Dose-Dependent Solubility–Permeability Interplay for Poorly Soluble Drugs under Non-Sink Conditions

We investigated the solubility–permeability interplay using a solubilizer additive under non-sink conditions. Sodium lauryl sulfate (SLS) was used as a solubilizer additive. The solubility and permeability of two poorly soluble drugs at various doses, with or without SLS, were evaluated by flux measurements. The total permeated amount of griseofulvin, which has high permeability, increased by the addition of SLS. On the other hand, triamcinolone, which has low permeability, showed an almost constant rate of permeation regardless of the SLS addition. The total permeated amount of griseofulvin increased by about 20–30% when the dose amount exceeded its solubility, whereas its concentration in the donor chamber remained almost constant. However, the total permeated amount of triamcinolone was almost constant regardless of dose amount. These results suggest that the permeability of the unstirred water layer (UWL) may be affected by SLS and solid drugs for high-permeable drugs. The effect of solid drugs could be explained by a reduction in the apparent UWL thickness. For the appropriate evaluation of absorption, it would be essential to consider these effects.

Mycorrhiza and Common Mycorrhizal Network Regulate the Production of Signal Substances in Trifoliate Orange (Poncirus trifoliata)

Common mycorrhizal networks (CMNs) connecting two or more neighbouring plants are confirmed to transfer signals, whereas little information about CMNs effects on the signal substances production is known. In this study, a two-chambered rootbox separated by 37 µm nylon mesh was used to establish donor and receptor chambers. Two chambers both were planted with trifoliate orange (Poncirus trifoliata) and then only donor chamber inoculated with Diversispora versiformis, Paraglomus occultum and Rhizoglomus intraradices. The roots of the donor and receptor plants both were mycorrhizated suggesting that CMNs were established between donor and receptor seedlings. Moreover, the AMF association dramatically increased plant height, stem diameter, leaf numbers, and shoot and root biomass in both the donor and receptor seedlings. The AMF inoculation in the donor plants and the subsequent mycorrhizal colonization by CMNs in the receptor plants significantly increased root calmodulin (CaM) and salicylic acid (SA) concentrations, while considerably decreased root nitric oxide (NO) and jasmonic acid (JA) concentrations. This was accompanied by down-regulated expression of three JA synthetic genes (PtLOX, PtAOS and PtAOC), regardless of donor and receptor seedlings. These results thus suggest that CMNs between trifoliate orange seedlings manifestly promote plant growth and affect the production of signal substances.