As flavonoids show pharmacological activity, in the present investigation, an economical
and efficient method for their trace determination was developed. In this context, the interfacial
behavior of three flavonoids, 3-hydroxyflavone (3HF), morin and hesperidin (Hesp) was studied
on the hanging mercury dropping electrode (HMDE) by phase sensitive ac voltammetry and cyclic
voltammetry (CV). The investigated flavonoids were strongly adsorbed which is the prerequisite
step for applying the cathodic adsorption stripping voltammetric determination of some flavonoids.
Based on the adsorption character of investigated flavonoids onto the surface of the HMDE,
validated, simple, fast and sensitive square-wave cathodic adsorptive stripping voltammetric
(SWCASV) procedure for the quantification of the flavonoids under investigation in bulk form
and in biological fluids was described. Moreover, controlled adsorptive accumulation of the Cu(II)
complex of flavonoids was also achieved to assay indirect determination of 3HF, morin and Hesp
via the reduction of the formed complex. Operational and solution conditions for the quantitative
ultra-trace determination of the investigated flavonoids were optimized in the absence and presence
of Cu(II). Limits of detection of 4.4 × 10-9, 7.19 × 10-9 and 7.54 × 10-9 mol L-1 3HF, morin and
Hesp in bulk form were achieved using SWCASV, respectively.

As flavonoids show pharmacological activity, in the present investigation, an economical
and efficient method for their trace determination was developed. In this context, the interfacial
behavior of three flavonoids, 3-hydroxyflavone (3HF), morin and hesperidin (Hesp) was studied
on the hanging mercury dropping electrode (HMDE) by phase sensitive ac voltammetry and cyclic
voltammetry (CV). The investigated flavonoids were strongly adsorbed which is the prerequisite
step for applying the cathodic adsorption stripping voltammetric determination of some flavonoids.
Based on the adsorption character of investigated flavonoids onto the surface of the HMDE,
validated, simple, fast and sensitive square-wave cathodic adsorptive stripping voltammetric
(SWCASV) procedure for the quantification of the flavonoids under investigation in bulk form
and in biological fluids was described. Moreover, controlled adsorptive accumulation of the Cu(II)
complex of flavonoids was also achieved to assay indirect determination of 3HF, morin and Hesp
via the reduction of the formed complex. Operational and solution conditions for the quantitative
ultra-trace determination of the investigated flavonoids were optimized in the absence and presence
of Cu(II). Limits of detection of 4.4 × 10-9, 7.19 × 10-9 and 7.54 × 10-9 mol L-1 3HF, morin and
Hesp in bulk form were achieved using SWCASV, respectively.

2'-Benzoyloxycinnamaldehyde (BCA), one of the derivatives of 2'-hydroxycinnamaldehyde (HCA) isolated from the bark of Cinnamomum cassia, induces apoptosis in human cancer cells. We found that BCA induces stronger antiproliferative effects in K-ras-transformed cells (RK3E-ras) than in isogenic non-transformed cells (RK3E). Treatment of RK3E-ras with BCA resulted in increased ROS generation and depletion of intracellular glutathione, whereas BCA-treated RK3E showed no significant increase in the ROS level with concurrent increase in intracellular glutathione (GSH). Thiol antioxidants recovered cell proliferation inhibition caused by BCA in both cell lines, while non-thiol antioxidants failed to recover cell death. BCA decreased metallothionein (MT) expression in RK3E-ras, while inducing remarkable MT expression in RK3E. The increase of intracellular GSH in RK3E is partially caused by differential induction of γ-glutamylcysteine synthetase (γ-GCS) due to BCA treatment. To evaluate the upstream pathway for differential expression of γ-GCS and MT, we analyzed early DJ-1 (PARK7) and NF-E2 p45-related factor 2 (Nrf2) changes after BCA treatment. In RK3E, DJ-1 expression considerably increased for 3 h with concurrent induction of Nrf2, whereas in RK3E-ras cells BCA decreased these protein levels. Based on these findings, it seems that the therapeutic selectivity of BCA in RK3E-ras results from decreased thiol antioxidants via decreased DJ-1 and Nrf2 expression.

2-Hydroxycinnamaldehyde (HCA) and curcumin have been reported to have antitumor effects against
various human tumor cells in vitro and in vivo by generation of ROS. Aldehyde-free HCA analogs were
synthesized based on the structure of curcumin, which we have called 2-hydroxycurcuminoids. The
hydroxyl group of curcuminoids enhances the ability to generate ROS. 2-Hydroxycurcuminoid (HCC-7)
strongly inhibited the growth of SW620 colon tumor cells with a GI50 value of 7 lM, while the parent
compounds, HCA and curcumin, displayed GI50 values of 12 and 30 lM, respectively. HCC-7 was found
to induce apoptosis through the reactive oxygen species–mitochondria pathway and cell cycle arrest
at G2/M phase.

This study was devoted to investigate production of hydrogen gas from acid hydrolyzed
molasses by Escherichia coli HD701 and to explore the possible use of the waste bacterial
biomass in biosorption technology. In variable substrate concentration experiments (1, 2.5,
5, 10 and 15 g L1), the highest cumulative hydrogen gas (570 ml H2 L1) and formation rate
(19 ml H2 h1 L1) were obtained from 10 g L1 reducing sugars. However, the highest yield
(132 ml H2 g1 reducing sugars) was obtained at a moderate hydrogen formation rate (11 ml
H2 h1 L1) from 2.5 g L1 reducing sugars. Subsequent to H2 production, the waste E. coli
biomass was collected and its biosorption efficiency for Cd2þ and Zn2þ was investigated.
The biosorption kinetics of both heavy metals fitted well with the pseudo second-order
kinetic model. Based on the Langmuir biosorption isotherm, the maximum biosorption
capacities (qmax) of E. coli waste biomass for Cd2þ and Zn2þ were 162.1 and 137.9 (mg/g),
respectively. These qmax values are higher than those of many other previously studied
biosorbents and were around three times more than that of aerobically grown E. coli. The
FTIR spectra showed an appearance of strong peaks for the amine groups and an increase
in the intensity of many other functional groups in the waste biomass of E. coli after
hydrogen production in comparison to that of aerobically grown E. coli which explain the
higher biosorption capacity for Cd2þ or Zn2þ by the waste biomass of E. coli after hydrogen
production. These results indicate that E. coli waste biomass after hydrogen production can
be efficiently used in biosorption technology. Interlinking such biotechnologies is potentially
possible in future applications to reduce the cost of the biosorption technology and
duplicate the benefits of biological H2 production technology.