Praziquantel, (-)- is oxopyrazinoisoquinoline derivative and a levorotated isomer of Praziquantel patented by Merck Patent G.m.b.H. as anthelmintics agent. In rabbits infested with S. japonicum, the therapeutic effect of Praziquantel, (-)-was greater than that of dl-praziquantel as rated by the number of the worms in tissues and by liver damage. Histopathological examination showed that liver egg granulomas in the levo-praziquantel group were fewer in no. and smaller in size and were predominantly composed of Pseudotubercles instead of eosinophilic abscesses. Levo-praziquantel is therapeutically superior to praziquantel, while dextro-praziquantel is almost ineffective.

MK-8033 is a dual c-Met/Ron inhibitor, which is under investigation by Merck for the treatment of cancer.

Imazapic is a selective herbicide for both the pre- and post-emergent control of some annual and perennial grasses and some broadleaf weeds. Imazapic kills plants by inhibiting the production of branched chain amino acids, which are necessary for protein synthesis and cell growth. It has been useful for weed control in natural areas, particularly in conjunction with the establishment of native warm-season prairie grasses and certain legumes. Imazapic is relatively non-toxic to terrestrial and aquatic mammals, birds, and amphibians. It has a low level of toxicity to birds but is more toxic to aquatic life and honey bees. It has a high potential for bioaccumulation. Imazapic has an average half-life of 120 days in soil. It is may be persistent in soil systems but usually degrades quickly in aquatic systems via photolysis. It has a high aqueous solubility, is volatile and, based on its chemical properties, is moderately mobile and may leach to groundwater.

The sesquiterpene lactone thapsigargin is found in the plant Thapsia garganica L., and is one of the major constituents of the roots and fruits of this Mediterranean species. In 1978, the first pharmacological effects of thapsigargin were established and the full structure was elucidated in 1985. Thapsigargin is a potent inhibitor of Sarco-endoplasmic reticulum Ca2+-ATPase (SERCA) and is widely used to study Ca2+-signaling. Thapsigargin is a non-cell-type specific toxin with documented ability to kill a broad spectrum of cancer cell lines as well as normal endothelial cells, fibroblasts and osteoblasts. It induces a rapid and pronounced increase in the concentration of cytosolic calcium, due to blockade of the Sarcoplasmic/Endoplasmic Reticulum Calcium ATPase (SERCA) pump to which it binds with high affinity. The increase in cytosolic calcium leads to induction of apoptosis and ensuing cell death. A prodrug, G-202 (mipsagargin) has been designed to target the blood vessels of cancer cells; the death of these blood vessels then leads to tumor necrosis. G-202 consists of a cytotoxic analog of thapsigargin coupled to a masking peptide which inhibits its biologic activity until proteolytic cleavage at the tumor site. The first clinical trials of this drug were initiated in 2008 for the treatment Advanced Solid Tumors.

Withaferin A is one of the most bioactive phytoconstituents of Withania somnifera, a well-known herb in Ayurvedic medical tradition of India. Due to the lactonal steroid's potential to modulate multiple oncogenic pathways, Withaferin A has gained much attention as a possible anti-neoplastic agent. Systematic research on the evaluation of anticancer activities of withaferin A was started around the 1970s. Since then, a large number of studies have demonstrated the ability of withaferin A to suppress the in vivo growth of various human cancer cells’ xenograft tumors as well as experimentally induced carcinogenesis in different rodent models. It has being reported that withaferin-A reduced the growth of human prostate cancer (PC3) cells tumor xenograft in nude mice by blocking the tumor angiogenesis and inducing intratumoral apoptosis. According to this study, i.p. administration of withaferin-A caused regression of implanted tumor cells by decreasing the expression of angiogenesis marker CD31, inducing the expression of proapoptotic protein Bax, and activating caspase-3 via inhibition of nuclear factor-κB (NF-κB) signaling pathway. In a separate study, intratumoral administration of withaferin-A arrested PC3 cells’ xenograft tumor growth in mice by inducing tumor cell death via upregulation of prostate apoptosis response-4 (Par-4). Anticancer activity of withaferin-A has also being demonstrated for gynecological cancer, melanoma, thyroid, gastrointestinal and other types of cancer. Mechanistic basis of the anticancer effects of withaferin-A includes: (1) reinforcement of cellular antioxidant and/or detoxification system; (2) suppression of inflammatory pathways; (3) selective inhibition of tumor cell proliferation and induction of apoptosis; (4) suppression of tumor angiogenesis; (5) blockade of epithelial-to-mesenchymal transition (EMT), tumor invasion, and metastasis; (6) alteration of tumor cell metabolism; (7) immunomodulation; and (8) eradication of cancer stem cells.

Cinobufotalin, the bufadienolide isolated from toad venom, has displayed antitumor activities in many in vitro systems. It has been shown that cinobufotalin induced significant apoptosis in cultured human lymphoma U-937 cells. It induced DNA fragmentation, mitochondrial membrane potential decrease, and reactive oxygen species (ROS) production in U-937 cells. Cinobufotalin induces cytotoxic effect in cultured lung cancer cells. Cinobufotalin (1/5 mg/kg, i.p. twice daily, for 7 days) significantly inhibited A549 xenograft growth in mice. Further, same cinobufotalin administration improved mice survival at week five. Cinobufotalin administration didn’t significantly affect mice body weight, indicating the relative safety of this regimen. Thus, cinobufotalin inhibits A549 xenograft growth in vivo and improves mice survival.