Revised Stereochemistry of So-Called Isoselagine and Spectroscopic Analysis of 6alpha-Hydroxylycopodine from Lycopodium serratum var. longipetiolatum

Three Lycopodium alkaloids from Thai club mosses

Phytochemical constituents in alkaloid extracts from three Thai club mosses Huperzia squarrosa, Huperzia phlegmaria and Phlegmariurus nummularifolius were investigated. Squarrosinoxide was an undescribed Lycopodium alkaloid from H. squarrosa possessing an unprecedented 6/5/7 tricyclic spiro system. Acetyllycophlegmarianol was an undescribed N-oxide lycopodine-type alkaloid isolated from H. phlegmaria. 4-Epilycopodine, an undescribed epimer of lycopodine, was first isolated from P. nummularifolius. The structural assignments were established through comprehensive spectroscopic techniques and chemical correlations. All compounds were assayed for their anti-acetylcholinesterase activity in vitro.

Huperzia quadrifariata and Huperzia reflexa alkaloids inhibit acetylcholinesterase activity in vivo in mice brain

Huperzine A, a Lycopodium alkaloid produced by Chinese folk herb Huperzia serrata (Lycopodiaceae), has been shown to be a promising agent for the treatment of Alzheimer's disease due to its potent acetylcholinesterase (AChE) activity, as well its efficacy in the treatment of memory of aged patients. Thus, the effects of two Huperzia species of habitats in Brazil (H. quadrifariata and H. reflexa) with described in vitro AChE inhibition activities were studied and their effects on mice brain AChE inhibition were determined after a single intraperitoneal (i.p.) injection. The alkaloid extracts were administered to mice in various doses (10, 1 and 0.5mg/kg) and acetylcholinesterase activity was measured post mortem in two brain areas using the Ellman's colorimetric method. The AChE activity was found to be significantly reduced in both the cortex and hippocampus, although this activity was less potent than that of reference inhibitor huperzine A (0.5mg/kg). Thus, it appears that H. quadrifariata and H. reflexa alkaloid extracts, shown to inhibit acetylcholinesterase in vitro, also have very potent in vivo effects, suggesting that the Huperzia species may still constitute a promising source of compounds with pharmaceutical interest for Alzheimer's disease.

Complete (1)H NMR spectral fingerprint of huperzine A

Complete analysis of the (1)H NMR spectrum of huperzine A, 1-amino-13-ethylidene-11-methyl-6-aza-tricyclo[7.3.1.0(2, 7)]trideca-2(7),3,10-trien-5-one, a Lycopodium alkaloid and anti-Alzheimer drug lead containing an ABCD(E)(MN)(OP)X(3)Y(3)-type system of 15 nonexchangeable proton spins, is reported for the first time, and earlier assignments are corrected. The complete (1)H parameter set of 11 chemical shifts clarifies the diastereotopism of both methylene groups, and provides a total of 38 observed H,H-couplings including 31 long-range ((4-6)J) connectivities. The NMR data is consistent with the comparatively rigid alicyclic backbone predicted by molecular mechanics calculations, and forms the basis for (1)H NMR fingerprint analysis for the purpose of dereplication, purity analysis, and elucidation of structural analogs.

Huperzia saururus, activity on synaptic transmission in the hippocampus

Huperzia saururus (Lam.) Trevis. (Lycopodiaceae) known as cola de quirquincho is used in folk medicine to improve memory. The cholinergic neurons of the basal forebrain, including those in the medial septum, and in the vertical limbs of the diagonal band of Broca and the nucleus basalis of Meynert, provide a major source of cholinergic enervation of the cortex and hippocampus. These neurons have also been shown to play an important role in learning and memory processes. Thus, the effects of this traditional Argentinean species were studied in relation to its activity on synaptic transmission in the hippocampus. The alkaloid extract obtained first by decoction of the aerial parts and by subsequent alkaline extraction, was purified by using a Sephadex LH 20 packed column. Electrophysiological experiments were developed with the purified extract (E(2)) on rat hippocampus slices, thus eliciting long-term potentiation (LTP). Results show a marked increase in the hippocampal synaptic plasticity. The threshold value for generation of LTP was 22 +/- 1.01 Hz on average for E(2), while for controls it was 86 +/- 0.92 Hz. All of these factors could explain the use of Huperzia saururus as a memory improver as is reported in the ethnomedicine.

Anticholinesterase activity in an alkaloid extract of Huperzia saururus

Huperzia saururus (Lam.) Trevis. (Lycopodiaceae) is used widely in Argentinian traditional medicine as an aphrodisiac and for memory improvement. An aqueous extract from the aerial parts was obtained by decoction, revealing the presence of alkaloids, among other constituents. By partition with organic solvent in alkaline media, alkaloids were extracted and then purified by gel permeation. We studied the anticholinesterase activity in vitro of the alkaloid extract using erythrocyte membranes and human serum as sources of acetylcholinesterase and pseudocholinesterase, respectively. The results show a marked inhibition of true acetylcholinesterase with an IC50 value of 0.58 microg/ml. Low inhibition of pseudocholinesterase was observed (IC50 value = 191 microg/ml). This shows a selectivity of the extract for the true acetylcholinesterase. Furthermore, chemical study of the bioactive extract was performed by GC-MS, revealing the presence of seven Lycopodium alkaloids, including some not identified previously: sauroxine, 6-hydroxylycopodine, N-acetyllycodine, lycopodine, lycodine, N-methyllycodine, and clavolonine. Further investigations will be undertaken in order to discover which compound/s are responsible for the aqueous extract's acetylcholinesterase activity.

Ten new Lycopodium alkaloids having the lycopodane skeleton isolated from Lycopodium serratum Thunb

Ten new alkaloids, lycoposerramines-F (1), -G (2), -H (3), -I (4), -J (5), -K (6), -L (7), -M (8), -N (9), and -O (10), having lycopodine-related structures, were isolated from the club moss Lycopodium serratum THUNB. and their structures were elucidated on the basis of spectroscopic analysis and/or chemical transformation.