A Study on Chemical Characterization and Biological Abilities of Alstonia boonei Extracts Obtained by Different Techniques.

In the quest for novel therapeutic agents from plants, the choice of extraction solvent and technique plays a key role. In this study, the possible differences in the phytochemical profile and bioactivity (antioxidant and enzyme inhibitory activity) of the Alstonia boonei leaves and stem bark extracted using water, ethyl acetate and methanol, and different techniques, namely infusion, maceration and Soxhlet extraction, were investigated. Data collected showed that methanol extracts of both A. boonei leaves (48.34-53.08 mg gallic acid equivalent [GAE]/g dry extract) and stem bark (37.08-45.72 mg GAE/g dry extract) possessed higher phenolic content compared to the ethyl acetate extracts (leaves: 30.64-40.19 mg GAE/g; stem bark: 34.25-35.64 mg GAE/g). The methanol extracts of A. boonei leaves showed higher radical scavenging and reducing capacity, and these findings were in accordance with phenolic content results. In general, water extracts of A. boonei leaves and stem bark obtained by infusion were poor inhibitors of acetylcholinesterase, α-amylase, α-glucosidase, and tyrosinase, except for butyrylcholinesterase. The chemical profiles of the extracts were determined by UHPLC-MS and the presence of several compounds, such as phenolic acids (caffeic, chlorogenic and ferulic acids, etc.), flavonoids (rutin and isoquercetin) and flavonolignans (Cinchonain isomers). Cell viability was tested using the human peripheral blood monocytic cell line (THP-1), and the extracts were safe up to 25 µg/mL. In addition, anti-inflammatory effects were investigated with the releasing of IL-6 TNF-α and IL-1ß. In particular, stem bark extracts exhibited significant anti-inflammatory effects. Data presented in this study highlight the key role of solvent choice in the extraction of bioactive secondary metabolites from plants. In addition, this study appraises the antioxidant and enzyme inhibitory action of A. boonei leaves and stem bark, which are extensively used in traditional medicine.

Calceolarioside A, a Phenylpropanoid Glycoside from Calceolaria spp., Displays Antinociceptive and Anti-Inflammatory Properties.

Phenylpropanoid glycosides are a class of natural substances of plant origin with interesting biological activities and pharmacological properties. This study reports the antinociceptive and anti-inflammatory effects of calceolarioside A, a phenylpropanoid glycoside previously isolated from various Calceolaria species. In models of acute nociception induced by thermal stimuli, such as the hot plate and tail flick test, calceolarioside administered at doses of 1, 5, and 10 µg in the left cerebral ventricles did not modify the behavioral response of mice. In an inflammatory based persistent pain model as the formalin test, calceolarioside A at the high dose tested (100 µg/paw) reduced the licking activity induced by formalin by 35% in the first phase and by 75% in the second phase of the test. In carrageenan-induced thermal hyperalgesia, calceolarioside A (50 and 100 µg/paw) was able to significantly reverse thermal hyperalgesia induced by carrageenan. The anti-inflammatory activity of calceolarioside A was then assessed using the zymosan-induced paw edema model. Calceolarioside A (50 and 100 µg/paw) induced a significant reduction in the edema from 1 to 4 h after zymosan administration. Measuring IL-6, TNFα, and IL-1ß pro-inflammatory cytokines released from LPS-stimulated THP-1 cells, calceolarioside A in a concentration-dependent manner reduced the release of these cytokines from THP-1 cells. Taken together, our results highlight, for the first time, the potential and selective anti-inflammatory properties of this natural-derived compound, prompting its rationale use for further investigations.

Ammonium Glycyrrhizinate Prevents Apoptosis and Mitochondrial Dysfunction Induced by High Glucose in SH-SY5Y Cell Line and Counteracts Neuropathic Pain in Streptozotocin-Induced Diabetic Mice.

Glycyrrhiza glabra, commonly known as liquorice, contains several bioactive compounds such as flavonoids, sterols, triterpene, and saponins; among which, glycyrrhizic acid, an oleanane-type saponin, is the most abundant component in liquorice root. Diabetic peripheral neuropathy is one of the major complications of diabetes mellitus, leading to painful condition as neuropathic pain. The pathogenetic mechanism of diabetic peripheral neuropathy is very complex, and its understanding could lead to a more suitable therapeutic strategy. In this work, we analyzed the effects of ammonium glycyrrhizinate, a derivate salt of glycyrrhizic acid, on an in vitro system, neuroblastoma cells line SH-SY5Y, and we observed that ammonium glycyrrhizinate was able to prevent cytotoxic effect and mitochondrial fragmentation after high-glucose administration. In an in vivo experiment, we found that a short-repeated treatment with ammonium glycyrrhizinate was able to attenuate neuropathic hyperalgesia in streptozotocin-induced diabetic mice. In conclusion, our results showed that ammonium glycyrrhizinate could ameliorate diabetic peripheral neuropathy, counteracting both in vitro and in vivo effects induced by high glucose, and might represent a complementary medicine for the clinical management of diabetic peripheral neuropathy.

Viscum album L. homogenizer-assisted and ultrasound-assisted extracts as potential sources of bioactive compounds.

Viscum album L. (Mistletoe) is one of the most famous plants in many countries utilized for several purposes. The current study aimed to describe chemical profiles and biological activities of homogenizer-assisted extract (HAE) and ultrasound-assisted extract (UAE)) of V. album parts (leaf, fruits, and seeds). Antioxidant (radical scavenging, reducing power, metal chelation, and phosphomolybdenum assays) and enzyme inhibitory properties (cholinesterases, amylase, glucosidase, and tyrosinase) were selected for biological evaluation. Chemical profiles were studied by HPLC-MS/MS and 32 compounds were identified in the extracts; caffeoylquinic acids and its derivatives, dimethylated flavonoids were the most significant compounds. Generally, the leaf extracts exhibited the best antioxidant and enzyme inhibitory effects in our tests. Multivariate analysis was performed to obtain more information for these data, then strong correlations between total bioactive compounds and tested parameters were observed. The present findings encourage us to further investigate V. album as a potential candidate for pharmaceutical and nutraceutical applications. PRACTICAL APPLICATIONS: Viscum album L. commonly called European mistletoe is a woody perennial shrub growing on coniferous trees with lathery leaves, small flowers, and white berries. It belongs to the Santalaceae R. Br. family from Europe and western/southern Asia. Traditional medicine recognizes mistletoe as a folk remedy to manage inflammation, hypertension, ulcers, and other diseases due to the presence of different bioactive compounds, among them mistletoe lectins and viscotoxins. Recent studies documented the possible therapeutic applications of Viscum extracts in association with cancer's therapy leading to improvements in health and patient's quality of life. Thus, this work gives novel data regarding the phytochemical characterizations and antioxidant/enzymatic inhibitor activities of different types of extracts from seeds, leaves, and fruits of Viscum L. obtained by homogenizer-assisted and ultrasound-assisted techniques, in order to increase the data set of potential applications in medicine.

Discovery of Kynurenines Containing Oligopeptides as Potent Opioid Receptor Agonists.

Kynurenine (kyn) and kynurenic acid (kyna) are well-defined metabolites of tryptophan catabolism collectively known as "kynurenines", which exert regulatory functions in host-microbiome signaling, immune cell response, and neuronal excitability. Kynurenine containing peptides endowed with opioid receptor activity have been isolated from natural organisms; thus, in this work, novel opioid peptide analogs incorporating L-kynurenine (L-kyn) and kynurenic acid (kyna) in place of native amino acids have been designed and synthesized with the aim to investigate the biological effect of these modifications. The kyna-containing peptide (KA1) binds selectively the m-opioid receptor with a Ki = 1.08 ± 0.26 (selectivity ratio m/d/k = 1:514:10000), while the L-kyn-containing peptide (K6) shows a mixed binding affinity for m, d, and k-opioid receptors, with efficacy and potency (Emax = 209.7 + 3.4%; LogEC50 = -5.984 + 0.054) higher than those of the reference compound DAMGO. This novel oligopeptide exhibits a strong antinociceptive effect after i.c.v. and s.c. administrations in in vivo tests, according to good stability in human plasma (t1/2 = 47 min).

Antinociceptive potency of a fluorinated cyclopeptide Dmt-c[D-Lys-Phe-p-CF3-Phe-Asp]NH2.

Opioid peptides and opiate drugs such as morphine, mediate their analgesic effects, but also undesired side effects, mostly through activation of the mu opioid receptor. However, delta- and kappa-opioid receptors can also contribute to the analgesic effects of opioids. Recent findings showed that simultaneous activation of multiple opioid receptors may result in additional analgesia with fewer side effects. Here, we evaluated the pharmacological profile of our formerly developed mixed mu/kappa-opioid receptor ligands, Dmt-c[D-Lys-Phe-Phe-Asp]NH2 (C-36) and Dmt-c[D-Lys-Phe-p-CF3-Phe-Asp]NH2 (F-81). The ability of these peptides to cross the blood-brain barrier was tested in the parallel artificial membrane permeability (PAMPA) assay. On the basis of the hot-plate test in mice after central and peripheral administration, analog F-81 was selected for the anti-nociceptive and anti-inflammatory activity assessment after peripheral administration.

"Curcumin-loaded Poly (d, l-lactide-co-glycolide) nanovesicles induce antinociceptive effects and reduce pronociceptive cytokine and BDNF release in spinal cord after acute administration in mice".

Given the poor bioavailability of curcumin, its antinociceptive effects are produced after chronic intravenous administration of high doses, while poly (d,l-lactide-co-glycolide)-loaded vesicles (PLGA) can improve drug delivery. This paper investigates the antinociceptive effects of curcumin-loaded PLGA nanovesicles (PLGA-CUR) administered via intravenous (i.v.) or intrathecal (i.t.) routes at low and high doses. The following models of pain were used: formalin test, zymosan-induced hyperalgesia and sciatic nerve ligation inducing neuropathic allodynia and hyperalgesia. PLGA-CUR administered intravenously was able to reduce the response to nociceptive stimuli in the formalin test and hyperalgesia induced by zymosan. Curcumin, instead, was inactive. Low-dose i.t. administration of PLGA-CUR significantly reduced allodynia produced by sciatic nerve ligation, whereas low doses of curcumin did not change the response to nociceptive stimuli. Long-lasting antinociceptive effects were observed when high doses of PLGA-CUR were administered intrathecally. At high doses, i.t. administration of curcumin only exerted rapid and transient antinociceptive effects. Measurement of cytokine and BDNF in the spinal cord of neuropathic mice demonstrate that the antinociceptive effects of PLGA-CUR depend on the reduction in cytokine release and BDNF in the spinal cord. The results demonstrate the effectiveness of PLGA-CUR and suggest that PLGA-CUR nanoformulation might be a new potential drug in the treatment of pain.

First evidence for an anxiolytic effect of a diterpenoid from Salvia cinnabarina.

The potential anxiolytic and anti-depressive activity of CMP1 was studied in the elevated plus-maze test and in the forced swimming test. Furthermore, CMP1 sedative activity was evaluated in pentobarbital treated animals; the effect of CMP1 on spontaneous motor activity (total locomotion) was also evaluated. Our data show that CMP1, at doses that did not affect locomotion, was able to induce anxiolytic and sedative, but not anti-depressive effects. In conclusion, our results represent first evidence for an anxiolytic activity of this diterpenoid from Salvia cinnabarina.