The peroxyl radicals generated by the activity of lipoxygenases (LOX) are mediators to trigger inflammatory diseases. Therefore, it is important to investigate potent LOX inhibitor for modulating the occurrence and resolving inflammatory processes. Artemisa vulgaris, is a herbal plant that is known for flavonoids, potentially inhibiting lipid peroxidation and scavenging radicals. The objectives of the present study were to obtain flavonoids rich extract from A. vulgaris, and determine the inhibitory mode of the extract against LOX. The flavonoids rich extract was optimized in an ultrasound assisted extraction using ionic liquids as extraction solvent. The results found that the optimum conditions; ratio of solid-to-liquid (1:10) and 30 min of extraction time could produce the high yield (10.14 %) and flavonoid content (5.30 mg QE/g). The LOX activity was demonstrated to follow a mixed mode of inhibition in the presence of the flavonoid rich extract as an inhibitor. The Michaelis-Menten constant (Km) was increased from 0.283 µM to 0.435 µM, whereas the maximum velocity was reduced from 0.22 µM/min to 0.058 µM/min in the inhibition. The flavonoids rich extract is likely to be a natural potent non-competitive inhibitor which may bind to free LOX or substrate-bound LOX.
The aim of the present study was to determine the content of phenolics, flavonoids and tannins, as well as the biological functions of propolis extracts from the stingless bee (Heterotrigona itama). The raw propolis was extracted via maceration with ultrasonic pretreatment in 100% water and 20% ethanol. The yield of ethanolic propolis extracts was about 1% higher than its aqueous counterpart. The colorimetric assays showed that the ethanolic propolis extract had about two times higher phenolics (17.043 mg GAE/g) and tannins (5.411 mg GAE/g), and four times higher flavonoids (0.83 mg QE/g). The higher phenolic content had enhanced the antiradical and antibacterial capacities of the ethanolic extract. The propolis extracts significantly exhibited higher antibacterial activity against gram-positive bacteria (Staphylococcus aureus) than gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa). However, aqueous extract was found to have a higher anticancer property based on the viability of lung cancer cells. No cytotoxic effect was observed on normal lung cells as the cell viability was maintained >50%, even the concentration of propolis extracts were increased up to 800 µg/mL. Different chemical compositions of propolis extract would show different bioactivities depending upon the individual applications. The high content of phenolics suggests that the propolis extract could be a natural source of bioactive ingredients for the development of innovative and functional foods.
HLA-B*58:01 allele is associated with allopurinol-induced severe cutaneous reaction (SCAR). Malaysia has a multiethnic population with limited data on the prevalence of HLA-B*58:01 among patients with gout treated in primary care settings. This cross-sectional study aimed to determine the prevalence of HLA-B*5801 in patients with gout from the Malay, Chinese and Indian ethnicities attending primary clinics in Malaysia.We collected blood samples from patients with gout attending three primary care clinics in Klang Valley, Malaysia, using convenience sampling. Genomic DNA samples were subjected to typing of HLA-B*5801 by a multiplex probe-based assay in a real-time PCR system, validated by PCR-resequencing approach.547 patients (194 Malay, 266 Chinese and 87 Indian) were recruited. The overall prevalence of HLA-B*58:01 was 16.8% (Chinese 21.8%, Indian 12.6% and Malay 11.9%). None of our 61 HLA-B*58:01 carriers who ever used allopurinol developed SCAR.The overall prevalence of HLA-B*58:01 allele in our patients with gout was high, particularly among the Chinese ethnicity (21.8%). None of our HLA-B*58:01 positive patients treated with allopurinol reported allopurinol-induced SCAR. A more accurate predictive model for allopurinol-induced SCAR is needed.