Thalictrum is an important plant genus that is widely used in traditional medicine. In this review considerable attention has been given to triterpenoid saponins in connection with their specific distribution in the Thalictrum genus and with their biological activity. All other non-alkaloid compounds isolated from the Thalictrum genus are also reviewed; these metabolites are discussed in relation to their structural features and to their role in the plants.

Structures and chemical and spectral properties of triterpenoids isolated from plants of the Thalictrum genus were systematized for the first time. Features of 13C NMR spectra of cycloartane triterpenoids were discussed. Data for the biological activities of certain cycloartane and oleanane triterpenoids were given.

The chemical composition of the above-ground parts of Astragalus danicus and A. inopinatus collected in the Baikal region (Eastern Siberia) was studied for the first time. From A. danicus, pentacyclic triterpene saponins were isolated and identified, viz., 3-O-(β-glucuronopyranosyl)-3β,22β,24-trihydroxyolean-12-ene, 3-O-[O-(β-d-xylopyranosyl)-(1→2)-(β-glucuronopyranosyl)]-3β,22β,24-trihydroxyolean-12-ene, 3-O-[O-(β-d-glucopyranosyl)-(1→2)-(β-glucuronopyranosyl)]-3β,22β,24-trihydroxyolean-12-ene, 3-O-[O-(α-l-rhamnopyranosyl)-(1→2)-O-(β-d-xylopyranosyl)-(1→2)-(β-glucuronopyranosyl)]-3β,22β,24-trihydroxyolean-12-ene, 3-O-[O-(α-l-rhamnopyranosyl)-(1→2)-O-(β-d-glucopyranosyl)-(1→2)-(β-glucuronopyranosyl)]-3β,22β,24-trihydroxyolean-12-ene, 3-O-methyl-d-chiro-inositol, and linolenic acid. In A. inopinatus, the same saponins were identified as well as tricosan-1-ol and tetracosan-1-ol, 5,7,4"-trihydroxyflavon (apigenin), and a tetracyclic triterpenoid, 20(R),24(S)-epoxycyclolanost-9(11)-ene-3β,6α,16β,25-tetrol (cycloastragenol). All reported compounds from the both genus of Astragalus were isolated for the first time. Methanolic extracts of A. danicusand A. inopinatus exhibited low inhibitory activity with respect to the growth of HeLa cells. The chloroform fraction of A. danicus showed a strong antimicrobial activity against Staphylococcus aureus and a strong cytotoxic activity against HeLa cells.

Acacetin, tilianin, linarin, and the new acylated flavone glycoside agastachoside have been isolated from the plantAgastache rugosa for the first time. On the basis of IR, UV, NMR, and mass spectra the structure of 6″-0-acetyl-7-β-D-glucopyranosyloxy-5-hydroxy-4′-methoxyflavone has been established for agastachoside.

Three new cycloartane bisdesmosides, two of which are based on a new genin, were isolated from the above-ground parts of Thalictrum minus. Thalicosides A1-A3 (1-3) were characterized as 3-O-beta-D-galactopyranosyl-29-O-beta-D-glucopyranosyl-3beta,16beta++ +, 29-trihydroxy-22(S),25-epoxycycloartane (1); 3-O-alpha-L-arabinopyranosyl-29-O-beta-D-glucopyranosyl-3beta,1 6beta, 29,22(S)-tetrahydroxycycloart-24-ene (2); and 3-O-alpha-L-arabinopyranosyl-29-O-beta-D-glucopyranosyl-3beta,1 6beta, 29-trihydroxy-22(S),25-epoxycycloartane (3), respectively. The structural assignments of these new compounds were based on interpretation of spectroscopic data. Thalicoside A2 showed in vitro inhibition of the fungus Candida albicans and also activity against Staphylococcus aureus.

From the terrestrial part ofThalictrum minus L. (Ranunculaceae) a novel triterpenoid diglycoside was isolated. The genin of this glycoside is a new cycloartane triterpenoid. The structure of the glycoside was established on the basis of 1D and 2D NMR spectroscopy and FAB mass spectrometry as 22S,25-epoxy-3-O-β-d-galactopyranosyl-29-O-β-d-glucopyranosyl-9β, 19-cyclo-20S-lanostane-3β,16β,24S,29-tetrol.

Two flavonoid allose diglycosides were found in the terrestrial part of Thalictrum squarrosum St. ex Willd. and T. minus L. (Ranunculaceae). 7,4′-Di- O -β-allopyranosylapigenin was isolated from T. minus . In T. squarrosum , its monoacetate was also found and characterized as 7- O -(6- O -acetyl-β-allopyranosyl)-4′- O -(β-allopyranosyl)apigenin. The sites of attachment of the carbohydrate residues were determined by HMBC; the location of the acetate group was identified by ROESY. Both substances were isolated from these plants for the first time.

Squarroside C (1), a new cycloartane 3,21-bisdesmoside, was isolated from the above-ground parts of Thalictrum squarrosum. The structure of 1 was established as 3-O-[O-alpha-L-rhamnopyranosyl-(1-->6)-beta-D-glucopyranosyl]-21-O-be ta-D-glucopyranosyl-21(S),22(S),23(R),3beta,21alpha,22beta, 30-tetrahydroxy-21,23-epoxycycloart-24-ene by 2D NMR spectroscopy and FABMS.

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A new triterpenoid saponin, thalicoside F was isolated from the above-ground part of Thalictrum minus L. (Ranunculaceae family) collected in Eastern Siberia (Russia). The structure of thalicoside F was elucidated by a combination of 1D- and 2D-NMR spectroscopy and mass spectroscopy, and was determined to be C47H74O17{3-beta-O-[alpha-L-rhamnopyranosyl-(1-->2)-beta-D- glucopyranosyl-(1-->4)-alpha-L-arabinopyranosyl]-11 alpha, 12 alpha-epoxyoleanane-28,13 beta-olide}.

Plants of the Thalictrum genus (Ranunculaceae family) grow in the temperate zones of the both hemispheres of the globe. Many of these species are met worldwide. Thalictrum minus, for example, is known in Europe, Asia, and North America. However, secondary metabolism in this species is variable. Thus, in the Bulgarian population of the plant a bisbenzylisoquinoline alkaloid, thalicarpin, has been isolated as a major secondary metabolite [1], whereas the Moldavian chemorace met hereabout produces a secoprotoberberine base, β-allocryptopine [2]. In general, all the Thalictrum species were thought to serve as producers of diverse isoquinoline and, on rare occasions, of diterpene alkaloids. T. minus widely spreads from east to west over the whole territory of Russia and is involved in the Siberian biocenoses. That is why 15 years ago we tried to assess its potential as a producer of alkaloids. However any tertiary bases have not been detected. Instead, we have found a fairly large amount of saponins. This seemed strange, since earlier in the literature there were only scarce and unreliable data on the presence of saponins of unidentified structure in the representatives of this genus. Therefore, we decided to concentrate all research efforts on the elucidation of the chemical nature of the glycosides found.

From the above-ground part ofThalictrum squarrosum St. ex Willd. (Ranunculaccae), an equilibrium mixture of two triterpene glycosides, squarrosidc B3 (1), 3-O-[O-(α-L-rhamno-pyranosyl)-(1←6)-β-D-glucopyranosyl]-21 (S),22(ɛ),23(R)-3β,21,22,30-tctralmydroxy-21, 23-cpoxycycloartlt-24-ene, and squarrosidc B4 (2), its 21(R) epimer, was isolated. Their structures were established on the basis of IR and 2D NMR spectra and FAB mass spectra.

Three serratene triterpenoids, 3\,21α-dihydroxy-26-nor-8,14-sekogammaser-14(27)-en-n-8-one (1), 3ß,21a-dihydroxy-8,14-sekogammasera-8(26),14(2?)-diene (2), and 3α,21ß,24-trihydroxyserrat-14-ene (3), were isolated from the Siberian chemorace ofLycopodium clavatum L. and identified. Compound1 was isolated fromL. clavatum L. for the first time.

From the epigeal part ofThalictrum minus L. (Ranuncluaceae) we have isolated a minor cycloartane trisdesmoside — thalicoside C — 3β,16β,22(S),29-tetrahydroxy-9,19-cyclo-20(S)-lanost-24-ene 3-O-β-galactopyranoside 22,29-di-O-β-D-glucopyranoside. Its structure was established from the results of chemical transformations and of FAB-mass and NMR spectroscopies (1H1,13C,1H-1H1, and13C-1H).