Re-discovering Prunus fruit varieties as antiangiogenic agents by metabolomic and bioinformatic approach

In this work, a comparative chemical-biological study of nine plum varieties (Prunus domestica L. and Prunus salicina Lindl.) with two commercial ones was carried out to improve their cultivation and use in the agri-food chain. The chemical quali-quantitative fingerprint by HR-Orbitrap/ESI-MS showed similar profiles, being 'Rossa Casa Velasco' the richest in phenols and anthocyanins. All the extracts were investigated for their in vitro antioxidant as well as antiangiogenic activity by two in vivo models, chick chorioallantoic membrane and zebrafish embryos. Among investigated varieties 'Scarrafona', 'Rusticano', 'Marisa', 'Rossa Casa Velasco', 'Verdone', and 'Sangue di Drago' showed the best antiangiogenic activities (30-50 % inhibition). Finally, the chemical/biological datasets processed with a bioinformatic approach revealed that a large group of flavonoids, procyanidins, and anthocyanins significantly correlated with all the three antioxidant tests (DPPH, FRAP, and ABTS), while quinic acid and icariside F2 resulted positively correlated with CAM at both 100 and 200 μg/egg.

Tributyltin causes generational neurodevelopmental toxicity and the protective effect of folic acid in zebrafish

Tributyltin (TBT), a common organotin environmental pollutant, may pose a threat to human development during critical early-life periods. We aimed to assess the neurodevelopmental intergenerational toxicity of early-life exposure to TBT and the protective effect of DNA methyl donor folic acid (FA). Specifically, after early-life exposure (1-21 days post-fertilization, dpf) to TBT (0, 1, 10 and 100 ng/L), zebrafish (Danio rerio) were cultured in clean medium until sexual maturity. The exposed females were mated with unexposed males to produce embryos (F1). The F1 generation were cultured (4-120 hours post-fertilization, hpf) with and without 1 mmol/L FA. The neurotoxic effects of early-life TBT exposure for zebrafish and their offspring (F1) were significantly enhanced anxiety and reduced aggression, decreased gene expression of DNA methyltransferase in the brain and increased serotonin levels in the body. Moreover, the intergenerational neurodevelopmental toxicity, as manifested in the F1 generation, was attenuated by FA supplementation. In summary, early-life TBT exposure led to intergenerational neurodevelopmental deficits in zebrafish, and DNA methyl donors had a protective effect on F1 neurodevelopment, which can inform the prevention and treatment of intergenerational neurotoxicity due to organotin pollutants.

A new approach to explore the correlation between declarative memory and anxiety in animal models of schizophrenia and microplastic pollution

The discovery of new detrimental effects associated with microplastic pollution is ever-growing and reaching alarming rates worldwide, as it is linked to numerous disorders such as lung diseases, gastrointestinal problems, and cancer. However, a less explored issue is their impact on mental health, more precisely schizophrenia, even though several studies have shown the presence of microplastics in air, water, soil, and even food, thus making them a significant part of our daily dietary intake. It is also well known that declarative memory and anxiety levels are impaired in schizophrenia. However, apart from the novel object recognition test, the possibilities for testing memory in zebrafish are quite limited. For these reasons, we designed a novel memory test based on rewards, a learning period, and zebrafish's natural preference for certain colors. Among the results, our fish preferred the color yellow over red, and we illustrated that ketamine and its combination with methionine provide a robust model that seems to better represent the aspects of schizophrenia in animal models. Moreover, surprisingly, we observed that microplastics (more precisely, polypropylene fibers) ingested by animals through the diet seem to act as a buffer against ketamine toxicity and as an enhancer for methionine exposure. Moreover, according to our results, groups with higher anxiety levels seem to perform better on the memory test.

Non-negligible vector effect of micro(nano)plastics on tris(1,3-dichloro-2-propyl) phosphate in zebrafish quantified by toxicokinetic model

Micro(nano)plastics (MNPs) inevitably interact with coexisting contaminants and can act as vectors to affect their fate in organisms. However, the quantitative contribution of MNPs in the in vivo bioaccumulation and distribution of their coexisting contaminants remains unclear. Here, by selecting tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) as the typical coexisting contaminant, we quantified the contribution of MNPs to bioaccumulation and distribution of TDCIPP with toxicokinetic models. Results indicated that MNPs differentially facilitated TDCIPP bioaccumulation and distribution, and NPs slowed down TDCIPP depuration more significantly than MPs. Model analysis further revealed increasing contributions of MNPs to whole-fish TDCIPP bioaccumulation over time, with NPs (33-42%) contributing more than MPs (12-32%) at 48 h exposure. NPs contributed more than MPs to TDCIPP distribution in the liver (13-19% for MPs; 36-52% for NPs) and carcass (24-45% for MPs; 57-71% for NPs). The size-dependent vector effect might be attributed to the fact that MNPs promote contaminant transfer by damaging biofilm structure and increasing tissue membrane permeability, with NPs exerting stronger effects. This work demonstrated the effectiveness of using modeling tools to understand the relative importance of MNPs as contaminant vectors in the TK process and highlighted the higher contaminant transfer potential of NPs under combined exposure scenarios.

A novel coumarin-fluorescein-based fluorescent probe for ultrafast and visual detection of H2S in a Parkinson's disease model

Hydrogen sulfide (H2S) has a crucial impact on diverse biological processes and has been shown to be related to various diseases. Many probes have been developed to detect intracellular H2S by fluorescent imaging. However, the development of rapid, highly selective and sensitive H2S probes remains a challenge. Herein, two fluorogenic probes, CNS and FCS, are designed and synthesized for the ultrafast detection of H2S with fluorescein and coumarin fluorophores. The results show that both probes can be applied to monitor and image endogenous H2S in cervical cancer HeLa cells and live zebrafish, and FCS shows a higher sensitivity, selectivity and fluorescence intensity. We then further applied FCS in a Parkinson's disease Drosophila model, and the results show that FCS can precisely indicate the level of H2S in the Parkinson's disease model. Thus, FCS will likely to be applied for the early diagnosis of Parkinson's disease.

A rhodamine NIR probe for naked eye detection of mercury ions and its application

Fluorescence imaging technology has developed rapidly with its advantages, and near-infrared probes are worthy of attention because of their less background interference, low light damage, and infinite potential. Rhodamine and its derivatives have the unique structure of lactam helices, which is an ideal platform for the construction of on-off fluorescent sensors. In this paper, a novel near-infrared fluorescent probe (RBLS) based on rhodamine derivatives was synthesized for the transient detection of mercury ions. The closed-on structure can realize reversible sensor recovery by adding S2-. The superior imaging capability in living cells and in vivo in zebrafish holds promise for biological applications. In addition, the naked eye test strips prepared with RBLS probes can be used to detect and screen Hg2+ in the environment and show good gradient change performance.

Meta-analysis of the hazards of microplastics in freshwaters using species sensitivity distributions

The environmental hazards of microplastics have raised concerns about their potential ecological risks. However, our understanding of the true risks may be limited because most laboratory studies used pristine microplastics. Here, we analyzed the available literature about ecotoxicological effects of microplastics, including weathered microplastics in particular, on freshwater biota and performed probabilistic species sensitivity distributions. The predicted no-effect concentrations for pristine microplastics were lower than those for weathered microplastics, both in mass concentration (6.1 and 4.8 × 102 μg/L) and number concentration (2.6 × 104 and 2.0 × 106 part/m3). In addition, the toxicological studies on microplastics contains often inconsistent and inconclusive information due to the complexity of the microplastics and the employed exposure conditions. The available data for Daphnia magna and Danio rerio was analyzed in detail to understand the effects of microplastic size, shape and polymer type on their ecotoxicity. Microplastic size was the biggest driving factor, followed by shape and polymer type. There was a tendency for increasing toxicity with smaller size, however, a high variability of effect data was observed for small microplastics. This study provided further insights into the effect thresholds for ecological risk assessment of microplastics and the effects of microplastic characteristics on toxicity.

Methylphenidate exposure in juvenile period elicits locomotion changes and anxiolytic-like behavior in adulthood: Evidence using zebrafish as a translational model

Methylphenidate (MPH) is a central nervous system stimulant that is mainly used for Attention-Deficit/Hyperactivity Disorder (ADHD). It is well known that there is a high rate of ADHD misdiagnosis, leading to a great number of neurotypical children chronically exposed to MPH in early periods of life. This increase raises concern about possible long-lasting effects of this exposure. We aimed to evaluate whether exposure to MPH during childhood might impact adult behavioral pattern. For this purpose, we used zebrafish as a translational model considering its robustness as experimental model and fast life cycle. Fish were exposed during juvenile period (from 30 to 60 post-natal day) at MPH therapeutic concentration (2 mg L-1), and behavioral tests were performed at fish adulthood (120 post-natal day). MPH provoked slight anxiolytic-like effects and hyperlocomotion, and no differences on sociability and cortisol levels were observed. Moreover, sex did not affect any of the parameters evaluated. These results demonstrate that early chronic exposure to MPH leads to neurobehavioral adaptations that persist into adulthood in zebrafish regardless of sex, suggesting that the misuse of MPH during childhood and adolescence can alter neurobehavioral plasticity and these alterations might persist until adulthood.

A unique phenothiazine-based fluorescent probe using benzothiazolium as a reactivity regulator for the specific detection of hypochlorite in drinking water and living organisms

As a common disinfectant and an essential reactive oxygen species (ROS), hypochlorite (ClO-) plays vital roles in both water treatment and cell metabolism, but its abnormal level can cause serious harm to human health. Therefore, quantifying ClO- level in drinking water and living organisms is extremely significant. Herein, we decorated different cationic heterocycles on phenothiazine core to construct three fluorescent probes for ClO-. According to the results, only benzothiazolium moiety reasonably adjusted the electron cloud density at sulfur atom of phenothiazine core for the specific oxidation with ClO-, thus endowing the prepared probe PT-BT with a perfect selectivity for ClO-. Meanwhile, PT-BT exhibited a low detection limit (38 nM) and a fast response (within 20 s) toward ClO-. Furthermore, this probe was utilized to fabricate a ready-to-use test strip, which could quantitatively measure ClO- level in real water samples by a portable smartphone sensing platform. Notably, PT-BT targeted mitochondria efficiently, and successfully visualized endogenous ClO- in living cells and zebrafish larvae. Especially, PT-BT was able to monitor the dynamic change of ClO- level in inflammatory mice. These results strongly manifested that probe PT-BT was a promising tool for detecting ClO- in drinking water and living organisms.

Dietary solutions for aluminum embryotoxicity: A study in Danio rerio using spirulina and okra-spirulina diets

Aluminum (Al) is a versatile element commonly employed in various industries and water treatment processes. However, its presence in aquatic ecosystems can elicit adverse effects on organisms, particularly the Danio rerio fish species. Aluminum exposure has been associated with a spectrum of issues, ranging from oxidative stress to behavioral anomalies, reproductive disruptions, and morphological alterations in these organisms. This research aimed to assess the impact of aluminum chloride (AlCl3) on D. rerio embryos and explore strategies to mitigate its effects. Three dietary groups (commercial, okra-spirulina, and spirulina) were studied, focusing on embryonic development, oxidative damage, and gene expression changes. The study revealed that diets enriched with spirulina and okra-spirulina effectively reduced aluminum-induced embryotoxicity, oxidative stress, and gene expression alterations, surpassing the commercial diet. However, all AlCl3-exposed groups experienced adverse effects on embryonic development, including hatching anomalies, structural deformities, and cardiac delays. The okra-spirulina group showed milder toxic responses. In conclusion, this study highlights the potential of spirulina and okra-spirulina diets in mitigating aluminum-triggered oxidative stress and apoptosis in D. rerio. It underscores the need for future research on embryonic development and carries significant implications for environmental conservation and the well-being of aquatic organisms in aluminum-contaminated environments.

A D-π-A-based near-infrared fluorescent probe with large Stokes shift for the detection of cysteine in vivo

D-π-A dyes are an ideal strategy for building near-infrared fluorescent probes that have a large Stokes shift due to their excellent properties of adjustable emission wavelength and Stokes shift. Developing a near-infrared (NIR) fluorescent probe (JTPQ-Cys) capable of detecting cysteine (Cys) was the aim of this study. In JTPQ-Cys, julolidine served as the electron donor (D) and quinoline as the electron acceptor (A), with 3,4-ethylenedioxythiophene as the π-bridge. The π-conjugation and vibrational/rotational activity of the molecule were increased by the introduction of 3,4-ethylenedioxythiophene, causing the molecule to exhibit NIR emission and a large Stokes shift. When JTPQ-Cys was used to detect Cys, a clear fluorescence turn-on signal was observed at 741 nm, together with a Stokes shift of 268 nm. The limit of detection of JTPQ-Cys for Cys is 24 nM. Moreover, JTPQ-Cys has been utilized successfully for imaging studies of Cys in cells and zebrafish because it has good photostability, low cytotoxicity, and a high signal-to-noise ratio. Overall, our findings demonstrate the potential of JTPQ-Cys to be one of the best choices for detecting Cys in biological systems, and JTPQ is an ideal fluorophore to construct fluorescence dyes for bioimaging.

yunnanensis cultivars and Paris luquanensis and their biological activity in zebrafish model

ETHNOPHARMACOLOGICAL RELEVANCE

Paris polyphylla var. Yunnanensis (Franch.) Hand.-Mazz., a perennial medicinal herb commonly known as "Chonglou" in Chinese, is mainly effective against innominate toxin swelling, insect sting, snake bite, traumatic injuries and various inflammatory. It is also recorded with mild toxicity. The rare species Paris luquanensis H. Li has been also used as folk medicine in Yunnan province for the same effects. Compared with P. polyphylla var. Yunnanensis (35-100 cm in height), this species has variegated leaves, and grows slower and is therefore shorter (6-23 cm in height). There are a number of different cultivars based on the shape of the petal and the height of Paris plant. However, currently, investigations into the differences of the chemical profiling of these cultivars are lacking.

AIM OF THE STUDY

This study aims to: (1) examine metabolites variations in Paris polyphylla var. Yunnanensis cultivars and Paris luquanensis; (2) investigate the different metabolite accumulation patterns between rhizomes and leaves and provide more useful information for the application of P. polyphylla var. Yunnanensis leaves; (3) compare in vivo effects on the recruitment of reactive oxygen species (ROS) and Neutrophils and toxic effects in zebrafish model between leaves and rhizomes of P. polyphylla var. Yunnanensis and P. luquanensis.

MATERIALS AND METHODS

The change patterns of metabolites in the leaves and rhizomes of four P. polyphylla var. Yunnanensis cultivars and one P. luquanensis cultivar were analyzed using an UPLC-ESI-MS/MS system. The total phenolic acid, total flavonoid, total saponin components and in vitro antioxidant activities were determined by spectrophotometric methods. The in vivo toxicity and their effects on the recruitment of ROS and neutrophils in zebrafish model were performed.

RESULTS

The widely targeted metabolomics method detected 695 metabolites in tested samples and classified as 15 known classes according to structures of the metabolites. By overall-comparing the SDMs discerned between leaves and rhizomes of each samples, 161 metabolites were substantially altered in all the cultivars. There are 62 and 64 SDMs showing constitutive differential accumulation between leaves and rhizomes of P. polyphylla var. Yunnanensis (samples A-D) and P. luquanensis (sample E), respectively. The levels of TSC, TPC and TFC decreased significantly in leaves as compared to rhizomes for all cultivars, with the exception of TPC in cultivar A, which is almost the same in leave and rhizome. The DPPH scavenging property and FRAP values of rhizomes are higher than those of leaves for all cultivars. However, there is no distinct different between leaves and rhizomes of different sample extracts for in vivo effects on the recruitment of ROS and neutrophils in zebrafish model. BL extracts showed high toxicity to the developing embryos.

CONCLUSION

As far as we are concerned, this study analyzes the P. polyphylla var. Yunnanensis and P. luquanensis variegation from the perspective of the metabolites pattern for the first time. The results give a valuable insight into the specie metabolic profiling and in vivo anti-oxidant, anti-inflammatory and toxic effects of these Paris plants.

Green rooibos (Aspalathus linearis) promotes gut health: insight into mechanisms

ETHNOPHARMACOLOGICAL RELEVANCE

Paralleling the increasing incidence of gastrointestinal disorders world-wide, therapeutic investigations of nutraceuticals to promote gastrointestinal health are gaining popularity. Although anecdotally well-known for its gut health promoting potential, sparse scientific evidence supports this action of Aspalathus linearis (Burm.f.) R. Dahlgren - or rooibos - at the gastrointestinal epithelial level.

AIM OF THE STUDY

Traditionally, rooibos is considered to exert antispasmodic, anti-inflammatory, and anti-nociceptive effects in the gut. However, the direct effect on intestinal epithelium is unknown. Thus, to assess the validity of anecdotal claims, two larval zebrafish models were utilized to evaluate effects of rooibos on intestinal health.

MATERIALS AND METHODS

Firstly, a larval zebrafish model of gastrointestinal inflammation (2-day TNBS-exposure) was employed. Co-administration of 6α-methylprednisolone served as an internal treatment control. Assessments included live imaging techniques and post-mortem immunofluorescent staining of epithelial tight junction proteins. In addition, whole body H2O2 and prostaglandin E2 assays were performed. Secondly, a gastrointestinal motility assay was performed, with known pro- and anti-kinetic mediators to assess the effect of rooibos to alter functional outcome in vivo.

RESULTS

Aqueous and ethanol extracts of green rooibos rescued TNBS-induced reductions in neutral red stained length of larval mid-intestines. Subsequent experiments confirmed the rescue capacity of the aqueous green rooibos extract regarding whole body oxidative and inflammatory status. Concerning tight junction proteins, only the aqueous green rooibos extract - and not prednisolone - normalized both zona occludens-1 and occludin expression levels when compared the TNBS group. In terms of gastrointestinal motility, the aqueous green rooibos extract significantly reduced the extent of gut motility dysregulation achieved by kinetic modulators.

CONCLUSIONS

Data indicates the potential of a 2 mg/ml aqueous extract of green rooibos to improve gastrointestinal integrity and functionality in vivo, suggesting beneficial effects of rooibos may already occur at the level of the gut. This provides some evidence to support indigenous knowledge.

Mechanism of Sophorae Flavescentis Radix (Kushen) in treating NSCLC: Insights from miRNA-mRNA network analysis

ETHNOPHARMACOLOGICAL RELEVANCE

Sophorae Flavescentis Radix (Kushen) is the primary herb component of Compound Kushen Injection (CKI), an approved clinical treatment for tumors. Despite CKI's widespread use, the underlying mechanisms of Kushen regarding microRNA-target and pathway remain unclear in non-small cell lung cancer (NSCLC).

AIM OF THE STUDY

This study aimed to elucidate the crucial miRNAs-targets and pathways responsible for the Kushen's impact on NSCLC.

MATERIALS AND METHODS

CCK8, colony formation, and apoptosis assays were performed to assess the effects of Kushen on NSCLC cells. Subsequently, we treated the A549 cell line with varying concentrations of Kushen to obtain mRNA and miRNA expression profiles. A DE (differentially expressed) miRNAs-DEGs network was then constructed to identify the critical miRNA-mRNA interaction influenced by Kushen. Furthermore, we performed clinical significance and prognosis analyses of hub genes to narrow down key genes and their corresponding miRNAs. Finally, the effects of Kushen on critical miRNA-mRNA interaction and related pathway were verified by in vitro and in vivo experiments.

RESULTS

In this study, we initially demonstrated that Kushen significantly inhibited cell proliferation, suppressed colony formation, and induced apoptosis in the A549 cells, PC9 cells, and the A549 zebrafish xenograft model. Through expression profile analysis, a DE miRs-DEGs network was constructed with 16 DE miRs and 68 DEGs. Through the network analysis and expression validation, we found Kushen could significantly down-regulate miR-183-5p expression and up-regulate EGR1 expression. Additionally, Kushen affected the PTEN/Akt pathway, increasing PTEN expression and decreasing pAkt expression. Finally, matrine, the essential active compound of Kushen, also inhibited cell growth, induced apoptosis, and regulated miR-183-5p/EGR1 and PTEN/AKT pathway.

CONCLUSIONS

Altogether, these findings supported the critical role of miR-183-5p/EGR1 and the PTEN/AKT pathway in the beneficial effects of Kushen on NSCLC, highlighting the therapeutic potential of Kushen in NSCLC treatment.

ameliorate TAA-induced zebrafish liver injury by inhibiting TLR4/MyD88/NF-κB signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Liver injury, the main factor in the pathogenesis of most liver diseases, is a known contributor to acute liver failure, liver fibrosis, or liver cancer. Curcuma phaeocaulis Val. (PEZ) has been broadly used in treating liver injury with satisfying therapeutic effects; however, the mechanism is still unclear.

AIM OF THE STUDY

This study aimed to explore the mechanism of PEZ in ameliorating thioacetamide (TAA)-induced zebrafish liver injury based on a comprehensive method integrating network-based computational prediction and experimental validations.

MATERIALS AND METHODS

Ultrahigh-performance liquid chromatography-quadrupole exactive mass spectrometry/mass spectrometry (UPLC-Q-Exactive MS/MS) analysis was used to analyze components in raw and vinegar-processed PEZ (VPEZ). Network pharmacology was used to construct a compound-target network for liver injury to predict the possible biological targets of PEZ along with potential signaling pathways. TAA-induced zebrafish larvae liver injury model was established, and the anti-liver injury effect of PEZ by a series of indexes was measured, including liver phenotype analysis, histopathological analysis of liver tissues, and biochemical indexes analysis. Remarkably, the predicted pathway by network pharmacology was further validated using RT-qPCR and Western blotting analyzes in animal experiments.

RESULTS

40 chemical constituents derived from PEZ were identified, while 45 chemical components derived from VPEZ were identified. Based on it, 565 genes related to these identified compounds in PEZ and 1023 genes linked to liver injury were collected by network pharmacology. Critically, KEGG analysis indicated that the TLR4/MyD88/NF-κB signaling pathway was recommended as one of the main pathways related to the anti-liver injury effect of PEZ. Experimentally, PEZ could alleviate TAA-induced liver injury. Compared to the liver injury model group without any treatment, the treatment of PEZ significantly reduced the expression of both mRNA and protein targets in the TLR4/MyD88/NF-κB signaling pathway. In addition, the effect of VPEZ was more significant than that of the raw one.

CONCLUSION

The raw and vinegar-processed PEZ could ameliorate TAA-induced zebrafish liver injury through TLR4/MyD88/NF-κB signaling pathway.

Sceletium tortuosum-derived mesembrine significantly contributes to the anxiolytic effect of Zembrin®, but its anti-depressant effect may require synergy of multiple plant constituents

ETHNOPHARMACOLOGY RELEVANCE

Sceletium tortuosum (L.) N.E.Br. (ST) is an alkaloid-rich succulent plant with various mechanisms of action that infer psychotropic effects. These actions correlate with clinical evidence suggesting efficacy in the treatment of depression and anxiety, in line with its use by indigenous populations. Its low side effect profile suggests potential of ST to improve the overall wellbeing and compliance of millions of patients that experience severe side effects and/or do not respond to current prescription medication. However, to elucidate specific physiological effects of ST extracts, it is necessary to first understand which of its constituents are the major contributors to beneficial effects demonstrated for ST in this context.

AIM OF THE STUDY

To determine an anxiolytic- and antidepressant-like effective concentration of a ST extract by means of a dose response in zebrafish (ZF) larvae, and to assess relative contributions of equivalent concentrations of isolated alkaloids contained in the effective concentration(s).

MATERIALS AND METHODS

A dose response study employing a light-dark transition test (LDTT) was done in ZF larvae (<5 days post fertilization) to track locomotor activity in terms of anxiety-like (hyperlocomotion) and depression-like (hypolocomotion) behaviour. Larvae were treated for 1 h directly before the LDTT with escalating concentrations of a ST extract commercially known as Zembrin® (Zem) ranging from 0.25 to 500 μg/mL and compared to an untreated control group (n = 12 per treatment concentration). LDTT was repeated after 24 h to evaluate long-term exposure toxicity. The concentration that best attenuated hyperlocomotion during the dark phase following light-dark transition was identified as the anxiolytic-like concentration. This concentration, plus one higher and one lower concentration, were used for subsequent tests. The percentage content of each alkaloid (mesembrine, mesembrenone, mesembrenol, and mesembranol) in these concentrations were calculated and applied to additional larvae to identify the most effective anxiolytic-like alkaloid in the LDTT. To identify antidepressant-like therapeutic concentration and equivalent alkaloid concentration, the same treatment concentrations were tested in larvae (n = 12 per treatment concentration) pre-exposed to reserpine for 24 h. Depending on normality of data distribution, Brown-Forsythe and Welch, or Kruskal-Wallis ANOVA were used, with Dunnett or Dunn's multiple comparisons tests.

RESULTS

Only the extreme concentration of Zem (500 μg/mL) elicited toxicity after treatment for 24 h. Zem 12.5 μg/mL was the most effective anxiolytic-like concentration as it significantly decreased locomotor activity (P = 0.05) in the LDTT. Low (5 μg/mL), optimal (12.5 μg/mL) and high (25 μg/mL) Zem concentrations, as well as treatment solutions of single alkaloids (mesembrine, mesembrenone, mesembranol and mesembrenol), prepared to contain equivalent concentrations of each major alkaloid contained within these three concentrations of Zem, were tested further. Only mesembrine concentrations equal to that contained within the optimal and high dose of Zem (12.5 and 25 μg/mL) showed significant anxiolytic-like effects (P < 0.05). Only the highest Zem concentration (25 μg/mL) reversed the effects of reserpine - indicating antidepressant-like properties (P < 0.05) - while isolated alkaloids failed to induce such effects when administered in isolation.

CONCLUSIONS

Current data provide evidence of both anxiolytic- and antidepressant-like effect of whole extract of Zem, with relatively higher concentrations required to achieve antidepressant-like effect. Of all alkaloids assessed, only mesembrine contributed significantly to the anxiolytic-like effects of Zem. No alkaloid alone could be pinpointed as a contributor to the antidepressant-like activity observed for higher concentration Zem. This may be due to synergistic effects of the alkaloids or may be due to other components not tested here. Current data warrants further investigation into mechanisms of action, as well as potential synergy, of ST alkaloids in suitable mammalian in vivo models.