Background
Tyrosinase is an oxidoreductase that is very important in medicine and cosmetics because the excessive production of melanin causes hyperpigmentation. The development of novel, effective tyrosinase inhibitors has long been pursued. In preliminary tests, we found that an extract of the wood of Artocarpus heterophyllous (AH) potently inhibited tyrosinase activity.ResultsTwo new flavonoids, artocaepin E (1) and artocaepin F (2), were isolated from the wood of AH, together with norartocarpetin (3), artocarpanone (4), liquiritigenin (5), steppogenin (6), and dihydromorin (7). Their structures were elucidated using one-dimensional (1D) and two-dimensional (2D) nuclear magnetic resonance (NMR) and mass spectrometry. The absolute configuration of 2 was determined from the circular dichroism (CD) spectrum. Artocarpanone (4) had the most potent tyrosinase inhibitory effect, with an IC50 of 2.0 ± 0.1 μM, followed by artocaepin E (1) and steppogenin (6), with IC50 values of 6.7 ± 0.8 and 7.5 ± 0.5 μM, respectively. A kinetic investigation indicated that 1 showed competitive inhibition, with an inhibition constant (Ki) of 6.23 μM.ConclusionsThese results demonstrate that extracts of the wood of AH and its phytochemical constituents are potential sources for skin-whitening agents.Graphical abstractArtocarmin E (1) and artocarmin F (2) were isolated from the wood of Artocarpus heterophyllous. Their structures were elucidated using nuclear magnetic resonance analysis and mass spectrometric methodsElectronic supplementary materialThe online version of this article (doi:10.1186/s13065-016-0150-7) contains supplementary material, which is available to authorized users.
Human pancreatic cancer cell lines such as PANC-1 have an altered metabolism, enabiling them to tolerate and survive under extreme conditions of nutrient starvation. The search for candidates that inhibit their viability during nutrition starvation represents a novel antiausterity strategy in anticancer drug discovery. A methanol extract of the bark of Mangifera indica was found to inhibit the survival of PANC-1 human pancreatic cancer cells preferentially under nutrient-deprived conditions with a PC50 value of 15.5 μg/mL, without apparent toxicity, in normal nutrient-rich conditions. Chemical investigation on this bioactive extract led to the isolation of 19 compounds (1-19), including two new cycloartane-type triterpenes, mangiferolate A (1) and mangiferolate B (2). The structures of 1 and 2 were determined by NMR spectroscopic analysis. Among the isolated compounds, mangiferolate B (2) and isoambolic acid (12) exhibited potent preferential cytotoxicity against PANC-1 human pancreatic cancer cells under the nutrition-deprived condition with PC50 values of 11.0 and 4.8 μM, respectively.
An analytical study was proposed in this paper to explore various behavioral aspects of group and single pedestrians. The results were obtained from reviewing the literature and studying primary data. Data collected from field surveys, direct observations, and video recordings were analyzed to produce the following findings. For crowds with densities between 0.4 and 0.8 persons per square meter, individuals walked faster than groups, on average. There was also significant evidence to suggest that individuals were likely to have more trajectory changes than groups. As the crowd density got higher, the likelihood of pedestrians splitting from groups of two decreased. With higher crowd densities, the rate at which split members came back to the group decreased. More individual pedestrians chose spacious stairs; groups of two were more likely to go for escalators.
Phytochemical analysis of an EtOAc extract of the stems of Artocarpus rigida led to the identification of seven new prenylated 4-chromenones, artocarmins G-M (1-7), and nine known compounds (8-17). Their structures were identified based on physical data analysis. In the tyrosinase inhibitory activity test, norartocarpetin (8) displayed the strongest effect, with an IC value of 0.023 μM.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.