Studies on constituents from Chamaecyparis pisifera and antibacterial activity of diterpenes.

In the course of our research for biologically active constituents from coniferous plants, a chromone derivative (1) and an abietane derivative (2) were isolated along with several diterpenes from Chamaecyparis pisifera. Structures of the new compounds were determined to be 5,7-dihydroxy-2-(1-acetyl-2-methoxycarbonylethyl)-chromone and rel-(8R,10R,20S)-8,10,20-trihydroxy-9(10-->20)-abeo-abieta-9,13-dien-12-one by means of spectral methods including two-dimensional NMR experiments. Some of these abietane-type compounds isolated from this plants showed antibacterial activitv against the gram-positive bacteria Staphylococcus aureus and Bacillus subtilis.

How to distinguish garlic from the other Allium vegetables.

The establishment of international monographs for herbs is in progress. Here, we propose both a marker compound and a method for its analysis for the identification of garlic bulbs and their products. The constituents in 26 kinds of fresh edible parts of Allium vegetables and three types of garlic preparations were analyzed. Sulfur compounds are the most characteristic constituents in garlic, but manufacturing processes of garlic products dramatically affect these constituents. Thus, no sulfur compound could be specified as a universal marker of identification applicable for any type of garlic. On the other hand, garlic contains other characteristic compounds, namely, saponins. After analyzing Allium vegetables and garlic preparations, we concluded that sapogenins, especially beta-chlorogenin, may be a viable candidate for identifying and distinguishing garlic from other Allium vegetables.

Hepatoprotective and hepatotoxic activities of sophoradiol analogs on rat primary liver cell cultures.

As a part of our studies of hepatoprotective drugs, we prepared kaikasaponin I (2), sophoradiol monoglucuronide (SoMG, 3) and sophoradiol (4) from kaikasaponin III (1). We examined the hepatoprotective effects of these analogs, using immunologically-induced liver injury in primary cultured rat hepatocytes and found that compound 1 was more effective than soyasaponin I (1a) while 2 was more effective than 1. On the other hand, 3 was less effective than 2 at 30-200 microm. Further, compound 3 was strongly cytotoxic at 500 microM while 4 exhibited hepatoprotective activity at the same dose, although less potent. When the cytotoxicity toward hepatocytes of these analogs was tested, only 3 was cytotoxic at doses of 200 and 500 microM. This is the first example of an oleanene glucuronide (OG) which is cytotoxic toward hepatocytes. Compound 3 exhibited hepatoprotective activity at 200 microM, while it was also cytotoxic at the same dose without antiserum. Therefore, the hepatoprotective activity of OG represents a balance between a hepatoprotective action and its cytotoxicity toward hepatocytes.

Study of structure--hepatoprotective relationships of oleanene-type triterpenoidal glucuronides obtained from several fabaceous plants on rat primary hepatocyte cultures.

The protective effects of nine oleanene-type triterpenoidal glucuronides obtained from several fabaceous plants (Lupinus polyphyllus x arboreus Hybrid, Astragalus complanatus, Wistaria brachybotrys) on in vitro immunological liver injury in primary cultured rat hepatocytes were studied. Although all tested saponins showed hepatoprotective action, the levels of activity of the individual saponins differed. Structure-activity relationships for the sapogenol moiety suggested that the presence of the carbonyl group at C-22 would show a similar hepatoprotective effect to that of the hydroxyl group at C-22 while the presence of the hydroxyl group at C-30 would reduce the hepatoprotective action. This structure-activity relationship substantiated other recently obtained data. Furthermore, the beta-orientation of the hydroxyl group at C-21 is more effective than the alpha-configuration in regard to the hepatoprotection. Furthermore, structure-activity relationships for the sugar moiety substantiated previously obtained data that the hydroxyl group at C-5" enhances the hepatoprotective action.

Hepatoprotective and hepatotoxic actions of oleanolic acid-type triterpenoidal glucuronides on rat primary hepatocyte cultures.

The protective effects of oleanolic acid-type saponins and their derivatives on in vitro immunological liver injury of primary cultured rat hepatocytes were studied. A known antihepatotoxic saponin (chikusetsusaponin IVa, 1) showed hepatoprotective activity in this model. Although a rhamnosyl derivative (2) of 1 similarly showed hepatoprotective activity, its prosapogenin (5) did not show any hepatoprotective activity. On the contrary, 5 exhibited cytotoxicity toward liver cells. In the absence of antiserum, monodesmosyl saponins showed hepatotoxicity, while the bisdesmosyl saponins except for 1, did not show such hepatotoxicity. In order to clarify the effects of the sugar residues at C-3 and C-28 responsible for hepatoprotective and hepatotoxic actions, oleanolic acid 3-O-glucuronide (2a) and oleanolic acid 28-O-glucoside (2b) were prepared and tested. 2b showed neither hepatoprotective action nor hepatotoxicity. In contrast, 2a was effective at 90 microM on hepatoprotection, although it showed strong hepatotoxicity. Oleanolic acid (2c) itself showed both hepatoprotective action and weak hepatotoxicity. Therefore, the hepatoprotective activity of these types of saponins could represent a balance between hepatoprotective action and hepatotoxicity.

Structures of three new oleanene glucuronides isolated from Lathyrus palustris var. pilosus and hepatoprotective activity.

Three new saponins, named palustrosides I, II and III, together with azukisaponins II, V and soyasapogenol B monoglucuronide, were isolated from the aerial parts of Lathylus palustris L. var. pilosus Ledeb. The structures of palustrosides I, II and III were identified as 3-O-beta-D-glucopyranosyl-(1-->2)-beta-D-glucuronopyranosides of soyasapogenol E, abrisapogenol E, and bredemolic acid 28-O-beta-D-glucopyranoside, respectively, by spectroscopic and chemical methods. As part of our studies on hepatoprotective drugs, we also examined the hepatoprotective effects of these saponins towards immunologically induced liver injury in primary cultured rat hepatocytes. The activity of the disaccharide group was greater than that of the trisaccharide group. This information regarding the structure-activity relationships substantiated previously obtained data. Structure-hepatoprotective relationships for the sapogenol moiety suggested that the hydroxyl group at C-30 reduces the hepatoprotective effect. On the other hand, the carbonyl group at C-22 may be equivalent to a hydroxyl group at C-22 in terms of hepatoprotective action. Oleanolic acid-type saponins also exhibited hepatoprotective action.

Preventive effects of saponins from the Pueraria lobata root on in vitro immunological liver injury of rat primary hepatocyte cultures.

Preventive effects of nine saponins obtained from Puerariae Radix (the roots of Pueraria lobata) on in vitro immunological liver injury in primary cultured rat hepatocytes were studied. Although all tested saponins showed hepatoprotective action, the levels of activity of individual saponins differed. Structure-activity relationships for the sapogenol moiety suggested that the hydroxy group at C-29 would reduce the hepatoprotective activity while the hydroxy group at C-21 could enhance the hepatoprotective activity. Furthermore, structure-activity relationships for the sugar moiety suggested that the oxygen-bearing group at C-5" would enhance the hepatoprotective activity, though the configuration of the hydroxy group at C-3" could be less important for hepatoprotective activity.

Triterpenoidal saponins from Baptisia australis.

Extraction of the roots of Baptisia australis afforded a new triterpenoid saponin, baptisiasaponin I together with kaikasaponin III. The structure of baptisiasaponin I was elucidated as 3-O-alpha-L-rhamnopyranosyl-(1-->2)-beta-D-xylopyranosyl- (1-->2)-beta-D-glucuronopyranosyl sophoradiol on the basis of its spectral data and chemical degradation.

Structure-hepatoprotective relationships study of soyasaponins I-IV having soyasapogenol B as aglycone.

As a part of our study on the leguminous plants, we investigated the constituents of the aerial parts of Glycine soya. We isolated and identified four known saponins, soyasaponins I, II, III, and IV which have the same aglycone, soyasapogenol B. As a part of our studies concerning hepatoprotective drugs, we also examined the hepatoprotective actions of these saponins towards immunologically induced liver injury on primary cultured rat hepatocytes. The action of soyasaponin II was almost comparable with that of soyasaponin I, whereas those of soyasaponin III and IV were more effective than soyasaponins I and II. This means that the disaccharide group shows greater action than the trisaccharide group. Furthermore, the saponin having a hexosyl unit shows a slightly greater action than that of the pentosyl unit in each disaccharide group or trisaccharide group. Structure-activity relationships suggest that the sugar moiety linked at C-3 may play an important role in hepatoprotective actions of soybean saponins.

HPLC profile analysis of oleanene-glucuronides in several edible beans.

HPLC analysis and yield of oleanene-glucuronide (OG) was done on some commercially available edible beans: seeds of Glycine max, Glycine max cv. Kuromame, Phaseolus vulgaris cv. Torosuku, Phaseolus vulgaris cv. Toramame, Phaseolus vulgaris cv. Taishokintoki, Phaseolus coccineus cv. Ooshirobana, Phaseolus coccineus cv. Murasakihanamame, Vigna unguiculata cv. Chuguro, Vigna angularis cv. Dainagon, Arachis hypogaea, Pisum sativum, and Vicia faba. All the beans listed above have OG, though in varying the amounts. Furthermore the HPLC profiles of beans belonging to the same genus were very similar except for that of the Vigna genus. There was no great difference of the HPLC profiles with respect to the cultivated varieties. The structures of the major OGs in each type of beans were identified as soyasaponins I (1) and V (2), and phaseoside I (3) (Phaseolus vulgaris and P. coccineus); 1 and soyasaponin II (4) (Glycine max); 1 and 2 (Vigna unguiculata); 1 (Pisum sativum, Arachis hypogaea and Vicia faba). In contrast, those in Dainagon (Vigna angularis cv. Dainagon) were identified as azukisaponins II (5) and VI (6).

A new oleanene glucuronide having a branched-chain sugar from Melilotus officinalis.

A new oleanene glucuronide called melilotus-saponin O1 (1) was isolated together with three known ones from the roots of Melilotus officinalis (L.) PALLAS (Leguminosae). The structure of 1 was determined to be 3-O-alpha-L-rhamnopyranosyl-(1-->2)-alpha-L-arabinopyranosyl-(1--> 3)]- beta-D-galactopyranosyl-(1-->2)-beta-D-glucuronopyranosyl soyasapogenol B by spectroscopic and chemical methods.

Kaikasaponin III and soyasaponin I, major triterpene saponins of Abrus cantoniensis, act on GOT and GPT: influence on transaminase elevation of rat liver cells concomitantly exposed to CCl4 for one hour.

The antihepatotoxic activities of soyasaponin I and kaikasaponin III, triterpenoidal saponins isolated from Abri Herba, the whole plant of Abrus cantoniensis, were studied on liver injury induced by CCl4 in primary cultured rat hepatocytes. The antihepatotoxic activities of these saponins and glycyrrhizin (positive control) were demonstrated by measuring the levels of glutamic pyruvic transaminase (GPT) and glutamic oxaloacetic transaminase (GOT). Soyasaponin I inhibited the elevation of GOT and GPT activities. The activities were comparable to those of glycyrrhizin. On the other hand, kaikasaponin III was more effective than soyasaponin I and glycyrrhizin. Kaikasaponin III showed the antihepatotoxic activity at less than 100 micrograms/ml. Furthermore, the highest activity was observed even in the lower doses (50, 100 micrograms/ml). However, soyasaponin I and kaikasaponin III showed some toxicity at the highest dose (500 micrograms/ml), though glycyrrhizin did not show toxicity at any dose.

Partial hydrolysis of soyasaponin I and the hepatoprotective effects of the hydrolytic products. Study of the structure-hepatoprotective relationship of soyasapogenol B analogs.

As a part of our studies of hepatoprotective drugs, we prepared some soyasapogenol B analogs from soyasaponin I. We examined the hepatoprotective effects of these analogs, using immunologically-induced liver injury, in primary cultured rat hepatocytes. Soyasaponin III and soyasapogenol B monoglucuronide were more effective than soyasaponin I. Both compounds were significantly effective even at 30 microM. The action of soyasapogenol B was almost equal to that of soyasaponin I, although glucuronic acid did not show any activity even at the highest dose (500 microM). When the two compounds were mixed, the hepatoprotective action did not change, compared with soyasapogenol B. Therefore, we concluded that the linkage between glucuronic acid and soyasapogenol B could enhance the hepato-protective activity.

Preventive effects of saponins from puerariae radix (the root of Pueraria lobata Ohwi) on in vitro immunological injury of rat primary hepatocyte cultures.

The preventive effects of saponins from Puerariae Radix toward in vitro immunological liver injury using an antiserum against the rat liver plasma membranes on primary cultured rat hepatocytes were studied. Crude saponin from Puerariae Radix inhibited the elevation of alanine aminotransferase (ALT) activity at the dose of 90 micrograms/ml. The inhibition was stronger than that of glycyrrhizin, which was a positive control drug. The representative saponins in this drug, soyasaponin I and kudzusaponin SA3, were also more effective than glycyrrhizin, although their effects were weaker than that of crude saponin at the lower doses (90, 200 micrograms/ml). At 500 micrograms/ml, kudzusaponin SA3 showed antihepatotoxic activity equal to that of crude saponin.