The Efficacy of Composite Essential Oils against Aflatoxigenic Fungus Aspergillus flavus in Maize

The efficacy of eleven essential oils (EOs) against Aspergillus flavus NRRL 3357 was investigated. The highest antifungal activity against this aflatoxigenic fungus was exhibited by cinnamon, oregano and lemongrass, which showed low minimum inhibitory concentration (MIC) values under vapor conditions. Interactions of the three EOs were evaluated by the fractional inhibition concentration index (FICI), and the composite essential oils (CEO) showed synergistic inhibitory activities. Chemical analysis of the composite essential oils of cinnamon, oregano, and lemongrass (COL-CEO) revealed that (Z)-citral (33.44%), (E)-citral (32.88%) and carvacrol (19.84%) were the dominant components, followed by limonene (4.29%) and cinnamaldehyde (3.76%). COL-CEO not only inhibited fungal growth but also decreased aflatoxin B1 production by A. flavus. Downregulation of the relative expression of aflatoxin genes in the aflatoxin biosynthetic pathway by COL-CEO revealed its anti-aflatoxigenic mechanism. COL-CEO could also affect the colonization of A. flavus on maize grains. Therefore, COL-CEO may be considered as a potential natural antifungal agent, which could be used for the storage of maize and other grains.

Aktivitas Antibakteri Ekstrak Kelopak Bunga Rosella Terenkapsulasi Maltodekstrin dan Sinergitasnya dengan Isoniazida dan Rifampisin Terhadap Mycobacterium tuberculosis H37rv

First-line drugs (Isoniazid and Rifampicin) for the treatment of tuberculosis are known to have experienced resistance to Mycobacterium tuberculosis. The aim of this study was to determine the minimum inhibitory concentration (MIC) of maltodextrin encapsulated rosella calyx extract and its ability to provide a synergistic effect with Isoniazid (INH) and Rifampicin (RIF) on M. tuberculosis R37rv. Rosella calyxs were macerated using 50% ethanol and encapsulated using maltodextrin. Antibacterial activity was carried out by determining MIC value using Microscopic Observation and Direct Susceptibility (MODS) method. The synergistic effect was carried out by calculating the Fractional Inhibition Concentration Index (FICI). The results showed that this extract was able to inhibit M. tuberculosis H37rv with MIC of 10 mg/ ml. The FICI value of the combination of extract with INH and rifampicin was obtained 1.25. This showed that rosella calyx extract is not synergistic with INH and rifampicin, might be due to rosella calyx extract has an antibacterial effect with a different mechanism with INH and Rifampicin.

Aktivitas Antibakteri Ekstrak Kelopak Bunga Rosella Terenkapsulasi Maltodekstrin dan Sinergitasnya dengan Isoniazida dan Rifampisin Terhadap Mycobacterium tuberculosis H37rv

First-line drugs (Isoniazid and Rifampicin) for the treatment of tuberculosis are known to have experienced resistance to Mycobacterium tuberculosis. The aim of this study was to determine the minimum inhibitory concentration (MIC) of maltodextrin encapsulated rosella calyx extract and its ability to provide a synergistic effect with Isoniazid (INH) and Rifampicin (RIF) on M. tuberculosis R37rv. Rosella calyxs were macerated using 50% ethanol and encapsulated using maltodextrin. Antibacterial activity was carried out by determining MIC value using Microscopic Observation and Direct Susceptibility (MODS) method. The synergistic effect was carried out by calculating the Fractional Inhibition Concentration Index (FICI). The results showed that this extract was able to inhibit M. tuberculosis H37rv with MIC of 10 mg/ ml. The FICI value of the combination of extract with INH and rifampicin was obtained 1.25. This showed that rosella calyx extract is not synergistic with INH and rifampicin, might be due to rosella calyx extract has an antibacterial effect with a different mechanism with INH and Rifampicin.

Sinergitas Aktivitas Antibakteri dari Kelopak Bunga Rosella dan Kitosan Terhadap Staphylococcus aureus

Currently, the antibacterial research is increasingly promoted primarily from natural materials, due to the increasing number of pathogenic bacteria that have been resistant to existing antibiotics. One of the pathogenic bacteria that has been much resistant to antibiotics is Staphylococcus aureus. Rosella calyx (Hibiscus sabdariffa L.) and chitosan are known to have antibacterial activity. The aim of this study to find out the antibacterial synergy of the roselle calyx extract and chitosan against. S.aureus ATCC 33592. Rosella calyx was extracted by maceration using 80 % ethanol, while chitosan is obtained from deasetilation chitin of shrimp husk. Test antibacterial synergism using checkboard assay method by calculating the minimum inhibitory concentration (MIC) using microdilution assay. The results showed minimum inhibitory concentration (MIC) value of roselle calyx extract and chitosan were 1250 ppm and 50 ppm, respectively. MIC value of rosella calyx extract in the presence of chitosan was 625 ppm, while the value of MIC chitosan in the presence of rosella calyx extract was < 0.19 ppm. Fractional Inhibition Concentration Index (FICI) was < 0.5 which concluded that the combination of roselle calyx extract with chitosan has a synergistic antibacterial effect on S.aureus ATCC 33592.

Luminal Ca2+ controls activation of the cardiac ryanodine receptor by ATP

The synergic effect of luminal Ca2+, cytosolic Ca2+, and cytosolic adenosine triphosphate (ATP) on activation of cardiac ryanodine receptor (RYR2) channels was examined in planar lipid bilayers. The dose–response of RYR2 gating activity to ATP was characterized at a diastolic cytosolic Ca2+ concentration of 100 nM over a range of luminal Ca2+ concentrations and, vice versa, at a diastolic luminal Ca2+ concentration of 1 mM over a range of cytosolic Ca2+ concentrations. Low level of luminal Ca2+ (1 mM) significantly increased the affinity of the RYR2 channel for ATP but without substantial activation of the channel. Higher levels of luminal Ca2+ (8–53 mM) markedly amplified the effects of ATP on the RYR2 activity by selectively increasing the maximal RYR2 activation by ATP, without affecting the affinity of the channel to ATP. Near-diastolic cytosolic Ca2+ levels (&lt;500 nM) greatly amplified the effects of luminal Ca2+. Fractional inhibition by cytosolic Mg2+ was not affected by luminal Ca2+. In models, the effects of luminal and cytosolic Ca2+ could be explained by modulation of the allosteric effect of ATP on the RYR2 channel. Our results suggest that luminal Ca2+ ions potentiate the RYR2 gating activity in the presence of ATP predominantly by binding to a luminal site with an apparent affinity in the millimolar range, over which local luminal Ca2+ likely varies in cardiac myocytes.

Effects of angiotensin II on the CO2 dependence of HCO3− reabsorption by the rabbit S2 renal proximal tubule

Previous authors showed that, at low doses, both basolateral and luminal ANG II increase the proximal tubule's HCO3− reabsorption rate ( JHCO3). Using out-of-equilibrium CO2/HCO3− solutions, we demonstrated that basolateral CO2 increases JHCO3. Here, we examine interactions between ANG II and CO2 in isolated, perfused rabbit S2 segments. We first used equilibrated 5% CO2/22 mM HCO3−/pH 7.40 in bath and lumen. At 10−11 M, basolateral (BL) ANG II increased JHCO3 by 41%, and luminal ANG II increased JHCO3 by 35%. At 10−9 M, basolateral ANG II decreased JHCO3 by 43%, whereas luminal ANG II was without effect. Second, we varied [CO2]BL from 0 to 20% at fixed [HCO3−]BL and pHBL. Fractional stimulation produced by BL 10−11 M ANG II falls when [CO2]BL exceeds 5%. Fractional inhibition produced by BL 10−9 M ANG II tends to rise when [CO2]BL exceeds 5%. Regarding luminal ANG II, fractional stimulation produced by 10−11 M ANG II fell monotonically as [CO2]BL rose from 0 to 20%. Fractional inhibition produced by 10−9 M ANG II rose monotonically with increasing [CO2]BL. Viewed differently, ANG II at 10−11 M tended to reduce stimulation by CO2, and at 10−9 M, produced an even greater reduction. In conclusion, the mutual effects of 1) ANG II on the JHCO3 response to basolateral CO2 and 2) basolateral CO2 on the JHCO3 responses to ANG II suggest that the signal-transduction pathways for ANG II and basolateral CO2 intersect or merge.