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Plants evolve the production of wound-activated compounds (WACs) to reduce grazing pressure. In addition, several plant-produced WACs are recognized by various invertebrates, playing the role of infochemicals. Due to co-evolutionary processes, some invertebrates recognize plant infochemicals and use them to identify possible prey, detect the presence of predators or identify algae containing various classes of toxic metabolites. Different metabolites present in the same algae can play the role of toxins, infochemicals or both simultaneously. We investigated the infochemical activity of compounds extracted from three diatoms epiphytes of the seagrass Posidonia oceanica, by conducting choice experiments on invertebrates living in the same community or in close proximity. Furthermore, the specific toxicity of the extracts obtained from the same algae was tested on sea urchin embryos using a standard bioassay procedure, to detect the presence of toxins. The comparison of the two effects demonstrated that invertebrates are subjected to diatom wound-activated toxicants when these algae are not associated with their own habitat, but they are able to recognize volatile infochemicals derived from diatoms associated with their habitats. The specific toxicity of WACs was shown to be inversely correlated to the perceptive ability of invertebrates towards volatile compounds liberated by the same algae. Hence, when the recognition of specific algae by a given invertebrate species evolves, their detrimental effects on the receiving organism may be lost., Introduction Diatoms are an important component of marine food webs (Steele 1974), and they represent one of the main food sources in the marine planktonic environment, as well as for [...]

The growing global need for antioxidative phenolics and flavonoids for maintenance of human health resulted into search of new sustainable unexplored medicinal plants used by the traditional healers for various ailments. Many synthetic based products of phenolics and flavonoids have been used, however the demand of eco-friendly, natural herbal based products are increasing. As a result, the current study aims to explore traditional potential of Polygonum posumbu related to its phenolics and flavonoids. Optimization of extraction parameters were employed which includes: solvent selection (water, ethanol, methanol, acetone and ethyl acetate), ethanol composition (40–100%), solvent to sample ratio (30–70 ml/g), temperature (50–80 °C) and time (1–5 h). Under optimal conditions, total phenolics (TPC), total flavonoids (TFC), the extract yield (EY) and antioxidant activities of leaves extract were 162.79 ± 2.28 mg GAE/g, 56.57 ± 6.22 mg QE/g 27.96 ± 0.91%, and 27.34 ± 0.98 μg/ml respectively. Seven flavonoids were quantified in different tissues with significant (p ≤ 0.05) differences found in flavonoids contents in different parts of the plant. Highest concentration of flavonoids was observed in stems: (−)-epicatechin-53.19 ± 1.13 mg/g, myricetin-15.90 ± 0.13 mg/g, quercetin-50.66 ± 0.08 mg/g, luteolin-43.10 ± 0.47 mg/g, apigenin-16.73 ± 0.43 mg/g. Leaves and roots had the highest amount of genistein (05.06 ± 0.01 mg/g) and kaempferol (11.13 ± 0.06 mg/g) respectively. From the study it had been found that Polygonum posumbu possess a very good amount of phenolics and flavonoids and this study details first ever investigation on this plant in terms of phenolics and flavonoids. Therefore, this study enhanced the importance of this bioresource in functional food or nutraceutical industries. [Display omitted] • Extraction of phenolics and flavonoids from Polygonum posumbu 's leaves is reported for the first time. • An optimal extraction condition was establishsed. • HPLC analysis identified and quantified seven flavonoid compounds. • Flavonoid compounds content were compared among three different tissues of the plant. • Stems showed the highest content of flavonoid compounds. [ABSTRACT FROM AUTHOR]