Specialized cockroach pollination in the rare and endangered plant Vincetoxicum hainanense in China.

PREMISE: Species of Apocynaceae are pollinated by a diverse assemblage of animals. Here we report the first record of specialized cockroach pollination in the family, involving an endangered climbing vine species, Vincetoxicum hainanense in China. Experiments were designed to provide direct proof of cockroach pollination and compare the effectiveness of other flower visitors. METHODS: We investigated the reproductive biology, pollination ecology, pollinaria removal, pollinia insertion, and fruit set following single visits by the most common insects. In addition, we reviewed reports of cockroaches as pollinators of other plants and analyzed the known pollination systems in Vincetoxicum in a phylogenetic context. RESULTS: The small, pale green flowers of V. hainanense opened during the night. The flowers were not autogamous, but were self-compatible. Flower visitors included beetles, flies, ants and bush crickets, but the most effective pollinator was the cockroach Blattella bisignata, the only visitor that carried pollen between plants. Less frequent and effective pollinators are ants and Carabidae. Plants in this genus are predominantly pollinated by flies, moths and wasps. CONCLUSIONS: Globally, only 11 plant species are known to be cockroach-pollinated. Because their range of floral features encompass similarities and differences, defining a "cockroach pollination syndrome" is difficult. One commonality is that flowers are often visited by insects other than cockroaches, such as beetles, that vary in their significance as pollinators. Cockroach pollination is undoubtedly more widespread than previously thought and requires further attention.

Chemical constituents with inhibition against TNF-α from Merrillanthus hainanensis.

Two new steroidal glycosides oxystauntoside A (1) and oxystauntoside B (2), together with sixteen known compounds (3-18) were isolated from the 95% ethanol extract of Merrillanthus hainanensis. Their structures were characterized by extensive spectroscopic analysis including NMR and mass spectra and single crystal X-ray crystallography. The absolute configuration of 1 and 2 were further determined by ECD calculations. All of these compounds were isolated from M. hainanensis for the first time. All the fractions and compounds were tested for the anti-inflammatory activity against the TNF-α factor. The ethyl acetate fraction showed the most potent inhibition (71.3%) at 10 µg/mL and compounds 5 (78.9%) and 9 (73.4%) in this fraction with both carboxyl and phenolic hydroxyl groups showed significant inhibition at 10 µM. Our study provided the first scientific report for the medicinal value of M. hainanensis.