Size-dependent toxicological effects of polystyrene microplastics in the shrimp Litopenaeus vannamei using a histomorphology, microbiome, and metabolic approach.

Due to the wide application of plastic products in human life, microplastic pollution in water has recently attracted more attention. Many studies have revealed the size-dependent toxicity of microplastics. Here, we investigated the toxicological effects of polystyrene microplastics (PS-MPs) on the white leg shrimp, Litopenaeus vannamei, a profitable aquaculture species, using a comprehensive histomorphological, microbiome, and metabolomic approach to verify whether smaller particles are more toxic than larger particles. L. vannamei were experimentally exposed to water containing PS-MPs of four sizes (0.1, 1.0, 5.0, and 20.0 µm) for 24 h at 10 mg/L (acute experiment) and 12 d at 1 mg/L (subchronic experiment). After 24 h of acute exposure, PS-MP accumulation in shrimp indicated that the ingestion and egestion of PS-MPs had a size-dependent effect, and smaller particles were more bioavailable. The tissue morphological results of subchronic experiments showed that, for the guts and gills, the smaller sizes of the PS-MPs exhibited greater damage. In addition, 16 S rRNA gene amplicon sequencing showed that the alpha diversity was higher under larger PS-MP exposure. Correlated with changes in intestinal bacteria, we found a greater enrichment of metabolic pathways in hemolymph proteins and metabolites in larger PS-MP groups, such as "arginine and proline metabolism", "protein digestion and absorption", "lysine degradation". Interestingly, the activity or content of biomarkers of oxidative stress showed a peak at 1 µm and 5 µm. Under specific sizes of PS-MPs, the abundance of the pathogen Vibrio and probiotic bacteria Rhodobacter (5-µm) and Bacillus and Halomonas (1-µm) were simultaneously enriched. Our results indicated that PS-MP exposure can cause size-dependent damage to shrimp, yet specific particle size can be influential differently in regard to some research indicators. Therefore, it can enhance our comprehensive understanding of the impacts of microplastics on shrimp health and suggests that specific particle size should be considered when assessing the size-dependent toxicity of microplastics.

Chemical constituents of Swertia delavayi and their anti-hepatitis B virus activity.

Fifteen known compounds were isolated from Swertia delavayi by silica gel, Sephadex LH-20 and Rp-18 column chromatographies. Based on extensive spectroscopic analysis (MS, 1H, 13C-NMR), their structures were identified aserythrocentaurin (1), erythrocentaurindimethylacetal (2), sweroside (3), swertiamarin (4), gentiopicroside (5), swertiakoside A (6), 2'-O-acetylswertiamarin (7), 4'-O-[(Z) -coumaroyl] swertiamarin (8), 1,5,8-trihydroxy-3-methoxyxanthone (9), 8-O-ß-D-glucopyranosyl-1-hydroxy-2,3, 5-trimethoxyxanthone (10), 8-O-[ß-D-xyl- opyranosyl-(1 --> 6)-ß-D-glucopyranosyl]-7,8-dihydroxy-3-methoxyxanthone (11), isovitexin (12), ß-sitosterol (13), daucosterol (14), and oleanolic acid (15). Among them, ten ones (14, 7-11, 13) were obtained from S. delavayi for the first time. The isolates were evaluated for their anti-HBV activities in HepG 2. 2. 15 cell line in vitro. The results showed that compound 1, 2, 6, 7, 9 and 12 exhibited significant inhibitory activity on HBV DNA replication with IC50 values from 0.05 to 1.46 mmol x L(-1).

Anti-hepatitis B virus active constituents from Swertia chirayita.

Four new compounds swertiachiralatone A (1), swertiachoside A (2), swertiachirdiol A (3) and swertiachoside B (4), together with twenty-six known ones were isolated from the ethanol extract of Swertia chirayita. Their structures were elucidated by extensive spectroscopic analyses (1D- and 2D-NMR, HRESIMS, UV, IR and [α]D). All compounds were evaluated for anti-hepatitis B virus (anti-HBV) activities on HepG 2.2.15 cells line in vitro, of which compounds 14 and 19 showed inhibitory activity on hepatitis B surface antigen (HBsAg) secretion with IC50 values of 0.31 ± 0.045 and 1.49 ± 0.033 mM; compounds 14 and 28 exhibited activity against hepatitis B e antigen (HBeAg) secretion with IC50 values of 0.77 ± 0.076 and 5.92 ± 1.02 mM; and eight compounds (8,9,13,14,24-26,29) possessed activity against HBV DNA replication with IC50 values of 0.07-0.33 mM. In particular (+)-cycloolivil-4'-O-ß-d-glucopyranoside (14) exhibited inhibition not only on the secretions of HBsAg and HBeAg with IC50 values of 0.31 ± 0.045 mM (SI=4.29) and 0.77 ± 0.076 mM (SI=1.75), respectively, but also on HBV DNA replication with an IC50 value of 0.29 ± 0.034 mM (SI=4.66).

(±)-Paeoveitol, a pair of new norditerpene enantiomers from Paeonia veitchii.

(+)-Paeoveitol and (-)-paeoveitol, a pair of new norditerpene enantiomers, were isolated from the root of Paeonia veitchii. Their structures and absolute configurations were determined on the basis of extensive analysis of 1D and 2D NMR spectra, crystal X-ray diffraction, and electronic circular dichroism (ECD). A possible biogenesis involving two molecules of paeoniflorin was postulated.

LC-MS guided isolation of (±)-sweriledugenin A, a pair of enantiomeric lactones, from Swertia leducii.

(±)-Sweriledugenin A, a pair of novel enantiomeric lactones, were isolated from Swertia leducii under the guidance of LC-MS investigation. The enantiomeric separation was achieved by HPLC on a chiral column. Their structures were determined by extensive NMR spectra, X-ray, and quantum calculations. (+)-Sweriledugenin A and (-)-sweriledugenin A showed activities inhibiting HBV DNA replication with the IC50 values of 36.86 and 26.55 µM on the HepG 2.2.15 cell line in vitro.

Chemical constituents of Swertia yunnanensis and their anti-hepatitis B virus activity.

Four new triterpenoids, sweriyunnangenin A (1), sweriyunnanosides A (2), B (3) and C (4), along with nineteen known compounds (5-23) were isolated from Swertia yunnanensis. Based on extensive spectroscopic analyses (1D- and 2D-NMR, HRESIMS, UV, IR, [α]D), the structures of sweriyunnangenin A (1), sweriyunnanosides A (2), B (3) and C (4) were elucidated as taraxer-14-ene-3α,6ß-diol, oleanolic acid 28-O-ß-D-glucopyranosyl-(1→2)-O-ß-D-glucopyranoside, 2α,3ß-di-hydroxyolean-12-en-28-oic acid 28-O-ß-D-glucopyranosyl(1→6)-ß-D-glucopyranosyl (1→6)-ß-D-glucopyranosyl(1→2)-ß-D-glucopyranoside and hederagenin 28-O-ß-D-glucopyranosyl(1→6)-ß-D-glucopyranosyl(1→6)-ß-D-glucopyranosyl(1→2)-ß-D-glucopyranoside, respectively. Twenty-two compounds were evaluated for their anti-HBV activities on the HepG 2.2.15 cell line in vitro, of which nine compounds showed potent anti-HBV activities. Compounds 1, 5-6, 14-16 and 19 showed activities against the secretion of HBsAg (IC50 values from 0.10 to 1.76 mM) and HBeAg (IC50 values from 0.04 to 1.41 mM), and compounds 11 and 13-16 exhibited significant inhibition on HBV DNA replication (IC50 values from 0.01 to 0.09 mM).

Xanthones with anti-hepatitis B virus activity from Swertia mussotii.

Two new xanthones, 8-O-ß-D-glucopyranosyl-1-hydroxy-2,3,5-trimethoxyxanthone (1) and 8-O-[ß-D-xylopyranosyl-(1 → 6)-ß-D-glucopyranosyl]-1-hydroxy-2,3,5-trimethoxyxanthone (2), along with eighteen known xanthones (3-20) were isolated from Swertia mussotii. Their structures were elucidated on the basis of extensive spectroscopic analyses (1D- and 2D-NMR, HRESIMS, UV, IR, [α]D). All compounds were evaluated for their anti-hepatitis B virus activities on HepG 2.2.15 cells line in vitro, and compounds 3-10 exhibited significant activity inhibiting hepatitis B virus DNA replication with IC50 values from 0.01 mM to 0.13 mM. Compounds 3-5 showed remarkable activity with IC50 values of 0.77, > 0.98, and 0.21 mM for HBsAg, and < 0.62, 0.35, and 0.04 mM for HBeAg, respectively. Meanwhile, the effects of different substitutions on the anti-hepatitis B virus activity of xanthones from S. mussotii were discussed.

Design, synthesis, and molecular hybrids of caudatin and cinnamic acids as novel anti-hepatitis B virus agents.

Forty-six conjugated derivatives of caudatin with substituted cinnamic acids were synthesized, and their anti-hepatitis B virus (HBV) activity was evaluated in HepG 2.2.15 cells. Most of the derivatives exhibited potent anti-HBV activity, especially inhibiting the HBV DNA replication with the IC(50) values from 2.44 to 22.89 µΜ. Compound 18 showed significant activity against the secretion of HBsAg, HBeAg, and HBV DNA replication with IC(50) values of 5.52, 5.52, 2.44 µΜ, respectively, and had good safety (LD(50) > 1250 mg/kg) according to the acute toxicity study. Preliminary mechanism investigation suggested that compound 18 exerted antivirus effects via interfering HBV X promoter and enhancer I to influence HBV transcriptions.