV) is an important human pathogen leading to hepatocellular carcinoma. Using an in vitro cell-based HCV replicon and JFH-1 infection system, we demonstrated that an aqueous extract of the seaweed Gracilaria tenuistipitata (AEGT) concentration-dependently inhibited HCV replication at nontoxic concentrations. AEGT synergistically enhanced interferon-α (IFN-α) anti-HCV activity in a combination treatment. We found that AEGT also significantly suppressed virus-induced cyclooxygenase-2 (COX-2) expression at promoter transactivation and protein levels. Notably, addition of exogenous COX-2 expression in AEGT-treated HCV replicon cells gradually abolished AEGT anti-HCV activity, suggesting that COX-2 down-regulation was responsible for AEGT antiviral effects. Furthermore, we highlighted the inhibitory effect of AEGT in HCV-induced pro-inflammatory gene expression such as the expression of tumour necrosis factor-α, interleukin-1β, inducible nitrite oxide synthase and COX-2 in a concentration-dependent manner to evaluate the potential therapeutic supplement in the management of patients with chronic HCV infections.
PMCID: PMC3585194  PMID: 23469054
5.  Withanolides-Induced Breast Cancer Cell Death Is Correlated with Their Ability to Inhibit Heat Protein 90 
PLoS ONE  2012;7(5):e37764.
Withanolides are a large group of steroidal lactones found in Solanaceae plants that exhibit potential anticancer activities. We have previously demonstrated that a withanolide, tubocapsenolide A, induced cycle arrest and apoptosis in human breast cancer cells, which was associated with the inhibition of heat shock protein 90 (Hsp90). To investigate whether other withanolides are also capable of inhibiting Hsp90 and to analyze the structure-activity relationships, nine withanolides with different structural properties were tested in human breast cancer cells MDA-MB-231 and MCF-7 in the present study. Our data show that the 2,3-unsaturated double bond-containing withanolides inhibited Hsp90 function, as evidenced by selective depletion of Hsp90 client proteins and induction of Hsp70. The inhibitory effect of the withanolides on Hsp90 chaperone activity was further confirmed using in vivo heat shock luciferase activity recovery assays. Importantly, Hsp90 inhibition by the withanolides was correlated with their ability to induce cancer cell death. In addition, the withanolides reduced constitutive NF-κB activation by depleting IκB kinase complex (IKK) through inhibition of Hsp90. In estrogen receptor (ER)-positive MCF-7 cells, the withanolides also reduced the expression of ER, and this may be partly due to Hsp90 inhibition. Taken together, our results suggest that Hsp90 inhibition is a general feature of cytotoxic withanolides and plays an important role in their anticancer activity.
PMCID: PMC3365124  PMID: 22701533
6.  Synthesis and Biological Evaluation of Phenanthrenes as Cytotoxic Agents with Pharmacophore Modeling and ChemGPS-NP Prediction as Topo II Inhibitors 
PLoS ONE  2012;7(5):e37897.
In a structure-activity relationship (SAR) study, 3-methoxy-1,4-phenanthrenequinones, calanquinone A (6a), denbinobin (6b), 5-OAc-calanquinone A (7a) and 5-OAc-denbinobin (7b), have significantly promising cytotoxicity against various human cancer cell lines (IC50 0.08–1.66 µg/mL). Moreover, we also established a superior pharmacophore model for cytotoxicity (r = 0.931) containing three hydrogen bond acceptors (HBA1, HBA2 and HBA3) and one hydrophobic feature (HYD) against MCF-7 breast cancer cell line. The pharmacophore model indicates that HBA3 is an essential feature for the oxygen atom of 5-OH in 6a–b and for the carbonyl group of 5-OCOCH3 in 7a–b, important for their cytotoxic properties. The SAR for moderately active 5a–b (5-OCH3), and highly active 6a–b and 7a–b, are also elaborated in a spatial aspect model. Further rational design and synthesis of new cytotoxic phenanthrene analogs can be implemented via this model. Additionally, employing a ChemGPS-NP based model for cytotoxicity mode of action (MOA) provides support for a preliminary classification of compounds 6a–b as topoisomerase II inhibitors.
PMCID: PMC3362575  PMID: 22666407
7.  An Aluminum Microfluidic Chip Fabrication Using a Convenient Micromilling Process for Fluorescent Poly(dl-lactide-co-glycolide) Microparticle Generation 
Sensors (Basel, Switzerland)  2012;12(2):1455-1467.
This study presents the development of a robust aluminum-based microfluidic chip fabricated by conventional mechanical micromachining (computer numerical control-based micro-milling process). It applied the aluminum-based microfluidic chip to form poly(lactic-co-glycolic acid) (PLGA) microparticles encapsulating CdSe/ZnS quantum dots (QDs). A cross-flow design and flow-focusing system were employed to control the oil-in-water (o/w) emulsification to ensure the generation of uniformly-sized droplets. The size of the droplets could be tuned by adjusting the flow rates of the water and oil phases. The proposed microfluidic platform is easy to fabricate, set up, organize as well as program, and is valuable for further applications under harsh reaction conditions (high temperature and/or strong organic solvent systems). The proposed method has the advantages of actively controlling the droplet diameter, with a narrow size distribution, good sphericity, as well as being a simple process with a high throughput. In addition to the fluorescent PLGA microparticles in this study, this approach can also be applied to many applications in the pharmaceutical and biomedical area.
PMCID: PMC3304121  PMID: 22438719
microfluidic emulsification; poly(lactic-co-glycolic acid) (PLGA); quantum dots (QDs); microsphere
8.  Automatic Morphological Subtyping Reveals New Roles of Caspases in Mitochondrial Dynamics 
PLoS Computational Biology  2011;7(10):e1002212.
Morphological dynamics of mitochondria is associated with key cellular processes related to aging and neuronal degenerative diseases, but the lack of standard quantification of mitochondrial morphology impedes systematic investigation. This paper presents an automated system for the quantification and classification of mitochondrial morphology. We discovered six morphological subtypes of mitochondria for objective quantification of mitochondrial morphology. These six subtypes are small globules, swollen globules, straight tubules, twisted tubules, branched tubules and loops. The subtyping was derived by applying consensus clustering to a huge collection of more than 200 thousand mitochondrial images extracted from 1422 micrographs of Chinese hamster ovary (CHO) cells treated with different drugs, and was validated by evidence of functional similarity reported in the literature. Quantitative statistics of subtype compositions in cells is useful for correlating drug response and mitochondrial dynamics. Combining the quantitative results with our biochemical studies about the effects of squamocin on CHO cells reveals new roles of Caspases in the regulatory mechanisms of mitochondrial dynamics. This system is not only of value to the mitochondrial field, but also applicable to the investigation of other subcellular organelle morphology.
Author Summary
Mitochondria are “cellular power plants” that synthesize adenosine triphosphate (ATP) from degradation of nutrients, providing chemical energy for cellular activities. In addition, mitochondria are involved in a range of other cellular processes, such as signaling, cell differentiation, cell death, cell cycle and cell growth. Dysfunctional mitochondrial dynamics have been linked to several neurodegenerative diseases, and may play a role in the aging process. Previous studies on the correlation between mitochondrial morphological changes and pathological processes involve mostly manual or semi-automated classification and quantification of morphological features, which introduces biases and inconsistency, and are labor intensive. In this work we have developed an automated quantification system for mitochondrial morphology, which is able to extract and distinguish six representative morphological subtypes within cells. Using this system, we have analyzed 1422 cells and extracted more than 200 thousand individual mitochondrion, and calculated morphological statistics for each cell. From the numerical results we were able to derive new biological conclusions about mitochondrial morphological dynamics. With this new system, investigations of mitochondrial morphology can be scaled up and objectively quantified, allowing standardization of morphological distinctions and replicability between experiments. This system will facilitate future research on the relation between subcellular morphology and various physiological processes.
PMCID: PMC3188504  PMID: 21998575
9.  Inhibitory Effects of 1,2,3,4,6-Penta-O-Galloyl-β-d-Glucopyranose on Biofilm Formation by Staphylococcus aureus▿ †  
1,2,3,4,6-Penta-O-galloyl-β-d-glucopyranose (PGG) is an active ingredient in plants that are commonly used in Chinese medicine to treat inflammation. We demonstrate here that PGG, at 6.25 μM, does not inhibit the growth of Staphylococcus aureus, and yet it prevents biofilm formation on polystyrene and polycarbonate surfaces. At the same concentration, PGG is not toxic to human epithelial and fibroblast cells. PGG has an IB50 value, i.e., the PGG concentration that inhibits 50% biofilm formation, of 3.6 μM. The value is substantially lower than that of N-acetylcysteine, iodoacetamide, and N-phenyl maleimide, which are known to inhibit biofilm formation by S. aureus. Biochemical and scanning electron microscopy results also reveal that PGG inhibits initial attachment of the bacteria to solid surface and the synthesis of polysaccharide intercellular adhesin, explaining how PGG inhibits biofilm formation. The results of this study demonstrate that coating PGG on polystyrene and silicon rubber surfaces with polyaniline prevents biofilm formation, indicating that PGG is highly promising for clinical use in preventing biofilm formation by S. aureus.
PMCID: PMC3067108  PMID: 21173176
10.  Antitumor Agents. 271. Total Synthesis and Evaluation of Brazilein and Analogs as Anti-inflammatory and Cytotoxic Agents 
The first total synthesis of the naturally occurring tetracyclic homoisoflavonoid brazilein (1) and 14 new analogs (1a–n) is reported. Target compounds and intermediates were assayed for anti-inflammatory effects on superoxide anion generation and elastase release by human neutrophils in response to fMLP/CB, and for cytotoxic activity against nasopharyngeal (KB), vincristine-resistant nasopharyngeal (KBvin), lung (A549) and prostate (DU-145) human cancer cell lines. The most active compound 1b showed potent effects on superoxide anion generation and elastase release with IC50 values of 1.2 and 1.9 µM, respectively, and was 65 times more potent than phenylmethylsulfonyl fluoride (PMSF), the positive control, in the latter assay. Additionally, 1b exhibited broad spectrum in vitro anticancer activity with IC50 values of 6–11 µM against the four tested cancer cell lines.
PMCID: PMC2831747  PMID: 20036537
homoisoflavonoid; brazilein; anti-inflammatory; cytotoxic
11.  Cytotoxic Phenanthrenequinones and 9,10-Dihydrophenanthrenes from Calanthe arisanensis 
Journal of natural products  2009;72(2):210-213.
Two new phenanthrenequinones, calanquinones B–C (2–3), four new 9,10-dihydrophenanthrenes, calanhydroquinones A–C (4–6), and calanphenanthrene A (7), along with five known compounds (1 and 8–11) were isolated from an EtOAc-soluble extract of Calanthe arisanensis through bioassay-guided fractionation. Their structures were identified from spectroscopic data, and the compounds were tested for in vitro cytotoxic activity against human lung (A549), prostate (PC-3 and DU145), colon (HCT-8), breast (MCF-7), nasopharyngeal (KB), and vincristine-resistant nasopharyngeal (KBVIN) cancer cell lines. Compound 1 showed the highest potency (EC50 < 0.5 μg/mL) against all seven cancer cell lines, with the greatest activity against breast cancer MCF-7 cells (EC50 < 0.02 μg/mL). Generally, except for 7, compounds 2–11 also showed significant cytotoxic activity (EC50 < 4μg/mL) against some cell lines (especially PC-3 and MCF-7) in the panel.
PMCID: PMC2880632  PMID: 19193043
12.  4β-Hydroxywithanolide E from Physalis peruviana (golden berry) inhibits growth of human lung cancer cells through DNA damage, apoptosis and G2/M arrest 
BMC Cancer  2010;10:46.
The crude extract of the fruit bearing plant, Physalis peruviana (golden berry), demonstrated anti-hepatoma and anti-inflammatory activities. However, the cellular mechanism involved in this process is still unknown.
Herein, we isolated the main pure compound, 4β-Hydroxywithanolide (4βHWE) derived from golden berries, and investigated its antiproliferative effect on a human lung cancer cell line (H1299) using survival, cell cycle, and apoptosis analyses. An alkaline comet-nuclear extract (NE) assay was used to evaluate the DNA damage due to the drug.
It was shown that DNA damage was significantly induced by 1, 5, and 10 μg/mL 4βHWE for 2 h in a dose-dependent manner (p < 0.005). A trypan blue exclusion assay showed that the proliferation of cells was inhibited by 4βHWE in both dose- and time-dependent manners (p < 0.05 and 0.001 for 24 and 48 h, respectively). The half maximal inhibitory concentrations (IC50) of 4βHWE in H1299 cells for 24 and 48 h were 0.6 and 0.71 μg/mL, respectively, suggesting it could be a potential therapeutic agent against lung cancer. In a flow cytometric analysis, 4βHWE produced cell cycle perturbation in the form of sub-G1 accumulation and slight arrest at the G2/M phase with 1 μg/mL for 12 and 24 h, respectively. Using flow cytometric and annexin V/propidium iodide immunofluorescence double-staining techniques, these phenomena were proven to be apoptosis and complete G2/M arrest for H1299 cells treated with 5 μg/mL for 24 h.
In this study, we demonstrated that golden berry-derived 4βHWE is a potential DNA-damaging and chemotherapeutic agent against lung cancer.
PMCID: PMC2830937  PMID: 20167063
13.  Cytotoxic Calanquinone A from Calanthe arisanensis and Its First Total Synthesis 
Calanquinone A (1) was isolated from an EtOAc-soluble extract of Calanthe arisanensis through bioassay-guided fractionation. Its structure was identified by spectroscopic methods. Compound 1 showed potent cytotoxicity (EC50 < 0.5 µg/mL) against lung (A549), prostate (PC-3 and DU145), colon (HCT-8), breast (MCF7), nasopharyngeal (KB), and vincristine-resistant nasopharyngeal (KB-VIN) cancer cell lines, and interestingly, showed an improved drug resistance profile compared to paclitaxel. The total synthesis of 1 was also achieved and reported herein.
PMCID: PMC2551759  PMID: 18640035
14.  First Total Synthesis of Protoapigenone and its Analogs as Potent Cytotoxic Agents 
Journal of medicinal chemistry  2007;50(16):3921-3927.
Protoapigenone (1), isolated from Thelypteris torresiana, previously showed significant cytotoxic activity against five human cancer cell lines. In a continued structure-activity relationship study, the first total synthesis and modification of 1 were achieved. All synthesized compounds and related intermediates were evaluated for cytotoxic activity against five human cancer cell lines, HepG2, Hep3B, MDA-MB-231, MCF-7 and A549. Among them, 24 showed 2.2-14.2 fold greater cytotoxicity than 1 and naphthyl A-ring analogs remarkably enhanced the activity.
PMCID: PMC2587018  PMID: 17622129
15.  Anti-AIDS Agents 69.1 Moronic Acid and Other Triterpene Derivatives as Novel Potent Anti-HIV Agents 
Journal of medicinal chemistry  2006;49(18):5462-5469.
In a continuing structure-activity relationship study of potent anti-HIV agents, seven new triterpene derivatives were designed, synthesized, and evaluated for in vitro antiviral activity. Among them, moronic acid derivatives 19, 20 and 21 showed significant activity in HIV-1 infected H9 lymphocytes. Compounds 19 and 20 were also evaluated against HIV-1 NL4−3 and drug resistant strains in the MT-4 cell line. Compounds 19 and 20 showed better antiviral profiles than the betulinic acid analog 8 (PA-457), which has successfully completed a Phase IIa clinical trial. Compound 20 showed potent anti-HIV activity with EC50 values of 0.0085 μM against NL4−3, 0.021 μM against PI-R (a multiple protease inhibitor resistant strain), and 0.13 μM against FHR-2 (an HIV strain resistant to 8), respectively. The promising compound 20 has become a new lead for modification, and further development of 20-related compounds as clinical trial candidates is warranted.
PMCID: PMC2512972  PMID: 16942019
16.  Aqueous Extract of Gracilaria tenuistipitata Suppresses LPS-Induced NF-κB and MAPK Activation in RAW 264.7 and Rat Peritoneal Macrophages and Exerts Hepatoprotective Effects on Carbon Tetrachloride-Treated Rat 
PLoS ONE  2014;9(1):e86557.
In addition to the previous investigations of bioactivity of aqueous extract of the edible Gracilaria tenuistipitata (AEGT) against H2O2-induced DNA damage and hepatitis C virus replication, the purpose of this study is to evaluate the potential therapeutic properties of AEGT against inflammation and hepatotoxicity using lipopolysaccharide (LPS)-stimulated mouse RAW 264.7 cells, primary rat peritoneal macrophages and carbon tetrachloride (CCl4)-induced acute hepatitis model in rats. AEGT concentration-dependently inhibited the elevated RNA and protein levels of inducible nitric oxide synthase and cyclooxygenase-2, thereby reducing nitric oxide and prostaglandin E2 levels, respectively. Moreover, AEGT significantly suppressed the production of LPS-induced proinflammatory cytokines, including interleukin (IL)-1β, IL-6 and tumor necrosis factor-α. These inhibitory effects were associated with the suppression of nuclear factor-kappa B activation and mitogen-activated protein kinase phosphorylation by AEGT in LPS-stimulated cells. In addition, we highlighted the hepatoprotective and curative effects of AEGT in a rat model of CCl4-intoxicated acute liver injury, which was evident from reduction in the elevated serum aspartate aminotransferase and alanine aminotransferase levels as well as amelioration of histological damage by pre-treatment or post-treatment of AEGT. In conclusion, the results demonstrate that AEGT may serve as a potential supplement in the prevention or amelioration of inflammatory diseases.
PMCID: PMC3903563  PMID: 24475143
17.  Golden Berry-Derived 4β-hydroxywithanolide E for Selectively Killing Oral Cancer Cells by Generating ROS, DNA Damage, and Apoptotic Pathways 
PLoS ONE  2013;8(5):e64739.
Most chemotherapeutic drugs for killing cancer cells are highly cytotoxic in normal cells, which limits their clinical applications. Therefore, a continuing challenge is identifying a drug that is hypersensitive to cancer cells but has minimal deleterious effects on healthy cells. The aims of this study were to evaluate the potential of 4β-hydroxywithanolide (4βHWE) for selectively killing cancer cells and to elucidate its related mechanisms.
Methodology and Principal Findings
Changes in survival, oxidative stress, DNA damage, and apoptosis signaling were compared between 4βHWE-treated oral cancer (Ca9-22) and normal fibroblast (HGF-1) cells. At 24 h and 48 h, the numbers of Ca9-22 cells were substantially decreased, but the numbers of HGF-1 cells were only slightly decreased. Additionally, the IC50 values for 4βHWE in the Ca9-22 cells were 3.6 and 1.9 µg/ml at 24 and 48 h, respectively. Time-dependent abnormal increases in ROS and dose-responsive mitochondrial depolarization can be exploited by using 4βHWE in chemotherapies for selectively killing cancer cells. Dose-dependent DNA damage measured by comet-nuclear extract assay and flow cytometry-based γ-H2AX/propidium iodide (PI) analysis showed relatively severer damage in the Ca9-22 cells. At both low and high concentrations, 4βHWE preferably perturbed the cell cycle in Ca9-22 cells by increasing the subG1 population and arrest of G1 or G2/M. Selective induction of apoptosis in Ca9-22 cells was further confirmed by Annexin V/PI assay, by preferential expression of phosphorylated ataxia-telangiectasia- and Rad3-related protein (p-ATR), and by cleavage of caspase 9, caspase 3, and poly ADP-ribose polymerase (PARP).
Together, the findings of this study, particularly the improved understanding of the selective killing mechanisms of 4βHWE, can be used to improve efficiency in killing oral cancer cells during chemoprevention and therapy.
PMCID: PMC3660349  PMID: 23705007
18.  Anti-proliferative effect of methanolic extract of Gracilaria tenuistipitata on oral cancer cells involves apoptosis, DNA damage, and oxidative stress 
Methanolic extracts of Gracilaria tenuistipitata (MEGT) were obtained from the edible red algae. Previously, we found that water extract of G. tenuistipitata was able to modulate oxidative stress-induced DNA damage and its related cellular responses.
In this study, the methanol extraction product MEGT was used to evaluate the cell growth inhibition in oral cancer cells and its possible mechanism was investigated.
The cell viability of MEGT treated Ca9-22 oral cancer cell line was significantly decreased in a dose–response manner (p < 0.05). The sub-G1 population and annexin V intensity of MEGT-treated Ca9-22 cancer cells were significantly increased in a dose–response manner (p < 0.0005 and p < 0.001, respectively). The γH2AX intensities of MEGT-treated Ca9-22 cancer cells were significantly increased in a dose–response manner (p < 0.05). The reactive oxygen species (ROS) and glutathione (GSH)-positive intensities of MEGT-treated Ca9-22 oral cancer cells were significantly increased and decreased, respectively, in a dose–response manner (p < 0.05). The DiOC2(3) intensity for mitochondrial membrane potential (MMP) of MEGT-treated Ca9-22 cancer cells was significantly decreased in a dose–response manner (p < 0.05).
These results indicated that MEGT had apoptosis-based cytotoxicity against oral cancer cells through the DNA damage, ROS induction, and mitochondrial depolarization. Therefore, MEGT derived from the edible algae may have potential therapeutic effects against oral squamous cell carcinoma (OSCC).
PMCID: PMC3495219  PMID: 22937998
Red algae; Oral cancer; Apoptosis; γ-H2AX; ROS; Mitochondrial membrane potential; Glutathione
19.  Direct Semi-Synthesis of the Anticancer Lead-Drug Protoapigenone from Apigenin, and Synthesis of Further New Cytotoxic Protoflavone Derivatives 
PLoS ONE  2011;6(8):e23922.
Protoapigenone, a natural flavonoid possessing an unusual p-quinol moiety on its B-ring, is a novel prospective anticancer agent with low toxicity that is currently in development. The first economical, one-step synthesis of protoapigenone from apigenin is described on up to gram scale. 13 new 1′-O-alkylflavone analogs were also synthesized, either from apigenin or β-naphthoflavone. The in vitro cytotoxic activity of each compound was tested on six human cancer cell lines (HepG2, Hep3B, Ca9-22, A549, MCF-7 and MDA-MB-231). In the case of 1′-O-alkyl-protoapigenone derivatives, structure-activity relationships were found depending on the side-chain, and protoapigenone 1′-O-butyl ether was found to exert significantly stronger activity against three of the cell lines (Hep3B, MCF-7 and MDA-MB-231) than its non-substituted analog, protoapigenone itself. In contrast to this, all β-naphthoflavone derivatives bearing the same pharmacophore on their B-ring showed decreased cytotoxic activities when substituted with an O-alkyl side-chain at position 1′, comparing to that of the non-substituted compound.
PMCID: PMC3166065  PMID: 21912610

Results 1-19 (19)