New alkaloids from Lycopodium japonicum

The Chemistry and Biology of Lycopodium Alkaloids

Lycopodiales, an order comprising 388 distinct species, is the source of Lycopodium alkaloids (LAs), a group of naturally occurring alkaloids that share a common biosynthesis and structural attributes. These remarkable organisms are considered vestiges of ancient ferns, with fossil evidence dating their existence back to an impressive 300 million years. LAs usually are tricyclic or tetracyclic compounds with C16N or C16N2 skeleton. But then there are also have a few C11N, C15N, C15N2, C22N2, and C27N3 skeleton. LAs have attracted much scientific attention because of their important biological activities related to acetylcholinesterase and unique structural characteristics. From 1881 to December 2023, there are 593 LAs from 49 species of Lycopodiales have been reported. Because the total amount of LAs is nearly five times that of 1994, the classification and group allocation of some newly isolated LAs is often challenging and not unambiguous by Ayer's simple classification. This review makes a more systematic and detailed classification for it and provides extensive coverage of naturally occurring LAs discovered from 1881 to December 2023. Until now, there is no comprehensively summary of biological activity of the LAs. This review is the first time covered the biological activity of the all LAs.

Plant carbonic anhydrase-like enzymes in neuroactive alkaloid biosynthesis

Plants synthesize numerous alkaloids that mimic animal neurotransmitters1. The diversity of alkaloid structures is achieved through the generation and tailoring of unique carbon scaffolds2,3, yet many neuroactive alkaloids belong to a scaffold class for which no biosynthetic route or enzyme catalyst is known. By studying highly coordinated, tissue-specific gene expression in plants that produce neuroactive Lycopodium alkaloids4, we identified an unexpected enzyme class for alkaloid biosynthesis: neofunctionalized α-carbonic anhydrases (CAHs). We show that three CAH-like (CAL) proteins are required in the biosynthetic route to a key precursor of the Lycopodium alkaloids by catalysing a stereospecific Mannich-like condensation and subsequent bicyclic scaffold generation. Also, we describe a series of scaffold tailoring steps that generate the optimized acetylcholinesterase inhibition activity of huperzine A5. Our findings suggest a broader involvement of CAH-like enzymes in specialized metabolism and demonstrate how successive scaffold tailoring can drive potency against a neurological protein target.

Identification and Analysis of Chemical Constituents and Rat Serum Metabolites in Lycopodium clavatum Using UPLC-Q-TOF/MS Combined with Multiple Data-Processing Approaches

Lycopodium clavatum is a dry whole grass of Lycopodium japonicum Thunb.; it has been extensively used to anti-inflammatory, antioxidant, and antimicrobial actions and inhibits acetylcholinesterase activity. However, it lacks further compounds research of Lycopodium clavatum in vivo and in vitro. In this work, a rapid method was established using the ultra high performance liquid chromatography with quadrupole-time-of-flight mass spectrometry (UPLC-Q-TOF/MS) combined with multiple data-processing approaches for compounds analysis of Lycopodium clavatum in vitro and in vivo. Finally, 30 peaks were characterized in 75% ethanol extract of Lycopodium clavatum and 17 peaks were characterized in rat plasma that including 12 prototype compounds and 5 metabolites. Methylation and demethylation are the main transformation reactions of Lycopodium clavatum in rat serum. This work could be helpful for understanding the complex compounds of Lycopodium clavatum and further analyzing the pharmacological studies of active compounds.

Pharmacokinetic Studies of Three Alkaloids in Rats After Intragastrical Administration of Lycopodii Herba Extract by LC-MS/MS

Lycopodii Herba is a widely used traditional medicinal herb, and contains diverse fascinating alkaloids. In this study, a fast and sensitive LC-MS/MS method for the simultaneous determination of lycodoline, α-obscurine, and N-demethyl-α-obscurine from Lycopodii Herba in rat plasma and brain tissue was developed and validated. Biological samples were extracted via a protein precipitation procedure using methanol as the extraction solvent and Huperzine B as the internal standard. Chromatographic separation was carried out using a Thermo Syncronis-C18 column (50 mm × 2.1 mm, 5 μm) and a gradient mobile phase containing methanol and water with 0.05% formic acid. The three alkaloids were detected by positive electrospray ionization in selective reaction monitoring mode. The selectivity, crosstalk, carryover effect, linearity, accuracy, precision, extraction recovery, matrix effect, and stability of the current method were validated. Then, using the validated method, the plasma pharmacokinetics and brain tissue distribution of the alkaloids in rats were investigated after intragastrical administration of Lycopodii Herba extract. The three alkaloids were shown to be rapidly absorbed into the blood (T_max, 0.79-1.58 h), and then also eliminated rapidly (t_1/2, 1.27-2.24 h). All of them could pass through the blood-brain barrier. The method provides a new research approach to expand preclinical studies of Lycopodii Herba.

Three new Lycopodium alkaloids from Lycopodium japonicum

Three new Lycopodium alkaloids (1-3), together with 15 known alkaloids, were isolated from club moss Lycopodium japonicum. Their structures were determined by extensive spectroscopic analysis, including 1D and 2D NMR spectra. Compound 1 has an unusual β-oriented methyl group substituted at C-15 and an α-hydroxy cyclopentenone moiety. All new alkaloids were evaluated for the inhibition of T-type calcium channel.

A New Lycopodine-type Alkaloid from Lycopodium japonicum

A new lycopodine-type alkaloid, 12β-hydroxy-acetylfawcettiine N-oxide (1), together with seven known analogues, acetyllycoposerramine M (2), lycopodine (3), lycoclavine (4), diphaladine A (5), lycoposerramine K (6), 11β-hydroxy-12-epilycodoline (7) and fawcettiine (8), were isolated from Lycopodium japonicum. Their structures were established by mass spectrometry and 1D and 2D NMR techniques. The isolated alkaloids were assayed for their inhibition activities against acetylcholinesterase, but no inhibitory activities for the compounds were detected.

Lycopodine-Type Alkaloids from Lycopodium japonicum

Three new lycopodine-type alkaloids, 4α-hydroxyanhydrolycodoline (1), 4α,6α-dihydroxyanhydrolycodoline (2), and 6-epi-8β-acetoxylycoclavine (3), and an artifact, lycoposerramine G nitrate (4), along with seventeen related known compounds, were isolated from the club moss Lycopodium japonicum Thunb. ex Murray (Lycopodiaceae). Their structures were elucidated by extensive spectroscopic methods as well as X-ray analysis. Compounds 1-4 were evaluated for their acetylcholine esterase inhibitory activity.