The dayflower, Commelina communis L., contains 1-deoxynojirimycin (DNJ) and (2R,3R,4R,5R)2,5-bis(hydroxymethyl)-3,4-dihydroxypyrrolidine (DMDP), potent alpha-glucosidase inhibitors. The extracts and powder of this herb are important food materials for prophylaxis against type 2 diabetes. Eleven flavonoid glycosides as antioxidants, isoquercitrin, isorhamnetin-3-O-rutinoside, isorhamnetin-3-O-beta-D-glucoside, glucoluteolin, chrysoriol-7-O-beta-D-glucoside, orientin, vitexin, isoorientin, isovitexin, swertisin, and flavocommelin, were identified from the aerial parts of C. communis. Their antioxidant activities were measured using in vitro assays employing the 1,1-diphenyl-2-picrylhydrazyl radical- and superoxide radical-scavenging assays. The results showed that glucoluteolin, orientin, isoorientin, and isoquercitrin are the predominant antioxidants in this herb. Moreover, isoquercitrin, isorhamnetine-3-O-rutinoside, vitexin, and swertisin inhibited the activity of alpha-glucosidase from rat intestine.

The nucleotide sequences of ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit gene (rbcL) of Glycyrrhiza glabra, G. uralensis, G. inflata, G. echinata, G. macedonica and G. pallidiflora have been determined to construct their phylogenetic tree. Based on these sequences, the six Glycyrrhiza species were divided into two groups: three, G. glabra, G. uralensis, and G. inflata, which produce glycyrrhizin as a major saponin, and the others, G. echinata, G. macedonica and G. pallidiflora, which produce macedonoside C as a major saponin. Among the three glycyrrhizin-producing species, only two nucleotide substitutions were observed between the rbcL sequences of G. glabra and G. uralensis, and the sequence of G. uralensis was identical to that of G. inflata, indicating that G. uralensis and G. inflata are closely related. Among the three macedonoside C-producing species, only one nucleotide substitution was observed between those of G. echinata and G. macedonica, indicating that these two species are also closely related.

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Several structurally related monocyclic and bicyclic polyhydroxy pyrrolidines have been reported to show various biological activities, such as competitive inhibition of glycosidases, [1][2][3][4] as antiviral agents, 5) and as acaricides. 6) In the course of our survey for biologically active constituents extracted from crude drugs with hot water, we have reported many pyrrolidine alkaloids, broussonetines from Broussonetia kazinoki SIEB. (Moraceae). [7][8][9][10][11][12][13][14] Our continuing search led us to isolate two new pyrrolidine alkaloid, radicamines A and B, from Lobelia chinensis LOUR. (Campanulaceae). This report deals with the structural elucidation and its inhibitory activities against a-glucosidase of these new natural products.The plant, Lobelia chinensis LOUR. (Japanese name "azemushiro"), is distributed throughout China, Taiwan, Korea, and Japan. The whole plants have been used as a diuretic, an antidote, hemostat, and as carcinostatic agents for stomach cancer in Chinese folk medicine. Various alkaloids, for example lobeline, lobelanine, lobelanidine and so on are known as constituents of this herb.The herb was extracted with hot water and the alkaloidal constituents were concentrated as described in the Experimental section. H-1 H COSY) cross-peaks and they were connected on the basis of the heteronuclear multiple bond correlation (HMBC) spectrum and characteristic mass fragment ion (m/z 131) to establish the planar structure (Fig. 2).The 1 H-and 13 C-NMR signals were reasonably assigned by heteronuclear single quantum coherence (HSQC), and distortionless enhancement by polarization transfer (DEPT), as shown in Table 1.The relative stereochemistry of the pyrrolidine moiety in 1 was determined by the vicinal coupling constants (J 2,3 ϭJ 3,4 ϭ 7.3 Hz, J 4,5 ϭ8.9 Hz) and nuclear Overhauser effects (NOEs) Two new pyrrolidine alkaloids, radicamines A and B were isolated as inhibitors of a a-glucosidase from Lobelia chinensis LOUR. (Campanulaceae). Radicamines A and B were formulated as (2S,3S,4S,5S)-2-hydroxymethyl-3,4-dihydroxy-5-(3-hydroxy-4-methoxyphenyl)-pyrrolidine (1) and (2S,3S,4S,5S)-2-hydroxymethyl-3,4-dihydroxy-5-(4-hydroxyphenyl)-pyrrolidine (2) on the basis of spectroscopic analyses and chemical methods.

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