The genus Sambucus includes up to 18 species, among them the widely known and used Sambucus nigra L. Elderberry fruits are rich in sugars, organic acids as well in anthocyanins and other polyphenols. The beneficial health-promoting effects of elderberries and elderflowers are well known, including beneficial effects against degenerative diseases (cardiovascular and inflammatory diseases), cancer, and diabetes, presenting antioxidant, anti-inflammatory, immune-stimulating, chemo-preventive, and atheroprotective effects. Although currently they are mainly used in the food industry as food colorants and flavouring agents due to their phytochemical composition and related bioactivities, elderberries and elderflowers or their extracts are becoming attractive for other uses such as food supplements, nutraceutical ingredients and as raw materials for the pharmaceutical industries.

In this work, three pesticides of different physicochemical properties: glyphosate (GLY, herbicide), imidacloprid (IMD, insecticide), and imazalil (IMZ, fungicide), were selected to assess their cytotoxicity against Caco-2 and HepG2 cells. Cell viability was assessed by the Alamar Blue assay, after 24 and 48 h exposure to different concentrations, and IC₅₀ values were calculated. The mechanisms underlying toxicity, namely cellular reactive oxygen species (ROS), glutathione (GSH) content, lipid peroxidation, loss of mitochondrial membrane potential (MMP), and apoptosis/necrosis induction were assessed by flow cytometry. Cytotoxic profiles were further correlated with the molecular physicochemical parameters of pesticides, namely: water solubility, partition coefficient in an n-octanol/water (Log P_ow) system, topological polar surface area (TPSA), the number of hydrogen-bonds (donor/acceptor), and rotatable bonds. In vitro outputs resulted in the following toxicity level: IMZ (Caco-2: IC₅₀ = 253.5 ± 3.37 μM, and HepG2: IC₅₀ = 94 ± 12 μM) > IMD (Caco-2: IC₅₀ > 1 mM and HepG2: IC₅₀ = 624 ± 24 μM) > GLY (IC₅₀ >>1 mM, both cell lines), after 24 h treatment, being toxicity time-dependent (lower IC₅₀ values at 48 h). Toxicity is explained by oxidative stress, as IMZ induced a higher intracellular ROS increase and lipid peroxidation, followed by IMD, while GLY did not change these markers. However, the three pesticides induced loss of MMP in HepG2 cells while in Caco-2 cells only IMZ produced significant MMP loss. Increased ROS and loss of MMP promoted apoptosis in Caco-2 cells subjected to IMZ, and in HepG2 cells exposed to IMD and IMZ, as assessed by Annexin-V/PI. The toxicity profile of pesticides is directly correlated with their Log P_ow, as affinity for the lipophilic environment favours interaction with cell membranes governs, and is inversely correlated with their TPSA; however, membrane permeation is favoured by lower TPSA. IMZ presents the best molecular properties for membrane interaction and cell permeation, i.e., higher Log P_ow, lower TPSA and lower hydrogen-bond (H-bond) donor/acceptor correlating with its higher toxicity. In conclusion, molecular physicochemical factors such as Log P_ow, TPSA, and H-bond are likely to be directly correlated with pesticide-induced toxicity, thus they are key factors to potentially predict the toxicity of other compounds.

BACKGROUND: The chemical composition, phenylalanine ammonia‐lyase (PAL), polyphenol oxidase (PPO) and peroxidase (POD) activity of the three main Portuguese elderberry cultivars were determined for the first time through five stages of maturation, in different harvesting years, to gain a deeper understanding of the effect of climatic conditions and enzymatic activity involved in the synthesis and degradation of phenolic compounds on the final quality of elderberries.RESULTS: Simple sugar and anthocyanin content increased with maturation but total acidity and flavonoids content decreased, and cinnamic acids did not show a clear trend. Climatic conditions seem to have a decisive influence on the elderberry maturation, namely the total number of hot (>30 °C) days. The PAL, PPO, and POD activity can explain the differences observed in elderberry phenolic content.CONCLUSION: These results highlighted the influence of climatic conditions in each harvesting season on elderberry development and quality. © 2022 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.