Twenty-seven flavonoids isolated from Dalbergia parviflora with vast structural diversity were screened for inhibitory activity against mushroom and murine tyrosinases using l-DOPA as the substrate. Among the flavonoids tested, only four—khrinone (5), cajanin (9), (3RS)-3′-hydroxy-8-methoxy vestitol (21), and (6aR,11aR)-3,8-dihydroxy-9-methoxy pterocarpan (27)—reacted with mushroom tyrosinase, with IC50 values of 54.0, 67.9, 67.8, and 16.7 μM, respectively, and only compound 27 showed inhibitory activity against murine tyrosinase. With cell-based assays, only compounds 9 and 27 effectively inhibited melanogenesis in B16-F10 melanoma cells (by 34% and 59%, respectively), at a concentration of 15 μM, without being significantly toxic to the cells. However, the crude extract of D. parviflora and some of the flavonoid constituents appeared to increase melanin production in B16-F10 cells, suggesting that there are flavonoids with both inhibitory and stimulatory melanogenesis in the crude extract. Studies on the correlation between the enzyme-based and cell-based assays showed that only the flavonoids with IC50 values below 50 μM against mushroom tyrosinase could inhibit the mammalian tyrosinase, and thus, reduce melanogenesis in B16-F10. Flavonoids with the IC50 values greater than 50 μM, on the other hand, could not inhibit the mammalian tyrosinase, and had either no effect or enhancement of melanogenesis. In conclusion, the tyrosinase enzyme from mushroom is not as selective as the one from mammalian source for the enzyme-based melanogenesis inhibitory screening, and the mammalian cell-based assay appears to be a more reliable model for screening than the enzyme-based one.

Aphanothece halophytica is a halotolerant alkaliphilic cyanobacterium that can grow in media of up to 3.0 M NaCl and pH 11. Here, we show that in addition to a typical H ؉ -ATP synthase,

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The mrp homolog gene cluster mrpCD1D2EFGAB (Ap-mrp) was found in a halotolerant cyanobacterium, Aphanothece halophytica, amplified, and expressed in Escherichia coli mutant TO114. Ap-mrp complemented the salt-sensitive phenotype of TO114 and exhibited Na(+)/H(+) and Li(+)/H(+) exchange activities, indicating that Ap-Mrp functions as a Na(+)/H(+) antiporter.

Abstract:The antioxidant activities of 24 isoflavonoids that were previously isolated as pure compounds from Dalbergia parviflora were evaluated using three different in vitro antioxidant-based assay systems: xanthine/xanthine oxidase (X/XO), ORAC, and DPPH. The isolates consisted of three subgroups, namely isoflavones, isoflavanones, and isoflavans, each of which appeared to have diversified substituents, and were thus ideal for the study of their structure-activity relationships (SARs). The SAR analysis was performed using the results obtained from both the inter-subgroup isoflavonoids with the same substitution pattern and the intra-subgroup compounds with different substitution patterns. The inter-subgroup comparison showed that the isoflavones exhibited the highest antioxidant activities based on all three assays. The intra-subgroup analysis showed that the additional presence of an OH group in Ring B at either R3′ or R5′ from the basic common structure of the R7-OH of Ring A and the R4′-OH (or -OMe) of Ring B greatly increased the antioxidant activities of all of the isoflavonoid subgroups and that other positions of OH and OMe substitutions exerted different effects on the activities depending on the subgroup and assay type. Therefore, based on the structural diversity of the isoflavonoids

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Abstract. Advances in understanding lung cancer biology and tumor markers aid clinicians in managing the disease. Cancer-associated antigen (CA)125 has garnered increasing attention in lung cancer research and may benefit the treatment and follow-up of this type of cancer. In Thai lung cancer patients, knowledge regarding ethnic differences in cancer cell biology is largely absent. We generated lung cancer cells from the pleural effusion fluids of a Thai patient and designated these as P1 cells. P1 cells were assessed for growth rate, response to chemotherapy, and the presence of tumor markers, in particular CA125 expression. Results of immunofluorescence indicated that P1 cells exhibited strong expression levels of CA125, comparable to that of established H460 lung cancer cells. Furthermore, P1 cells were analyzed for the expression of additional markers. Results revealed that H460 cells exhibited strong immunofluorescent signals from cytokeratin-19 fragments (CYFRA 21-1) and squamous cell carcinoma antigen (SCCA) while P1 presented only CYFRA 21-1 signals. We also found evidence of relative cisplatin resistance in P1 compared to the susceptibility level of established lung cancer cells. Thus, the results and methodology described in this study may aid the development of lung cancer diagnostic and therapeutic approaches and, in particular, advance understanding of ethnic differences.

Pseudomonas putida HK5 produces three different quinoprotein alcohol dehydrogenases: ADH-I, ADH-IIB and ADH-IIG. Gene organization of qedA, the gene for ADH-I, and other 10 genes in the cluster was related to the genome sequences of five other Pseudomonas strains. Insertion mutations in either qedA, exaE or agmR eliminated ADH-I activity, although the mutants were still able to grow on ethanol but more slowly than the wild-type strain. Mutant analysis demonstrated the requirement of agmR and exaE in ADH-I expression, and the tentative involvement of agmR, but not exaE, in the induction of ADH-IIB and ADH-IIG activities.