Solanum nigrum Extract and Solasonine Affected Hemolymph Metabolites and Ultrastructure of the Fat Body and the Midgut in Galleria mellonella

Solanaceae Glycoalkaloids Disturb Lipid Metabolism in the Tenebrio molitor Beetle

Glycoalkaloids (GAs) are produced naturally by plants and affect insect survivability and fertility. These compounds can be considered potential bioinsecticides; however, the mechanisms and effects of their action remain undiscovered. As lipids are essential molecules for the proper functioning of an insect organism, this research aimed to determine the effects of GAs on the lipid metabolism of the Tenebrio molitor beetle. Solanine, chaconine, tomatine, and tomato leaf extract were applied to larvae by injection at two concentrations, 10-8 and 10-5 M. Then, the tissue was isolated after 2 and 24 h to determine the levels of free fatty acids, sterols and esters using the GC-MS technique. Moreover, the triacylglyceride level and the activity of the key β-oxidation enzyme, 3-hydroxyacyl-CoA dehydrogenase (HADH), were measured. The results indicate that GAs affect the content and composition of lipid compounds in the beetles' haemolymph and fat body. The effects depend on the GA concentrations, incubation time, and kind of tissue. Moreover, the tested compounds decrease HADH activity, especially in the fat body, which may affect energy production. To our knowledge, this is the first study concerning lipid metabolism in T. molitor after GA application. Our results provide some insights into that topic.

Molecular identification of carboxylesterase genes and their potential roles in the insecticides susceptibility of Grapholita molesta

Grapholita molesta is one of the most damaging pests worldwide in stone and pome fruits. Application of chemical pesticides is still the main method to control this pest, which results in resistance to several types of insecticides. Carboxylesterase (CarE) is one of the important enzymes involved in the detoxification metabolism and tolerance of xenobiotics and insecticides. However, the roles of CarEs in insecticides susceptibility of G. molesta are still unclear. In the present study, the enzyme activity of CarEs and the mRNA expression of six CarE genes were consistently elevated after treatment with three insecticides (emamectin benzoate, lambda-cyhalothrin, and chlorantraniliprole). According to spatio-temporal expression profiles, six CarE genes expressed differently in different developmental stages, and highly expressed in some detoxification metabolic organs. RNAi-mediated knockdown of these six CarE genes indicated that the susceptibility of G. molesta to all these three insecticides were obviously raised after GmCarE9, GmCarE14, GmCarE16, and GmCarE22 knockdown, respectively. Overall, these results demonstrated that GmCarE9, GmCarE14, GmCarE16, and GmCarE22 play a role in the susceptibility of G. molesta to emamectin benzoate, lambda-cyhalothrin, and chlorantraniliprole treatment. This study expands our understanding of CarEs in insects, that the same CarE gene could participate in the susceptibility to different insecticides.

Atomic force microscopy study of the complexation of sterols and the glycoalkaloid α-tomatine in Langmuir-Blodgett monolayers

Glycoalkaloids are secondary metabolites produced by plants that aid in their protection from pathogens and pests. They are known to form 1:1 complexes with 3β-hydroxysterols such as cholesterol causing membrane disruption. So far, the visual evidence showcasing the complexes formed between glycoalkaloids and sterols in monolayers has been mainly restricted to some earlier studies using Brewster angle microscopy which were of low resolution showing the formation of floating aggregates of these complexes. This study is aimed at using atomic force microscopy (AFM) for topographic and morphological analysis of the aggregates of these sterol-glycoalkaloid complexes. Langmuir-Blodgett (LB) transfer of mixed monolayers of the glycoalkaloid α-tomatine, sterols, and lipids in varying molar ratios onto mica followed by AFM examination was performed. The AFM method allowed visualization of the aggregation of sterol-glycoalkaloid complexes at nanometer resolution. While aggregation was observed in mixed monolayers of α-tomatine with cholesterol and in mixed monolayers with coprostanol, no sign of complexation was observed for the mixed monolayers of epicholesterol and α-tomatine, confirming their lack of interaction found in prior monolayer studies. Aggregates were observed in transferred monolayers of ternary mixtures of α-tomatine with cholesterol and the phospholipids 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) or egg sphingomyelin (egg SM). The formation of aggregates was found to be less prevalent for mixed monolayers of DMPC and cholesterol containing α-tomatine than it was for mixed monolayers containing egg SM and cholesterol with α-tomatine. The observed aggregates were generally elongated structures, of a width ranging from about 40-70 nm.

Solanum nigrum Fruit Extract Modulates Immune System Activity of Mealworm Beetle, Tenebrio molitor L

Here, we report the first evidence concerning the modulation of insect immune system activity after applying Solanum nigrum fruit extract (EXT). We focused on two main issues: (1) is EXT cytotoxic for Tenebrio molitor haemocytes? and (2) how EXT affects the basic immune mechanisms of T. molitor. The results indicate cytotoxic action of 0.01 and 0.1% EXT on beetle haemocytes. Both the injection of EXT and incubating haemocytes with the EXT solution on microscopic slides significantly increased the number of apoptotic cells. However, 24 h after injection of 0.1% EXT cytotoxic effect of the tested extract probably was masked by the increased number of circulating haemocytes. Application of 0.01 and 0.1% EXT led to impairment of the activity of basic immune mechanisms such as phenoloxidase activity and the lysozyme-like antimicrobial activity of T. molitor haemolymph. Moreover, the EXT elicited significant changes in the expression level of selected immune genes. However, some of the immunomodulatory effects of EXT were different in beetles with and without an activated immune system. The obtained results are an essential step toward a complete understanding of the EXT mode of action on the T. molitor physiology and its potential usage in pest control.

Anticancer activity of glycoalkaloids from Solanum plants: A review

Cancer is still one of the main causes of death worldwide. For this reason, new compounds that have chemotherapeutic potential have been identified. One such group of substances is Solanaceae glycoalkaloids (GAs). They are natural compounds produced by plants widely used in traditional medicine for healing many disorders. Among others, GAs exhibit significant antitumor properties, for example, a strong inhibitory effect on cancer cell growth. This activity can result in the induction of tumor cell apoptosis, which can occur via different molecular pathways. The molecular mechanisms of the action of GAs are the subject of intensive research, as improved understanding could lead to the development of new cancer therapies. The genetic basis for the formation of neoplasms are mutations in protooncogenes, suppressors, and apoptosis-controlling and repair genes; therefore, substances with antineoplastic properties may affect the levels of their expression or the levels of their expression products. Therapeutic compounds can be applied separately or in combination with other drugs to increase the efficiency of cancer therapy; they can act on the cell through various mechanisms at different stages of carcinogenesis, inducing the process of apoptosis, blocking cell proliferation and migration, and inhibiting angiogenesis. This review summarizes the newest studies on the anticancer properties of solanine (SN), chaconine (CH), solasonine (SS), solamargine (SM), tomatine (TT) and their extracts from Solanum plants.

Solanaceae glycoalkaloids: α-solanine and α-chaconine modify the cardioinhibitory activity of verapamil

CONTEXT

Solanaceae glycoalkaloids (SGAs) possess cardiomodulatory activity.

OBJECTIVE

This study investigated the potential interaction between verapamil and glycoalkaloids.

MATERIAL AND METHODS

The cardioactivity of verapamil and glycoalkaloids (α-solanine and α-chaconine) was tested in adult beetle (Tenebrio molitor) myocardium in vitro using microdensitometric methods. The myocardium was treated with pure substances and mixtures of verapamil and glycoalkaloids for 9 min with saline as a control. Two experimental variants were used: simultaneous application of verapamil and glycoalkaloids or preincubation of the myocardium with one of the compounds followed by perfusion with a verapamil solution. We used 9 × 10^-6-5 × 10^-5 M and 10^-9-10^-5 M concentration for verapamil and glycoalkaloids, respectively.

RESULTS

Verapamil, α-solanine and α-chaconine showed cardioinhibitory activity with IC₅₀ values equal to 1.69 × 10^-5, 1.88 × 10^-7 and 7.48 × 10^-7 M, respectively. When the glycoalkaloids were applied simultaneously with verapamil, an antagonistic effect was observed with a decrease in the maximal inhibitory effect and prolongation of t₅₀ and the recovery time characteristic of verapamil. We also confirmed the expression of two transcript forms of the gene that encodes the α1 subunit of L-type calcium channels in the myocardium and brain with equal transcription levels of both forms in the myocardium and significant domination of the shorter form in the brain of the insect species tested.

DISCUSSION AND CONCLUSIONS

The results show that attention to the composition of the daily diet during therapy with various drugs is particularly important. In subsequent studies, the nature of interaction between verapamil and SGAs on the molecular level should be checked, and whether this interaction decreases the efficiency of cardiovascular therapy with verapamil in humans.