María del Carmen Juárez-Vázquez

Background: The plant-derived compound n-butylidenephthalide (BP) is an isobenzofuranone that has shown neuropharmacological effects on preclinical models of Parkinson’s, Alzheimer’s, and amyotrophic lateral sclerosis. Methods: This study evaluated the anti-inflammatory, antinociceptive, anxiolytic-like, hypnotic, anticonvulsant, and antidepressant-like effects of BP (50–200 mg/kg p.o.) using Balb/c mice in acute assays. This study also evaluated the antidepressant-like effects of BP in a mouse model of reserpine-induced depression-like behavior for 20 days. Inhibitors involved in the molecular process of depression and in silico studies were used to evaluate a possible mechanism of action for the antidepressant-like effects of BP. Results: BP induced low anti-inflammatory effects, showed low anticonvulsant effects, and lacked hypnotic effects or motor impairment in acute assays. The antidepressant-like effects of BP (100–200 mg/kg p.o.) were comparable to amitriptyline (25 mg/kg p.o.) in acute assays. The participation of serotonergic and adrenergic systems is involved in the acute antidepressant-like effects of BP. In the reserpine-induced depression model, BP (100 mg/kg p.o.) showed antidepressant-like effects in one of the two antidepressant tests, but with a lower effect than amitriptyline (20 mg/kg p.o.). Conclusions: BP (100 and 200 mg/kg) showed antidepressant-like effects in acute assays and, to a lesser extent, in a reserpine-induced chronic model of depression-like behavior.

Parkinson’s disease is the second most common neurodegenerative disease in the world. Natural products can offer a possible option of neuroprotective agents for preventing neurodegenerative diseases. D-Pinitol is a cyclic polyol with anxiolytic and antidepressant effects in acute assays. This work aimed to evaluate the effects of D-Pinitol (10, 50, and 100 mg/kg p.o.) in a chronic reserpine-induced depression model (19 days), using the forced swimming and tail suspension tests in female Balb/c mice, and the neuroprotective effects in an MPTP-induced Parkinsonism model (30 days) in male C57bL/6 mice, using behavioral tests such as wire grip, rotarod, catalepsy, and others. D-Pinitol showed low antidepressant-like effects in the reserpine-induced chronic depression model, compared to amitriptyline (25 mg/kg p.o.). D-Pinitol protected MPTP-treated mice from motor impairment with similar effects to those shown by L-Dopa (25 mg/kg p.o.) as evaluated in different behavioral tests. The inhibition of oxidative stress markers, increase in dopamine levels, and avoidance of apoptosis in neuronal cells were the mechanisms by which D-Pinitol protects MPTP-treated mice from motor impairment.

A literature review was undertaken by analyzing distinguished books, undergraduate and postgraduate theses, and peer‐reviewed scientific articles and by consulting worldwide accepted scientific databases, such as SCOPUS, Web of Science, SCIELO, Medline, and Google Scholar. Medicinal plants used as immunostimulants were classified into two categories: (1) plants with pharmacological studies and (2) plants without pharmacological research. Medicinal plants with pharmacological studies of their immunostimulatory properties were subclassified into four groups as follows: (a) plant extracts evaluated for in vitro effects, (b) plant extracts with documented in vivo effects, (c) active compounds tested on in vitro studies, and (d) active compounds assayed in animal models. Pharmacological studies have been conducted on 29 of the plants, including extracts and compounds, whereas 75 plants lack pharmacological studies regarding their immunostimulatory activity. Medicinal plants were experimentally studied in vitro (19 plants) and in vivo (8 plants). A total of 12 compounds isolated from medicinal plants used as immunostimulants have been tested using in vitro (11 compounds) and in vivo (2 compounds) assays. This review clearly indicates the need to perform scientific studies with medicinal flora from Mexico, Central America, and the Caribbean, to obtain new immunostimulatory agents.