Landform and lithospheric development contribute to the assembly of mountain floras in China.

Although it is well documented that mountains tend to exhibit high biodiversity, how geological processes affect the assemblage of montane floras is a matter of ongoing research. Here, we explore landform-specific differences among montane floras based on a dataset comprising 17,576 angiosperm species representing 140 Chinese mountain floras, which we define as the collection of all angiosperm species growing on a specific mountain. Our results show that igneous bedrock (granitic and karst-granitic landforms) is correlated with higher species richness and phylogenetic overdispersion, while the opposite is true for sedimentary bedrock (karst, Danxia, and desert landforms), which is correlated with phylogenetic clustering. Furthermore, we show that landform type was the primary determinant of the assembly of evolutionarily older species within floras, while climate was a greater determinant for younger species. Our study indicates that landform type not only affects montane species richness, but also contributes to the composition of montane floras. To explain the assembly and differentiation of mountain floras, we propose the 'floristic geo-lithology hypothesis', which highlights the role of bedrock and landform processes in montane floristic assembly and provides insights for future research on speciation, migration, and biodiversity in montane regions.

Novel and Neuroprotective Tetranortriterpenoids from Chinese Mangrove Xylocarpus granatum Koenig.

Eight new tetranortriterpenoids (1-8) were isolated from the twigs and leaves of the Chinese mangrove plant Xylocarpus granatum, together with four related known ones (9-12). The structures of new compounds were elucidated by detailed spectroscopic analysis. The absolute configuration of 9-epixylogranatin A (1) was determined by time-dependent density functional theory-electronic circular dichroism (TDDFT-ECD) calculations of the solution conformers. Xylogranatumin A (2) represents the first example of the 9, 10-seco limonoid with an unprecedented oxygen-bridged B ring (2,7-dioxabicyclo[2.2.1]-heptane). All the isolates were evaluated for the in vitro neuroprotective activity, both compounds 11 and 12 displayed moderate effects against H2O2-induced neurotoxicity in PC12 cells at the concentration of 10 µM, with an increase in cell viability of 12.0% and 11.6%, respectively.

Testing stem cell therapy in a rat model of inflammatory bowel disease: role of bone marrow stem cells and stem cell factor in mucosal regeneration.

BACKGROUND: The gastrointestinal (GI) mucosal cells turnover regularly under physiological conditions, which may be stimulated in various pathological situations including inflammation. Local epithelial stem cells appear to play a major role in such mucosal renewal or pathological regeneration. Less is clear about the involvement of multipotent stem cells from blood in GI repair. We attempted to explore a role of bone marrow mesenchymal stromal cells (BMMSCs) and soluble stem cell factor (SCF) in GI mucosa regeneration in a rat model of inflammatory bowel diseases (IBD). METHODS: BMMSCs labelled with the fluorescent dye PKH26 from donor rats were transfused into rats suffering indomethacin-induced GI injury. Experimental effects by BMMSCs transplant and SCF were determined by morphometry of intestinal mucosa, double labeling of PKH26 positive BMMSCs with endogenous proliferative and intestinal cell markers, and western blot and PCR analyses of the above molecular markers in the recipient rats relative to controls. RESULTS: PKH26 positive BMMSCs were found in the recipient mucosa, partially colocalizing with the proliferating cell nuclear antigen (PCNA), Lgr5, Musashi-1 and ephrin-B3. mRNA and protein levels of PCNA, Lgr5, Musashi-1 and ephrin-B3 were elevated in the intestine in BMMSCs-treated rats, most prominent in the BMMSCs-SCF co-treatment group. The mucosal layer and the crypt layer of the small intestine were thicker in BMMSCs-treated rats, more evident in the BMMSCs-SCF co-treatment group. CONCLUSION: BMMSCs and SCF participate in but may play a synergistic role in mucosal cell regeneration following experimentally induced intestinal injury. Bone marrow stem cell therapy and SCF administration may be of therapeutic value in IBD.

Absolute configurations of integracins A, B, and 15'-dehydroxy-integracin B.

Integracins A (1) and B (2), potent HIV-1 integrase inhibitors, and 15'-dehydroxy-integracin B (3) were isolated for the first time from Chinese mangrove plant Sonneratia hainanensis. Their absolute configurations were determined by the Mosher's method and specific rotation analysis of alcohols (6 and 7) obtained from integracin A in two steps and by chemical correlation. Integracin A (1) also exhibited significant cytotoxicity against the tumor cell lines HepG2 and NCI-H460 with both 100% inhibitions at 25 µg/ml.

Paracaseolide A, first α-alkylbutenolide dimer with an unusual tetraquinane oxa-cage bislactone skeleton from Chinese mangrove Sonneratia paracaseolaris.

A novel α-alkylbutenolide dimer, paracaseolide A (2), characterized by an unusual tetraquinane oxa-cage bislactone skeleton bearing two linear alkyl chains, was isolated from the mangrove plant Sonneratia paracaseolaris. The structure of 2 was elucidated by extensive spectroscopic analysis. A plausible retrosynthetic pathway for paracaseolide A (2) was proposed. Compound 2 exhibited significant inhibitory activity against dual specificity phosphatase CDC25B, a key enzyme for cell cycle progression, with an IC(50) value of 6.44 µM.

Piperidine alkaloids from Chinese mangrove Sonneratia hainanensis.

A new diphenacyl-piperidine alkaloid, sonneratine A (2), identified as a piperidine ring bearing two phenacyl substitutes at C-2 and C-6, and a known related derivative, (+/-)1-(2-piperidyl)-4-( P-methoxyphenyl)-butanone-2 (3), were isolated from the leaves and stems of the Hainan mangrove Sonneratia hainanensis. The structure of the new compound was determined by extensive analysis of its spectroscopic data and by comparison of its NMR data with those reported in the literature.

Diastereoisomeric macrocyclic polydisulfides from the mangrove Bruguiera gymnorrhiza.

The uncommon macrocyclic polydisulfides, trans-3,3'-dihydroxy-1,5,1',5'-tetrathiacyclodecane (1), cis-3,3'-dihydroxy-1,5,1',5'-tetrathiacyclodecane (2), along with five known related cyclic disulfides, gymnorrhizol (3), neogymnorrhizol (4), bruguiesulfurol (5), brugierol (6), and isobrugierol (7), were isolated from the mangrove Bruguiera gymnorrhiza collected from Guangdong Province, China. Structures of compounds 1 and 2 were determined by extensive analysis of their spectroscopic data, by comparison of their NMR spectroscopic data with those of the co-occurring known compounds, as well as by single-crystal X-ray diffraction analysis. A possible biogenetic origin was also proposed.