Structures of Phytosterols and Triterpenoids with Potential Anti-Cancer Activity in Bran of Black Non-Glutinous Rice

Structures of some bioactive phytochemicals in bran extract of the black rice cv. Riceberry that had demonstrated anti-cancer activity in leukemic cell line were investigated. After saponification with potassium hydroxide, separation of the unsaponified fraction by reversed-phase high performance liquid chromatography (HPLC) resulted in four sub-fractions that had a certain degree of anti-proliferation against a mouse leukemic cell line (WEHI-3 cell), this being IC₅₀ at 24 h ranging between 2.80–467.11 μg/mL. Further purification of the bioactive substances contained in these four sub-fractions was performed by normal-phase HPLC. Structural characterization by gas chromatography-mass spectrometry (GC-MS), liquid chromatography-mass spectrometry (LC-MS) and nuclear magnetic resonance spectroscopy (NMR) resulted in, overall, the structures of seven phytosterols and four triterpenoids. Four phytosterols, 24-methylene-ergosta-5-en-3β-ol, 24-methylene-ergosta-7-en-3β-ol, fucosterol, and gramisterol, along with three triterpenoids, cycloeucalenol, lupenone, and lupeol, were found in the two sub-fractions that showed strong anti-leukemic cell proliferation (IC₅₀ = 2.80 and 32.89 μg/mL). The other sterols and triterpenoids were campesterol, stigmasterol, β-sitosterol and 24-methylenecycloartanol. Together with the data from in vitro biological analysis, we suggest that gramisterol is a significant anti-cancer lead compound in Riceberry bran extract.     

Autolytic properties of glycopeptide-intermediate Staphylococcus aureus Mu50

Whole-cell autolytic activity of prototypical glycopeptide-intermediate Staphylococcus aureus (GISA) Mu50 was reduced versus that of hetero-GISA Mu3 and glycopeptide-susceptible S. aureus, consistent with other GISA strains. In contrast, autolytic activity was relatively high in Mu50 crude cell walls and autolysin extracts against purified cell walls, reflecting the complexities of autolytic activity regulation.     

Enteropathogenic bacteria and enterotoxin-producing Staphylococcus aureus isolated from ready-to-eat foods in Khon Kaen, Thailand

The objective of this study was to investigate the microbiological quality of ready-to-eat food in the Municipality of Khon Kaen, Thailand. Four categories of 186 food samples were collected: (1) high heat food; (2) low heat food; (3) no heat food; and, 4) on-site prepared fruit juices and beverages. Of the food samples, 145 (78%) failed to meet acceptable microbiological standards, including fruit juice and beverages (100%), no heat food (91.7%), low heat food (81.7%) and high heat food (57.9%). The most frequent bacterial indexes indicating unacceptability were the most probable number (MPN) of coliforms (78%), the bacterial colony count (58%), and the MPN of E. coli (46%). Pathogenic bacteria were found in 6.5% of food samples. Salmonella, Vibrio cholerae non O1 and Aeromonas hydrophila were found in 4.3, 1.6 and 0.5% of the total food samples, respectively. The serovars of Salmonella found in food were S. Derby, S. Give, S. Krefield, S. Paratyphi B, S. Verchow, S. Lexington and S. Senftenberg. Staphylococcus aureus concentrations of >10(2) CFU/g and >10(5) CFU/g were found in 10.8% and 1.1% of the food samples. Enterotoxin types AB and A of S. aureus were found in 2.7% of the food samples. These results indicate that more than half of the ready-to-eat foods tested in Khon Kaen municipality did not meet microbiological national standards and many kinds of enteropathogenic bacteria were found, suggesting food stalls may be a source of foodborne disease.     

Characterization of diarrheagenic Escherichia coli isolated from food in Khon Kaen, Thailand

Four categories of 186 ready-to-eat food samples in Khon Kaen municipality, Thailand, were collected and investigated for fecal contamination by enumeration of Escherichia coli using the most probable number (MPN) method. Then, the E. coli isolates were presumptively identified as diarrheagenic E. coil by agglutinating with polyvalent O-antisera and monovalent O-antisera commonly found in diarrheagenic strains and were subsequently investigated for the presence of the recognized virulence genes for enteroaggregative (EAEC), enteroinvasive (EIEC), enteropathogenic (EPEC), enterotoxigenic (ETEC), and shiga toxin-producing E. coli (STEC or EHEC) by multiplex PCR assays. All E, coli isolates were examined for antimicrobial susceptibilities by the agar disc diffusion method, and the results were compared with those obtained from clinical samples. The percentage of each type of food with E. coli, including no heat food, low heat food, high heat food, and fruit juices and beverages, was higher than accepted standards at 60.4, 46.5, 38.6 and 20%, respectively. Of 140 E. coli isolates obtained from food samples, 11 isolates (7.9%) agglutinated with 6 monovalent O-antisera, including one isolate each of O6, O8, O114 and O159, two isolates of O1, and five isolates of O157. None of the 11 isolates harbored the virulence genes for EPEC, ETEC, EAEC, EIEC and STEC. Although O157 E. coli isolates were found, the most frequent, E. coli O157:H7, was not found in this study. The astA gene, however, was found in 1 E. coli isolate that showed weakly positive agglutination against the polyvalent antisera. Approximately 50% of the 140 E. coli isolates were resistance to at least one antimicrobial agent. The resistant strains showed high resistance to tetracycline (43%), co-trimoxazole (36%), ampicillin (26%) and chloramphenicol (23%), respectively. The resistance of E. coli was high for nearly all antimicrobial agents, particularly ampicillin (76%), tetracycline (70%), co-trimoxazole (69%) and nalidixic acid (44%). The results show that nearly half of the ready-to-eat food samples evaluated in Khon Kaen Municipality had levels of E. coli higher than acceptable standards. Of the diarrheagenic E. coli classified by serogroup, almost none of the isolates had virulence genes. These results indicate the disadvantage of relying on serogrouping alone for the recognition of diarrheagenic E. coli. E. coli isolated from food may not be an enteropathogenic strain. We also found that E. coli antimicrobial resistant strains are widespread in both food and humans.     

Resistant starch from black rice,Oryza sativa L. var. ameliorates renal inflammation,fibrosis and injury in insulin resistant rats

It has recently been reported that black rice (BR) extract has anti-obesity, anti-diabetic, and anti-osteoporosis effects. It has been shown to reduce obese-related kidney dysfunction in animal models. This study aimed to investigate the effect of resistant starch from BR (RS) on renal inflammation, oxidative stress, and apoptosis in obese insulin resistant rats. Male Wistar rats were divided into six groups: normal diet (ND), ND treated with 150 mg of RS (NDRS150), high-fat (HF) diet, HF treated with 100 and 150 mg of RS (HFRS100), (HFRS150), and HF treated with metformin as a positive control. Insulin resistance was shown in the HF rats by glucose intolerance, increased insulin, total area under the curve of glucose and homeostasis model assessment of insulin resistance and dyslipidemia. The resulting metabolic disturbance in the HF rats caused renal inflammation, fibrosis and apoptosis progressing to kidney injury and dysfunction. Prebiotic RS including anthocyanin from BR at doses of 100 and 150 mg ameliorated insulin resistance, dyslipidemia and liver injury. Treatment with RS reduced TGF-β fibrotic and apoptotic pathways by inhibition of NF-κB and inflammatory cytokines which potentially restore kidney damage and dysfunction. In conclusion, prebiotic RS from BR ameliorated obesity induced renal injury and dysfunction by attenuating inflammatory, fibrotic, and apoptotic pathways in insulin resistant rats induced by HF.