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Synthetic insecticides are effective in controlling insect pests but can also harm nontarget organisms and the environment. During the last 40 years, there has been an increasing interest in alternative insecticides, particularly those derived from plants, commonly known as botanical insecticides. However, commercially available botanical insecticides remain limited. Rotenone is one of the earliest identified compounds and was used as fish poison and pest management. Due to its link with Parkinson disease, the use of rotenone was banned in many developed countries. Rotenone used to be isolated from Derris spp. and Lonchocarpus spp., and it can also be isolated from Tephrosia species. In this article, we present basic botanical information on selected Tephrosia species and their major compounds related to insecticidal activities and highlight the current use of extracts derived from some species, Tephrosia vogelii in particular, for control of insect pests in stored grains and crop production. The crude extracts contain multiple bioactive compounds, mainly rotenone, deguelin, rotenolone, and tephrosin, which act in either additive or synergistic fashion, resulting in effective control of insect pests. There are about 400 species in the genus Tephrosia, and species and even strains or variants vary greatly in these active compounds. We argue that a systematic evaluation of bioactive compounds in different species are needed, and species or strains with high insecticidal activities should be selected for use in the sustainable control of insect pests.

Tephrosin is a natural rotenoid isoflavonoid that has been shown to have potent anticancer activities. In this study, we reported the anticancer activity of tephrosin against pancreatic cancer cells. Tephrosin potently suppressed cell viability in various cancer cell lines and promoted apoptosis of PANC-1 and SW1990 pancreatic cancer cells evidenced by enhanced cleavage of caspase-3/-9 and PARP. Further studies showed that tephrosin increased the production of intracellular reactive oxygen species (ROS) and led to mitochondrial membrane potential depolarization, and subsequent cytochrome c release. DNA damage was also identified by increased tail DNA and phosphorylation of H2AX. Intracellular ROS production seems to be essential for the anticancer activity of tephrosin, alleviation of ROS production by ROS scavengers weakened the apoptotic effects of tephrosin. Importantly, in PANC-1 xenografted nude mice, potent antitumor activity and low toxicity of tephrosin were observed. In conclusion, these results indicated that tephrosin could be developed as a potential chemotherapeutic agent for the treatment of human pancreatic cancer.

Ovarian cancer is the leading cause of death among gynecologic cancers. Paclitaxel is used as a standard first-line therapeutic agent for ovarian cancer. However, chemotherapeutic resistance and high recurrence rates are major obstacles to treating ovarian cancer. We have found that tephrosin, a natural rotenoid isoflavonoid, can resensitize paclitaxel-resistant ovarian cancer cells to paclitaxel. Cell viability, immunoblotting, and a flow cytometric analysis showed that a combination treatment made up of paclitaxel and tephrosin induced apoptotic death. Tephrosin inhibited the phosphorylation of AKT, STAT3, ERK, and p38 MAPK, all of which simultaneously play important roles in survival signaling pathways. Notably, tephrosin downregulated the phosphorylation of FGFR1 and its specific adapter protein FRS2, but it had no effect on the phosphorylation of the EGFR. Immunoblotting and a fluo-3 acetoxymethyl assay showed that tephrosin did not affect the expression or function of P-glycoprotein. Additionally, treatment with N-acetylcysteine did not restore cell cytotoxicity caused by a treatment combination made up of paclitaxel and tephrosin, showing that tephrosin did not affect the reactive oxygen species scavenging pathway. Interestingly, tephrosin reduced the expression of the anti-apoptotic factor XIAP. This study demonstrates that tephrosin is a potent antitumor agent that can be used in the treatment of paclitaxel-resistant ovarian cancer via the inhibition of the FGFR1 signaling pathway.

Rotenone and rotenoid-containing botanicals, important insecticides and fish poisons, are reported to have anticancer activity in rats and mice. The toxic action of rotenone is attributed to inhibition of NADH:ubiquinone oxidoreductase activity and the purported cancer chemopreventive effect of deguelin analogs has been associated with inhibition of phorbol ester-induced ornithine decarboxylase (ODC) activity. This study defines a possible relationship between these two types of activity important in evaluating the toxicology of rotenoid pesticides and the suitability of the anticancer model. Fractionation of cube resin (the commercial rotenoid pesticide) establishes that the activity in both assays is due primarily to rotenone (IC50 = 0.8-4 nM), secondarily to deguelin, and in small part to rotenolone and tephrosin. In addition, the potency of 29 rotenoids from cube insecticide for inhibiting NADH:ubiquinone oxidoreductase in vitro assayed with bovine heart electron transport particles satisfactorily predicts their potency in vivo in the induced ODC assay using noncytotoxic rotenoid concentrations with cultured MCF-7 human breast cancer cells (r = 0.86). Clearly the molecular features of rotenoids essential for inhibiting NADH:ubiquinone oxidoreductase are similar to those for blocking ODC induction. This apparent correlation extends to 11 flavonoids and stilbenoids from cube resin (r = 0.98) and genistein and resveratrol except for lower potency and less selectivity than the rotenoids relative to cytotoxicity. These findings on cube insecticide constituents and our earlier study comparing rotenone and pyridaben miticide indicate that inhibition of NADH:ubiquinone oxidoreductase activity lowers the level of induced ODC activity leading to the antiproliferative effect and anticancer action