Abstract. Synapsin I is a synaptic vesicle-specific phosphoprotein composed of a globular and hydrophobic head and of a proline-rich, elongated and basic tail Synapsin I binds with high affinity to phospholipid and protein components of synaptic vesicles. The head region of the protein has a very high surface activity, strongly interacts with acidic phospholipids and penetrates the hydrophobic core of the vesicle membrane. In the present paper, we have investigated the possible functional effects of the interaction between synapsin I and vesicle phospholipids. Synapsin I enhances both the rate and the extent of CaZ+-dependent membrane fusion, although it has no detectable fusogenic activity per se. This effect, which appears to be independent of synapsin I phosphorylation and localized to the head region of the protein, is attributable to aggregation of adjacent vesicles. The facilitation of Ca2÷-induced liposome fusion is maximal at 50-80% of vesicle saturation and then decreases steeply, whereas vesicle aggregation does not show this biphasic behavior. Association of synapsin I with phospholipid bilayers does not induce membrane destabilization. Rather, 31p-nuclear magnetic resonance spectroscopy demonstrated that synapsin I inhibits the transition of membrane phospholipids from the bilayer (L) to the inverted hexagonal (Hn) phase induced either by increases in temperature or by Ca 2+. These properties might contribute to the remarkable selectivity of the fusion of synaptic vesicles with the presynaptic plasma membrane during exocytosis.

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Cannabis sativa L. is a dioecious plant belonging to the Cannabaceae family. The discovery of the presence of many biologically-active metabolites (cannabinoids) in fibre-type Cannabis (hemp) has recently given rise to the valorisation of this variety. In this context, the present study was aimed at the multi-component analysis and determination of the main non-psychoactive cannabinoids (cannabidiol, cannabidiolic acid, cannabigerol and cannabigerolic acid) in female inflorescences of different hemp varieties by means of 13C quantitative nuclear magnetic resonance spectroscopy (qNMR). The method proposed here for the first time for the determination of cannabinoids provided reliable results in a competitive time with respect to the more consolidated HPLC technique. In fact, it gave sufficiently precise and sensitive results, with LOQ values lower than 750 μg/mL, which is easily achievable with concentrated extracts, without affecting the quality of 13C-qNMR spectra. In conclusion, this method can be considered as a promising and appropriate tool for the comprehensive chemical analysis of bioactive cannabinoids in hemp and other derived products in order to ensure their quality, efficacy and safety.

Propolis has various biological activities closely related to the composition which varies according to environmental factors and also to the method of production. The present study was aimed at determining whether or not HR-NMR and multivariate statistical analysis were able to classify propolis according to the method used to harvest it. Sixty propolis samples were analysed in all. The ethanolic propolis extracts were initially analysed for quantification of the main bioactive substances, balsams and waxes. The 1H NMR and heteronuclear multiple bond correlation (HMBC) spectra were then acquired. Spectral data were analysed by application of multivariate statistical techniques (Factor Analysis and General Discriminant Analysis). The best results were obtained using the 1H NMR which furnishes a sufficiently effective model by analysing the spectral region between 4.50 and 13.00 ppm (predictive capacity: 96.7%).Keywoards: propolis; NMR; chemometrics; harvesting methods; chemical fingerprint