The comparison of biochemical composition of Actinidia kolomikta and Actinidia polygama fruits

The demand for natural products, which are rich in biologically active compositions, grows constantly. The choice and production of such products can minimize the deficit of importance for human organism components, which are contained only in plant food. The paper contains the laboratory studying results of the chemical composition of the fruits of two Actinidia Lindl. cultivars of Federal State Budgetary Scientific Institution Federal Horticultural Research Center for Breeding, Agrotechnology, and Nursery (FSBSI FSC for Horticulture) genetic collection: Actinidia kolomikta (Rupr. et Maxim.) Maxim. and Actinidia polygama (Siebold et Zucc.) Maxim. All the presented samples are grown in field conditions. The fruits were picked up in the phase of harvest maturity while ripening. The data on antioxidant activity of water and methanol extracts, the content of phenolic compounds sum, soluble solids, and titratable acids in the fruits, and on qualitative composition of secondary metabolites (organic acids, fatty acids, mono-, di- and polysaccharides) are given in the paper. The variation limits of the parameters under study depending on the sample are presented. As a result of the laboratory studies, it was stated that A. kolomikta fruits 10 times exceed A. polygama fruits on all the stated parameters. Only the results on the soluble solids content in the fruits of both cultivars are approximately at the same level (A. kolomikta > A. polygama on 1.16%). The positive correlation between antioxidant activity and the general content of polyphenols is confirmed at both cultivars. Actinidia kolomikta genotypes Chempion and Lakomka and Actinidia polygama ones Tselebnaya and Uzorchataya showed the best results. The correct individual choice of actinidia fruits that are the best ones at the biochemical composition and the content of micronutrients allows supplying the consumers with food products.

Lactobacillus reuteri BM53-1 Produces a Compound That Inhibits Sticky Glucan Synthesis by Streptococcus mutans

Cariogenic bacteria, such as Streptococcus (S.) mutans and S. sobrinus, produce insoluble and sticky glucans as a biofilm material. The present study demonstrates that a lactic acid bacterium (LAB) named BM53-1 produces a substance that inhibits the sticky glucan synthesis. The BM53-1 strain was isolated from a flower of Actinidia polygama and identified as Lactobacillus reuteri. The substance that inhibits sticky glucan synthesis does not exhibit antibacterial activity against S. mutans. The cariogenic S. mutans produces glucans under the control of three glucosyltransferase (GTF) enzymes, named GtfB, GtfC, and GtfD. Although GtfB and GtfC produce insoluble glucans, GtfD forms soluble glucans. Through quantitative reverse-transcriptional (qRT)-PCR analysis, it was revealed that the BM53-1-derived glucan-production inhibitor (GI) enhances the transcriptions of gtfB and gtfC genes 2- to 7-fold at the early stage of cultivation. However, that of gtfD was not enhanced in the presence of the GI, indicating that the glucan stickiness produced by S. mutans was significantly weaker in the presence of the GI. Our result demonstrates that Lb. reuteri BM53-1 is useful to prevent dental caries.

The characteristic response of domestic cats to plant iridoids allows them to gain chemical defense against mosquitoes

Domestic cats and other felids rub their faces and heads against catnip (Nepeta cataria) and silver vine (Actinidia polygama) and roll on the ground as a characteristic response. While this response is well known, its biological function and underlying mechanism remain undetermined. Here, we uncover the neurophysiological mechanism and functional outcome of this feline response. We found that the iridoid nepetalactol is the major component of silver vine that elicits this potent response in cats and other felids. Nepetalactol increased plasma β-endorphin levels in cats, while pharmacological inhibition of μ-opioid receptors suppressed the classic rubbing response. Rubbing behavior transfers nepetalactol onto the faces and heads of respondents where it repels the mosquito, Aedes albopictus. Thus, self-anointing behavior helps to protect cats against mosquito bites. The characteristic response of cats to nepetalactol via the μ-opioid system provides an important example of chemical pest defense using plant metabolites in nonhuman mammals.

Iridoids content in aboveground plant organs of berry crops

A study of iridoid content in fruits, leaves and sprouts of untraditional berry plants — Actinidia polygama, Actinidia macrosperma, Viburnum opulus and Lonicera caerulea is presented. The highest content of iridoids is observed in the fruits, buds and leaves of V. opulus. It was determined, that their content in the bark and the leaves of the plants during vegetation almost do not change and reach 2–3%. Meanwhile the content of iridoids in the fruits varies in more broad bounds and depends on the phase of growth of the plants. So, it reaches 6.85% at the end of July, but it was equals to 3.75% at the end of September. The highest content of iridoids was found in unripe fruits of Viburnum. The fruit, bark and leaves of bitter-fruited form V. opulus have the higher content of iridoids compared to sweet-fruited. There were not any iridoids in roots of both forms of V. opulus. The presence of iridoids in the fruit and leaves of A. polygama and A. macrosperma in the introduction of conditions in the forest-steppe of Ukraine was found. Given this, the leaves of these species, especially A. macrosperma, can be used as a medicinal plant. It was found, that A. polygama leaves, which change its color to silver, have higher contents of iridoids compared to green ones (silver leaves — 0.22%, green leaves — 0.18%). In fruits of honeysuckle, which do not have a bitter taste, iridoids are not found, while, forms and varieties of L. caerulea with bitter fruits accumulate the largest quantity of iridoids. So, when using fruits V. opulus and L. caerulea as medicinal plants, bitter-fruited forms should be preferred.