Synthesis and structure-activity relationships of andrographolide analogues as novel cytotoxic agents.

Andrographolide 1, the cytotoxic agent of the plant Andrographis paniculata was subjected to semi-synthetic studies leading to the preparation of a number of potent and novel analogues. Of the analogues synthesized, while 8,17-epoxy andrographolide 6 retained the cytotoxic activity of 1, ester derivatives of 6 exhibited considerable improvement in activity. Lower activity was observed when the epoxy moiety in the triacetate 9, derived from 6 was modified. Synthesis and structure-activity relationships are discussed.

Anticancer and immunostimulatory compounds from Andrographis paniculata.

Andrographis paniculata extract is traditionally used as a medicine to treat different diseases in India, China and Southeast Asia. In the present study, we evaluated the anticancer and immunomodulatory activity of the methanolic extract of Andrographis paniculata in human cancer and immune cells. The methanolic extract of Andrographis paniculata was fractionated into dichloromethane, petroleum ether and aqueous extracts and screened for bioactivity. Our results indicate that the dichloromethane fraction of the methanolic extract retains the active compounds contributing for both the anticancer and immunostimulatory activity. Dichloromethane fraction significantly inhibits the proliferation of HT-29 (colon cancer) cells and augments the proliferation human peripheral blood lymphocytes (HPBLs) at low concentrations. On further fractionation of the dichloromethane extract we could isolate three diterpene compounds, i.e. [1] andrographolide, [2] 14-deoxyandrographolide and [3] 14-deoxy-11,12-didehydroandrographolide. Andrographolide showed anticancer activity on diverse cancer cells representing different types of human cancers. Whereas all the three molecules showed enhanced proliferation and interleukin-2 (IL-2) induction in HPBLs.

Andrographolide, a potential cancer therapeutic agent isolated from Andrographis paniculata.

Andrographis paniculata plant extract is known to possess a variety of pharmacological activities. Andrographolide, the major constituent of the extract is implicated towards its pharmacological activity. We studied the cellular processes and targets modulated by andrographolide treatment in human cancer and immune cells. Andrographolide treatment inhibited the in vitro proliferation of different tumor cell lines, representing various types of cancers. The compound exerts direct anticancer activity on cancer cells by cell-cycle arrest at G0/G1 phase through induction of cell-cycle inhibitory protein p27 and decreased expression of cyclin-dependent kinase 4 (CDK4). Immunostimulatory activity of andrographolide is evidenced by increased proliferation of lymphocytes and production of interleukin-2. Andrographolide also enhanced the tumor necrosis factor-alpha production and CD marker expression, resulting in increased cytotoxic activity of lymphocytes against cancer cells, which may contribute for its indirect anticancer activity. The in vivo anticancer activity of the compound is further substantiated against B16F0 melanoma syngenic and HT-29 xenograft models. These results suggest that andrographolide is an interesting pharmacophore with anticancer and immunomodulatory activities and hence has the potential for being developed as a cancer therapeutic agent.

Biological investigation and structure-activity relationship studies on azadirone from Azadirachta indica A. Juss.

Azadirone 1, a limonoidal constituent of Azadirachta indica is found to possess potent cytotoxic activity against a panel of human cancer cell lines in our in vitro studies. In vitro screening of a number of semi-synthetic analogues of 1 revealed that the alpha,beta-unsaturated enone moiety or its equivalent conjugated system in A-ring, C-7 acetyloxy/chloroacetyloxy or keto group in B-ring and the furan moiety are responsible for the activity of 1 and its analogues. Compound 1 and two of the semi-synthetic analogues 10 and 13 were found to possess good in vivo antitumor activity in modified hollow fiber animal models.