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.

Glabridin plays dual action to intensify anti-metastatic potential of paclitaxel via impeding CYP2C8 in liver and CYP2J2/EETs in tumor of an orthotopic mouse model of breast cancer.

In spite of unprecedented advances in modern cancer therapy, there is still a dearth of targeted therapy to circumvent triple-negative breast cancer (TNBC). Paclitaxel is the front-line therapy against TNBC, but the main constraints of its treatment are dose-related adverse effects and emerging chemoresistance. In this context, glabridin (phytoconstituent from Glycyrrhiza glabra) is reported to hit multiple signalling pathways at the in-vitro level, but hardly any information is known at the in-vivo level. We aimed here to elucidate glabridin potential with an underlying mechanism in combination with a low dose of paclitaxel using a highly aggressive mouse mammary carcinoma model. Glabridin potentiated the anti-metastatic efficacy of paclitaxel by substantially curtailing tumor burden and diminishing lung nodule formation. Moreover, glabridin remarkably attenuated epithelial-mesenchymal transition (EMT) traits of hostile cancer cells via up-regulating (E-cadherin & occludin) and down-regulating (Vimentin & Zeb1) vital EMT markers. Besides, glabridin amplified apoptotic induction effect of paclitaxel in tumor tissue by declining or elevating pro-apoptotic (Procaspase-9 or Cleaved Caspase-9 & Bax) and reducing anti-apoptotic (Bcl-2) markers. Additionally, concomitant treatment of glabridin and paclitaxel predominantly lessened CYP2J2 expression with marked lowering of epoxyeicosatrienoic acid (EET)'s levels in tumor tissue to reinforce the anti-tumor impact. Simultaneous administration of glabridin with paclitaxel notably enhanced plasma exposure and delayed clearance of paclitaxel, which was mainly arbitrated by CYP2C8-mediated slowdown of paclitaxel metabolism in the liver. The fact of intense CYP2C8 inhibitory action of glabridin was also ascertained using human liver microsomes. Concisely, glabridin plays a dual role in boosting anti-metastatic activity by augmenting paclitaxel exposure via CYP2C8 inhibition-mediated delaying paclitaxel metabolism and limiting tumorigenesis via CYP2J2 inhibition-mediated restricting EETs level. Considering the safety, reported protective efficacy, and the current study results of boosted anti-metastatic effects, further investigations are warranted as a promising neoadjuvant therapy for crux paclitaxel chemoresistance and cancer recurrence.

Photoprotective effect of 18ß-glycyrrhetinic acid derivatives against ultra violet (UV)-B-Induced skin aging.

Excessive exposure to sun can harm the skin, causing sunburn, photo-aging, and even skin cancer. Different benzylidene derivatives (A02-A18 and A19-A34) of 18ß-Glycyrrhetinic acid (A01) were designed and synthesized in an effort to discover photo-protective compounds against UV-B -induced skin aging. The synthesized derivatives were subjected to cellular viability test using MTT assay in primary Human Dermal Fibroblasts (HDFs). The results indicate A01, A05, A15, A22, A23, A25, A26, A28, A29, A32, A33, and A34 significantly enhanced cell viability of HDFs. Compound A33 at 10 and 25 µM showed a significant photo-protective effect against UV-B (10 mJ/cm2) -induced damage in HDFs. A33 at 25 µM significantly restored the UV-B -induced damage via its potent anti-oxidant, anti-apoptotic effects and ability to prevent collagen degradation. These findings pave the way for further development of A33 as a photo-protective skin agent.

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.