Phytol-derived novel isoprenoid immunostimulants

Isoprenoid CARTs: In Vitro and In Vivo mRNA Delivery by Charge-Altering Releasable Transporters Functionalized with Archaea-inspired Branched Lipids

The delivery of oligonucleotides across biological barriers is a challenge of unsurpassed significance at the interface of materials science and medicine, with emerging clinical utility in prophylactic and therapeutic vaccinations, immunotherapies, genome editing, and cell rejuvenation. Here, we address the role of readily available branched lipids in the design, synthesis, and evaluation of isoprenoid charge-altering releasable transporters (CARTs), a pH-responsive oligomeric nanoparticle delivery system for RNA. Systematic variation of the lipid block reveals an emergent relationship between the lipid block and the neutralization kinetics of the polycationic block. Unexpectedly, iA21A11, a CART with the smallest lipid side chain, isoamyl-, was identified as the lead isoprenoid CART for the in vitro transfection of immortalized lymphoblastic cell lines. When administered intramuscularly in a murine model, iA21A11-mRNA complexes induce higher protein expression levels than our previous lead CART, ONA. Isoprenoid CARTs represent a new delivery platform for RNA vaccines and other polyanion-based therapeutics.

Phytol from Scoparia dulcis prevents NF-κB-mediated inflammatory responses during macrophage polarization

Macrophages are primary immune cells that mediate a wide range of inflammatory diseases through their polarization potential. In this study, phytol isolated from Scoparia dulcis has been explored against 7-ketocholesterol and bacterial lipopolysaccharide-induced macrophage polarization in IC-21 cells. Isolated phytol has been characterized using GC-MS, TLC, HPTLC, FTIR, 1H-NMR, and HPLC analyses. The immunomodulatory effects of viable concentrations of phytol were tested on oxidative stress, arginase activity, nuclear and mitochondrial membrane potentials in IC-21 cells in addition to the modulation of calcium and lipids. Further, gene and protein expression of atherogenic markers were studied. Results showed that the isolated phytol at a viable concentration of 400 µg/ml effectively reduced the production of nitric oxide, superoxide anion (ROS generation), calcium and lipid accumulation, stabilized nuclear and mitochondrial membranes, and increased arginase activity. The atherogenic markers including iNOS, COX-2, IL-6, IL-1β, MMP-9, CD36, and NF-κB were significantly downregulated at the levels of gene and protein expression, while macrophage surface and nuclear receptor markers (CD206, CD163, and PPAR-γ) were significantly upregulated by phytol pre-treatment in macrophages. Therefore, the present pharmacognostic study supports the role of phytol isolated from Scoparia dulcis in preventing M2-M1 macrophage polarization under inflammatory conditions, making it a promising compound.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-024-03924-9.

Secondary Terpenes in Cannabis sativa L.: Synthesis and Synergy

Cannabis is a complex biosynthetic plant, with a long history of medicinal use. While cannabinoids have received the majority of the attention for their psychoactive and pharmacological activities, cannabis produces a diverse array of phytochemicals, such as terpenes. These compounds are known to play a role in the aroma and flavor of cannabis but are potent biologically active molecules that exert effects on infectious as well as chronic diseases. Furthermore, terpenes have the potential to play important roles, such as synergistic and/or entourage compounds that modulate the activity of the cannabinoids. This review highlights the diversity and bioactivities of terpenes in cannabis, especially minor or secondary terpenes that are less concentrated in cannabis on a by-mass basis. We also explore the question of the entourage effect in cannabis, which studies to date have supported or refuted the concept of synergy in cannabis, and where synergy experimentation is headed, to better understand the interplay between phytochemicals within Cannabis sativa L.

Liposomal drug delivery of Corchorus olitorius leaf extract containing phytol using design of experiment (DoE): In-vitro anticancer and in-vivo anti-inflammatory studies

Phytol, a pharmacologically active compound present in Corchorus olitorius leaf exhibit a range of activity including anti-inflammatory, antioxidant, anticancer, hepatoprotective etc. However, phytol is poorly soluble and absorbed through the intestine wall, therefore the aim of this study is to develop liposomal drug delivery of Corchorus olitorius leaf extract with an average particle size below 150 nm and drug loading efficiency of ≥ 85 %. The impact of different process parameters and material attributes were studied on the average particle size and polydispersity of liposomal batches using design of experiment (DoE). Corchorus olitorius leaf extraction was performed using maceration method and characterised using GC-MS. Liposomal batches of Corchorus olitorius leaf extract were characterized using Malvern zetasizer, transmission electron microscopy (TEM) and UV spectroscopy. The in-vivo anti-inflammatory study of the liposomal preparation of phytol was evaluated using a rat model and in-vitro cancer cell line study was performed on AML and Leukamia cell lines. GC-MS study data showed that phytol is present in C. olitorius leaf extract. Process parameters and material attributes perspective processing temperature, buffer pH and drug: lipid ratio is found as major parameters affecting the average particle size and PDI value of liposomes. Liposomes were prepared in the range of 80-250 nm and optimized batches of liposomes showed drug entrapment efficiency of 60-88 %. In-vivo anti-inflammatory study showed significant activity for C. olitorius leaf extract against carrageenan induced paw edema, which is significantly increased while delivered through liposomes. In-vitro cancer cell line study data suggests that liposomal delivery of phytol was more active at lower concentration compared to pure phytol, for specific cell lines.

Lavatera critica controls systemic insulin resistance by ameliorating adipose tissue inflammation and oxidative stress using bioactive compounds identified by GC-MS

BACKGROUND

Lavatera critica, a leafy green herb, is reported to have many pharmacological activities; but, the improvement of insulin sensitivity against the high gram-fat diet (HGFD)-caused insulin resistance (IR) has not yet been studied.

OBJECTIVE

This study evaluated the role of Lavatera critica leaf extract (LCE) in systemic insulin resistance through the alleviation of adipose tissue inflammation and oxidative damage in HGFD fed mice.

METHODS

The mice were fed with HGFD for 10 weeks and the diet was supplemented with LCE each day for the next five weeks. Body weight, food intake, leptin, blood glucose, insulin, insulin resistance, and pro- and anti-inflammatory genes expression were assessed on day 106.

RESULTS

The HGFD control mice displayed markedly elevated adipose tissue inflammation, oxidative stress, insulin inactivity, and hyperglycemia. Administration of LCE in the HGFD mice, especially a dose of 100 mg/kg, lowered the body weight, food intake, plasma leptin, plasma glucose, plasma insulin, insulin resistance, and increased the food efficacy ratio when compared with the HGFD control mice. The oral glucose tolerance test (OGTT) revealed that LCE prevented further increase in the circulating levels after the glucose load. LCE-treated mice demonstrated a marked suppression of pro-inflammatory cytokines mRNA expression. On the other hand, the mice showed a higher anti-inflammatory genes mRNA expression in the adipose tissue. In addition, LCE treatment improved the oxidative damage as evidenced by the reduced levels of lipid hydroperoxides and thiobarbituric acid reactive substances coupled with the increased antioxidants (superoxide dismutase, total glutathione, glutathione/glutathione disulfide ratio and glutathione peroxidase) in the adipose tissue, plasma and erythrocytes. Gas chromatography-mass spectrometry analysis of the bioactive compounds revealed the presence of 9, 12, 15-octadecatrienoic acid, vitamin E, phytol, hexadecanoic acid, benzenepropanoic acid, and stigmasterol.

CONCLUSIONS

These findings prove that LCE improves the insulin-sensitizing activity in the mouse model of HGFD-caused IR, probably due to the amelioration of adipose tissue inflammation and oxidative damage. Hence, the LCE could serve as a useful anti-diabetic agent.

Virtual screening of plant compounds and nonsteroidal anti-inflammatory drugs for inhibition of quorum sensing and biofilm formation in Salmonella

Salmonella belongs to the Enterobacteriaceae family which is widely distributed in the environment due to its adaptive capacity to stress conditions. In addition, Salmonella is able to perform a type of cell-to-cell communication called quorum sensing, which leads to differential gene expression. The quorum sensing system mediated by AI-1, acyl homoserine lactones (AHLs), is incomplete in Salmonella because the luxI homolog gene, which encodes for AI-1 synthase, is missing in the genome. However, a homologue of LuxR, known as SdiA, is present and allows the detection of signaling molecules produced by other species of bacteria, leading to regulation of gene expression, mainly related to virulence and biofilm formation. Thus, in view of the importance of quorum sensing on the physiology regulation of microorganisms, the aim of the present study was to perform a virtual screening of plant compounds and nonsteroidal anti-inflammatory drugs (NASIDs) for inhibition of quorum sensing by molecular docking and biofilm formation in Salmonella. In general, most plant compounds and all NSAIDs bound in, at least, one of the three modeled structures of SdiA proteins of Salmonella Enteritidis PT4 578. In addition, many tested compounds had higher binding affinities than the AHLs and the furanones which are inducers and inhibitors of quorum sensing, respectively. The Z-phytol and lonazolac molecules were good candidates for the in vitro inhibition tests of quorum sensing mediated by AI-1 and biofilm formation in Salmonella. Thus, this study directs future prospecting of plant extracts for inhibition of quorum sensing mechanism depending on AHL and biofilm formation. In addition, the use of inhibitors of quorum sensing and biofilm formation can be combined with antibiotics for better treatment efficacy, as well as the use of these compounds to design new drugs.

Toxicological evaluation of an aqueous suspension from leaves and stems of Petiveria alliacea L. (Phytolaccaceae)

ETHNOPHARMACOLOGICAL RELEVANCE

Petiveria alliacea L. (Phytolaccaceae) is used in folk medicine due to its antispasmodic, diuretic, hypoglycemic, abortive, anti-inflammatory and anticancerogenic properties. Although P. alliacea is considered toxic by people, its toxicity remains a concern since it is strongly dependent on the extraction method and the part of the plant used during tests. Even if some healers prefer to use the aerial parts in a liquefied form or by chewing them, instead of decoctions or infusions, no toxicological studies exist using whole dried stems and leaves.

MATERIALS AND METHODS

The toxicity of a suspension of the powder from the leaves and stems of P. alliacea was assessed in Sprague Dawley rats by oral administration using two tests: 1) the acute toxic class method, which allows classification of substances according to their intrinsic toxicity and 2) the repeated dose 28-day method, following the guidelines 423 and 407 respectively from the Organization for the Economic Cooperation and Development. Chemical characterization of this powder was performed by GC-MS, UV-fluorescence, proximate and elemental analysis.

RESULTS AND CONCLUSIONS

P. alliacea powder from stems and leaves was classed in the hazard category 5 (LD₅₀ > 2000mg/kg) according to the acute toxicology study. There were no toxicity signs at 1000mg/kg in the repeated dose study, although higher values of total leukocytes were found in the satellite and males of the experimental group, which were attributed to the immunomodulatory properties of this plant. According to GC-MS, the prevailing compounds identified were phytol, (R)-(-)-(Z)-14-methyl-8-hexadecen-1-ol, 1-(2-hydrohyethyl)-1,2,4-triazole and methyl β-dimethylaminoisobutyrate. In conclusion, the oral administration of the P. alliacea powder to Sprague Dawley rats did not result in deaths and was not associated with adverse effects reflected in the general condition, body weights or histopathological abnormalities.

A novel function of geranylgeraniol in regulating testosterone production

Isoprenoids play widely differing roles in various physiological processes in animals and plants. Geranylgeraniol (GGOH) is an isoprenoid found in plants, and is an important metabolic derivative in the isoprenoid/cholesterol synthesis pathway. Earlier studies focused on GGOH's ability to improve the side effects of bisphosphonate therapy by regulating the mevalonate pathway. More recently, the mevalonate pathway-independent effects of GGOH have been described, including anti-inflammatory, anti-tumorigenic, and neuroprotective activities. It is noteworthy that GGOH regulates the steroidogenesis pathway in testis-derived I-10 tumor cells. Testosterone is a hormone produced via steroidogenesis in testicles and plays a role in fetal development and the male reproductive system. GGOH enhanced testosterone and progesterone (its precursor) levels in I-10 cells by activating adenylate cyclase via cAMP/PKA signaling, without altering phosphodiesterase activity. These findings highlight the potential benefits of GGOH as a therapeutic agent for low testosterone levels, such as late-onset hypogonadism in men.

The Role of Natural Products in Drug Discovery and Development against Neglected Tropical Diseases

Endemic in 149 tropical and subtropical countries, neglected tropical diseases (NTDs) affect more than 1 billion people annually, including 875 million children in developing economies. These diseases are also responsible for over 500,000 deaths per year and are characterized by long-term disability and severe pain. The impact of the combined NTDs closely rivals that of malaria and tuberculosis. Current treatment options are associated with various limitations including widespread drug resistance, severe adverse effects, lengthy treatment duration, unfavorable toxicity profiles, and complicated drug administration procedures. Natural products have been a valuable source of drug regimens that form the cornerstone of modern pharmaceutical care. In this review, we highlight the potential that remains untapped in natural products as drug leads for NTDs. We cover natural products from plant, marine, and microbial sources including natural-product-inspired semi-synthetic derivatives which have been evaluated against the various causative agents of NTDs. Our coverage is limited to four major NTDs which include human African trypanosomiasis (sleeping sickness), leishmaniasis, schistosomiasis and lymphatic filariasis.

Neuroprotective effect of the marine macroalga Gelidiella acerosa: identification of active compounds through bioactivity-guided fractionation

Context Gelidiella acerosa (Forsskål) Feldmann & G. Hamel (Rhodophyta-Gelidiales) is a marine red macroalga. Our previous work found that a benzene extract of G. acerosa possesses noticeable neuroprotective activity, when evaluated through in vitro and in vivo systems. Objective Bioactive-guided fractionation and identification of active compounds by column chromatography using solvents of varying polarity. Materials and methods Fractionation was done by column chromatography, antioxidant and anticholinesterase activity was assessed by DPPH and cholinesterase inhibition assays (50-200 μg/ml), compound identification was done by LC-MS analysis, the mode of interaction of active compound was analyzed through docking studies and quantification was done by high-performance thin-layer chromatography (HPTLC) analysis. Results The results suggest that fractions F9-F13 exhibited significant (p < 0.05) antioxidant and anticholinesterase activities. Hence, these fractions were pooled together and verified for neuroprotective activity. The pooled fraction was subjected to LC-MS analysis and among all the compounds, phytol was previously reported to possess excellent neuroprotective potential. Hence, the neuroprotective potential of phytol was assessed. The results suggest that phytol showed significant (p < 0.05) antioxidant activities (25-125 μg/ml) with an IC50 value of 95.27 ± 1.65 μg/ml and cholinesterase inhibitory potential (5-25 μg/ml) with IC50 values of 2.704 ± 0.07 and 5.798 ± 0.72 μg/ml for AChE and BuChE, respectively. Molecular docking studies suggest that phytol interacts with cholinesterase through the arginine residue of the enzyme. HPTLC quantification showed that about 6.266 μg of phytol was present per mg of pooled fraction. Conclusion The study suggests that phytol might act as the key compound in contributing to the neuroprotective potential of G. acerosa.

Geranylgeraniol enhances testosterone production via the cAMP/protein kinase A pathway in testis-derived I-10 tumor cells

Testosterone levels in men decrease with age; this decline has been linked to various diseases and can shorten life expectancy. Geranylgeraniol (GGOH) is an isoprenoid found in plants that plays an important role in several biological processes; however, its role in steroidogenesis is unknown. Here, we report that GGOH enhances the production of testosterone and its precursor progesterone in testis-derived I-10 tumor cells. GGOH induced protein kinase A (PKA) activity and increased cAMP levels and was found to regulate cAMP/PKA signaling by activating adenylate cyclase without altering phosphodiesterase activity. GGOH also stimulated mRNA and protein levels of steroidogenic acute regulatory protein, a downstream effector in the cAMP/PKA pathway. These results demonstrate that GGOH enhances steroidogenesis in testis-derived cells by modulating cAMP/PKA signaling. Our findings have potential applications for the development of therapeutics that increase testosterone levels in aging men.

Phytol, a diterpene alcohol from chlorophyll, as a drug against neglected tropical disease Schistosomiasis mansoni

BACKGROUND

Schistosomiasis is a major endemic disease that affects hundreds of millions worldwide. Since the treatment and control of this parasitic disease rely on a single drug, praziquantel, it is imperative that new effective drugs are developed. Here, we report that phytol, a diterpene alcohol from chlorophyll widely used as a food additive and in medicinal fields, possesses promising antischistosomal properties in vitro and in a mouse model of schistosomiasis mansoni.

METHODS AND FINDINGS

In vitro, phytol reduced the motor activity of worms, caused their death and confocal laser scanning microscopy analysis showed extensive tegumental alterations in a concentration-dependent manner (50 to 100 µg/mL). Additionally, phytol at sublethal doses (25 µg/mL) reduced the number of Schistosoma mansoni eggs. In vivo, a single dose of phytol (40 mg/kg) administered orally to mice infected with adult S. mansoni resulted in total and female worm burden reductions of 51.2% and 70.3%, respectively. Moreover, phytol reduced the number of eggs in faeces (76.6%) and the frequency of immature eggs (oogram pattern) was significantly reduced. The oogram also showed increases in the proportion of dead eggs. Confocal microcopy studies revealed tegumental damage in adult S. mansoni recovered from mice, especially in female worms.

CONCLUSIONS

The significant reduction in parasite burden by this chlorophyll molecule validates phytol as a promising drug and offers the potential of a new direction for chemotherapy of human schistosomiasis. Phytol is a common food additive and nonmutagenic, with satisfactory safety. Thus, phytol has potential as a safe and cost-effective addition to antischistosomal therapy.

Efficacy of phytol-derived diterpenoid immunoadjuvants over alum in shaping the murine host's immune response to Staphylococcus aureus

The ubiquitous gram-positive bacterium Staphylococcus aureus occupies a unique niche in humans for its ability to survive both as a commensal and a life-threatening pathogen. Its complex relationship with the host and its ability to engender a throng of virulence factors, have hindered the development of a successful vaccine against it. The use of immunoadjuvants to enhance host immunity and prevent the shift from commensalism to pathogenicity is a rational approach for containing infection. The objective of this study was to understand the mechanisms by which alum and two phytol-derived immunoadjuvants, phytanol (PHIS-01)(1) and phytanyl chloride (PCl)(2) shape the interaction between S. aureus and its murine host. We studied the effects of the phytol derivatives, relative to alum, on the induction of inflammatory cytokines and chemokines, recruitment of CD11b(+) cells, generation of specific anti-S. aureus antibodies and in vitro clearance of S. aureus. Our results showed that both PHIS-01 and PCl were stronger inducers of protective cytokines IL-17 and IL-1β than alum, and far exceeded alum in enhancing anti-S. aureus antibody response. However, both alum and the phytol derivatives (particularly PCl) promoted efficient recruitment of CD11b(+) cells. Furthermore, PHIS-01, alum and to a lesser extent, PCl were able to up-regulate the expression of key inflammation-related genes that were highly down-regulated by S. aureus alone. In vitro killing assays showed that both PHIS-01 and PCl were far more potent than alum in promoting S. aureus clearance; this indicated their efficiency in shaping an effective anti-S. aureus immune microenvironment. In summary, our study provides evidence for the better effectiveness of phytol-derived immunoadjuvants over alum in enhancing anti-S. aureus immunity.

Synthetic adjuvants for vaccine formulations: phytol derivatives

INTRODUCTION

The development of vaccines is considered a key milestone in preventive medicine. There is no comparable cost-effective means for controlling or eradicating infectious diseases. Yet, a persistent societal problem is the concern about vaccine's safety and long-term effects, and this caters to detractors of vaccination. Pathogen-derived antigen(s) as well as adjuvants/immunostimulants are essential for vaccine efficacy. Currently, adjuvant selection is largely empirical, but the mechanism underlying adjuvanticity is beginning to unravel. This should help develop more defined or targeted adjuvants.

AREAS COVERED

This review provides a brief account and analysis of the host immune parameters modulated by some commonly used as well as new adjuvants, including phytol-based diterpenoids. The major efforts are directed toward evaluating their relative safety and immunomodulatory efficiency, compared to known synthetic and natural adjuvants. Concerns for adverse pathological inflammation and autoimmunity are also addressed.

EXPERT OPINION

The phytol-based adjuvants hold great promise for improving vaccine efficacy, as they cause little or no persistent inflammation, but are highly effective in stimulating a multifaceted immune response, characterized by proficient recruitment of immune cells, generation of antibody and immunological memory, and activation of both Th1 and Th2 responses. Future focus will be on developing cocktail adjuvants to activate the complement system, mobilize follicular T helper cells as well as NKT and γδ T cells and activate cross-presenting dendritic cells to stimulate CD8(+) effector T cells.

Melanoma vaccines and modulation of the immune system in the clinical setting: building from new realities

To endow the immune system with the capacity to fight cancer has always attracted attention, although the clinical results obtained have been until recently disappointing. Cutaneous melanoma is a highly immunogenic tumor; therefore most of the attempts to produce cancer vaccines have been addressed to this disease. New advances in the comprehension of the mechanisms of antigen presentation by dendritic cells, in the immune responses triggered by adjuvants, as well as the understanding of the role of immunosuppressor molecules such as cytotoxic T-lymphocyte antigen-4 (CTLA-4), which led to the recent approval of the anti-CTLA-4 monoclonal antibody ipilimumab, have opened new hopes about the installment of immunotherapy as a new modality to treat cancer.