Alkaloids from Pandanus amaryllifolius: Isolation and Their Plausible Biosynthetic Formation

Botany, phytochemistry, pharmacology, and applications of Pandanus amaryllifolius Roxb.: A review

Pandan (Pandanus amaryllifolius Roxb.), a member of the Pandanaceae family, has been consumed as food and medicine since ancient times. The current paper provides an overview of the botanical profile, phytochemistry, pharmacology, and applications of P. amaryllifolius. Information regarding P. amaryllifolius was collected from online sources (using PubMed, Science Direct, Google Scholar, Web of Science, ACS, and CNKI) as well as traditional textbooks. Over 100 compounds have been identified, including its characteristic components 2-Acetyl-1-pyrroline and Pandanus alkaloids. Several therapeutic uses of P. amaryllifolius, such as antioxidant, hypoglycemic, antimicrobial, and antitumor activities, have been demonstrated in modern pharmacological studies. Additionally, it could be applied in various fields, including food, energy, material, and the environment. Continued research on P. amaryllifolius can contribute to the development of new drugs and therapies for various diseases. And further studies are needed to improve its utilization.

Pandanus amaryllifoius Roxb. Leaves Ethanol Extract Ameliorates Lipid and Proinflammatory Cytokines Profiles in a Rat Model of Dyslipidemia

Objectives

Dyslipidemia has currently become a major health challenge that still opens for safer and more effective modes of treatment. The plant Pandanus amaryllifolius Roxb. (pandan) has been indicated to contain active ingredients that interfere with the pathological pathway of dyslipidemia. The aim of the study was to test the effects of pandan leaves ethanol extract on lipid and proinflammatory profiles in a rat dyslipidemic model.

Methods

Dyslipidemia was induced by administration of high-fat feed for 8 weeks. Treatments (vehicle, the reference drug simvastatin at 1.8 mg/kg, and extract at 200, 300 or 600 mg/kg) were given for 4 weeks following the completion of induction.

Results

Significant post-treatment decreases in total cholesterol, low density lipoprotein (LDL), and triglyceride levels in groups receiving all doses of extract and simvastatin were observed. Similar results were also found in regards to proinflammatory cytokines levels. Pandan extracts significantly lowered the concentrations of IL-6, TNF-α, and NFκB p65. Characterization of metabolite contents of the extract confirmed the presence of the previously suggested active alkaloids pandamarilactonine-A and B.

Conclusion

Taken together, results of the present study implied the ameliorating effects of pandan leaves ethanol extract in dyslipidemic condition which is potential for opening an avenue in combating this essential component of metabolic disorder.

Naming of new natural products: Standard, pitfalls and tips-and-tricks

Naming a newly discovered natural product (NP) is a pleasant but difficult exercise. In most cases, the NP name will be given with reference to the species of origin, be it a plant, a marine organism, a mammalian or microbial species. For a long time, the use of biologically-based trivial names has been recommended to identify the parental linkage between the product and the originating genus or species. But the recommendation is not always followed and a multiplicity of trivial names have been attributed to NP, based on locations (country, region, city), foods, music, animals, forenames, etc. Tips-and-tricks associated with the naming of NP are underlined here. Usually, NP are differentiated across a homogeneous chemical series with a letter (from the Latin or Greek alphabet), followed or not with a number. In other cases, the change of a single letter distinguishes a series of NP. Common pitfalls associated with the naming of NP are enumerated, including the complexity of names, use of synonyms, duplicated names, confusing names and inappropriate terminology. The difficulties regularly encountered with the naming of NP are discussed. Four essential recommendations are recalled: (i) a thorough analysis of the existing products to avoid duplicated names and confusion, (ii) the use of a biologically-based trivial name to retrace the origin of the product, (iii) the strict adherence to the codes of chemical nomenclature, and (iv) the preference for simple names to facilitate transmission. Naming a new NP is a rewarding task, which shall be performed with all due skill, care and diligence.

Recent reports on the synthesis of γ-butenolide, γ-alkylidenebutenolide frameworks, and related natural products

γ-Butenolides are fundamental frameworks found in many naturally occurring compounds, and they exhibit tremendous biological activities. γ-Butenolides also have proven their potential as useful synthetic intermediates in the total synthesis of natural compounds. Over the years, many γ-butenolide natural products have been isolated, having exocyclic γ-δ unsaturation in their structure. These natural products are collectively referred to as γ-alkylidenebutenolides. Considering the different biological profiles and wide-ranging structural diversity of the optically active γ-butenolide, the development of synthetic strategies for assembling such challenging scaffolds has attracted significant attention from synthetic chemists in recent times. In this report, a brief discussion will be provided to address isolation, biogenesis, and current state-of-the-art synthetic protocols for such molecules. This report aims to focus on synthetic strategies for γ-butenolides from 2010-2020 with a particular emphasis on γ-alkylidenebutenolides and related molecules. Metal-mediated catalytic transformation and organocatalysis are the two main reaction types that have been widely used to access such molecules. Mechanistic considerations, enantioselective synthesis, and practical applications of the reported procedures are also taken into consideration.

Biologically active indolizidine alkaloids

Indolizidine alkaloids are chemical constituents isolated from various marine and terrestrial plants and animals, including but not limited to trees, fungi, ants, and frogs, with a myriad of important biological activities. In this review, we discuss the biological activity and pharmacological effects of indolizidine alkaloids and offer new avenues toward the discovery of new and better drugs based on these naturally occurring compounds.

Synthesis of Substituted Indolizidines and Quinolizidines by Regioselective Intramolecular Modified Julia Olefination of Imides

We report the synthesis of substituted indolizidines and quinolizidines using the modified Julia olefination previously developed on imides. The study focuses on the regioselectivity of this reaction on unsymmetrically substituted imides. The scope and regioselectivity of the reaction are presented here, and its utility as a tool for synthesizing natural products is demonstrated through the total synthesis of Pandalizine A.

Chemoselective Ring Closure of 4-(3-Methyl-2-oxo-2,5-dihydro-1H-pyrrol-1-yl)butanal Leading to Pandalizine A

Starting from methylmaleic anhydride, a facile total synthesis of pandalizine A alkaloid is described via the regioselective reduction of methylmaleimide and acid-catalyzed enolization of 4-(3-methyl-2-oxo-2,5-dihydro-1H-pyrrol-1-yl)butanal followed by chemoselective intramolecular dehydrative cyclization as the key steps. It is noteworthy that the analogous model system with an additional β-methyl group followed an alternative chemoselective intermolecular aldol condensation pathway.

Total Synthesis of γ-Alkylidenebutenolides, Potent Melanogenesis Inhibitors from Thai Medicinal Plant Melodorum fruticosum

A hitherto unreported member of γ-alkylidenebutenolides in Melodorum fruticosum (Annonaceae), (4 E)-6-benzoyloxy-7-hydroxy-2,4-heptadiene-4-olide, named as isofruticosinol (4) was isolated from the methanol extract of flowers, along with the known related butenolides, namely, the (4 Z)-isomer (3) of 4, melodrinol (1), and its (4 E)-isomer (2). To unambiguously determine the absolute configuration at the C-6 position in these butenolides, the first total syntheses of both enantiomers of 2-4 were achieved over 6-7 steps from commercially available D- or L-ribose (D- and L-5). Using the same protocol, both enantiomers of 1 were also synthesized. Based on chiral HPLC analysis of all synthetic compounds ( S- and R-1-4), all naturally occurring butenolides were assigned as partial racemic mixtures with respect to the chiral center at C-6 (enantiomeric ratio, 6 S/6 R = ∼83/17). Furthermore, the melanogenesis inhibitory activities of S- and R-1-4 were evaluated, with all shown to be potent inhibitors with IC₅₀ values in the range 0.29-2.9 μM, regardless of differences in the stereochemistry at C-6. In particular, S-4 (IC₅₀ = 0.29 μM) and R-4 (0.39 μM) showed potent inhibitory activities compared with that of reference standard arbutin (174 μM).

Recent developments in multicomponent synthesis of structurally diversified tetrahydropyridines

Tetrahydropyridines (THPDs) have recognized as a major constituent of naturally occurring alkaloids and exhibits various biological and pharmacological profiles. For their synthesis, MCRs are employed as an excellent tool to generate vast libraries.

Enantioselective synthesis of chiral α,β-unsaturated γ-substituted butyrolactams by organocatalyzed direct asymmetric vinylogous Michael addition of α,β-unsaturated γ-butyrolactam to 2-enoylpyridines

Approach providing a series of optically active α,β-unsaturated γ-substituted butyrolactams in high yields with excellent diastereo- and enantioselectivities.