An analysis of compiled literature nanoindentation contact hardness (H_c) and elastic modulus (E) values of molecular crystals revealed a wide range of mechanical properties (0.001–1.80 GPa for H_c and 0.27–46.8 GPa for E).

The gastrointestinal (GI) stability of three flavonoids, dihydromyricetin (DMY), myricetin (MYR), and myricitrin (MYT), was examined in simulated physiological fluids. Several factors that may influence the degradation rate of theses flavonoids were evaluated, including pH and the presence of pepsin and pancreatin enzymes. We found that GI stability followed the order of MYT > DMY > MYR. These flavonoids were stable in simulated gastric fluids and buffer solutions (pH 1.2), but encountered a pseudo-first-order kinetic degradation in simulated intestinal fluids and buffer solutions (pH 6.8). We conclude that it is the pH, rather than the presence of pepsin or pancreatin, which most strongly influences the stability of these three flavonoids. Further study of the stability of the compounds using a pH range (1.0–8.0) indicated potential instability in the duodenum, small intestine, and colon. Therefore, we conclude that the low bioavailability of these flavonoids may be due to their poor stability in the GI tract. Graphical Abstract

Berberine is a drug with an intense bitter taste. The high aqueous solubility of its chloride salt, which is commonly used in commercial drug products of berberine, worsens the challenge of taste masking. We have approached this drug delivery challenge by forming salts with the sweeteners acesulfame and saccharine, through the anion exchange reaction. In addition to the intrinsic sweetness of the two counterions, both salts also exhibit reduced aqueous solubility, which further alleviates the problem of bitter taste of the drug by limiting dissolution of berberine. Moreover, both salts exhibit good tableting performance. They are also non-hygroscopic and stable against high humidity and temperature. The stability against humidity variations makes the two sweet salts more amenable for tablet development over the chloride salt, which undergoes complex hydration/dehydration phase changes when relative humidity varies. Collectively, the two novel solid phases of berberine are sweet and exhibit superior properties for developing pharmaceutically elegant drug products.