C-30 analogues of betulinic acid as potent cytotoxic agents: design, synthesis, biological evaluation and in-silico studies.

In an endeavour to improve the anti-cancer activity of betulinic acid (BA), a series of C-30 derivatives were envisaged and synthesized with a novel synthetic approach. All the derivatives were evaluated for cytotoxic activity by MTT assay against six different human cancer cell lines: prostate (PC3), lung (A549), human hepatocellular carcinoma (HepG2), human leukemia (Molt-4), pancreatic (Panc-1) and breast (MCF-7). The data revealed that compound 16 was observed most promising cytotoxic agent with IC50 values of 7.43 µM, 9.1 µM, and 9.64 µM against A549, MCF-7, and PC3 cancer cell lines respectively. A further mechanistic study confirmed compound 16 showed significant cell death by arresting the cell cycle in the G1 phase and inducing apoptosis in A549 cells.Communicated by Ramaswamy H. Sarma.

Recent Advances in the Chemistry and Biology of Bakuchiol and its Derivatives: An Updated Review.

Bakuchiol is a meroterpene natural product distributed in various plants. It possesses several biological activities particularly anticancer. A large number of analogs have been prepared by various researchers by targeting several positions such as phenolic -OH, ethenyl and isopropylidene groups present in the bakuchiol to develop potent therapeutic agents with improved pharmaceutical properties. The present review describes the isolation, organic synthetic schemes, chromatographic study, and biological activities of bakuchiol reported till date. Further, the review also provides an insight into the skin care effects of bakuchiol and structure-activity relationship studies of reported derivatives. Moreover, the biosynthetic pathway of bakuchiol has also been described. All the articles published on bakuchiol revealed that bakuchiol and its analogs possess a remarkable potential for the development of potent anticancer and several other therapeutic agents. The reported synthetic schemes can be utilized for the industrial production of bakuchiol. Finally, we believe that this review will provide important information to the researchers interested in the chemistry and biology of Bakuchiol.

Synthesis, Biological Activity and Molecular Docking Studies of Heterocyclic Chalcones.

Nineteen heterocyclic chalcones were synthesized from 4-acetyl-5-methylquinolylpyrazole and heteroaryl (imidazole, pyrazole, thiophene, indole and triazole) aldehydes and were screened in vitro using four tumor cell lines for their cytotoxic capability and for antimicrobial activity. The chalcone 5b exhibited the highest activity with IC50 values 2.14 µM against colon (HCT-116) and 5.0 µM, against prostate (PC-3) cancer cell lines and also displayed good activity against fungal strain (A. niger) with MIC value 9.1 µM. The chalcones 5q and 5p displayed good activity against bacterial strains (S. aureus) having MIC value 2.6 µM and fungal strain (C. albicans) having MIC value 5.4 µM, respectively. The molecular docking outcome revealed that the synthesized heterocyclic chalcones demonstrated hydrogen bond, hydrophobic and electrostatic interactions with their respective biochemical targets.

Effect of IS01957, a para-coumaric acid derivative on pharmacokinetic modulation of diclofenac through oral route for augmented efficacy.

Diclofenac is one of the world's largest selling nonsteroidal anti-inflammatory drugs. The major concerns related to oral diclofenac therapy are gastrointestinal and cardiovascular side effects for which explicitly emphasis has been given to use it at lowest effective dose for the shortest duration. On the other hand, IS01957 has been designed under the purview of anti-inflammatory drug and bioavailability enhancer. IS01957 have dual action on inflammation and nociception with acceptable safety profile. In the quest for a suitable combination with improved therapeutic efficacy and better tolerability, pharmacodynamic and pharmacokinetic interaction studies were performed for diclofenac with or without IS01957 in mice model. Results showed that IS01957 enhanced both anti-inflammatory effect and plasma concentration of diclofenac upon concomitant oral administration. These interesting results steered to enumerate the possible role of IS01957 towards diclofenac pharmacokinetics through a panel of mechanistic investigations: (a) BCRP dependent ATPase activity was markedly interfered by IS01957; (b) IS01957 increased the intestinal permeability of diclofenac in the single pass in-situ perfusion model; (c) IS01957 inhibited the CYP2C9 catalyzed diclofenac 4-hydroxylation in human liver microsomes. Immunoblotting results suggest that diclofenac action was improved significantly in the presence of IS01957 involving MAPK pathways. Finally acute gastric damage study showed that IS01957 in combination with diclofenac was better to improve the desired PGE2 level as compare to alone. In nutshell, IS01957 have potential to augment the efficacy of diclofenac through pharmacokinetic modulation. Further investigations are required for dose reduction of diclofenac to combat its liabilities before going into clinical setting.

Synthesis and biological evaluation of novel bavachinin analogs as anticancer agents.

A library of 28 analogs of bavachinin including aliphatic and aromatic ethers, epoxide, chalcone, oxime, semicarbazide, oxime ether and triazole derivatives have been synthesized and evaluated for cytotoxicity against four different human cancer cell lines. Bio-evaluation studies exhibited better cytotoxic profile for many analogs compare to bavachinin. Best results were observed for a 1,2,3-triazole analog (17i) with IC50 values 7.72, 16.08, 7.13 and 11.67 µM against lung (A549), prostate (PC-3), colon (HCT-116) and breast (MCF-7) cancer cell lines respectively. This analog showed three and four fold improvement in cytotoxicity against HCT-116 and A549 cell lines than parent molecule (1). Structure activity relationship (SAR) study for all synthesized analogs was carried out. Further, mechanistic study of the lead molecule (17i) revealed that it inhibits colony formation and in vitro migration of human colon cancer cells (HCT-116). Also, it induced the morphological changes and mediated the apoptotic cell death of HCT-116 cells with perturbance in mitochondrial membrane potential (MMP) and PARP cleavage.

Synthesis of novel benzylidene analogues of betulinic acid as potent cytotoxic agents.

Different benzylidene derivatives (15a-o and 16a-o) of betulinic acid were designed and synthesized in an effort to develop potent anticancer agents. All the synthesized derivatives along with betulinic acid were evaluated for cytotoxicity against a panel of five different human cancer cell lines A-549 (Lung), PC-3 (Prostate), HCT 116 (Colon), MCF-7 (Breast) and MIA PaCa-2 (Pancreatic) using SRB assay. Pharmacological results showed that compounds 15b, 15c, 15i, 15k, 16a-c and 16l were found to have promising cytotoxic profile against various cancer cell lines tested (IC50 1-2 µM). Best results were observed for compound 16c with IC50 values 1.5, 1.6, 1.36, 3.5 and 3.2 µM against A-549, PC-3, HCT 116, MCF-7 and MIA PaCa-2 cell lines, respectively. Mechanistic study of compound 16c revealed that it inhibits the colony formation and restrict the migration in HCT 116 cells in vitro. It also induces growth arrest with characterized morphological changes and loss of mitochondrial membrane potential (MMP) in a concentration dependent manner.

A convergent synthesis of novel alkyne-azide cycloaddition congeners of betulinic acid as potent cytotoxic agent.

In an endeavour to develop potent anti-tumor agents from betulinic acid (BA), a series of C-28 derived 1,2,3-triazolyl derivatives were designed and synthesized by employing Cu(I) catalyzed Huisgen 1,3-dipolar cycloaddition reaction. All the derivatives were evaluated for cytotoxic activity by MTT assay against five different human cancer cell lines: lung (A549), colon (HCT116), prostate (PC3), pancreatic (MIA PaCa-2) and breast (T47D). The data revealed that compounds 11c, 11d, 11g, 11h and 13a possess most promising cytotoxic potential. The compound 11h was one of the most active compounds, with IC50 values in the range of 4-6µM against all the five cancer cell lines. The results of this study suggested that derivatives with free -OH (11c, 11d and 11g) and free -COOH (11h and 13a) substitutions in the triazole moiety introduced at the C-28 position significantly improved the anti-tumor activity and may be the favourable position to synthesize potent anticancer leads from BA. Introduction of a non polar alkyl groups at C-28 position (10, 12 and 14) resulted in the significant loss of the activity. Further, DAPI staining, ROS generation and wound healing experiments revealed that compound 11h induces apoptosis in HCT-116 cells.

Synthesis of α-santonin derivatives for diminutive effect on T and B-cell proliferation and their structure activity relationships.

A new library of 20 compounds from α-santonin was synthesized and tested against Con-A induced T-cell proliferation and LPS-induced B-cell proliferation via MTT assay. The study resulted in the identification of potent immunosuppressant molecules, which were further screened along with α-santonin for Tumor Necrosis Factor Alpha (TNF-α) inhibitory activity. One of the molecules (7) at 10 µM showed equipotency to that of dexamethasone (1 µM conc.) used as a standard. Structure activity relationships of the synthesized compounds along with our earlier reported α-santonin derivatives have been studied. Inferences from the modifications carried out at all the three sites of α-santonin have been elaborated. Computational study of the active compounds shows TNF-α protein as its preferable target rather than Inosine Monophosphate Dehydrogenase (IMPDH).

Biologically active xanthones from Codonopsis ovata.

Five new xanthones, named coxanthones A-E (1-5), together with 21 known secondary metabolites (6-26) that include seven xanthones, five flavonoids, two steroids and seven triterpenoids were isolated from the chemically unexplored whole plant Codonopsis ovata. The structures of new metabolites were elucidated by HRMS, interpretation of NMR spectra and other spectroscopic techniques. The absolute configuration of the stereogenic centre of coxanthone B (2) was determined by electronic circular dichroism (ECD) spectroscopy. This is the first report of xanthones from the genus Codonopsis. All isolated metabolites were evaluated for cytotoxic activity by SRB assay against six human cancer cell lines A549 (lung), PC-3 (prostate), HCT-116 (colon), MCF-7 (breast), SF-295 (CNS), and MDAMB-435 (melanoma). Among the new compounds, coxanthone B (2) exhibited significant inhibitory activity against SF-295 and MDAMB-435 with IC50 values of 7.0 and 15.0 µM, respectively. Coxanthone A (1) displayed cytotoxicity against A549 cell line at IC50 value of 22.5 µM. Cytotoxic activity of 1-hydroxy-3,5-dimethoxyxanthone (7), swertiperenine (9) and 1,7,8-trihydroxy-3-methoxyxanthone (10) are reported here first time that exhibited the IC50 values of 3.0, 5.0 and 21.0 µM against A549, MDAMB-435, and A549 cell lines, respectively. Kaempferol (13) showed most potent cytotoxic activity with an IC50 values in the 1.0-2.3 µM range against all tested cancer cell lines.

PI3K target based novel cyano derivative of betulinic acid induces its signalling inhibition by down-regulation of pGSK3ß and cyclin D1 and potentially checks cancer cell proliferation.

In spite of the Betulinic acid (BA) being recognized as anticancerous source; its further use in clinical development is greatly hampered because of its poor pharmacokinetic properties. To circumvent these limitations, we synthesized a PI3K target based library of 18 triazole based derivatives and we identified a C-3 cyano analog of betulinic acid (CBA) with significant cell death effects with 5-7 fold higher potency than BA in various cancers. Importantly, no such report is available demonstrating the involvement of BA or its structural analogs in the modulation of PI3K pathway. Using, human leukemia HL-60 cells as a model, we for the first time report that CBA decreased expression of PI3K p110α, p85α, and pAKT in HL-60. Furthermore, we could find significant depletion of pGSK3ß, cyclin D1 and increased expression of p21/cip, p27/Kip proteins. CBA induced G0/G1 cell cycle arrest, increased sub-G0 DNA fraction and annexin V binding of the cells besides imparting the typical surface features of cell death. Also, this target specific inhibition was associated with mitochondrial apoptosis as was reflected by expression studies of various proteins together with reactive oxygen species generation and decline in mitochondrial trans membrane potential. The apoptotic effectors i.e., caspase 8 and caspase 9 were found to get upregulated besides PI3K associated DNA repair enzyme i.e., PARP cleavage was observed. Thus, our results elucidated that CBA or other BA based small molecules inhibit PI3K/AKT pathway with induction of subsequent cancer cell death which may be useful therapeutic strategy against leukemias and possibly other cancers.

A novel triazole derivative of betulinic acid induces extrinsic and intrinsic apoptosis in human leukemia HL-60 cells.

In an attempt to arrive at more potent cytotoxic agent than the bioactive natural product betulinic acid, influence of small structural modifications of its 1, 2, 3 triazole derivatives tethered at C-28 and both C3, C-28 using click chemistry approach has been studied. The chemically characterized triazoles have been screened for in vitro cytotoxicity against four human cancer cell lines HL-60, MiaPaCa-2, PC-3 and A549 which has allowed to identify triazole derivative 28{1N (4-fluoro phenyl)-1H-1, 2, 3-triazol-4-yl} methyloxy betulinic ester having better potency profile than the parent compound with IC50 values in the range of 5-7 µM. It caused disruption of mitochondrial membrane potential, rendered Bcl-2 cleavage, Bax translocation and decrease Bcl-2/Bax ratio. These events are accompanied by activation of caspases -9, -3, which cleave the PARP-1. It also induces caspase-8, which is involved in extrinsic apoptotic pathway. Therefore, it induces apoptosis through both intrinsic and extrinsic pathways in human leukemia HL-60 cells.

Isolation, cytotoxic evaluation, and simultaneous quantification of eight bioactive secondary metabolites from Cicer microphyllum by high-performance thin-layer chromatography.

Chemical investigation of Cicer microphyllum resulted in the isolation and characterization of eight natural products viz. Stigmasterol, Oleanolic acid-3-acetate, Oleanolic acid, Biochanin A, Genistein, Pratensein, Chrysoeriol, and Luteolin. Herein, we report a novel, accurate, and cost-effective high-performance thin-layer chromatography method for the simultaneous quantification of the isolated natural products on silica-gel 60F254 plates using the solvent system n-hexane/ethyl acetate/formic acid (9.0:6.5:0.8, v/v/v). Natural products were quantified after postchromatographic derivatization with ceric ammonium sulfate. The method was validated as per the International Conference on Harmonization guidelines. All calibration curves showed a good linear relationship (r > 0.9943) within the test range. Precision was assessed by intra- and interday tests with relative standard deviations <1.82%, accuracy validation recovery 98.38-99.57% with relative standard deviations <1.00%. On quantification, Pratensein was a major constituent (0.921%). The screening for cytotoxic activity using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay resulted into identification of Luteolin as potent molecule with IC50 3.5 and 25.6 µg/mL against murine melanoma and human epidermoid carcinoma cell lines, respectively.

Simultaneous quantification of eight bioactive secondary metabolites from Codonopsis ovata by validated high performance thin layer chromatography and their antioxidant profile.

Chemical investigation of Codonopsis ovata resulted in the isolation and identification of ß-sitosterol-3-O-glycoside, luteolin, apigenin, gentiacaulein, swertiaperenine, ß-sitosterol, taraxeryl-3-acetate, and 3ß-acetoxyoleanane-12-one. A rapid, precise, sensitive and validated HPTLC method for simultaneous quantification of these natural products (NPs) was developed on silica-gel 60F254 plate using ternary solvent system, n-hexane:ethyl acetate:formic acid (10.5:3.5:0.43, v/v/v). Markers were quantified after post chromatographic derivatization with cerric ammonium sulfate reagent. The method was validated for accuracy, precision, LOD, LOQ and all calibration curves showed a good linear relationship (r>0.9924) within test range. Precision was evaluated by intra- and inter-day tests with RSDs <2.59%, accuracy validation recovery 92.43-99.50% with RSDs <1.00%. Apigenin was found major component (natural abundance: 1.103%) and ß-sitosterol the least (0.0263%). The NPs displayed antioxidant activity with luteolin exhibiting maximum effect at 1µg/mL concentration (75.9% for DPPH and 43.7% for ABTS) and others at 10 and 25µg/mL, suggesting thereby their apparent potential use for the prevention of free radical induced diseases or as an additive element to food and pharmaceutical industry.

A validated high-performance thin-layer chromatography method for the identification and simultaneous quantification of six markers from Platanus orientalis and their cytotoxic profiles against skin cancer cell lines.

Betulinic acid (1), betulinic acid-3-acetate (2), 3-acetylbetulinaldehyde (3), oleanolic acid-3-acetate (4), 3-ß-hydroxy-28,19-ß-olenolide (5), and ß-sitosterol (6) were isolated from Platanus orientalis and a high-performance thin-layer chromatography method was developed for their simultaneous quantification. The markers were first derivatized on the chromatogram with ceric ammonium sulfate and then high-performance thin-layer chromatography densitometry was carried out. Chromatographic separation of these markers was carried out on silica gel 60 plates using a ternary solvent system n-hexane/toluene/acetone (6:3.5:1 v/v/v) as a mobile phase. For marker 1, a deuterium (D2) lamp and wavelength of 420 nm was used. A tungsten (W) lamp was used for markers 2 and 3 at 550 nm and for 4-6 at 500 nm. The method was validated for accuracy, precision, LOD, and LOQ. All calibration curves showed a good linear relationship (r > 0.9919). The precision evaluated by an intra- and interday study showed RSDs < 2.51% and accuracy validation recovery between 95.54 and 99.33% with RSDs < 1.55%. The successful application of the validated method showed 1 as the most abundant component (4.63%) and 5 (0.017%) the least. The markers displayed a significant cytotoxic effect against human keratinocyte, mouse melanoma, and human skin epithelial carcinoma cancer cells by using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay.

Synthesis of 3-O-propargylated betulinic acid and its 1,2,3-triazoles as potential apoptotic agents.

Cytotoxic agents from nature are presently the mainstay of anticancer chemotherapy, and the need to reinforce the arsenal of anticancer agents is highly desired. Chemical transformation studies carried out on betulinic acid, through concise 1,2,3-triazole synthesis via click chemistry approach at C-3position in ring A have been evaluated for their cytotoxic potentiation against nine human cancer cell lines. Most of the derivatives have shown higher cytotoxic profiles than the parent molecule. Two compounds i.e. 3{1N(2-cyanophenyl)-1H-1,2,3-triazol-4yl}methyloxy betulinic acid (7) and 3{1N(5-hydroxy-naphth-1yl)-1H-1,2,3-triazol-4yl}methyloxy betulinic acid (13) displayed impressive IC50 values (2.5 and 3.5 µM respectively) against leukemia cell line HL-60 (5-7-fold higher potency than betulinic acid). As evident from various biological end points, inhibition of cell migration and colony formation, mitochondrial membrane disruption followed by DNA fragmentation and apoptosis, is demonstrated.

Bakuchiol derivatives as novel and potent cytotoxic agents: a report.

A library of 28 compounds comprising of acyl, amino, halo, nitro, styryl and cyclized derivatives of bakuchiol have been evaluated against a panel of eight human cancer cell lines. Bioevaluation studies have resulted in the identification of potent cytotoxic molecules exhibiting concentration dependent growth inhibition against leukemia cancer cells with best results observed for compounds 17 and 22 exhibiting IC(50) 1.8 and 2.0 µM respectively. As evident from various biological end-points, inhibition of cell proliferation by inducing G2/M cell cycle arrest, mitochondrial membrane disruption followed by DNA fragmentation and apoptosis is demonstrated.

Ten marker compounds-based comparative study of green tea and guava leaf by HPTLC densitometry methods: antioxidant activity profiling.

High-performance thin layer chromatography (HPTLC) method for the separation and quantitative determination of ten markers (catechins, flavonoids, and phenolics) in different extracts of green tea and guava leaf has been developed and the antioxidant activity profiles of the two plant extracts have been determined. Ten marker compounds have been resolved using silica gel 60 F(254) plates, toluene/acetone/formic acid (5:4:1 v/v/v) for markers 1-6, and toluene/ethyl acetate/formic acid/methanol (3:3:0.8:0.2 v/v/v/v) for markers 7-10 as the mobile phases. The high-performance thin layer chromatography densitometry was performed at wavelengths of 282 and 285 nm for the markers 1-6 and 7-10, respectively. Potent antioxidant activity and the presence of phenolics and flavan-3-ols has been observed for the guava leaf extracts suggestive of its use as an alternate economical source of antioxidants over green tea--the well-established food additive/nutraceutical agent.