Polyphenolic acids are the widely occurring natural products in almost each herbal plant, among which rosmarinic acid (RA, C 18 H 16 O 8 ) is well-known, and is present in over 160 species belonging to many families, especially the Lamiaceae. Aside from this herbal ingredient, dozens of its natural derivatives have also been isolated and characterized from many natural plants. In recent years, with the increasing focus on the natural products as alternative treatments, a large number of pharmacological studies have been carried out to demonstrate the various biological activities of RA such as anti-inflammation, anti-oxidation, anti-diabetes, anti-virus, anti-tumor, neuroprotection, hepatoprotection, etc. In addition, investigations concerning its biosynthesis, extraction, analysis, clinical applications, and pharmacokinetics have also been performed. Although many achievements have been made in various research aspects, there still exist some problems or issues to be answered, especially its toxicity and bioavailability. Thus, we hope that in the case of natural products, the present review can not only provide a comprehensive understanding on RA covering its miscellaneous research fields, but also highlight some of the present issues and future perspectives worth investigating later, in order to help us utilize this polyphenolic acid more efficiently, widely, and safely.

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For many years, the battle between humans and the multitudes of infection and disease causing pathogens continues. Emerging at the battlefield as some of the most significant challenges to human health are bacterial resistance and its rapid rise. These have become a major concern in global public health invigorating the need for new antimicrobial compounds. A rational approach to deal with antibiotic resistance problems requires detailed knowledge of the different biological and non-biological factors that affect the rate and extent of resistance development. Combination therapy combining conventional antibiotics and essential oils is currently blooming and represents a potential area for future investigations. This new generation of phytopharmaceuticals may shed light on the development of new pharmacological regimes in combating antibiotic resistance. This review consolidated and described the observed synergistic outcome between essential oils and antibiotics, and highlighted the possibilities of essential oils as the potential resistance modifying agent.

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Efflux pump genes and proteins are present in both antibiotic-susceptible and antibiotic-resistant bacteria. Pumps may be specific for one substrate or may transport a range of structurally dissimilar compounds (including antibiotics of multiple classes); such pumps can be associated with multiple drug (antibiotic) resistance (MDR). However, the clinical relevance of efflux-mediated resistance is species, drug, and infection dependent. This review focuses on chromosomally encoded pumps in bacteria that cause infections in humans. Recent structural data provide valuable insights into the mechanisms of drug transport. MDR efflux pumps contribute to antibiotic resistance in bacteria in several ways: (i) inherent resistance to an entire class of agents, (ii) inherent resistance to specific agents, and (iii) resistance conferred by overexpression of an efflux pump. Enhanced efflux can be mediated by mutations in (i) the local repressor gene, (ii) a global regulatory gene, (iii) the promoter region of the transporter gene, or (iv) insertion elements upstream of the transporter gene. Some data suggest that resistance nodulation division systems are important in pathogenicity and/or survival in a particular ecological niche. Inhibitors of various efflux pump systems have been described; typically these are plant alkaloids, but as yet no product has been marketed.

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Background and aims Silicon (Si) in plants provides structural support and improves tolerance to diseases, drought and metal toxicity. Shoot Si concentrations are generally considered to be greater in monocotyledonous than in non-monocot plant species. The phylogenetic variation in the shoot Si concentration of plants reported in the primary literature has been quantified. Methods Studies were identified which reported Si concentrations in leaf or non-woody shoot tissues from at least two plant species growing in the same environment. Each study contained at least one species in common with another study. Key results Meta-analysis of the data revealed that, in general, ferns, gymnosperms and angiosperms accumulated less Si in their shoots than non-vascular plant species and horsetails. Within angiosperms and ferns, differences in shoot Si concentration between species grouped by their higher-level phylogenetic position were identified. Within the angiosperms, species from the commelinoid monocot orders Poales and Arecales accumulated substantially more Si in their shoots than species from other monocot clades. Conclusions A high shoot Si concentration is not a general feature of monocot species. Information on the phylogenetic variation in shoot Si concentration may provide useful palaeoecological and archaeological information, and inform studies of the biogeochemical cycling of Si and those of the molecular genetics of Si uptake and transport in plants.

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The enzyme xanthine oxidase catalyses the oxidation of hypoxanthine to xanthine and then to uric acid, which plays a crucial role in gout. A total of 122 traditional Chinese medicinal plants, selected according to the clinical efficacy and prescription frequency for the treatment of gout and other hyperuricemia-related disorders, have been evaluated for the enzyme inhibitory activity. Among the 122 methanol extracts derived from these species, 69 were shown to be inhibitory at 100 microg/ml, with 29 having greater than 50% inhibition. As to the equal amount of water extracts, 40 were disclosed to be active at 100 microg/ml, with 13 possessing more than 50% inhibition. At 50 microg/ml, 58 methanol and 24 water extracts exhibited inhibitory activity, with 15 of the former and two of the latter showing greater than 50% inhibition. The most active was the methanol extract of the twig of Cinnamomum cassia (Lauraceae) (IC(50), 18 microg/ml), which was followed immediately by those of the flower of Chrysanthemum indicum (Asteraceae) (IC(50), 22 microg/ml) and the leaves of Lycopus europaeus (Lamiatae) (IC(50), 26 microg/ml). Among the water extracts, the strongest inhibition of the enzyme was observed with that of the rhizome of Polygonum cuspidatum (Polygonaceae) (IC(50), 38 microg/ml). The IC(50) value of allopurinol used as a positive control was 1.06 microg/ml. The study demonstrated that the effects for these medicinal plants used for the gout treatment were based, at least in part, on the xanthine oxidase inhibitory action.

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