Lepithiohydimerins A—D: Four Pairs of Neuroprotective Thiohydantoin Dimers Bearing a Disulfide Bond from Maca ( Lepidium meyenii Walp.)

Spiroleiferthione A and Oleiferthione A: Two Unusual Isothiocyanate-Derived Thioketone Alkaloids from Moringa oleifera Lam. Seeds

Spiroleiferthione A (1), with a 2-thiohydantoin a heterocyclic spiro skeleton, and oleiferthione A (2), an imidazole-2-thione derivative, were isolated from the aqueous extract of Moringa oleifera Lam. seeds. The unprecedented structures of 1 and 2 were elucidated by extensive spectroscopic data, X-ray diffraction, and gauge-independent atomic orbital (GIAO) NMR calculation, as well as electronic circular dichroism (ECD) calculation. The structures of 1 and 2 were determined to be (5R,7R,8S)-8-hydroxy-3-(4′-hydroxybenzyl)-7-methyl-2-thioxo-6-oxa-1, 3-diazaspiro [4.4] nonan-4-one, and 1-(4′-hydroxybenzyl)-4,5-dimethyl-1,3-dihydro-2H-imidazole-2-thione, respectively. Biosynthetic pathways for 1 and 2 have been proposed. Compounds 1 and 2 are considered to have originated from isothiocyanate and then undergone a series of oxidation and cyclization reactions to form 1 and 2. Compounds 1 and 2 demonstrated weak inhibition rates of NO production, 42.81 ± 1.56% and 33.53 ± 2.34%, respectively, at a concentration of 50 μM. Additionally, Spiroleiferthione A demonstrated moderate inhibitory activity against high glucose-induced human renal mesangial cell proliferation in a dosage-dependent manner. A wider range of biological activities, and the diabetic nephropathy protective activity of Compound 1 in vivo and its mechanism of action, need further investigation after the sufficient enrichment of Compound 1 or total synthesis.

Deep Eutectic Solvent-Based Ultrasound-Assisted Strategy for Simultaneous Extraction of Five Macamides from Lepidium meyenii Walp and In Vitro Bioactivities

This study aimed to develop an integrated approach of deep eutectic solvent-based ultrasound-assisted extraction (DES-UAE) to simultaneously extract five major bioactive macamides from the roots of Lepidium meyenii Walp. Ten different DESs containing choline chloride and selected hydrogen-bond donors were prepared and evaluated based on the extracted macamide content determination using high-performance liquid chromatography (HPLC). Choline chloride/1,6-hexanediol in a 1:2 molar ratio with 20% water exhibited the most promising extraction efficiencies under the optimized parameters verified using single-factor optimization as well as Box-Behnken design. Using the optimized DES-UAE method, the extraction efficiencies of the five macamides were up to 40.3% higher compared to those using the most favorable organic solvent petroleum ether and were also superior to those of the other extraction methods, such as heating and combination of heating and stirring. Furthermore, using the macroporous resin HPD-100, the recoveries of the five target macamides from the DES extraction reached 85.62-92.25%. The 20 μg/mL group of the five macamide extracts showed superior neuroprotective activity against PC12 cell injury than that of the positive drug nimodipine. The macamide extracts also showed higher NO inhibition in LPS-stimulated RAW264.7 cells. Thus, the developed approach was a green and potential alternative that can be used to extract bioactive macamide constituents from L. meyenii in the pharmaceutical and food industries.

Current Naturopathy to Combat Alzheimer's Disease

Neurodegeneration is the progressive loss of structure or function of neurons, which may ultimately involve cell death. The most common neurodegenerative disorder in the brain happens with Alzheimer's disease (AD), the most common cause of dementia. It ultimately leads to neuronal death, thereby impairing the normal functionality of the central or peripheral nervous system. The onset and prevalence of AD involve heterogeneous etiology, either in terms of genetic predisposition, neurometabolomic malfunctioning, or lifestyle. The worldwide relevancies are estimated to be over 45 million people. The rapid increase in AD has led to a concomitant increase in the research work directed towards discovering a lucrative cure for AD. The neuropathology of AD comprises the deficiency in the availability of neurotransmitters and important neurotrophic factors in the brain, extracellular betaamyloid plaque depositions, and intracellular neurofibrillary tangles of hyperphosphorylated tau protein. Current pharmaceutical interventions utilizing synthetic drugs have manifested resistance and toxicity problems. This has led to the quest for new pharmacotherapeutic candidates naturally prevalent in phytochemicals. This review aims to provide an elaborative description of promising Phyto component entities having activities against various potential AD targets. Therefore, naturopathy may combine with synthetic chemotherapeutics to longer the survival of the patients.

Macathiohydantoin L, a Novel Thiohydantoin Bearing a Thioxohexahydroimidazo [1,5-a] Pyridine Moiety from Maca (Lepidium meyenii Walp.)

Five new thiohydantoin derivatives (1–5) were isolated from the rhizomes of Lepidium meyenii Walp. NMR (¹H and ¹³C NMR, ¹H−¹H COSY, HSQC, and HMBC), HRESIMS, and ECD were employed for the structure elucidation of new compounds. Significantly, the structure of compound 1 was the first example of thiohydantoins with thioxohexahydroimidazo [1,5-a] pyridine moiety. Additionally, compounds 2 and 3 possess rare disulfide bonds. Except for compound 4, all isolates were assessed for neuroprotective activities in corticosterone (CORT)-stimulated PC12 cell damage. Among them, compound (−)-3 exhibited moderate neuroprotective activity (cell viability: 68.63%, 20 μM) compared to the positive control desipramine (DIM) (cell viability: 88.49%, 10 μM).