In Vitro Antileishmanial Effects of Saffron Compounds, Crocin and Stigmasterol, on Iranian Strain of Leishmania major (MHOM/IR/75/ER)

Marine Natural Products as Novel Treatments for Parasitic Diseases

Parasitic diseases including malaria, leishmaniasis, and trypanosomiasis have received significant attention due to their severe health implications, especially in developing countries. Marine natural products from a vast and diverse range of marine organisms such as sponges, corals, molluscs, and algae have been found to produce unique bioactive compounds that exhibit promising potent properties, including antiparasitic, anti-Plasmodial, anti-Leishmanial, and anti-Trypanosomal activities, providing hope for the development of effective treatments. Furthermore, various techniques and methodologies have been used to investigate the mechanisms of these antiparasitic compounds. Continued efforts in the discovery and development of marine natural products hold significant promise for the future of novel treatments against parasitic diseases.

Natural products derived steroids as potential anti-leishmanial agents; disease prevalence, underlying mechanisms and future perspectives

Leishmaniasis is a vector-borne infection caused by protozoan parasites from the genus leishmania and is among the most neglected tropical diseases. It is highly prevalent disease, affecting about 350 million population worldwide. Only limited number of anti-leishmanial agents are approved for clinical use till now and they are associated with side effects and have limited efficacy. Subsequently, natural products based discovery of more safe and effective drugs against leishmania is under scientific consideration. Various studies reported the efficacy of natural products against intracellular and extracellular forms of leishmania species. This work is aimed to evaluate current literature focused on the anti-leihmanial efficacy of steroidal moieties from natural products and their mechanism of action. Compounds including steroidal saponins, steroidal alkaloids and phytosterols were found to exhibit considerable anti-leishmanial efficacy. For instance, steroidal saponin, (25R)-spirost-5-en-3b-ol,3-O-α-rhamnopyranosyl-(1 → 4)-α-rhamnopyranosyl-(1 → 4)-[a-rhamnopyranosyl-(1 → 2)]-glucopyranoside isolated from A. paradoxum has completely eradicated Leishmania major promastigotes at 50 µg mL-1 dose. Spirostanic saponins isolated from Solanum paniculatum L. were effective against Leishmania amazonensis promastigotes. Turgidosterones isolated from Panicum turgidum exhibited high leishmanicidal potentials against Leishmania donovani promastigotes with IC50 of 4.95-8.03 µg mL-1 and even better activity against amastigotes exhibiting an IC50 of 4.50-9.29 µg mL-1. Likewise, racemoside-A from Asparagus racemosus was found effective against an antimonial sensitive (AG83) and antimonial resistant (GE1F8R) strains of the L. donovani. Moreover, steroidal alkaloids including hookerianamide-1, hookerianamide-H, hookerianamide-J, hookerianamide-K, dehydrosarsalignone, vagenine-A, sarcovagine-C, holaphylline, saracodine, holamine, 15-α hydroxyholamine, holacurtin, N-desmethyl holacurtine and elasticine has exhibited time and dose-dependent efficacy against various strains of leishmania. β-sitosterol was found active against multiple strains of leishmania. These compounds mainly exhibit their therapeutic efficacy via liberation of ROS, mitochondrial depolarization, morphological and ultra-structural changes, accumulation of lipid droplets, depletion of non-protein thiols and triggering apoptotic pathways. In conclusion, leishmaniasis is a major health problem in many countries. Plants-derived steroids moieties have reveled efficacy against leishmaniasis and is a source of lead compounds. Further detailed molecular studies are warranted for the discovery of more effective and safe anti-leishmanial drugs.

Health Benefits and Pharmacological Properties of Stigmasterol

Stigmasterol is an unsaturated phytosterol belonging to the class of tetracyclic triterpenes. It is one of the most common plant sterols, found in a variety of natural sources, including vegetable fats or oils from many plants. Currently, stigmasterol has been examined via in vitro and in vivo assays and molecular docking for its various biological activities on different metabolic disorders. The findings indicate potent pharmacological effects such as anticancer, anti-osteoarthritis, anti-inflammatory, anti-diabetic, immunomodulatory, antiparasitic, antifungal, antibacterial, antioxidant, and neuroprotective properties. Indeed, stigmasterol from plants and algae is a promising molecule in the development of drugs for cancer therapy by triggering intracellular signaling pathways in numerous cancers. It acts on the Akt/mTOR and JAK/STAT pathways in ovarian and gastric cancers. In addition, stigmasterol markedly disrupted angiogenesis in human cholangiocarcinoma by tumor necrosis factor-α (TNF-α) and vascular endothelial growth factor receptor-2 (VEGFR-2) signaling down-regulation. The association of stigmasterol and sorafenib promoted caspase-3 activity and down-regulated levels of the anti-apoptotic protein Bcl-2 in breast cancer. Antioxidant activities ensuring lipid peroxidation and DNA damage lowering conferred to stigmasterol chemoprotective activities in skin cancer. Reactive oxygen species (ROS) regulation also contributes to the neuroprotective effects of stigmasterol, as well as dopamine depletion and acetylcholinesterase inhibition. The anti-inflammatory properties of phytosterols involve the production of anti-inflammatory cytokines, the decrease in inflammatory mediator release, and the inhibition of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). Stigmasterol exerts anti-diabetic effects by reducing fasting glucose, serum insulin levels, and oral glucose tolerance. Other findings showed the antiparasitic activities of this molecule against certain strains of parasites such as Trypanosoma congolense (in vivo) and on promastigotes and amastigotes of the Leishmania major (in vitro). Some stigmasterol-rich plants were able to inhibit Candida albicans, virusei, and tropicalis at low doses. Accordingly, this review outlines key insights into the pharmacological abilities of stigmasterol and the specific mechanisms of action underlying some of these effects. Additionally, further investigation regarding pharmacodynamics, pharmacokinetics, and toxicology is recommended.