The absolute configuration determination of naturally occurring diacetylenic spiroacetal enol ethers from Artemisia lactiflora

Scalemic diacetylenic spiroacetal enol ethers from the flowers of Tanacetum tatsienense

Six scalemic mixtures of previously undescribed diacetylenic spiroacetal enol ethers (DSEEs) and six scalemic mixtures of known DSEEs were isolated from the flowers of Tanacetum tatsienense. Except for E-epidendranthemenol, Z-O-acetyl-epi dendranthemenol, and Z-O-isovaleryl-epidendranthemenol, the remaining scalemic mixtures of DSEEs were resolved by chiral HPLC, and their structures were determined through an analysis of HR-ESI-MS and NMR data. The absolute configurations of seven pairs of enantiomers and one pair of epimers were determined by comparing the experimental and calculated electronic circular dichroism (ECD) spectra. In addition, the inhibitory effects of all of the DSEEs on nitric oxide (NO) production were evaluated in LPS-stimulated RAW264.7 cells. The results showed that (+)-tatsienenol B had a weak inhibitory effect on NO production. The IC₅₀ value of the compound was 19.78 ± 0.78 μM. This study is the first to report that DSEEs are isolable from plants as scalemic mixtures. Moreover, this study is the first to determine the absolute configurations of DSEEs by chiral resolution and ECD calculations.

Assessment of Polyphenols Bioaccessibility, Stability, and Antioxidant Activity of White Mugwort (Artemisia lactiflora Wall.) during Static In Vitro Gastrointestinal Digestion

White mugwort (Artemisia lactiflora Wall.), a traditional Chinese medicine, has been widely consumed in different forms for health care purposes. In this study, the in vitro digestion model of INFOGEST was used to investigate the bioaccessibility, stability, and antioxidant activity of polyphenols from two different forms of white mugwort, including dried powder (P 50, 100, and 150 mg/mL) and fresh extract (FE 5, 15, and 30 mg/mL). During digestion, the bioaccessibility of TPC and antioxidant activity were influenced by the form and ingested concentration of white mugwort. The highest bioaccessibility of the total phenolic content (TPC) and relative antioxidant activity were found at the lowest P and FE concentrations, as calculated relative to the TPC and antioxidant activity of P-MetOH and FE-MetOH based on the dry weight of the sample. Post-digestion, in comparison to P, FE had higher bioaccessibility (FE = 287.7% and P = 130.7%), relative DPPH radical scavenging activity (FE = 104.2% and P = 47.3%), and relative FRAP (FE = 673.5% and P = 66.5%). Nine compounds, 3-caffeoylquinic acid, 5-caffeoylquinic acid, 3,5-di-caffeoylquinic acid, sinapolymalate, isovitexin, kaempferol, morin, rutin, and quercetin, identified in both samples were modified during digestion, yet still provided strong antioxidant activity. These findings suggest that white mugwort extract possesses a higher polyphenol bioaccessibility, showing great potential as a functional ingredient.

Naturally Occurring Organohalogen Compounds-A Comprehensive Review

The present volume is the third in a trilogy that documents naturally occurring organohalogen compounds, bringing the total number-from fewer than 25 in 1968-to approximately 8000 compounds to date. Nearly all of these natural products contain chlorine or bromine, with a few containing iodine and, fewer still, fluorine. Produced by ubiquitous marine (algae, sponges, corals, bryozoa, nudibranchs, fungi, bacteria) and terrestrial organisms (plants, fungi, bacteria, insects, higher animals) and universal abiotic processes (volcanos, forest fires, geothermal events), organohalogens pervade the global ecosystem. Newly identified extraterrestrial sources are also documented. In addition to chemical structures, biological activity, biohalogenation, biodegradation, natural function, and future outlook are presented.

Recent progress in the isolation, bioactivity, biosynthesis, and total synthesis of natural spiroketals

The isolation, bioactivity, biosynthesis, and total synthesis of natural spiroketals from 2011 to July 2017 have been summarized in this review.

Isolation, cytotoxicity evaluation and HPLC-quantification of the chemical constituents from Artemisia amygdalina Decne

The hexane extracts of both shoot and root parts of Artemisia amygdalina Decne displayed potent cytotoxic effects. Phytochemical analysis of these active extracts led to the isolation of six cytotoxic constituents, viz., Ergostadien-3β-ol (1), ludartin (2), 5-hydroxy-6,7,3',4'-tetramethoxyflavone (3) (from shoot) and trans-matricaria ester (4), diacetylenic spiroenol ether (5) and cis-matricaria ester (6) (from root) for the first time from this plant. The constituents were identified using spectral techniques in the light of literature. Sulphorhodamine B cytotoxicity screening of the isolated constituents was carried out against four human cancer cell lines including Lung (A-549), Leukaemia (THP-1), Prostate (PC-3) and Colon (HCT-116) cell lines. Ludartin (2) exhibited the highest cytotoxicity with IC50 values of 7.4μM, 3.1μM, 7.5μM and 6.9μM against Lung (A-549), Leukaemia (THP-1), Prostate (PC-3), Colon (HCT-116) cancer cell lines respectively. To test against in vitro skin cancer models [human dermal fibroblasts (CRL-1635)] all the isolates were further subjected to 3-(4,5-Dimethylthiazol-yl)-diphenyl tetrazolium bromide (MTT) cytotoxicity screening. Ludartin (2) being highly cytotoxic was again evaluated against mouse melanoma (B16F10) and human epidermoid carcinoma (A-431) cells by MTT assay displaying IC50 values of 6.6μM and 19.0μM respectively. Finally a simple and reliable HPLC method was developed (RP-HPLC-DAD) and validated for the simultaneous quantification of these cytotoxic constituents in A. amygdalina Decne. Excellent specificity and high linearity for all the standard calibration curves having regression coefficients of the respective linear equations in the range of 0.9962-0.9999 was observed. Relative recovery rates varied between 98.37±0.90 and 105.15±1.74 with relative standard deviation less than 4%. Based on our results, the developed method features good quantification parameters, accuracy, precision and can serve as effective quality control method for standardisation of A. amygdalina Decne.

Natural products chemistry research: progress in China in 2011

This article reviews the progress made by Chinese scientists in the field of natural products chemistry in 2011. Selected compounds with unique structural features and/or promising bioactivities are described herein on the basis of structural types.