Auricularia auricula-judae is currently grown in Malaysia. In the present study, the methanolic extracts from fruit bodies (fresh, oven-dried, and freeze-dried) and mycelium of A. auricula-judae were evaluated for their antioxidant capacities based on 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging activity and ferric reducing antioxidant power (FRAP) assay. The total phenolic content in the extracts were also measured. The extract of freeze-dried fruit bodies of A. auricula-judae had potent DPPH free radical scavenging activity with a 50% effective concentration of 2.87 mg/mL, whereas the FRAP value of A. auricula-judae mycelium was 5.22 micromol of FeSO(4).7H(2)O equivalents/g of mycelium sample. Further, a positive correlation (R(2) = 0.7668) between FRAP level of A. auricula-judae extracts and the total phenolic contents was observed. Thus the method of processing of fresh fruit bodies had an effect on the antioxidant potential of A. auricula-judae.
The preservation of active constituents in fresh herbs is affected by drying methods. An effective drying method for Strobilanthes crispus which is increasingly marketed as an important herbal tea remains to be reported. This study evaluated the effects of conventional and new drying technologies, namely vacuum microwave drying methods, on the antioxidant activity and yield of essential oil volatiles and phytosterols. These drying methods included convective drying (CD) at 40 °C, 50 °C, and 60 °C; vacuum microwave drying (VMD) at 6, 9, and 12 W/g; convective pre-drying and vacuum microwave finish drying (CPD-VMFD) at 50 °C and 9 W/g; and freeze-drying (FD). GC–MS revealed 33 volatiles, and 2-hexen-1-ol, 2-hexenal, 1-octen-3-ol, linalool, and benzaldehyde were major constituents. The compounds β-sitosterol and α-linolenic acid were the most abundant phytosterol and fatty acid, respectively, in fresh S. crispus. The highest phenolic content was achieved with CD at 60 °C. The highest antioxidant activity was obtained with CD at 40 °C and VMD at 9 W/g. On the contrary, the highest total volatiles and phytosterols were detected with CD at 50 °C and VMD at 9 W/g, respectively. This study showed that CD and VMD were effective in producing highly bioactive S. crispus. A suitable drying parameter level, irrespective of the drying method used, was an important influencing factor.
Diabetes mellitus is a major cause of morbidity and mortality worldwide. Although scientific evidence supporting its therapeutic efficacy is lacking, the use of the tiger's milk mushroom (TGM; Lignosus rhinocerotis), which is native to tropical areas such as Malaysia, Indonesia, and the Philippines, has been found to contain a very large amount of potential antioxidants. In this study, rats were weighed and then intravenously injected with 35 mg/kg streptozotocin (STZ). Rats were left for 1 week before blood glucose concentrations were measured to determine the onset of diabetes before the next procedure was conducted. Rats with blood glucose exceeding 7.0 mmol/L were considered diabetic and were included in the experiment. All groups were fed their respective treatments twice daily for 2 months throughout the experiment. Antidiabetic and antioxidant properties of freeze-dried TGM powder, such as reduced glutathione (GSH), superoxide dismutase (SOD), lipid peroxidation (LPO), and catalase (CAT) activities, were investigated in liver samples. The biological compounds present in the freeze-dried TGM powder was found to exhibit antidiabetic properties by significantly reducing elevated blood glucose concentrations to a normal range (3.0-7.0 mmol/L) in Sprague-Dawley rats with streptozotocin-induced diabetes, and increasing the body weight of the rats. Freeze-dried TGM powder was also found to possess antioxidant activity by significantly increasing GSH, CAT, and SOD activities while reducing LPO (P < 0.05). THis study shows that freeze-dried TGM powder exhibits significant antidiabetic properties and may be a potential supplement in ameliorating diabetic complications.
There are many factors influencing the stability and color variation of natural colorant anthocyanin and pH is among the most significant factor. This study aims to determine the stability of the anthocyanins in freeze-dried Hibiscus sabdariffa, Melastoma malabathricum and Ipomoea batatas in various acidic pH (pH 2.0, 2.5, 3.0, 3.5, 4.0 and 4.5). Total monomeric anthocyanin, degradation index, color density and percent polymeric color were analyzed to determine anthocyanins degradation and their color variations. Among the samples, H.sabdariffa contain the highest monomeric anthocyanins (163.3 mg/L) followed by M. malabathricum (49.9 mg/L) and the lowest is I.batatas (13.8 mg/L). Monomeric anthocyanins from I.batatas were found to be very stable and not affected by changes in pH than in H. sabdariffa and M. malabathricum. However, degradation index (DI) of H. sabdariffa was the lowest with value of 0.365 ± 0.049 at pH 3.5. The lowest percentage of polymeric color (4.94 ± 0.64) was also shown by H. sabdariffa at pH 2.5 and maintained a deep red color with increasing pH indicating higher color stability compared to M. malabathricum and I. batatas. Overall, natural pigment in H. sabdariffa was found to be the most stable in both monomeric anthocyanin content and chromaticity properties. These results provided information that will further proven the potential usage of H. sabdariffa, M. malabathricum and I. batatas as natural coloring agents to replace the synthetic colorant in food and beverage industries.
Conventional polymerase chain reaction (PCR) testing requires many pipetting steps and has to be transported and stored in cold chain. To overcome these limitations, we designed a ready-to-use PCR test for Salmonella typhi using PCR reagents, primers against the ST50 gene of S. typhi, a built-in internal amplification control (IAC), and gel loading dye mixed and freeze-dried in a single tube. The 2-step dry-reagent-based assay was used to amplify a 1238-bp target gene and an 810-bp IAC gene from 73 BACTEC blood culture broths (33 true positives for S. typhi and 40 true negatives for non-S. typhi). The sensitivity, specificity, positive predictive value, and negative predictive value of the PCR assay were 87.9%, 100%, 100%, and 90.9%, respectively. We suggest that this rapid 2-step PCR test could be used for the rapid diagnosis of typhoid fever.
A shelf-stable loop-mediated isothermal amplification (LAMP) reagent for Burkholderia pseudomallei detection is described. The coupling of LAMP reagents with the indirect colorimetric indicator and consequently its lyophilization enable the simple evaluation of results without the need for any advance laboratory instruments. The reagents were found to have a stable shelf life of at least 30 days with well-maintained sensitivity and specificity.
Mixed reagents for the Glucose-6-phosphate dehydrogenase (G6PD) deficiency fluorescent screening test were freeze-dried in plastic tubes. The reagents were then reconstituted with distilled water and the test was performed in the usual way. Initial testing with the freeze-dried mixed reagents gave consistent positive reaction to 12 normal blood samples and negative reaction to 9 G6PD deficient blood samples. This will enable a laboratory with freeze-drying facilities to prepare reagent tubes in bulk. As these tubes can be kept at 4 degrees C and do not require to be stored at -20 degrees C, a major laboratory can prepare these tubes and supply small laboratories for screening purposes.
Klebsiella pneumoniae and Haemophilus influenzae are two common pathogens associated with respiratory tract infections. The identification of these pathogens using conventional molecular diagnostic tests requires trained personnel, cold-chain transportation, and storage-dependance, which does not render them user-friendly. The aim of this study was to develop a thermostabilized, cold-chain-free, one-step multiplex PCR for simultaneous detection of K. pneumoniae and H. influenzae. The multiplex PCR assay was designed to amplify the php gene of K. pneumoniae (202 bp) and p6 gene of H. influenzae (582 bp). In addition, the specific primer to amplify glm gene of Helicobacter pylori (105 bp) was included as an internal amplification control. Subsequently, the designed primers and all PCR reagents were thermostabilized by lyophilization. The stability of the thermostabilized PCR was evaluated using the Q(10) method. The sensitivity and specificity of performances for thermostabilized PCR were evaluated using 127 clinical isolates and were found to be 100% sensitive and specific. The thermostabilized PCR mix was found to be stable for 30 days and the Q10 accelerated stability was found to be 3.02 months. A cold-chain-free, PCR assay for easy, rapid, and simultaneous detection of K. pneumoniae and H. influenzae was successfully developed in this study.