Immunobiological properties of sesquiterpene lactones obtained by chemically transformed structural modifications of trilobolide

Inhibitory Effect of Selected Guaianolide and Germacranolide Sesquiterpene Lactones on Nitric Oxide Production

Trilobolide and its analogues belong to the guaianolide type of sesquiterpene lactones, which are characteristic and widely distributed within the families Asteraceae and Apiaceae. Certain guaianolides are receiving continuously increasing attention for their promising sarco-endoplasmic reticulum Ca2+-ATPase (SERCA)-inhibitory activity. However, because of their alkylation capabilities, they are generally toxic. Therefore, the search for compounds with significant immunobiological properties but with decreased cytotoxicities suitable for use in immune-based pharmacotherapy is ongoing. Therefore, we extended our previous investigation of the immunobiological effects of trilobolide to a series of structurally related guaianolides and germacranolides. To evaluate the relationship, we tested a series of selected derivatives containing α-methyl lactone or exomethylene lactone ring. For a wider comparison, we also included some of their glycosidic derivatives. We assessed the in vitro immunobiological effects of the tested compounds on nitric oxide (NO) production, cytokine secretion, and prostaglandin E2 (PGE2) release by mouse peritoneal cells, activated primarily by lipopolysaccharide (LPS), and evaluated their viability. The inhibitory effects of the apparently most active substance, 8-deoxylactucin, seem to be the most promising.

In Vitro, In Vivo, and In Silico Studies of Cumanin Diacetate as a Potential Drug against Trypanosoma cruzi Infection

The sesquiterpene lactones cumanin, helenalin, and hymenin and their semisynthetic derivatives were evaluated against Trypanosoma cruzi epimastigotes. The cytotoxicity of the compounds was evaluated on murine splenocytes. Cumanin diacetate was one of the most active and selective compounds [IC₅₀ = 3.20 ± 0.52 μg/mL, selectivity index (SI) = 26.0]. This sesquiterpene lactone was selected for its evaluation on trypomastigote and amastigote forms of the parasite. The diacetylated derivative of cumanin showed moderate activity on trypomastigotes (IC₅₀ = 32.4 ± 5.8 μg/mL). However, this compound was able to efficiently inhibit parasite replication with an IC₅₀ value of 2.2 ± 0.05 μg/mL against the amastigote forms. Cumanin diacetate showed selectivity against the intracellular forms of Trypanosoma cruzi with an SI value of 52.7. This cumanin analogue was also active on an in vivo model of Chagas disease, leading to a reduction in the parasitemia levels in comparison with nontreated animals. Histopathological analysis of skeletal muscular tissues from treated mice showed only focal interstitial lymphocyte inflammatory infiltrates with slight myocyte necrosis; in contrast, nontreated animals showed severe lymphocyte inflammatory infiltrates with necrosis of the myocytes. A molecular docking study of cumanin and its derivatives on trypanothione reductase from T. cruzi (TcTR) was performed. The results of ΔG docking achieved let the identification of diacetylated and O-alkylated derivatives of cumanin as good inhibitors of TcTR. Cumanin diacetate could be considered a potential candidate for further studies for the development of new therapies against Chagas disease.

Spirostanol Saponins from Flowers of Allium Porrum and Related Compounds Indicating Cytotoxic Activity and Affecting Nitric Oxide Production Inhibitory Effect in Peritoneal Macrophages

Saponins, a diverse group of natural compounds, offer an interesting pool of derivatives with biomedical application. In this study, three structurally related spirostanol saponins were isolated and identified from the leek flowers of Allium porrum L. (garden leek). Two of them were identical with the already known leek plant constituents: aginoside (1) and 6-deoxyaginoside (2). The third one was identified as new component of A. porrum; however, it was found identical with yayoisaponin A (3) obtained earlier from a mutant of elephant garlic Allium ampeloprasun L. It is a derivative of the aginoside (1) with additional glucose in its glycosidic chain, identified by MS and NMR analysis as (2α, 3β, 6β, 25R)-2,6-dihydroxyspirostan-3-yl β-D-glucopyranosyl-(1 → 3)-β-D-glucopranosyl-(1 → 2)-[β-D-xylopyranosyl-(1 → 3)]-β-D-glucopyranosyl]-(1 → 4)-β-D-galactopyranoside, previously reported also under the name alliporin. The leek native saponins were tested together with other known and structurally related saponins (tomatonin and digitonin) and with their related aglycones (agigenin and diosgenin) for in vitro cytotoxicity and for effects on NO production in mouse peritoneal cells. The highest inhibitory effects were exhibited by 6-deoxyaginoside. The obtained toxicity data, however, closely correlated with the suppression of NO production. Therefore, an unambiguous linking of obtained bioactivities of saponins with their expected immunobiological properties remained uncertain.

Sarco/Endoplasmic Reticulum Calcium ATPase Inhibitors: Beyond Anticancer Perspective

The sarco/endoplasmic reticulum calcium ATPase (SERCA), which plays a key role in the maintenance of Ca²⁺ ion homeostasis, is an extensively studied enzyme, the inhibition of which has a considerable impact on cell life and death decision. To date, several SERCA inhibitors have been thoroughly studied and the most notable one, a derivative of the sesquiterpene lactone thapsigargin, is gradually approaching a clinical application. Meanwhile, new compounds with SERCA-inhibiting properties of natural, synthetic, or semisynthetic origin are being discovered and/or developed; some of these might also be suitable for the development of new drugs with improved performance. This review brings an up-to-date comprehensive overview of recently discovered compounds with the potential of SERCA inhibition, discusses their mechanism of action, and highlights their potential clinical applications, such as cancer treatment.

Composition and Antimicrobial Properties of Essential Oils of Laser Trilobum Rhizomes and Fruits

The compositions of hydrodistillated essential oils of Laser trilobum (L.) Borkh. rhizomes and fruits from Serbia, were investigated using GC and GC/MS. In the dark-blue rhizome oil forty-six compounds (93.1% of the total oil) were identified, with α-pinene (31.5%), γ-terpinene (9.0%), p-cymene (7.9%), β-pinene (6.1%) and 1,4-dimethylazulene (6.0%) as the major components. In the colorless fruits oil, twenty components (96.8% of the total oil) were identified, and the main constituents were limonene (51.6%) and perillaldehyde (26.8%). The antimicrobial activity of the oils was tested using the broth microdilution method against nine bacterial and two fungal strains. The oils revealed significant antimicrobial effect, mainly better than that of thymol, used as a reference compound. The strongest activity was recorded for the rhizome oil against Escherichia coli, Klebsiella pneumoniae and Candida albicans (MICs=25 μg/mL), and the fruit oil against C. albicans ATCC 10259 (MIC=12.5 μg/mL).

Trilobolide-steroid hybrids: Synthesis, cytotoxic and antimycobacterial activity

Sesquiterpene lactone trilobolide is a sarco/endoplasmic reticulum Ca²⁺-ATPase (SERCA) inhibitor, thus depleting the Ins(1,4,5)P3-sensitive intracellular calcium stores. Here, we describe a synthesis of a series of 6 trilobolide-steroids conjugates (estradiol, pregnene, dehydroepiandrosterone, and testosterone). We found that the newly synthesized Tb-based compounds possess different remarkable biological activities. Cancer cell cytotoxicity and preferential selectivity is represented in our study by a Tb-pregnene derivative. The most cytotoxic clickates of estradiol and pregnene were studied by FACS where impact on cell cycle and RNA synthesis was observed; live-cell microscopy revealed the impact on cell organelle morphology particularly endoplasmic reticulum, mitochondria and nucleus. Further, we have studied the estrogenic and androgenic properties of the clickate molecules using cell-based luciferase assays. Finally, antimycobacterial tests revealed that testosterone and estradiol derivatives potentiated the antimycobacterial activity up to IC50 of 10.6μM.

Immunoassay for determination of trilobolide

Trilobolide (Tb) is a pharmacologically interesting sesquiterpene lactone isolated from Laser trilobum (L.) Borkh. Structural relation to a sarco/endoplasmic reticulum Ca²⁺-ATPase inhibitor thapsigargin bring promising prospects for Tb to be used in the development of new anti-cancer drugs. As long as there are still unanswered questions regarding its investigation, a need for novel analytical tools emerge. Since immunoassays serve as one of powerful tools within the investigation of natural products, the development of indirect competitive enzyme-linked immunosorbent assay (ELISA) utilizing coating based on avidin-biotin technology is described. In our set-up of ELISA, newly synthesized biotinylated Tb served as immobilized competitor. Tb-carboxymethyloxime-bovine serum albumin (BSA) and Tb-succinoyl-BSA conjugates were used separately for immunization of rabbits. Two sets of polyclonal antibodies (RAbs) were obtained. Antibodies against Tb-succinoyl-BSA conjugate (RAb No. 206) were chosen as the best. Under optimized conditions, limit of detection and 50% intercept of our ELISA were 849pg/mL and 8.89ng/mL, respectively. The cross-reactivity (CR) was tested on 10 structurally related compounds and CR did not exceed 6.1%. The reproducibility of the system is expressed as intra- and inter-assay coefficients of variation (9.7% and 11.4%, respectively). Based on conducted experiments, we proposed the use of ELISA for quantification of Tb in complex biological matrices such as plant extracts. A method was applied to analyze three extracts obtained from different parts of L. trilobum. Data obtained were compared to those acquired by UHPLC-MS/MS. The concordance between the methods (103-87%) showed the ability of ELISA to quantify Tb.

Antiviral activities of atractylon from Atractylodis Rhizoma

Atractylodis Rhizoma is a traditional medicinal herb, which has antibacterial, antiviral, anti-inflammatory and anti-allergic, anticancer, gastroprotective and neuroprotective activities. It is widely used for treating fever, cold, phlegm, edema and arthralgia syndrome in South-East Asian nations. In this study, 6 chemical compositions of Atractylodis Rhizoma were characterized by spectral analysis and their antiviral activities were evaluated in vitro and in vivo. Among them, atractylon showed most significant antiviral activities. Atractylon treatment at doses of 10–40 mg/kg for 5 days attenuated influenza A virus (IAV)-induced pulmonary injury and decreased the serum levels of interleukin (IL)-6, tumor necrosis factor-α and IL-1β, but increased interferon-β (IFN-β) levels. Atractylon treatment upregulated the expression of Toll-like receptor 7 (TLR7), MyD88, tumor necrosis factor receptor-associated factor 6 and IFN-β mRNA but downregulated nuclear factor-κB p65 protein expression in the lung tissues of IAV-infected mice. These results demonstrated that atractylon significantly alleviated IAV-induced lung injury via regulating the TLR7 signaling pathway, and may warrant further evaluation as a possible agent for IAV treatment.