Nisar A. Dangroo

Isolation, Cytotoxicity Evaluation and HPLC-Quantification of the Chemical Constituents from Prangos pabularia

Phytochemical analysis of the dichloromethane:methanol (1∶1) extract of root parts of Prangos pabularia led to the isolation of twelve cytotoxic constituents, viz., 6-hydroxycoumarin (1), 7-hydroxycoumarin (2), heraclenol-glycoside (3), xanthotoxol (4), heraclenol (5), oxypeucedanin hydrate (6), 8-((3,3-dimethyloxiran-2-yl)methyl)-7-methoxy-2H-chromen-2-one (7), oxypeucedanin hydrate monoacetate (8), xanthotoxin (9), 4-((2-hydroxy-3-methylbut-3-en-1-yl)oxy)-7H-furo[3,2-g]chromen-7-one (10), imperatorin (11) and osthol (12). The isolates were identified using spectral techniques in the light of literature. 3-(4,5-dimethyl thiazol-2yl)-2,5-diphenyltetrazolium bromide (MTT) cytotoxicity screening of the isolated constituents was carried out against six human cancer cell lines including lung (A549 and NCI-H322), epidermoid carcinoma (A431), melanoma (A375), prostate (PC-3) and Colon (HCT-116) cell lines. Osthol (12) exhibited the highest cytotoxicity with IC50 values of 3.2, 6.2, 10.9, 14.5, 24.8, and 30.2 µM against epidermoid carcinoma (A431), melanoma (A375), lung (NCI-H322), lung (A549), prostate (PC-3) and colon (HCT-116) cell lines respectively. Epidermoid carcinoma cell line A431 was sensitive to most of the compounds followed by lung (A549) cancer cell line. Finally a simple and reliable HPLC method was developed (RP-HPLC-DAD) and validated for the simultaneous quantification of these cytotoxic constituents in Prangos pabularia. The extract was analyzed using a reversed-phase Agilent ZORBAX eclipse plus column C18 (4.6×250 mm, 5 µm) at 250 nm wavelength using a gradient water-methanol solvent system at a flow rate of 0.8 ml/min. The RP-HPLC method is validated in terms of recovery, linearity, accuracy and precision (intra and inter-day validation). This method, because of shorter analysis time, makes it valuable for the commercial quality control of Prangos pabularia extracts and its future pharmaceutical preparations.

Synthesis and anti-proliferative evaluation of novel 3,4-dihydro-2H-1,3-oxazine derivatives of bakuchiol

A new series of 3,4-dihydro-2H-1,3-oxazine derivatives of bakuchiol 1 was synthesized through the Mannich-type condensation–cyclization reaction of 1 with formaldehyde and appropriate primary amines. On cytotoxicity evaluation against a panel of four human cancer cell lines, most of the derivatives showed a higher cytotoxic profile than the parent molecule. The best results were observed for compound 15 with IC50 values of 2, 2, 2.4 and 3 μM against MIA-Pa-Ca-2, HCT-116, MCF-7 and HL-60 cells, respectively. A mechanistic study of compound 15 revealed that it caused a loss in the mitochondrial membrane potential in a concentration-dependent manner, accompanied by the activation of caspase-9 and -3, which cleave PARP-1. It also activated caspase-8, which is involved in the extrinsic apoptotic pathway. Therefore, we demonstrated that it induces apoptosis via both intrinsic and extrinsic pathways in human pancreatic cancer MIA-Pa-Ca-2 cells.

Streptomyces puniceus strain AS13., Production, characterization and evaluation of bioactive metabolites: A new face of dinactin as an antitumor antibiotic

A highly active actinobacterial strain isolated from untapped areas of Northwestern Himalayas and characterised as Streptomyces puniceus strain AS13 by 16S rRNA gene sequencing was selected for production of bioactive metabolites. The bioassay-guided fractionation of microbial cultured ethyl acetate extract of the strain, led to isolation of macrotetrolide compound 1 (Dinactin) and compound 2 (1-(2,4-dihydroxy-6-methylphenyl)-ethanone). Structures of the isolated compounds were elucidated by [corrected] interpretation of NMR and other spectroscopic data including HR-ESI-MS, FT-IR. These compounds are reported for first time from Streptomyces Puniceus. Compound 1 exhibited strong anti-microbial activity against all tested bacterial pathogens including Mycobacterium tuberculosis. The MIC values of compound 1 against Gram negative and Gram positive bacterial pathogens ranged between 0.019 - 0.156μgml-1 and 1μgml-1 against Mycobacterium tuberculosis H37Rv. Dinactin exhibited marked anti-tumor potential with IC50 of 1.1- 9.7μM in various human cancerous cell lines and showed least cytotoxicity (IC50∼80μM) in normal cells (HEK-293). Dinactin inhabited cellular proliferation in cancer cells, reduced their clonogenic survival as validated by clonogenic assay and also inhabited cell migration and invasion characteristics in colon cancer (HCT-116) cells. Our results expressed the antimicrobial potential of dinactin and also spotted its prospective as an antitumor antibiotic.

A convergent synthesis of novel alkyne–azide cycloaddition congeners of betulinic acid as potent cytotoxic agent ☆

&NA; 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 4–6 &mgr;M 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. Graphical abstract Design and synthesis of C‐28 derived 1,2,3‐triazolyl betulonic acid as apoptotic agents. Figure. No caption available. HighlightsSynthesis of 22 betulinic acid/betulonic acid derivatives.Several derivatives were active against human cancer cell lines.The molecule 11h is apoptotic inducer on HCT‐116 cells.