The 170 kDa plasma membrane P-glycoprotein (Pgp) causes the efflux of chemotherapeutic drugs from cells and is believed to be an important mechanism in multidrug resistance (MDR) in human cancer. This study demonstrates that some putative flavonoids, i.e., flavonols (quercetin and kaempferol) and isoflavones (genistein and daidzein) markedly increase the sensitivity of the multidrug-resistant human cervical carcinoma KB-V1 cells (high Pgp expression) to vinblastine and paclitaxel dose-dependently, and also decrease the relative resistance of these anti-cancer-drugs in KB-V1 cells. None of the flavonoids had a significant effect on vinblastine and paclitaxel cytotoxicity in wildtype drug-sensitive KB-3-1 cells (lacking Pgp). These flavonoids also caused an increase in intracellular accumulation, and reduced the efflux of Rh123 and 3[H]vinblastine in KB-V1 cells, but not in KB-3-1 cells. The flavonols increased the inhibitory effectiveness of Pgp activity in MDR KB-V1 cells more than isoflavones. Only treatment with flavonols up to 48 h was able to significantly decrease the Pgp expression in a dose-dependent manner in KB-V1 cells. These findings provide evidence that flavonols reduced Pgp expression and function resulting in the inhibition of Pgp activity, but isoflavones modulated intracellular drug levels by inhibiting Pgp function with no effect on Pgp expression. Among the flavonoids tested, flavonols, particularly kaempferol, exhibit the most potent MDR reversing property in KB-V1 cells.

Zearalenone (ZEA) is a phytoestrogen from Fusarium species. The aims of the study was to identify mode of human leukemic cell death induced by ZEA and the mechanisms involved.

The worldwide demand for a natural dye by the cosmetic and food industry has recently gained interest. To provide scientific data supporting the usage of Thai henna leaf as a natural colorant, the phytochemical constituents, safety, and bioactivity of aqueous extract of the henna leaf by autoclave (HAE) and hot water (HHE) were determined. HAE contained a higher amount of total phenolic and flavonoid contents than HHE. The major constituents in both extracts were ferulic acid, gallic acid, and luteolin. The extracts displayed no marked mutagenic activity both in vitro and in vivo mammalian-like biotransformation. HAE and HHE also exhibited non-cytotoxicity to human immortalized keratinocyte cells (HaCaT), peripheral blood mononuclear cells (PBMCs), and murine macrophage RAW 264.7 cell line with IC₂₀ and IC₅₀ > 200 μg/ml. The extracts exhibited antioxidant and anti-inflammatory activity as evidenced by significant scavenging of ABTS and DPPH radicals and decreasing NO levels in LPS-induced RAW 264.7 cells. The antioxidant and anti-inflammatory properties of the extracts might be attributed to their phenolic and flavonoid contents. In conclusion, the traditional use of henna as a natural dye appears not to exert toxic effects and seems biosecure. Regarding safety, antioxidant, and anti-inflammatory properties, the aqueous extract of Thai henna leaf might thus serve as a readily available source for utilization in commercial health industries.