Synthetic Peroxides Promote Apoptosis of Cancer Cells by Inhibiting P-Glycoprotein ABCB5

This article discloses a new horizon for the application of peroxides in medical chemistry. Stable cyclic peroxides are demonstrated to have cytotoxic activity against cancer cells; in addition a mechanism of cytotoxic action is proposed. Synthetic bridged 1,2,4,5-tetraoxanes and ozonides were effective against HepG2 cancer cells and some ozonides selectively targeted liver cancer cells (the selectivity indexes for compounds 11 b and 12 a are 8 and 5, respectively). In some cases, tetraoxanes and ozonides were more selective than paclitaxel, artemisinin, and artesunic acid. Annexin V flow-cytometry analysis revealed that the active ozonides 22 a and 23 a induced cell death of HepG2 by apoptosis. Further study showed that compounds 22 a and 23 a exhibited a strong inhibitory effect on P-glycoprotein (P-gp/ABCB5)-overexpressing HepG2 cancer cells. ABCB5 is a key player in the multidrug-resistant phenotype of liver cancer. Peroxides failed to demonstrate a direct correlation between oxidative potential and their biological activity. To our knowledge this is the first time that peroxide diastereoisomers have been found to show stereospecific antimalarial action against the chloroquine-sensitive 3D7 strain of Plasmodium falciparum. Stereoisomeric ozonide 12 b is 11 times more active than stereoisomeric ozonide 12 a (IC₅₀=5.81 vs 65.18 μm ). Current findings mean that ozonides merit further investigation as potential therapeutic agents for drug-resistant hepatocellular carcinoma.     

Phytosterols and γ‐oryzanol in rice bran oils and distillates from physical refining process

Commercially available refined rice bran oil (RBO) contained high contents of phytosterol and γ‐oryzanol, that is, 858–1034 and 248–887 mg per 100 g oil, respectively. Although the crude rice bran oil (CRBO) had high contents of both phytochemicals (1362–1376 mg phytosterol per 100 g and 1599–1666 mg γ‐oryzanol per 100 g), physical refining process resulted in their reduction to 820–895 mg phytosterol per 100 g and 933–960 mg γ‐oryzanol per 100 g in RBO (P < 0.05). Both phytochemicals evaporated and accumulated in the deodoriser distillate (DD) to some extent during the deodorising step. Further distillation of DD using molecular distillation (MD) evaporated the free fatty acids (FFAs), resulting in the unevaporated fraction (UMD) having the acid values of 5.6–9.3 mg KOH g^?1. The UMD also contained 1585–3391 mg phytosterol per 100 g and 781–848 mg γ‐oryzanol per 100 g. Results suggest potential use of DD as the source of phytochemicals for further concentration by MD.     

Biohydrogen production by a novel thermotolerant photosynthetic bacterium Rhodopseudomonas pentothenatexigens strain KKU-SN1/1

Thirty-nine purple non-sulfur bacteria (PNSB) were isolated from 162 environmental samples. These isolates of PNSB were tested for their ability to produce biohydrogen (Bio-H₂) at 40 °C and only 14 isolates were noted to possess such ability, which were considered as thermotolerant photosynthetic Bio-H₂ producing bacteria (tt-PHPB). Of 14 isolates of tt-PHPB, KKU-SN1/1 was observed to have the highest Bio-H₂ productivity. Central composite design was employed to optimize the operating conditions for maximal Bio-H₂ production by the strain KKU-SN1/1. Under optimal conditions (7.6 g/L malic acid, 11 g/L glutamic acid, pH 6.7, at 40 °C) the Bio-H₂ production was increased by 68.28%. The purity of Bio-H₂ produced was 92.22%, as suggested by gas chromatography (GC-TCD). Based on morphological characteristics and 16S rDNA sequence analysis, the strain KKU-SN1/1 was identified as Rhodopseudomonas pentothenatexigens, with 99.7% similarity. To our knowledge, this is the first report on Bio-H₂ production by R. pentothenatexigens KKU-SN1/1.     

On the gelation of mungbean starch and its composites

Light microscopy and the concentration dependence of the elastic modulus of mungbean starch (MB) gel indicate that the gelation of MB is mainly governed by a close‐packing mechanism. The mechanical property of the entire network is influenced by the strength of swollen amylose‐rich discrete gel particles rather than the surrounding matrix. However, when the physicochemical properties of the surrounding matrix is altered by the presence of flour fillers possessing lower gelatinisation temperature and enthalpy, both the stress‐related and strain‐related parameters of MB‐based mixed flour gels were reduced (P < 0.05). Addition of iota‐carrageenan (1.0% w/v), in both the absence and presence of calcium lactate (0–20 mm ), further reduced both the stress‐related and strain‐related parameters of the composite gels. This study shows the detrimental effect of the anionic hydrocolloids and divalent cation addition on the mechanical properties of a composite structure stabilised by close‐packing mechanism.     

Property improvement of thermoplastic mung bean starch using cotton fiber and low‐density polyethylene

Due to high water uptake and low mechanical properties of biodegradable thermoplastic starch, thermoplastic starch prepared from mung bean starch (TPMBS) was modified by the incorporation of cotton fiber and low‐density polyethylene (LDPE). The effect of different ratios of cotton fiber/LDPE, i.e., 10:0, 7:3, 5:5, 3:7, and 0:10, on water uptake, mechanical, thermal, and biodegradable properties of TPMBS was examined. Different TPMBS samples were prepared using internal mixer for compounding and compression molding machine for shaping samples. It was found that the TPMBS incorporated with 10:0, 7:3, and 3:7 cotton fiber/LDPE showed an increase in the stress at maximum load and Young's modulus. Moreover, the water absorption of all of the modified TPMBS samples tended to decrease as compared to the pure TPMBS. Morphological, thermal, and biodegradable properties of different TPMBS samples were also investigated.     

Palm Oil Removal from Fabric Using Microemulsion-Based Formulations

Laundry detergency of palm oil on a polyester/cotton blend was measured using an anionic extended surfactant/nonionic secondary alcohol surfactant blend under conditions corresponding to ultralow oil/water interfacial tension microemulsion formation. The oil removal for the surfactant blend could exceed 90%, which was greater than that for either component surfactant alone or for a commercial liquid laundry detergent. Presoaking produced better detergency than increasing the number of wash cycles beyond two due to fabric abrasion (leading to a brightness decrease) with an excessive number of wash cycles. Higher oil contact angles and shorter oil droplet detachment times were found to correspond to higher detergency. High speed photography showed that snap-off occurred rather than roll-up for these systems.     

Effect of storage proteins on pasting properties and microstructure of Thai rice

This study investigated the influences of rice storage proteins, in relation to amylose content, on pasting properties of newly harvested Thai rice. The polished rice cultivars investigated included waxy rice SPT1, which contained 1.3% amylose and 8.3% protein; and non-waxy rice, namely PTT1 and LPT123, which contained 14.1% and 28.6% amylose, and 6.7% and 9.6% protein, respectively. The characteristics of protein fractions were altered by accelerated aging at 60 °C and 70% relative humidity (RH) for 5 days, and/or by alkali deproteinisation and cysteine addition during Rapid Visco Analyser (RVA) pasting characterisation. Accelerated aging, deproteinisation and the reduction of disulfide bonds changed the RVA pasting curves of all Thai rice cultivars, particularly the waxy one (p < 0.05). This study has quantified the contribution of protein in relation to amylose on the RVA pasting profiles and demonstrated that protein and starch were in separated phases after heating. The continuity of the protein network in cooked non-waxy rice grains observed under confocal laser scanning microscopy (CLSM) indicated bi-continuous structure of starch and protein phases.     

Comparative Studies on Physico-Chemical Properties of Starches from Jackfruit Seed and Mung Bean

The physico-chemical properties of starch from jackfruit seed and mung bean were investigated. Jackfruit seed starch had much higher resistant starch content (26.99%) than that of mung bean starch (4.04%). Furthermore, jackfruit seed starch had a higher gelatinization temperature (T_o) that required more gelatinization energy (ΔH) compared to mung bean starch. However, mung bean starch had higher amylose content and its granules were much larger than that of jackfruit seed starch. Mung bean starch had the highest peak viscosity, breakdown, and setback whereas jackfruit seed starch had the highest pasting temperature. Amylopectin chain length of mung bean starch contained higher proportion of short chains (degrees of polymerization 6–12) but lower proportion of very long chains (degrees of polymerization > 37 ) comparing with jackfruit seed starch. The X-ray diffraction patterns showed both starches to be Type-A crystallinity. In addition, both starch gels showed higher the storage modulus (G′) than the loss modulus (G?) designating as rubber like material. However, mung bean starch gel exhibited higher G’ and less tan δ than that of jackfruit seed starch indicating much stronger of gel structure.