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Abstract: The stable carbon isotope ratio of archaeological human skeletons has been increasingly used to reconstruct paleodiet, which in turn may provide deep insight into the origin and spread of agriculture. However, little is known about the spatial and temporal variability of some staple crops in many areas of the world. Here, we present radiocarbon ages and stable carbon isotope data of charred millet and rice grains from 14 Neolithic and Bronze Age archaeological sites in the lower Yellow River area, a region which has not been adequately considered. The mean δ13C value of prehistoric millet grains is −9.13‰, which is ca. 2‰ higher than that of modern millet grains. The mean δ13C value of prehistoric rice grains is −24.14‰, which is very close to that of modern rice grains. Our study not only provides updated information that facilitates a more precise reconstruction of human paleodiet based on δ13C analysis of skeletal remains, but also supports previous conclusions that C4 plants can be used as a reliable proxy for atmospheric carbon isotopic composition. [ABSTRACT FROM AUTHOR]

A chemical investigation of the plant Psidium guajava L., collected in Guangdong province, afforded two novel skeleton sesquiterpenoids 1 and 2. Compound 2 also known as isocaryolan-9-one was a new natural product. The structure of the novel compound 1 was determined as guavacid A by various spectroscopic methods. A possible biosynthetic pathway for 1 and 2 was proposed. [ABSTRACT FROM AUTHOR]

Objective: To study the chemical constituents from ethyl acetate extract of Psidium guajava leaves., Methods: The constituents were separated and purified by silica gel and Sephadex LH-20 column chromatography and their structures were identified on the basis of physicochemical properties and spectral data., Results: Eleven compounds were isolated and identified as 6,10,14-trimethyl-2-pentadecanone (1), phytyl-acetate (2), cubenol (3), eucalyptin (4), n-docosanoic acid-p-hydroxy-phenethylol ester (5),8-methyl-5,7- dihydroxy-flavonone (6), 6-methyl-5,7-dihydroxy-flavonone (7), betulinic acid (8), carnosol (9), quercetin (10), and 2,4,6-tirhydroxy- 3,5-dimethyl-diphenylketone-4-O-(6'"-O-galloyl)-β-D-glucoside (11)., Conclusion: Compounds 1-9 are isolated from this plant for the first time.

Objective: To analyze the chemical components of essential oil from the leaves of Rubus corchorifolius., Methods: The essential oil was extracted by steam distillation, and then an analysis was conducted by applying GC-MS and Xcalibur Software. K-B filter paper method was used for their bacteriostasish., Results: 44 compounds were identified, accounting for 88.52% of the total essential oil. The volatile oil concentration of 50% had a good bactericidal effect and the concentration of 0.5% still had excellent antibacterial effect., Conclusion: It provides the foundation for reasonable utilization and development of the leaves of Rubus corchorifolius.