Saponin Profile of Wild Asparagus Species

Phytochemical Profile and In Vitro Bioactivities of Wild Asparagus stipularis

In this study, Asparagus stipularis was characterized concerning its phytochemical composition, antioxidant potential, cytotoxicity, and pancreatic lipase inhibitory activities. Twenty-seven compounds were identified and quantified by HPLC-DAD-MS in the leaf, stem, pericarp, and rhizome of ethanolic extracts. Seven steroidal saponins were detected, and the highest content was quantified in rhizome and pericap. A. stipularis also contained significant amounts of flavonoids in the aerial part. Isorhamnetin tetra-glycoside, quercetin-3-glucosyl-rutinoside, and rutin were the main flavonoid derivatives in leaf, stem, and pericarp extracts, respectively. In addition, eleven phenolic acids were also detected; among them, caffeic acid, protocatechuic acid, p-hydroxybenzoic acid, and ferulic acid were the predominant phenolics, with these having the highest amounts quantified in the rhizome extracts. All the tested extracts possessed antioxidant capacities, with pericarp and rhizome extracts exhibiting the highest activity in DPPH, ABTS, and FRAP assays. The extracts from pericarp and rhizome were revealed to also be the strongest inhibitors of pancreatic lipase. The rhizome extracts exhibited potent cytotoxic activity against HCT-116 and HepG2 with IC50 values of 30 and 54 µg/mL after 48 h of treatment. The present study demonstrated that A. stipularis can be used as a new source of natural antioxidants and potential anticancer and antiobesity compounds.

Applications of Saponin Extract from Asparagus Roots as Functional Ingredient

When replanting an asparagus field, the roots of the previous crop are crushed and incorporated into the soil, creating problems of autotoxicity and fungal infections. Asparagus roots can be considered as a valuable byproduct, since they are very rich in saponins (3-6%), compounds currently considered as bio-emulsifiers. The objective is to evaluate the emulsifying and foaming capacity of a saponin extract from asparagus roots (ARS) and compare it with other commercial extracts. ARS was obtained using a process patented by our research group. The results have shown that ARS has activity similar to Quillaja extract. Its critical micellar concentration falls between that of Quillaja and Tribulus extracts (0.064, 0.043, and 0.094 g/100 mL, respectively). Both emulsifying and foaming activities are affected by pH, salt, and sucrose to a similar extent as the other extracts. Additionally, it has demonstrated an inhibitory effect on pancreatic lipase, which is even better than the other two studied extracts, as indicated by its IC50 value (0.7887, 1.6366, and 2.0107 mg/mL for asparagus, Quillaja, and Tribulus, respectively). These results suggest that ARS could serve as a natural emulsifying/foaming agent for healthier and safer food products and as a potential aid in treatments for obesity and hyperlipidemia.

Sustainable valorization of co-products from asparagus cultivation by obtaining bioactive compounds

Asparagus cultivation generates every year a significant amount of by-products that consist of root and frond. Leaving these residues on the fields after harvesting negatively affects the following asparagus crops, since they release autotoxic (allelopathic) substances into the soil, whose accumulation causes that asparagus yields gradually decrease over the years, becoming an unprofitable crop in a period of about 10 to 15 years. This phenomenon is known as decay and forces the entire asparagus plantation to be lifted (abandoned). On the other hand, once a certain plantation has been lifted, it is not profitable to immediately re-plant new asparagus plants, since the yields that are achieved are never more than half of normal ones. It is necessary to wait an average of 4 or 5 years before replanting asparagus in these lands. This phenomenon is known as the replanting problem, and causes the need to continually search for new land for growing asparagus. Another added problem for farmers is that the elimination of those plant residues from asparagus cultivation entails significant economic costs. For all these reasons, it is essential to seek alternatives for the management of that waste that improve the sustainability of the crop within the scope of the circular economy. In this context, this work proposes the valorization of asparagus by-products by obtaining bioactive compounds. Main objectives of the present work include: i) phytochemical analyses of asparagus fronds and roots; ii) obtaining bioactive extracts, with distinct technological and nutritional functionalities, by using an environmentally sustainable extraction process, easy to implement in the practice of a food industry and with methods compatible with food use. Characterization of asparagus by-products shown that fronds had an average flavonoid content of 2.637 ± 0.014 g/Kg fresh weight, which is up to 5-6 times higher than that of the spears; and roots contained up to 10 times more saponins (2.25 g/Kg fresh weight), which were accompanied by lower quantities of phenolic acids (368 mg/Kg fresh weight). Statistical analysis revealed that those phytochemical contents were mainly determined by location and phase of the vegetative cycle, whereas genetic factors did not significantly influence them. Based on the results of the present work, the proposal for the recovery and valorization of asparagus by-products is based on obtaining two bioactive extracts, the first being an antioxidant extract enriched in flavonoids, with an average yield of 10.7 g/Kg fresh frond and a flavonoid richness of 17%; and the second, a saponins extract with an average yield of 10.3 g/Kg fresh root and a richness of 51%. These natural extracts have great techno-functional potential in the agri-food industry and some of them are already being tested as additives in the preparation of soups, breads and meat products.

Evaluation of immunological adjuvant activities of saponin rich fraction from the fruits of Asparagus adscendens Roxb. with less adverse reactions

The hemolytic activity, in vitro as well as in vivo toxicity, and immunomodulatory potential of saponins-rich fraction of Asparagus adscendens Roxb. fruit (AA-SRF) have been assessed in this study in order to explore AA-SRF as an alternative safer adjuvant to standard Quil-A saponin. The AA-SRF showed lower hemolytic activity (HD₅₀ = 301.01 ± 1.63 µg/ml) than Quil-A (HD₅₀ = 17.15 ± 2.12 µg/ml). The sulforhodamine B assay also revealed that AA-SRF was less toxic to VERO cells (IC₅₀≥200 ± 4.32 µg/ml) than Quil-A (IC₅₀ = 60 ± 2.78 µg/ml). The AA-SRF did not lead to mortality in mice up to 1.6 mg and was much safer than Quil-A for in vivo use. Conversely, mice were subcutaneously immunized with OVA 100 μg alone or along with Alum (200 μg) or Quil-A (10 μg) or AA-SRF (50 μg/100 μg/200 μg) on days 0 and 14. The AA-SRF at 100 μg dose best supported the LPS/Con A primed splenocyte proliferation activity, elevated the serum OVA-specific total IgG antibody, IL-12, CD4 titer and upsurged CD3/CD19 expression in spleen as well as lymph node sections which in turn advocated its adjuvant potential. Thus, AA-SRF can be further studied for use as a safe alternative adjuvant in vaccines.

Characterization of the Phenolic Profile and Antioxidant Activity of Cathissa reverchonii (Lange) Speta

Cathissa reverchonii (formerly Ornithogalum reverchonii) is a threatened species, constituting an endemism present in the south of Spain and northern Morocco. In Spain, it is only found in two disjoint populations in the region of Andalusia. The determination of its chemical composition and the influence that environmental factors have on it can contribute significantly to the development of appropriate protection and conservation plans. However, there are no previous reports about this species to date. Consequently, this research aimed to study the phenolic composition and antioxidant activity of C. reverchonii and to assess the influence of environmental factors on the phenolic profile and bioactivity. The vegetal material was collected in seven places inhabited by the two separate populations in Spain. The phenolic composition of methanolic extracts of the species was determined by HPLC-ESI-Q-TOF-MS, and the antioxidant activity was assessed by DPPH and ABTS assays. Fifteen compounds were characterized in the extracts of the aerial parts of C. reverchonii, revealing differences in the phytochemical profile between both populations analyzed, mainly in the saponin fraction. The main phenolics were flavone di-C-glucoside (lucenin-2), followed by a quercetin-di-C-glucoside. The composition of the extracts of C. reverchonii and their radical scavenging power were compared with those of other species of the genus Ornithogalum L., revealing significant differences between the latter and the genus Cathissa.

Metabolomics Reveals Heterogeneity in the Chemical Composition of Green and White Spears of Asparagus (A. officinalis)

Green and white asparagus are quite different crops but can be harvested from the same plant. They have distinct morphological differences due to their mode of cultivation and they are characterised by having contrasting appearance and flavour. Significant chemical differences are therefore expected. Spears from three varieties of both green and white forms, harvested in two consecutive seasons were analysed using headspace GC-MS and LC-MS with an untargeted metabolomic workflow. Mainly C5 and C8 alcohols and aldehydes, and phenolic compounds were more abundant in green spears, whereas benzenoids, monoterpenes, unsaturated aldehydes and steroidal saponins were more abundant in white ones. Previously reported key asparagus volatiles and non-volatiles were detected at similar or not significantly different levels in the two asparagus types. Spatial metabolomics revealed also that many volatiles with known positive aroma attributes were significantly more abundant in the upper parts of the spears and showed a decreasing trend towards the base. These findings provide valuable insights into the metabolome of raw asparagus, the contrasts between green and white spears as well as the different chemical distributions along the stem.

Phytochemical Characterization and Bioactivity of Asparagus acutifolius: A Focus on Antioxidant, Cytotoxic, Lipase Inhibitory and Antimicrobial Activities

The phytochemical composition of leaves, stems, pericarps and rhizomes ethanolic extracts of Asparagus acutifolius were characterized by HPLC-DAD-MS. A. acutifolius samples contain at least eleven simple phenolics, one flavonon, two flavonols and six steroidal saponins. The stem extracts showed the highest total phenolic acid and flavonoid contents, where cafeic acid and rutin were the main compounds. No flavonoids were detected in the leaf, pericarp or rhizome while caffeic acid and ferulic acid were the predominant. Steroidal saponins were detected in the different plant parts of A. acutifolius, and the highest contents were found in the rhizome extracts. The stem extracts exhibited the highest antioxidant activity against 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) and the highest 2,2-azino-bis (3 ethylbenzothiazoline-6-sulphonic acid) (ABTS) scavenging activity was found in the pericarp extracts. The rhizome and leaf extracts showed a potent cytotoxic activity against HCT-116 and HepG2 cell lines. Moreover, the pericarp and rhizome extracts revealed a moderate lipase inhibitory activity. The leaf and rhizome extracts were screened for their antimicrobial activity against human pathogenic isolates. The leaf extract exhibited a powerful inhibitory activity against all the bacteria and fungi tested.

Pharmacokinetics of Ginsenoside Compound K From a Compound K Fermentation Product, CK-30, and From Red Ginseng Extract in Healthy Korean Subjects

Natural protopanaxadiol ginsenosides exhibit low absorption in the human intestine. However, ginsenoside compound K (CK) with 1 conjugated glucose molecule exhibits favorable absorption. The purpose of this study was to compare the pharmacokinetics of ginsenoside CK from a CK fermentation product, CK-30, and from a red ginseng extract. A randomized, open-label, 2-treatment, 2×2 crossover study was conducted. The volunteers were randomly divided into 2 groups. One group received CK-30, and the other group received 2.94 g of a red ginseng extract. After a 7-day washout period, the subjects received an alternative treatment for a single dose. The pharmacokinetic parameters, including the maximum plasma concentration (C_max ) and area under the plasma concentration-time curve from time 0 to time of last measurable concentration, were calculated. The median time to reach C_max of ginsenoside CK after administration of CK-30 was 3.0 hours, whereas the corresponding value of the red ginseng extract was 10.0 hours. Compared with the red ginseng extract, CK-30 resulted in a higher systemic exposure to ginsenoside CK, with a 118.3-fold increase in C_max and a 135.1-fold increase in area under the plasma concentration-time curve from time 0 to time of last measurable concentration. The systemic exposure to ginsenoside CK was significantly higher after administration of CK-30 than red ginseng extract.

Improving the bioactive ingredients and functions of asparagus from efficient to emerging processing technologies: A review

Historically, asparagus is a vegetable with abundant phytochemicals (polyphenols, saponins, asparagusic acid, and alkaloids) and crucial bioactivities (neuroprotective, antianxiety, antityrosinase, antioxidant, antibacterial, and antiasthma effects). Numerous investigations indicated that processing technologies have a significant influence on the physicochemical, functional, and microstructural characteristics of asparagus. This review presents an updated overview of novel applications of processing technologies, including ultrasound treatments (in terms of extraction, purification, and preservation), heating treatments (hydrothermal treatments, thermal treatments, and combination heating treatments), high-pressure processing, representative shelf-life extension technologies, and green extraction technologies. These physical technologies enhance the yields of bioactive substances, bioactivities and product quality. In addition, utilizing the novel technologies (ohmic heating, cold plasma, pulsed electric fields, membrane processing) and conventional technologies with novel effects to fully develop the potential of asparagus should also be taken into consideration in the future.

Identification of Bioactive Compounds of Asparagus officinalis L.: Permutation Test Allows Differentiation among "Triguero" and Hybrid Green Varieties

In this study, we determined the phytochemical profile of the Spanish “triguero” asparagus landrace “verde-morado” (Asparagus officinalis L.), a wild traditional landrace, and the improved “triguero” HT-801, together with two commercial green asparagus varieties. For comparison, we used reverse-phase high-performance liquid chromatography coupled with diode array electrospray time-of-flight mass spectrometry (RP-HPLC-DAD-ESI-TOF/MS) followed by a permutation test applied using a resampling methodology valid under a relaxed set of assumptions, such as i.i.d. errors (not necessarily normal) that are exchangeable under the null hypothesis. As a result, we postulate that “triguero” varieties (the improved HT-801 followed by its parent “verde-morado”) have a significantly different phytochemical profile from that of the other two commercial hybrid green varieties. In particular, we found compounds specific to the “triguero” varieties, such as feruloylhexosylhexose isomers, or isorhamnetin-3-O-glucoside, which was found only in the “triguero” variety HT-801. Although studies relating the phytochemical content of “triguero” asparagus varieties to its health-promoting effects are required, this characteristic phytochemical profile can be used for differentiating and revalorizating these asparagus cultivars.

Comparative Metabolome and Transcriptome Analyses of Susceptible Asparagus officinalis and Resistant Wild A. kiusianus Reveal Insights into Stem Blight Disease Resistance

Phomopsis asparagi is one of the most serious fungal pathogens, which causes stem blight disease in Asparagus officinalis (AO), adversely affecting its production worldwide. Recently, the development of novel asparagus varieties using wild Asparagus genetic resources with natural P. asparagi resistance has become a priority in Japan due to the lack of resistant commercial AO cultivars. In this study, comparative metabolome and transcriptome analyses of susceptible AO and resistant wild Asparagus kiusianus (AK) 24 and 48 h postinoculated (AOI_24 hpi, AOI_48 hpi, AKI_24 hpi and AKI_48 hpi, respectively) with P. asparagi were conducted to gain insights into metabolic and expression changes associated with AK species. Following infection, the resistant wild AK showed rapid metabolic changes with increased levels of flavonoids and steroidal saponins and decreased asparagusic acid glucose ester content, compared with the susceptible AO plants. Transcriptome data revealed a total of 21  differentially expressed genes (DEGs) as the core gene set that displayed upregulation in the resistant AK versus susceptible AO after infection with P. asparagi. Kyoto Encyclopedia of Genes and Genomes pathway analysis of these DEGs identified 11 significantly enriched pathways, including flavonoid biosynthesis and primary metabolite metabolism, in addition to plant signaling and defense-related pathways. In addition, comparative single-nucleotide polymorphism and Indel distributions in susceptible AO and resistant AK plants were evaluated using the latest AO reference genome Aspof.V1. The data generated in this study are important resources for advancing Asparagus breeding programs and for investigations of genetic linkage mapping, phylogenetic diversity and plant defense-related genes.

Effects of superfine grinding on asparagus pomace. Part I: Changes on physicochemical and functional properties

The effects of superfine grinding on the physicochemical and functional properties of asparagus pomace were investigated. The results showed that in terms of the specific surface area, water solubility, soluble dietary fiber content, and ratio of insoluble dietary fiber to soluble dietary fiber, finer samples usually possessed better physicochemical properties compared with coarse samples. However, grinding samples excessively to produce small particle sizes could reduce the water-holding capacity, oil-binding capacity, and swelling capacity. In addition, the extraction of both free and bound phenolics in asparagus pomace powder samples and the samples' absorption of both nitrite ion and glucose showed typical bell-shaped curves, demonstrating that superfine grinding could significantly impact the various properties of asparagus pomace. This study should provide insights into the effect of micronization on the functionalities of fiber-rich food materials. PRACTICAL APPLICATION: This article deals with the effects of superfine grinding on the physicochemical and functional properties of asparagus pomace. The results showed that the properties of asparagus pomace did not always improve gradually with decreasing particle size. With a decrease in granularity, some parameters showed a bell-shaped curve whereas others initially increased and then stabilized, indicating that in actual production, the crushing particle size should be determined according to actual needs or target parameters.

Green and White Asparagus (Asparagus officinalis): A Source of Developmental, Chemical and Urinary Intrigue

Asparagus (Asparagus officinalis) is one of the world's top 20 vegetable crops. Both green and white shoots (spears) are produced; the latter being harvested before becoming exposed to light. The crop is grown in nearly all areas of the world, with the largest production regions being China, Western Europe, North America and Peru. Successful production demands high farmer input and specific environmental conditions and cultivation practices. Asparagus materials have also been used for centuries as herbal medicine. Despite this widespread cultivation and consumption, we still know relatively little about the biochemistry of this crop and how this relates to the nutritional, flavour, and neutra-pharmaceutical properties of the materials used. To date, no-one has directly compared the contrasting compositions of the green and white crops. In this short review, we have summarised most of the literature to illustrate the chemical richness of the crop and how this might relate to key quality parameters. Asparagus has excellent nutritional properties and its flavour/fragrance is attributed to a set of volatile components including pyrazines and sulphur-containing compounds. More detailed research, however, is needed and we propose that (untargeted) metabolomics should have a more prominent role to play in these investigations.

Phytoestrogens, phytosteroids and saponins in vegetables: Biosynthesis, functions, health effects and practical applications

Phytoestrogens are non-steroidal secondary metabolites with similarities in structure and biological activities with human estrogens divided into various classes of compounds, including lignans, isoflavones, ellagitannins, coumestans and stilbenes. Similarly, phytosteroids are steroidal compounds of plant origin which have estrogenic effects and can act as agonists, antagonists, or have a mixed agonistic/antagonistic activity to animal steroid receptors. On the other hand, saponins are widely distributed plant glucosides divided into triterpenoid and steroidal saponins that contribute to plant defense mechanism against herbivores. They present a great variation from a structural point of view, including compounds from different classes. In this chapter, the main vegetable sources of these compounds will be presented, while details regarding their biosynthesis and plant functions will be also discussed. Moreover, considering the significant bioactive properties that these compounds exhibit, special focus will be given on their health effects, either beneficial or adverse. The practical applications of these compounds in agriculture and phytomedicine will be also demonstrated, as well as the future prospects for related research.

The phytochemical and bioactivity profiles of wild Asparagus albus L. plant

The ethanolic extracts from the leaves, pericarps and rhizomes of Asparagus albus L. were investigated for their phytochemical composition, antioxidant (DPPH and FRAP assays), anti-microbial against human pathogenic isolates and cytotoxic (human colon carcinoma HCT-116 cells) activities. The highest flavonoid content was obtained in the leaf extract followed by the pericarp but there were no flavonoids detected in the rhizome. However, the rhizome had a high concentration of saponins. Flavonoid and saponin profiles were similar to those previously described for the triguero Huetor Tajar asparagus landrace. It was found that the pericarp ethanolic extract exhibited higher antioxidant activity than rhizome and leaf extracts. Moreover, the rhizome possessed more evident cytotoxic activity against HCT-116 cells in comparison to leaf and pericarp. All extracts showed varying degrees of antimicrobial activity against most of the human pathogenic isolates. In addition, the leaves showed more powerful inhibitory activities against the maximum number of bacteria and all the fungai isolated and the highest activity was in the pericarp extract against multidrug resistant Pseudomonas aeruginosa (MDR) and Erythromycin resistant Streptococcus agalactiae (ER) with an inhibition zone of 21mm and 19mm, respectively. The results show that A. albus could be a new crop with pharmaceutical interest because its richness in bioactive compounds provides considerable benefits for human health.