[Correlation between endogenous harmful components in mainstream cigarette smoke and chemical constituents in tobacco leaves].

Correlation analysis between main chemical constituents of tobacco leaves and endogenous harmful components in mainstream cigarette smoke was conducted. Leaf stalk positions exhibited a high relation with endogenous harmful components and hazard index (H). Upper stalk position leaves had greater release of 1-butanone,4-(methylnitrosoamino)-1-(3-pyridinyl)-(NNK), B[a]P, HCN, NH3 and phenol in mainstream cigarette smoke, and a higher hazard index than middle position leaves except for crotonaldehyde, which had greater release from middle position leaves.

Triterpenoids from the leaves of Toona ciliata.

One new limonoid, toonaciliatone A (1), and one new tirucallane-type triterpenoid, toonaciliatine A (4), along with three known compounds, methyl-3beta-acetoxy-1-oxomelic-14(15)-enate (2), perforin A (3), and cholest-14-ene-3,7,24,25-tetrol-21,23-epoxy-21-methoxy-4,4,8-trimethyl-3-(3-methyl-2-butenoate) (5), were isolated from the leaves of Toona ciliata. The structures of the new compounds were established by spectroscopic methods.

Tetranortriterpenoids from the Leaves of Cipadessa cinerascens.

Seven known and six new tetranortriterpenoids, cineracipadesins A-F (1-6), were isolated from the leaves of Cipadessa cinerascens. Compound 1 has a mexicanolide-type structural skeleton with a rare 9alpha,11alpha-epoxide ring; compound 2 has a methyl angolensate-type structure with 9,11-dihydroxy groups, representing the first example of a precursor of a trijugin-type limonoid; and 3 is the first reported methyl angolensate-type limonoid with a ketone group at ring C. Their structures were determined with extensive spectroscopic analysis.

Enriching plant microbiota for a metagenomic library construction.

Plant microbiota (the microorganisms that live in any associations with plant tissues) represents a rather unexplored area of metagenomic research compared with soils and oceans. Constructing a metagenomic library for plant microbiota is technically challenging. Using all the biomass without pre-enrichment could lead to vast proportions of the host plant DNA in the metagenomic library, doubtless obliterating the microbial contribution.