Nigella sativa and its chemical constituents: pre-clinical and clinical evidence for their potential anti-SARS-CoV-2 effects.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused over 500 million reported cases of COVID-19 worldwide with relatively high morbidity and mortality. Although global vaccination drive has helped control the pandemic, the newer variant of the virus still holds the world in ransom. Several medicinal herbs with antiviral properties have been reported, and one such promising herb is Nigella sativa (NS). Recent molecular docking, pre-clinical, and clinical studies have shown that NS extracts may have the potential to prevent the entry of coronaviruses into the host cell as well as to treat and manage COVID-19 symptoms. Several active compounds from NS, such as nigelledine, α-hederin, dithymoquinone (DTQ), and thymoquinone (TQ), have been proposed as excellent ligands to target angiotensin-converting enzyme 2 (ACE2 receptors) and other targets on host cells as well as the spike protein (S protein) on SARS-CoV-2. By binding to these target proteins, these ligands could potentially prevent the binding between ACE2 and S protein. Though several articles have been published on the promising therapeutic role of NS and its constituents against SARS-CoV-2 infection, in this review, we consolidate the published information on NS and SARS-CoV-2, focusing on pre-clinical in silico studies as well as clinical trials reported between 2012 and 2023.

The wound healing and hypoglycemic activates of date palm (Phoenix dactylifera) leaf extract and saponins in diabetic and normal rats.

INTRODUCTION: Indigenous plants have historically been crucial in treating human diseases across various cultures worldwide. Research continues to uncover new therapeutic uses for indigenous plants, from treating infectious diseases to managing chronic conditions such as diabetes and wound care. This study aimed to examine the effect of palm tree leaves "Phoenix dactylifera L" extract and its topical film formulation on wound healing and blood glucose levels. METHODS: Palm leaves were collected, authenticated, powdered, and extracted with ethanol by cold maceration. Saponins were isolated. The dried extract was analyzed using reverse-phase high-pressure liquid chromatography to identify the phytochemicals present. Diabetes mellitus was induced by a single intraperitoneal injection of Streptozotocin (40mg/kg). Rats with blood glucose levels ≥ 200 mg/dl were used to determine the reduction in blood glucose with or without the oral extract. Incision and excision wounds were induced in both diabetic and normal rats. Topical films containing extract or saponin and inert films were applied to the wounds every other day, and wound sizes were recorded until the wound was completely healed. RESULTS: The presence of six flavonoids, Naringin, Rutin, Quercetin, Kaempferol, Apigenin, and Catechin, and five phenolic acids, Syringic acid, p Coumaric acid, Caffeic acid, Ferulic acid, Ellagic acid were detected in the dried extract. A significant reduction in blood sugar in diabetic rats and wound diameter in the treated group compared to the control group in both diabetic and normal rats was observed, confirming the promising role of palm leaf extract on diabetes and wound care. Macroscopic, morphometric, and histological data suggested that the cutaneous wound healing in rats treated with the leaf extract was better and faster than the control or inert groups. CONCLUSIONS: Our research findings highlight the marked effect of Phoenix dactylifera extract as a supportive or alternative treatment for both hyperglycemia and incision or excision wounds. Further research and clinical trials are warranted to validate these findings and explore the underlying mechanisms of action.

Inhibition of human α7 nicotinic acetylcholine receptors by cyclic monoterpene carveol.

Cyclic monoterpenes are a group of phytochemicals with antinociceptive, local anesthetic, and anti-inflammatory actions. Effects of cyclic monoterpenes including vanilin, pulegone, eugenole, carvone, carvacrol, carveol, thymol, thymoquinone, menthone, and limonene were investigated on the functional properties of the cloned α7 subunit of the human nicotinic acetylcholine receptor expressed in Xenopus oocytes. Monoterpenes inhibited the α7 nicotinic acetylcholine receptor in the order carveol>thymoquinone>carvacrol>menthone>thymol>limonene>eugenole>pulegone≥carvone≥vanilin. Among the monoterpenes, carveol showed the highest potency on acetylcholine-induced responses, with IC50 of 8.3µM. Carveol-induced inhibition was independent of the membrane potential and could not be reversed by increasing the concentration of acetylcholine. In line with functional experiments, docking studies indicated that cyclic monoterpenes such as carveol may interact with an allosteric site located in the α7 transmembrane domain. Our results indicate that cyclic monoterpenes inhibit the function of human α7 nicotinic acetylcholine receptors, with varying potencies.

Effects of monoterpenes on ion channels of excitable cells.

Monoterpenes are a structurally diverse group of phytochemicals and a major constituent of plant-derived 'essential oils'. Monoterpenes such as menthol, carvacrol, and eugenol have been utilized for therapeutical purposes and food additives for centuries and have been reported to have anti-inflammatory, antioxidant and analgesic actions. In recent years there has been increasing interest in understanding the pharmacological actions of these molecules. There is evidence indicating that monoterpenes can modulate the functional properties of several types of voltage and ligand-gated ion channels, suggesting that some of their pharmacological actions may be mediated by modulations of ion channel function. In this report, we review the literature concerning the interaction of monoterpenes with various ion channels.