Antitumor activity of arylacetylshikonin analogues

Twenty one phenylacetylshikonin analogues were synthesized from various substituted phenyl acetic acids and their cytotoxicity values against A549, K562 and L1210 cell lines and antitumor action in mice bearing S-180 cells were measured. All of phenylacetylshikonin analogues expressed a potent cytotoxicity (ED₅₀, 0.1–1.80 μg/ml) against L1210 and K562 cells. L 1210 cells were the most sensitive to shikonin analogues among these cells. Except 4-methoxyphenylacetylshikonin (0.098μg/ml) and α-acetoxyphenylacetylshikonin (0.10μg/ml), all other shikonin derivatives showed higher ED₅₀ values than phenylacetylshikonin (0.13μg/ml) in L 1210. In K562 cell, α-substitution of phenylacetylshikonin (0.1 μg/ml), while other substitutions increased it slightly; 4-methoxyphenylacetylshikonin (0.033 μg/ml) showed a exceptionally good cytotoxicity against K562 cell. 4-Halogenation tended to decrease the cytotoxic effect on L1210 cells, while it enhanced the effect on K562; 4-bromophenylacetyl [ED₅₀ (L1210)=1.76 μ/ml, ED₅₀ (K 562)=0.32 μg/ml] and 4-chlorophenylacetyl shikonin [ED₅₀ (L 1210)=1.64 μg/ml, ED₅₀ (K562)=0.32 μg/ml]. In contrast, A549 cells were much less sensitive to these shikonin analogues which showed ED₅₀ values of 1.5–13.5 μg/ml. Most of phenylacetylshikonin derivatives showed good antitumor activity in mice bearing S-180 cells. α-A-cetoxyphenylacetylshikonin and 4-dimethylaminophenylacetylshikonin showed highest T/C value (192–195%), implying that introduction of α-acetyl or of 4-dimethyl amino group gave a positive effect on the antitumor activity. Introduction of 4-dimethylamino group enhanced the antitumor activity as shown for 4-dimethylaminophenylacetylshikonin (T/C, 192%). It might be due to improvement of water solubility by dimethylamino group in the molecule.     

Structure activity relationship of ar-turmerone analogues

For the analysis of structure activity relationship of ar-turmerone analogues, the compounds containing the various substituents on the phenyl ring and 1(or 2)-naphthyl group in the place of phenyl of ar-turmerone were prepared and tested their cytotoxicity against HL-60, K-562, and L1210 leukemia cellsin vitro. The substituents at para position are methoxy, phenoxy, methyl, trifluoromethyl, fluoro, and chloro. Atmeta position methoxy, methyl, trifluoromethyl, or chloro groups and atortho position methoxy or chloro group were introduced. Against HL-60 and K-562 cells, ED₅₀ values of the analogues are ranged from 0.8 to 30.0 μg/ml. Against L1210 cell, these are located more than 20.0 μg/ml. However, 5-carboethoxy-2-methyl-6-(1-naphthyl)-2-octen-4-one (5n) possesses ED50 valuses 0.8, 2.1, 6.5 μg/ml against HL-60, K-562, L1210 cells, respectively. The electronic nature of the subsituents on phenyl ring of ar-turmerone dose not affect the biological activity. Therefore the flat structure of aromatic portion of ar-turmerone analogues is the more important factor for their activity rather than its electronic nature. The potentiation of the cytotoxicity with the enlargement of aromatic ring region also supports the importance of the plane structure of this area. The restriction of the single bond rotation between C-6 and aromatic ring through the introduction of substituents at theortho position of phenyl ring and the increment of size of alkyl group at C-6 position enhances the activity. Therefore the effective conformation should be the one having the orthogonal arrangement between the aromatic ring and the side chain.     

Synthesis andin vitro cytotoxicity of cinnamaldehydes to human solid tumor cells

Cinnamaldehydes and related compounds were synthesized from various cinnamic acids based on the 2′-hydroxycinnamaldehyde isolated from the bark ofCinnamomum cassia Blume. The cytotoxicity to human solid tumor cells such as A549, SK-OV-3, SK-MEL-2, XF498 and HCT15 were measured. Cinnamic acid, cinnamates and cinnamyl alcohols did not show any cytotoxicity against the human tumor cells. Cinnamaldehydes and realted compounds were resistant to A549 cell line up to 15 μg/ml. In contrast, HCT15 and SK-MEL-2 cells were much sensitive to these cinnamaldehyde analogues which showed ED₅₀ values 0.63-8.1 μg/ml. Cytotoxicity of the saturated aldehydes was much weak compared to their unsaturated aldehydes. From these studies, it was found that the key functional group of the cinnamaldehyde-related compounds in the antitumor activity is the propenal group.     

Synthesis of benzo[c]phenanthridine derivatives and theirin vitro antitumor activities

Aiming at the development of anticancer agents by modification of phenolic benzo[c]phenanthridine alkaloid, additional hydroxyl group was put on C10 position of fagaridine (1) by a biomimetic synthetic procedure to afford 10-hydroxyfagaridine (12). All of the synthetic intermediates were also screenedin vitro antitumor activities against five different cell lines as well as12. Among them the representative cytotoxic results are shown as follows;p-quinone (11) [ED₅₀ (A549=0.22 μg/ml), (HCT15=0.21 μg/ml), fagaridine (1) (HCT 15=0.41 μg/ml), olefin (6) (HCT 15=0.06 μg/ml), acetal (7) (SKMEL-2=0.07 μg/ml), dihydrofagaridne (10) (A549=0. 38 μg/ml), 10-hydroxyfagaridine (12) (A 549=0.45 μg/ml). From these observation three main remarks can be drawn; (i) the iminium part of benzo[c]phenanthridine is not essential for showing acitvities, (ii) the additional hydroxyl group did not contribute to enhance the cytotoxicity, (iii) the 3-arylisoquinolin-1(2H)-one derivatives were found to display significantin vitro antitumor activity.     

Antineopastic natural products and the analogues IV. Aurapten,the cytotoxic coumarin fromPoncirus trifoliata against L1210 cell

A cytotoxic coumarin against L1210 cell was isolated from the unripe fruit ofPoncirus trifoliata (ED₅₀=10.2 μg/ml). Its structure was identified as aurapten, 7-geranyloxycoumarin. Hydrolysis of the substance gave umbelliferone and geraniol. Only geraniol showed the cytotoxic activity (ED₅₀=6.5 μg/ml) while umbelliferone and its methyl or allyl derivatives were not active.     

2-(1-Oxyalkyl)-1,4-dioxy-9,10-anthraquinones: Synthesis and evaluation of antitumor activity

Fourty eight derivatives of 2-(1-oxyalkyl)-1,4-dioxy-9,10-anthraquinone were synthesized, and their antitumor activity was evaluated. On the whole, 2-(1-hydroxyalkyl)-1,4-dihydroxy-9,10-anthraquinones (DHAQ=1,4-dihydroxy-9,10-anthraquinone) showed stronger cytotoxic activity againnst L1210 cells than 2-(1-hydroxyalkyl)-1,4-dimethoxy.-9,10-anthraquinones(DMAQ=1,4-dimethoxy-9,10-anthraquinone), implying that free hydroxy groups at C-1 and C-4 of the anthraquinone structure are necessary for the cytotoxic activity. The bioactivity of 2-(1-hydroxyalkyl)-DHAQ derivatives differed according to the size of alkyl group at C-1, while the elongation of alkyl group over 7 carbon atoms failed to enhance, the bioactivity, the derivatives possessing alkyl moiety of 1–6 carbon atoms showed an increase in the cytotoxicity and the antitumor activity in Sarcoma-180; 2-hydroxymethyl-DHAQ (ED₅₀, 15 μg/ml; T/C, 125%), 2-(1-hydroxyethyl)-DHAQ(1.9 μg/ml; 139.2%), 2-(1-hydroxypropyl)-DHAQ (7.2 μg/ml; 135.1%), 2-(1-hydroxybutyl)-DHAQ (10.2 μg/ml; 125.3%), 2-(1-hydroxypentyl)-DHAQ (23.7 μg/ml; 110.1%) and 2-(1-hydroxyhexyl)-DHAQ (58 μg/ml; 108%). Next, 2-(1-Hydroxyalkyl)-DHAQ derivatives were acetylated to produce 2-(1-acetoxyalkyl)-DHAQ analogues. Although the acetylation somewhat enhanced the cytotoxicity, but not the antitumor action. In addition, the presence of phenyl group at C-1' enhanced the cytotoxicity and the T/C value, compared to alkyl groups of same size; 2-(1-hydroxy-1-phenyl)-DHAQ (ED₅₀, 5.6 μg/ml; T/C., 137%).     

Activation of caspases and poly (ADP-ribose) polymerase cleavage to induce apoptosis in leukemia HL-60 cells by Inula racemosa

Inula racemosa Hook.f. commonly known as Pushkarmula (Compositae) has been used as a traditional drug in India, China and Europe. In the present study, 95% ethanolic extract of roots and its fractions (n-hexane, chloroform, n-butanol and aqueous) were evaluated for in vitro cytotoxicity against cancer cell lines of colon, ovary, prostate, lung, CNS and leukemia. The n-hexane fraction containing alantolactone and isoalantolactone as its major constituents was further studied for its mode of action in HL-60 cells. The lowest IC₅₀ value of n-hexane fraction was 10.25 μg/ml for Colo-205, a colon cancer cell line whereas, 17.86 μg/ml was the highest IC₅₀ value observed against CNS cancer cell line SF-295. Further studies on HL-60 cells treated with n-hexane fraction at 10, 25 and 50 μg/ml for 6 h, revealed that it induces apoptosis through intrinsic as well as extrinsic pathways by generating reactive oxygen species (ROS) intermediates. Mitochondrial dysfunction prompted the release of cytochrome c, translocation of pro-apoptotic protein (Bax), activation of caspase cascade, resulting in the cleavage of some specific substrates for caspase-3 such as poly (ADP-ribose) polymerase (PARP), which eventually leads to apoptosis. The results of present study strongly support further research and development of bioactive constituents from Inula racemosa as potential anticancer agent with possible therapeutic implication.     

Synthesis and anticancer activity of para-xylyl linked bis-benzimidazolium salts and respective Ag(I) N-heterocyclic carbene complexes

The article describes synthesis, characterization (NMR, FT-IR, microanalysis, X-ray crystallography), and in vitro anticancer activity of para-xylyl linked bis-benzimidazolium salts and respective dinuclear Ag–NHC complexes. All the compounds were tested for their cytotoxicity against human colorectal cancer (HCT 116) and promyelocytic leukemia (HL-60) cell lines. According to cell viability measurements using MTT assay, all tested compounds showed dose-dependent cytotoxic activity against both cell lines. The tested compounds demonstrated significant activity with IC₅₀ values range 0.01–18.7 μM for HCT 116 and 0.7–55.7 μM for HL-60 cells. 5-Fluorouracil was used as standard drug (IC₅₀ 19.2 μM for HCT 116 and 5.4 μM for HL-60). We found that as the size of N-alkyl substitution on benzimidazolium salt increases its cytotoxicity decreases whereas a reverse occurred in case of respective complexes.     

Synthesis and antitumor activity of cannabigerol

Cannabigerol(3) was synthesized and evaluated for its inhibitory activity against mouse skin melanoma cells. Cannabigerol displayed significant antitumor activity [inhibitory concentration (IC₅₀)=31.3l μ/mL]in vitro assay.     

Improved Dissolution and Cytotoxicity of Camptothecin Incorporated into Oxidized-Cellulose Microspheres Prepared by Spray Drying

Oxidized celluloses (OC) containing 7, 13, and 20% carboxylic content (OC-7, OC-13, and OC-20, respectively) have been converted into aqueous colloidal dispersions and used to prepare microspheres of the antineoplastic agent camptothecin (CPT) by spray drying. Plasticizers used were glycerin, polyethylene glycol 400 (PEG-400), and polyethylene glycol 6000 (PEG-6000). Irrespective of the carboxylic content of OC and the nature of plasticizer employed, the size of microspheres varied from 1.25 ± 0.40 to 1.52 ± 0.47 μm. The release studies in pH 7.4 buffer revealed the dissolution of CPT to be faster from the microsphere formulations than from physical mixtures and free CPT. The times to release 50% CPT (T-50%) from microspheres prepared using OC-7, OC-13, and OC-20 were about 31, 37, and 19 h, respectively. The in vitro cytotoxicity results indicated OC-20/CPT microspheres to be more effective than free CPT against human-derived RPMI-8402 lymphoid and THP-1 myeloid leukemia cell lines. The ED₅₀ values for the OC-20/CPT microspheres and free CPT were 1 × 10^?5 and 0.25 × 10^?1 μg/mL, respectively, against the RPMI-8402 line and 0.5 × 10^?2 and 0.75 μg/mL, respectively, against the THP-1 line. The higher activity of OC-20/CPT microspheres compared to that of the free drug is attributed to increased dissolution of CPT from microspheres.     

Cross-talk between phosphatidic acid and ceramide during ethanol-induced apoptosis in astrocytes

Background

Anticancer bisdioxopiperazines, including ICRF-154, razoxane (Raz, ICRF-159) and ICRF-193, are a family of anticancer agents developed in the UK, especially targeting metastases of neoplasms. Two other bisdioxopiperazine derivatives, probimane (Pro) and MST-16, were synthesized at the Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China. Cytotoxic activities and mechanisms of Raz (+)-steroisomer (ICRF-187, dexrazoxane), Pro and MST-16 against tumor cells were evaluated by MTT colorimetry, flow cytometry and karyotyping.

Results

Pro was cytotoxic to human tumor cell lines in vitro (IC₅₀<50 μM for 48 h). Four human tumor cell lines (SCG-7901, K562, A549 and HL60) were susceptible to Pro at low inhibitory concentrations (IC₅₀ values < 10 μM for 48 h). Although the IC₅₀ against HeLa cell line of vincristine (VCR, 4.56 μM), doxorubicin (Dox, 1.12 μM) and 5-fluoruouracil (5-Fu, 0.232 μM) are lower than Pro (5.12 μM), ICRF-187 (129 μM) and MST-16 (26.4 μM), VCR, Dox and 5-Fu shows a low dose-related – high cytotoxic activity. Time-response studies showed that the cytotoxic effects of Pro are increased for 3 days in human tumor cells, whereas VCR, Dox and 5-Fu showed decreased cytotoxic action after 24 h. Cell cycle G₂/M phase arrest and chromosome segregation blocking by Pro and MST-16 were noted. Although there was similar effects of Pro and MST-16 on chromosome segregation blocking action and cell cycle G₂/M phase arrest at 1- 4 μM, cytotoxicity of Pro against tumor cells was higher than that of MST-16 in vitro by a factor of 3- 10 folds. Our data show that Pro may be more effective against lung cancer and leukemia while ICRF-187 and MST-16 shows similar IC₅₀ values only against leukemia.

Conclusion

It suggests that Pro has a wider spectrum of cytotoxic effects against human tumor cells than other bisdioxopiperazines, especially against solid tumors, and with a single cytotoxic pathway of Pro and MST-16 affecting chromosome segregation and leading also to cell G₂/ M phase arrests, which finally reduces cell division rates. Pro may be more potent than MST-16 in cytotoxicity. High dose- and time- responses of Pro, when compared with VCR, 5-Fu and Dox, were seen that suggest a selectivity of Pro against tumor growth. Compounds of bisdioxopiperazines family may keep up their cytotoxic effects longer than many other anticancer drugs.     

Fucoxanthin induces apoptosis in human leukemia HL-60 cells through a ROS-mediated Bcl-xL pathway

Fucoxanthin, a natural biologically active substance isolated from Ishige okamurae, evidences antitumor activity in human leukemia cell HL-60 cells via the induction of apoptosis. However, the mechanism underlying fucoxanthin-induced apoptosis in HL-60 cells remains unclear. In this study, we focused on the effect of fucoxanthin induction on the accumulation of reactive oxygen species (ROS), and on the triggering of Bcl-xL signaling pathway in HL-60 cells. We determined that ROS are generated during fucoxanthin-induced cytotoxicity and apoptosis in HL-60 cells, and that N-acetylcysteine (NAC), a ROS scavenger, suppressed fucoxanthin-induced cytotoxicity and apoptosis. Moreover, fucoxanthin-induced the cleavage of caspases -3 and -7, and poly-ADP-ribose polymerase (PARP) and a decrease of Bcl-xL levels, whereas NAC pre-treatment significantly inhibited caspase-3, -7, and PARP cleavage and the reduction in Bcl-xL levels. In this study, it was demonstrated for the first time that fucoxanthin generated ROS and that the accumulation of ROS performed a crucial role in the fucoxanthin-induced Bcl-xL signaling pathway.     

Mangiferin activates Nrf2-antioxidant response element signaling without reducing the sensitivity to etoposide of human myeloid leukemia cells in vitro

Aim： Mangiferin is glucosylxanthone extracted from plants of the Anacardiaceae and Gentianaceae families. The aim of this study was to investigate the effects of mangiferin on Nrf2-antioxidant response element （ARE） signaling and the sensitivity to etoposide of human myeloid leukemia cells in vitro. Methods： Human HL-60 myeloid leukemia cells and mononuclear human umbilical cord blood cells （MNCs） were examined. Nrf2 protein was detected using immunofluorescence staining and Western blotting. Binding of Nrf2 to ARE was examined with electrophoretic mobility shift assay. The level of NQ01 was assessed with real-time RT-PCR and Western blotting. DCFH-DA was used to evaluate intracellular ROS level. Cell proliferation and apoptosis were analyzed using MTT and flow cytometry, respectively. Results： Mangiferin （50 pmol/L） significantly increased Nrf2 protein accumulation in HL-60 cells, particularly in the nucleus. Mangiferin also enhanced the binding of Nrf2 to an ARE, significantly up-regulated NQ01 expression and reduced intracellular ROS in HL60 cells. Mangiferin alone dose-dependently inhibited the proliferation of HL-60 cells. Mangiferin （50 mol/L） did not attenuate etoposide-induced cytotoxicity in HL-60 cells, and combined treatment of mangiferin with low concentration of etoposide （0.8 pg/mL） even increased the cell inhibition rate. Nor did mangiferin change the rate of etoposide-induced apoptosis in HL-60 cells. In MNCs, mangiferin significantly relieved oxidative stress, but attenuated etoposide-induced cytotoxicity. Conclusion： Mangiferin is a novel Nrf2 activator that reduces oxidative stress and protects normal cells without reducing the sensitivity to etoposide of HL-60 leukemia Cells in vitro. Mangiferin may be a potential chemotherapy adjuvant.     

Antitumor activities of hypericin as a protein tyrosine kinase blocker

Naphtodianthrone hypericin produced a potent antitumor activityin vitro against several tumor cells. However, it did not show any cytotoxicity on normal cells such asMacaccus rheus monkey kidney cells (MA-104) and primary cultured rat hepatocytes up to 500 μM concentration. Hypericin added to A431 human epidermoid carcinoma cell membrane inhibited the autophosphorylation of the epidermal growth factor (EGF) receptor and the tyrosine phosphorylation of RR-SRC peptide catalyzed by an EGF-receptor. Similarly, treatment of the A431 cells with hypericin inhibited the tyrosine phosphorylation of EGF-dependent endogenous EGF-receptor by western blotting analysis. Hypericin also inhibited the T cell PTK, P56 ^lck , in a dose-dependent fashion with an IC₅₀=5 μM. The tyrosine phosphorylation on RR-SRC peptide and EGF-induced receptor autophosphorylation, eitherin vitro or in intact cells was inhibited by hypericin at the same concentration as that in A431 cell proliferation. These data suggest that hypericin directly inhibits EGF-receptor and P56 ^lck PTK activityin vitro and can mediate such actionin vivo.     

DNA interstrand cross-linking and <Emphasis Type="Italic">in vivo</Emphasis> antitumor activity of the extended pyrrolo[2,1-<Emphasis Type="Italic">c</Emphasis>][1,4]benzodiazepine dimer SG2057

The pyrrolobenzodiazepines (PBDs) are naturally occurring antitumor antibiotics and a PBD dimer (SJG-136, SG2000) is in Phase II trials. SG2000 is a propyldioxy linked PBD dimer which binds sequence selectively in the minor groove of DNA forming DNA interstrand and intrastrand cross-linked adducts, and also mono-adducts depending on sequence. SG2057 is the corresponding dimer containing a pentyldioxy linkage. SG2057 has multilog differential in vitro cytotoxicity against a panel of human tumour cell lines with a mean GI₅₀ of 212 pM. The agent is highly efficient at producing DNA interstrand cross-links in cells which form rapidly and persist over a 48 h period. Significant antitumor activity was demonstrated in several human tumor xenograft models. Cures were obtained in a LOX-IMVI melanoma model following a single administration and dose-dependent activity, including regression responses, observed in SKOV-3 ovarian and HL-60 promyelocytic leukemia models following repeat dose schedules. In the advanced stage LS174T model, SG2057 administered either as a single dose, or in two repeat dose schedules, was superior to irinotecan. SG2057 is therefore a highly active antitumor agent, with more potent in vitro activity and superior in vivo activity to SG2000, warranting further development.     

Novel ceramides from aerial parts of <Emphasis Type="Italic">Saussurea involucrata</Emphasis> Kar. et. Kir.

Novel ceramides, together with nine known compounds were isolated from aerial parts of the Saussurea involucrata Kar. et. Kir. The novel structures were determined by spectroscopic methods and microscale chemical degradation. The ceramides showed appreciable cytotoxicity against three human tumor cell lines including human promyelocytic leukemia (HL-60), human melanoma (A375-S2) and human cervical carcinoma (HeLa) cell lines. The results suggested that this class of ceramides may have potential as an antitumor agent.     

Recognition of pharmacophore of ar-turmerone for its anticancer activity

For the analysis of structure activity relationship of ar-turmerone analogues, the compounds containing the various substituents on the phenyl ring and 1(or 2)-naphthyl group in the place of phenyl of ar-turmerone were prepared and tested their cytotoxicity against HL-60, K-562, and L1210 leukemia cellsin vitro. The substituents at para position are methoxy, phenoxy, methyl, trifluoromethyl, fluoro, and chloro. Atmeta position methoxy, methyl, trifluoromethyl, or chloro groups and atortho position methoxy or chloro group were introduced. Against HL-60 and K-562 cells, ED₅₀ values of the analogues are ranged from 0.8 to 30.0 μg/ml. Against L1210 cell, these are located more than 20.0 μg/ml. However, 5-carboethoxy-2-methyl-6-(1-naphthyl)-2-octen-4-one (5n) possesses ED50 valuses 0.8, 2.1, 6.5 μg/ml against HL-60, K-562, L1210 cells, respectively. The electronic nature of the subsituents on phenyl ring of ar-turmerone dose not affect the biological activity. Therefore the flat structure of aromatic portion of ar-turmerone analogues is the more important factor for their activity rather than its electronic nature. The potentiation of the cytotoxicity with the enlargement of aromatic ring region also supports the importance of the plane structure of this area. The restriction of the single bond rotation between C-6 and aromatic ring through the introduction of substituents at theortho position of phenyl ring and the increment of size of alkyl group at C-6 position enhances the activity. Therefore the effective conformation should be the one having the orthogonal arrangement between the aromatic ring and the side chain.     

Beziehung zwischen dem UV-Absorptionsmuster einiger Flavone und ihrer gegen L1210-Zellen cytotoxischen Aktivität

The UV-pattern of several flavones, their cytotoxicities against L1210 cell and their Inhibiting effects on ATPase from the cell seem to be correlated. 5,2′-Dihydroxy-6,7,8,6′-tetramethoxyflavone (ED₅₀=2.3 ug/ml) and 5,2′,6′-trihydroxy-6,7,8-trimethoxyflavone (ED₅₀=4.5 ug/ml), the most active flavones studied, have shown a narrow range of the absorbance ratio, Log εII/Log εI=1.073～1.109. They have inhibited the ATPase-activity to the greatest extent. These findings suggest that a certain angle between the flavone rings B and C plays an important role for the inhibition of the enzyme activity and thus the cytotoxicity.     

Bioactivity Investigation of Lauraceae Trees Grown in Taiwan

Abstract

This research collected 27 Lauraceae tree species in Taiwan, and the extracts prepared from leaves and branches were selected to evaluate and characterize their putative bioactivities and potential medicinal applications. Several bioactivity assays, including antifungal tests, antioxidant evaluation, anti-inflammation activity, and cytotoxicity were preformed in this study.The results showed no significant antifungal activity by Lauraceae extracts. Neolitsea parvigemma. (Hay.) Kanehira et Sasaki expresses the best antioxidant activity (IC₅₀ = 5.73 µg/mL) in the DPPH assay.The extracts of Litsea akoensis. Hay. and Cryptocarya concinna. Hance had significant anti-inflammation activity, and they can inhibit the nitric oxide (NO) production in the LPS-induced microphage assay at the dose of 25 µg/mL. According to the cytotoxicity assay, Lindera aggregate. (Sims) Kosterm and Cryptocarya concinna. Hance extracts showed in vitro. cytotoxicity against human umbilical vein endothelial cell line (HUVEC) with IC₅₀ values of 43.15 µg/mL and 49.36 µg/mL, respectively, and Phoebe formosana. (Matsum. et Hay.) Hay. extract exhibited marked cytotoxicity (IC₅₀ = 42.87 µg/mL) against a human leukemia cell line (HL-60). Results from this preliminary investigation suggest that these Lauraceae tree species may have a great potential for further development as cancer chemoprevention agents or food supplements for promoting human health.     

Synthesis and cytotoxicity of triterpenoids derived from betulin and betulinic acid via click chemistry

In this study, a series of triazole substituted betulin and betulinic acid derivatives was designed and synthesized via click chemistry at C-30 position. Eighteen target compounds were evaluated in vitro for their antitumor activities against leukemia cell-line HL-60. Seventeen compounds have not reported before. The cytotoxic experiment showed that most of betulinic acid derived triazoles have higher cytotoxic profile than betulinic acid. Among them, compound 30-[4-(4-fluorophenyl)-1H-1,2,3-triazol-1-yl] betulinic acid (7b) showed the best IC₅₀ value (1.3 μM) against leukemia cell-line HL-60 (eight- to ninefold higher potency than betulinic acid).