Xanthones are unique chemical compounds found in nature, composed of a tricyclic aromatic system with a variety of phenolic, methoxy, and isoprene substituents, giving rise to numerous derivatives. They dissolve to varying degrees in solvents ranging from alcohol to hexane. An optimum solvent mixture of acetone/water (80:20) selectively and effectively extracts a wide variety of xanthones. Subsequent HPLC analysis using standard C-18 RP and a 30-min gradient of 65-90% MetOH in 0.1% formic acid detects and separates numerous different xanthones with UV detection at 254 nm. The xanthones alpha-mangostin, 8-desoxygartanin, gartanin, beta-mangostin, 3-mangostin, and 9-hydroxycalabaxanthone have been extracted, identified, and quantitatively determined using this method. This analytical method is applied to the analysis of these xanthones in the rind of the mangosteen fruit, Garcinia mangostana.

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The addition of ketorolac to lidocaine for ankle block contributed to longer duration and better quality analgesia after foot surgery compared with plain 1.73% lidocaine or 1.73% lidocaine plus intravenous ketorolac. The ethanol vehicle is unlikely responsible for the analgesic effects of ketorolac. Ketorolac retains its chemical stability when placed in local solutions of lidocaine or bupivacaine.

Abstract— Stentorin acts as the photoreceptor for the step‐up photophobic and negative phototactic responses in Stentor coeruleus. The chromophore of stentorin appears to be hypericin which is linked to apoprotein. In addition to the photomovement responses of the organism, S. coeruleus was found to be photodynamically sensitive to light absorbed by the hypericin chromophore, as the apparent action spectrum for the photodynamic killing matches the absorption spectrum of stentorin. The protective effect of β‐carotene and crocetin on the photodynamic killing of S. coeruleus suggests that singlet oxygen generated by the stentorin‐sensitization plays an important role, according to the so‐called Type II mechanism of photosensitization. The generation of singlet oxygen via hypericin triplet was confirmed by in vitro photooxidation of tryptophan as a substrate. The photodynamic killing was more effective in deuterium oxide than in H2O in both the photosensitization by stentorin (endogenous) and added hypericin (exogenous). These results are consistent with the involvement of singlet oxygen in the photodynamic killing of S. coeruleus.

Abstract— The blue light absorption band of roseoflavin is polarized along the axis roughly connecting N3‐C8 positions. A weak, second π→π* transition with a polarization angle of ca. 25° is hidden under the short wavelength side of the blue absorption band. The excited state of roseoflavin is somewhat more basic than the ground state, by a 1.5 pKa unit. The fluorescence quantum yield and lifetime of roseoflavin are substantially lower than those of other flavins, thus making it kinetically less efficient as a blue light photoreceptor.