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Geniposidic acid (GEA), the main ingredient of several medicinal herbs, has pharmacological effects on hypertension, inflammation, diabetes, atherosclerosis, and cancer. The current study evaluated the mechanism underlying the hypotensive effects of a single oral administration of 100 mg GEA/kg in male spontaneously hypertensive rats. Blood pressure was significantly reduced at 6 h post GEA treatment, as compared with control rats. Plasma levels of atrial natriuretic peptide (ANP) were also upregulated by GEA, indicating that its anti-hypertensive activity involved enhanced ANP secretion from cardiomyocytes. This could reflect GEA-mediated activation of glucagon-like peptide-1 (GLP-1) receptors on atrial cardiomyocytes. Plasma GLP-1 levels were not significantly altered by GEA. This study is the first to report that orally administered GEA produces beneficial effects on heart tissue by increasing plasma ANP levels, although GEA is a known GLP-1 receptor agonist. These effects could underlie the broad physiological effects of medicinal herbs containing GEA.

1. Chemistry Eucommia ulmoides Oliver is a single species of the genus Eucommia which is the only genus in the family Eucommiaceae. The bark has been traditionally used in analgesics, tonics, and hypotensives in China. Moreover, the Chinese medical book “Bencao gangmu” describes fresh Eucommia leaf (EL) as being “consumed as a vegetable.” The product “Tochu-cha,” which is available in the Japanese markets and used in beverages, is roasted EL containing the iridoid glycosides: geniposidic acid and asperuloside, and a caffeic acid derivative: chlorogenic acid as its major ingredients. Eight iridoids, together with 14 known compounds were isolated from Eucommia leaf extract (ELE). The detailed investigation of the constituents of Eucommia green leaf powder (EGLP) led to the isolation of six iridoids, five flavonoids, and chlorogenic acid. Three additional new iridoids were obtained, two of which (eucomoside B and eucomoside C) were isolated by the condensation of geniposidic acid and amino acids (phenylalanine and tryptophan, respectively), whereas the third (eucomoside A) was determined to be an acetal compound with a linkage from C-3 of the iridoid to C-2 of the glucose unit, each being the first such natural compound described. 2. Bioactivities Spontaneously hypertensive rats fed ELE exhibited a dose-dependent antihypertensive effect. Moreover, follow-up studies have confirmed that ELE decreases systolic blood pressure in humans after long-term intake. These antihypertensive effects are presumed to be due to the activity of a so-called EL glycoside, which contains geniposidic acid as a major component. The extract from ELs containing EL glycoside is used as the food supplement in the food for specified health uses (FOSHU). Metabolic syndrome (MS)-like rats fed ELE or EGLP exhibited dose-dependent antiobesity and anti-MS effects. Both forms of ELs minimized increases in body weight and visceral fat in a dose-dependent manner. Concomitantly, an increase in plasma adiponectin levels and a suppression of plasma resistin and tumor necrosis factor α levels were demonstrated. The chronic administration of asperuloside isolated from ELs suppressed increases in body weight, white adipose tissue (WAT) weight, plasma triglyceride levels, and free fatty acid levels in a mouse model. Further, the chronic administration of asperuloside enhanced the basal metabolic rate in rats fed a high-fat diet (HFD) and significantly decreased respiratory quotientsmore than that in the HFD control group, suggesting an acceleration of lipid metabolism. Real-time PCR studies showed that ELE and asperuloside enhanced metabolic function in several organs, including the diminution of adenosine 5′-triphosphate production in WAT, the acceleration of β-oxidation in the liver, and an increase in the use of ketone bodies/glucose in skeletal muscle, all of which may exert antiobesity effects under HFD conditions due to novel mechanisms. To our knowledge, this is the first study showing the antiobesity effects of iridoid asperuloside. These findings are expected to result in new health applications of EL and the development of EL as a FOSHU.

Many Phenylethanoid glycosides were isolated from Cistanche Herb, produced from Cistanche deserticola, C. salsa, and other Cistanche plants, C. tubulosa, C. sinensis and C. phelypaea (Orobanchaceae). Cistanoside A-I and tubuloside A-E were isolated from C. deserticola and C. tubulosa, respectively, together with known phenylethanoid glycosides; echinacoside, acteoside and isoacteoside. They possessed rhamnosyl (1 → 3)glucosyl group. Suspensaside and forsythiaside, possessed rhamnosyl (1 → 6)glucosyl group, were isolated as main components from Forsythia suspensa (Oleaceae), not from F. viridissima. On the other hand, acteoside and β-hydroxyacteoside were isolated from F. viridissima as main components, not from F. suspensa. Plantamajoside, isoplantamajoside and hellicoside, possessed glucosyl (1 → 3)glucosyl group, were isolated from Plantago asiatica (Plantaginaceae) together with acteoside, β-oxoacteoside, β-hydroxyacteoside, and campenoside. Several phenylethanoid glycosides, forsythiaside, suspensaside, acteoside, β-hydroxyacteoside and plantamajoside, showed an antibiotic activity against Staphylococcus aureus. Forsythiaside, suspensa-side, plantamajoside and iso-plantamajoside showed a strong inhibitory activity against cAMP phosphodiesterase, whereas acteoside and β-hydroxyacteoside showed a weak activity. Plantamajo-side, hellicoside exhibited a strong inhibitory activity on arachidonic acid-induced mouse ear edema. Acteoside and isoacteoside showed a weak activity. Suspensaside showed a continuous hypotensive activity on spontaneously hypertensive rat (SHR).

The emergence of fungal infections due to the increase in the number of immunocompromised patients has become a matter of concern. Among the available sources for treating fungal infections, natural products can play a significant role. In this article, we have tried to categorize the different sources and chemical classes of fungitoxic agents as following: (1) animal sources such as defensins and other peptides, (2) plant sources such as terpenoids, flavonoids, and coumarins, (3) fungal metabolites like fatty acids, sugar derivatives and polyenes and (4) bacterial sources such as amino acids. The potentials of coumarins, which are mainly distributed in four plant families, Umbelliferae, Rutaceae, Leguminosae and Compositae, have been uncovered in this respect. In addition to antifungal property, the other bioactivities of coumarins include: anticoagulant, antibacterial, antiparasitie, anticancer, photodynamic, edema relieving, anti-inflammatory, radical scavenging, lipolytic, antiplatelet, and anti-allergic properties. Studies in structure-antifungal activity relationships of coumarins, which is presented here, reveal the essential strucutral features for their activity. In order to have a better understanding of the mode of action of coumarins, the cellular sites and the interactions of coumarins with biological systems have been explained. Effects on the enzymes gyrase and topoisomerase, and photodynamic reaction with lipids, proteins and DNA are among the main issues discussed. In this respect, morphological changes of Candida albicans cells due to coumarins, which are studied by scanning electron microscopy (SEM), support their biochemical effects.

Publisher Summary Woody plants are capable of synthesizing a wide range of phenylpropane derivatives, including lignans, neolignans, coumarins, and flavonoids. The chapter presents a study in which the wood of A. sachalinensis was extracted with 95% EtOH. Repeated silica-gel column chromatographies of the diethyl ether solubles of the EtOH extract resulted in the isolation of fourteen lignans. Todolactol A, B, C, and D have not been reported as naturally occurring lignans, but similar types of lignans have been isolated from Carissa edulis , Piper clusii , P. cubeba , Dacrydium intermedium , Abies mariesii, and A. koreana . The family, Salicaceae, is very widely distributed in the temperate and subarctic zones of the northern hemisphere. Taxonomically, the family is usually divided into four genera, Populus , Salix , Toisusu , and Chosenia . The EtOH extracts of the wood of S. sachallnensis was fractionated with diethyl ether and the solubles subjected to silica-gel column and preparative thin-layer chromatographies to give (+)-syringaresinol and two lignan esters.