Steroidal glycosides of gitogenin from Allium rotundum

Chemical Constituents, Biological Activities, and Proposed Biosynthetic Pathways of Steroidal Saponins from Healthy Nutritious Vegetable-Allium

Allium is a common functional vegetable with edible and medicinal value. Allium plants have a special spicy taste, so they are often used as food and seasoning in people's diets. As a functional food, Allium also has abundant biological activities, some of which are used as drugs to treat diseases. By consuming Allium on a daily basis, people can receive active compounds of natural origin, thereby improving their health status and reducing the likelihood of disease. Steroidal saponins are important secondary metabolites of Allium, which are formed by the steroidal aglycone group and sugar. Steroidal saponins have various physiological activities, such as hypoglycemic, antiplatelet aggregation, anti-inflammatory, antitumor, antimicrobial, and enzyme activity inhibition, which is one of the key reasons why Allium has such significant health benefits. The structural diversity and rich biological activities of steroidal saponins make Allium important plants for both food and medicine. In this paper, the chemical structures, biological activities, and structure-activity relationships of steroidal saponins isolated from Allium are reviewed, and the biosynthetic pathways of some key compounds are proposed as well, to provide a molecular reference basis based on secondary metabolites for the health value of Allium.

Spirostanol Saponins from Flowers of Allium Porrum and Related Compounds Indicating Cytotoxic Activity and Affecting Nitric Oxide Production Inhibitory Effect in Peritoneal Macrophages

Saponins, a diverse group of natural compounds, offer an interesting pool of derivatives with biomedical application. In this study, three structurally related spirostanol saponins were isolated and identified from the leek flowers of Allium porrum L. (garden leek). Two of them were identical with the already known leek plant constituents: aginoside (1) and 6-deoxyaginoside (2). The third one was identified as new component of A. porrum; however, it was found identical with yayoisaponin A (3) obtained earlier from a mutant of elephant garlic Allium ampeloprasun L. It is a derivative of the aginoside (1) with additional glucose in its glycosidic chain, identified by MS and NMR analysis as (2α, 3β, 6β, 25R)-2,6-dihydroxyspirostan-3-yl β-D-glucopyranosyl-(1 → 3)-β-D-glucopranosyl-(1 → 2)-[β-D-xylopyranosyl-(1 → 3)]-β-D-glucopyranosyl]-(1 → 4)-β-D-galactopyranoside, previously reported also under the name alliporin. The leek native saponins were tested together with other known and structurally related saponins (tomatonin and digitonin) and with their related aglycones (agigenin and diosgenin) for in vitro cytotoxicity and for effects on NO production in mouse peritoneal cells. The highest inhibitory effects were exhibited by 6-deoxyaginoside. The obtained toxicity data, however, closely correlated with the suppression of NO production. Therefore, an unambiguous linking of obtained bioactivities of saponins with their expected immunobiological properties remained uncertain.

Natural Antioxidants, Health Effects and Bioactive Properties of Wild Allium Species

BACKGROUND

There is an increasing interest from the pharmaceutical and food industry in natural antioxidant and bioactive compounds derived from plants as substitutes for synthetic compounds. The genus Allium is one of the largest genera, with more than 900 species, including important cultivated and wild species, having beneficial health effects.

OBJECTIVE

The present review aims to unravel the chemical composition of wild Allium species and their healthrelated effects, focusing on the main antioxidant compounds. For this purpose, a thorough study of the literature was carried out to compile reports related to health effects and the principal bioactive compounds. Considering the vast number of species, this review is divided into subsections where the most studied species are presented, namely Allium ampeloprasum, A. flavum, A. hookeri, A. jesdianum, A. neapolitanum, A. roseum, A. stipitatum, A. tricoccum, and A. ursinum, with an additional composite section for less studied species.

METHODS

The information presented in this review was obtained from worldwide accepted databases such as Scopus, ScienceDirect, PubMed, Google Scholar and Researchgate, using as keywords the respective names of the studied species (both common and Latin names) and the additional terms of"antioxidants" "health effects" and "bioactive properties".

CONCLUSION

The genus Allium includes several wild species, many of which are commonly used in traditional and folklore medicine while others are lesser known or are of regional interest. These species can be used as sources of natural bioactive compounds with remarkable health benefits. Several studies have reported these effects and confirmed the mechanisms of action in several cases, although more research is needed in this field. Moreover, considering that most of the studies refer to the results obtained from species collected in the wild under uncontrolled conditions, further research is needed to elucidate the effects of growing conditions on bioactive compounds and to promote the exploitation of this invaluable genetic material.

Steroidal saponins from the genus Allium

Steroidal saponins are widely distributed among monocots, including the Amaryllidaceae family to which the Allium genus is currently classified. Apart from sulfur compounds, these are important biologically active molecules that are considered to be responsible for the observed activity of Allium species, including antifungal, cytotoxic, enzyme-inhibitory, and other. In this paper, literature data concerning chemistry and biological activity of steroidal saponins from the Allium genus has been reviewed.

Cytotoxic steroidal glycosides from Allium flavum

Three new spirostane-type glycosides (1-3) were isolated from the whole plant of Allium flavum. Their structures were elucidated mainly by 2D NMR spectroscopic analysis and mass spectrometry as (20S,25R)-2α-hydroxyspirost-5-en-3β-yl O-β-D-xylopyranosyl-(1→3)-[β-D-galactopyranosyl-(1→2)]-β-D-galactopyranosyl-(1→4)-β-D-galactopyranoside (1), (20S,25R)-2α-hydroxyspirost-5-en-3β-yl O-β-D-xylopyranosyl-(1→3)-[β-D-glucopyranosyl-(1→2)]-β-D-galactopyranosyl-(1→4)-β-D-galactopyranoside (2), and (20S,25R)-spirost-5-en-3β-yl O-α-L-rhamnopyranosyl-(1→4)-[β-D-glucopyranosyl-(1→2)]-β-D-glucopyranoside (3). The three saponins were evaluated for cytotoxicity against a human cancer cell line (colorectal SW480).