Echium Species Research Articles

Echium vulgare and Echium plantagineum: A Comparative Study to Evaluate Their Inclusion in Mediterranean Urban Green Roofs

Green roofs (GRs) are proposed to offset against numerous environmental and socio-economic concerns associated with climate change and urban sprawl. In Mediterranean urban areas, to protect and conserve biodiversity through GRs, the use of native plant species from arid environments and with shallow roots is generally recommended. In north Europe, Echium vulgare L. is widely used on GRs for its tolerance to abiotic stresses and its attractiveness for bees; unfortunately, since this species requires cold winters to induce flowering and warm wet summers for vegetative growths, its adaptability to Mediterranean GRs has been questioned. The current study is based on the hypothesis that Echium plantagineum L. can adapt better to the Mediterranean environment than E. vulgare and offer blooms to pollinators, thus providing the important urban ecosystem service (UES) of protecting entomofauna biodiversity. To compare the adaptability of E. plantagineum vs. E. vulgare, both Echium species were grown and studied on the extensive GR installed at ENEA Casaccia Research Center, in the north of Rome, Lazio, Italy. The comparative analysis of the GR performance of the two species was based on several plant-related traits, including seed morphology, rosette stage, inflorescence, flower and root-related traits, and their biological life cycle, most of them showing significant differences (for example, rosette area was 1.42-fold major in E. plantagineum than in E. vulgare). The information provided in this manuscript will be useful to update the herbarium records for conservation biology. A dramatic water stress was purposely applied in the GR before the end of the hot summer season, and while E. plantagineum faced with success the imposed dehydration (88.4% vegetation cover), E. vulgare did not (7.5% vegetation cover), presumably because of its biennial life cycle which did not allow it to complete seed maturation (only 46.9% percentage mature seeds in E. vulgare respect to 89.5% in E. plantagineum). In summary, as the main result, this work shows that in Mediterranean areas, the inclusion of E. plantagineum in seed mixes for flower meadow GRs could represent a valuable alternative to E. vulgare in temperate areas, providing a safeguard for pollinators and allowing water and energy saving.

Antioxidant Properties and Reported Ethnomedicinal Use of the Genus Echium (Boraginaceae).

The genus Echium L. from the Boraginaceae family consists of 67 recognised species. The genus is widely distributed in the Mediterranean, having been documented in the traditional medicine of the area since 300 B.C. Current pharmacological studies have validated early ethnomedicinal properties showing that Echium spp. possesses antioxidant, analgesic, anxiolytic, anti-inflammatory, antibacterial, and antiviral effects. Nevertheless, only limited papers report specifically on the phytochemistry of this genus. Furthermore, the potential of utilising extracts from Echium species as natural antioxidant preparations has been significantly neglected. For the first time, this review comprehensively describes and discusses the presence of recorded Echium species with ethnomedicinal uses, their antioxidative properties in vitro and in vivo when available, and major phytochemical components recognised as potent antioxidants, as well as the possibilities and opportunities for future research.

A Simple Isocratic High-perfomance Liquid Chromatography Method for the Simultaneous Determination of Shikonin Derivatives in Some Echium Species Growing Wild in Turkey.

Dried roots of Echium species are used in Turkey for the treatment of wounds, inflammation, and depression. In this study, an reversed-phase-liquid chromatographic method with isocratic elution was developed to determine shikonin derivatives in Echium species. The chromatographic separation and quantification was performed on a C18 column (ACE, 150 mm × 4.6 mm, 5 μm), with a mobile phase of acetonitrile and 0.1 M acetic acid (70: 30, v/v) at a flow rate of 1 mL/min, and ultraviolet detection at 520 nm. Linear behavior was observed over the investigated concentration range (2-500 ppm) for all analytes, with a correlation coefficient of >0.998. The proposed method was found to be specific and precise for the quantification of shikonin derivatives in Echium species. The highest content of shikonin derivatives was observed in E. italicum L. compared with the other species studied herein, advocating the use of E. italicum L. roots as an alternate source for shikonin derivatives.

873. ECHIUM NERVOSUM

SummaryThe Madeiran endemic Echium nervosum W.T. Aiton is illustrated based on plants grown at the Royal Botanic Gardens, Kew. Its ecology; phylogenetic and taxonomic placement, and conservation status are discussed. Twenty‐nine species of Echium are endemic to the Macaronesian Islands and they represent one of the most spectacular and best known examples of adaptive radiation on oceanic islands.

Ecology and genetics affect relative invasion success of two Echium species in southern Australia

Echium plantagineum and E. vulgare are congeneric exotics first introduced to Australia in the early 1800 s. There, E. plantagineum is now highly invasive, whereas E. vulgare has a limited distribution. Studies were conducted to evaluate distribution, ecology, genetics and secondary chemistry to shed light on factors associated with their respective invasive success. When sampled across geographically diverse locales, E. plantagineum was widespread and exhibited a small genome size (1 C = 0.34 pg), an annual life cycle, and greater genetic diversity as assessed by DNA sequence analysis. It was found frequently in areas with temperature extremes and low rainfall. In contrast, E. vulgare exhibited a larger genome size (1 C = 0.43 pg), a perennial lifecycle, less chloroplast genetic diversity, and occurred in areas with lower temperatures and higher rainfall. Twelve chloroplast haplotypes of E. plantagineum were evident and incidence aligned well with reported historical introduction events. In contrast, E. vulgare exhibited two haplotypes and was found only sporadically at higher elevations. Echium plantagineum possessed significantly higher levels of numerous pyrrolizidine alkaloids involved in plant defence. We conclude that elevated genetic diversity, tolerance to environmental stress and capacity for producing defensive secondary metabolites have contributed to the successful invasion of E. plantagineum in Australia.

Bioassay-guided isolation of wound healing active compounds from Echium species growing in Turkey

Ethnopharmacological relevanceThe roots and root barks of Echium sp. have been used to treat ulcers, burns and wounds in traditional Turkish medicine. Aim of the studyOn the basis of them traditional use and literature references, four Echium species were selected for evaluation of them wound healing potential. Isolation of active component(s) from the active extracts through the bioassay guided fractionation procedures. Material and methodsIn vivo the wound healing activity of the plants was evaluated by linear incision experimental models. The chloroform extract of Echium italicum L. was fractionated by successive chromatographic techniques. Wound healing activity of each fraction was investigated following the bioassay-guided fractionation procedures. Moreover, the tissue samples of isolated compounds were examined histopathologically. The healing potential was comparatively assessed with a reference ointment Madecassol®, which contains 1% extract of Centella asiatica. ResultsSignificant wound healing activity was observed from the ointment prepared with ethanol extract at 1% concentration. The ethanol root extract treated in groups of animals showed a significant increase (37.38%, 40.97% and 35.29% separately for E. italicum L, Echium vulgare L. and Echium angustifolium Miller) wound tensile strength in the incision wound model. Subfractions showed significant but reduced wound healing activity on in vivo wound models. Shikonin derivatives “Acetylshikonin”, “Deoxyshikonin” and “2-methyl-n-butyrylshikonin+Isovalerylshikonin”, were isolated and determined as active components of active final subfraction from E. italicum L. roots. The results of histopathological examination supported the outcome of linear incision wound models. ConclusionThe experimental study revealed that Echium species display remarkable wound healing activity.

Determination of Shikonin and Rosmarinic Acid in Echium vulgare L. and Echium russicum J.F. Gmel. by Capillary Electrophoresis

A simple and rapid capillary zone electrophoresis (CZE) procedure for determination of shikonin and rosmarinic acid in roots of Echium vulgare L. and Echium russicum J.F. Gmel. is described. The separation was achieved in less than 4 min. The analysis was performed in fused silica capillary (i.d. 75 µm, 48.5 cm total length) using 50 mM borate, at pH 9.5 as the run buffer with applied voltage of 30 kV and constant temperature (27 °C). The method ensures good linearity and repeatability with high correlation coefficients (0.994 and 0.998 for shikonin and rosmarinic acid, respectively). The compounds were detected by UV absorption at 218 (shikonin) and 202 nm (rosmarinic acid). The limits of detection (LOD) for shikonin and rosmarinic acid were 0.603 ppm and 0.270 ppm, respectively. The method was used for estimation of both components in Echium plants. We found out that the content of shikonin and rosmarinic acid were 4.4–4.8 mg/kg air-dry material and 20.0–54.2 mg/kg air-dry material, respectively, in the Echium species analyzed.

New seed oils of Boraginaceae rich in stearidonic and gamma-linolenic acids from the Maghreb region

The main goal of this work was to find new seed oils rich in γ-linolenic acid (GLA, 18:3n-6) and stearidonic acid (SDA, 18:4n-3) as alternatives to the commercially available oils, such as those from fish and borage. To this end, seeds of selected Boraginaceae species growing wild in the North Africa region (Maghreb) were collected and analyzed. The key finding is that two Echium species have been identified as new sources of valuables fatty acids (FAs): Echium sericeum and Echium parviflorum, showing 18.3% GLA and 17.3% SDA on total FAs respectively. Both of them could be cultivated to provide functional oils, polyunsaturated FA (PUFA) concentrates or pure FAs, among other uses. It is also noteworthy that the seed oils of Borago officinalis and Echium plantagineum gathered in different locations showed different GLA and SDA percentages, respectively.

Pyrrolizidine alkaloids in two endemic capeverdian Echium species

Abstract Echium hypertropicum Webb and Echium stenosiphon Webb subsp. stenosiphon are capeverdian shrubs used in folk medicine for the treatment of cough and gastrointestinal diseases. Acid-base extraction was used to obtain alkaloid-rich fractions from both species. GC–MS and ESI-MS/MS analysis indicated the presence of pyrrolizidine alkaloids (PAs) and purified substances were also analyzed by 1D and 2D NMR experiments. A total of ten alkaloids were detected, eight of which were identified by comparing their molecular masses and mass fragmentation patterns with the NIST database and data in the literature. The hepatotoxic diesters echimidine and 7-(2-methylbutyryl)-9-echimidinylretronecine were identified in both species. Echimidine was the major component in the diethyl ether fraction from leaves of E. hypertropicum , whereas the 7-(2-methylbutyryl)-9-echimidinylretronecine was the major component in the dichloromethane fraction from leaves of E . stenosiphon . To our knowledge, this is the first report on the occurrence of pyrrolizidine alkaloids in capeverdian species of Echium . This study on Echium led to the identification of constituent pyrrolizidine alkaloids, serving to assist taxonomists with the complex taxonomy of this genus.

Delta-6 desaturase makes a different fatty acid profile of seed oil in Iranian borage (Echium amoenum Fisch. and Mey.)

Iranian borage (Echium amoenum) from Boraginaceae is a valuable medicinal plant native to Iran and Syria. We determined fatty acid profile and individual fatty acid contents in E. amoenum seed oil using gas chromatography. Nevertheless, the cumulative amount of ω-6 and ω-3 fatty acids in E. amoenum (78.5 %) was in great accordance with those of other species of Echium, Stearidonic acid (SDA, C18:4ω3) and gamma-linolenic acid (GLA, C18:3ω6) constituted only 9.7 % of seed oil in this plant. This observation elucidated the weak activity of delta-6 desaturase (D6DES) in E. amoenum compared with D6DESs of other species. As D6DES enzyme is responsible for converting linoleic acid (LA, C18:2ω6) and alpha-linolenic acid (ALA, C18:3ω3) to GLA and SDA, we isolated coding sequence of D6DES gene and characterized primary structure of the translated protein to probably find some evidences explaining the weak activity of D6DES enzyme in E. amoenum. Gene sequence from E. amoenum showed a high identity of 94–96 % with the other Echium species and the amino acid homology increased by 98 %. All the expected signatures including cytochrome b5 domain and three conserved histidine-rich motifs were found in the translated amino acid sequence. Protein alignment revealed that all the conserved motifs in D6DES sequence from E. amoenum are coincident with its counterparts from other Echium species. However, secondary structure of the enzyme deduced from its primary structure using computational simulation represented obvious differences with D6DES proteins of the other species.

Accumulation patterns of some seed oil components from wild sources of Turkey

Accumulation profiles of fatty acids and α-tocopherol were analysed at three ripening stages in the seed oils of Primula and Echium species. Total seed oils were increased considerably with maturation, while α-tocopherol contents decreased in both species. Increased levels of ALA and oleic acid, and decrease in linoleic and palmitic acids at late ripening stages of Primula sibthorpii, and slightly fluctuations of all examined fatty acids in Echium italicum were observed. Considerable amounts of α-tocopherol (27.4 mg/100 g), linoleic acid (42.76%) and ALA (25.46%) and GLA (4.11%) were detected in Ribes alpinum. Typical accumulation patterns of the examined parameters may be useful for species characterisation and biochemical monitoring of seed development in natural conditions.

Searching for health beneficial n‐3 and n‐6 fatty acids in plant seeds

Various plant seeds have received little attention in fatty acid research. Seeds from 30 species mainly of Boraginaceae and Primulaceae were analysed in order to identify potential new sources of the n-3 PUFA α-linolenic acid (ALA) and stearidonic acid (SDA) and of the n-6 PUFA γ-linolenic acid (GLA). The fatty acid distribution differed enormously between genera of the same family. Echium species (Boraginaceae) contained the highest amount of total n-3 PUFA (47.1%), predominantly ALA (36.6%) and SDA (10.5%) combined with high GLA (10.2%). Further species of Boraginaceae rich in both SDA and GLA were Omphalodes linifolia (8.4, 17.2%, resp.), Cerinthe minor (7.5, 9.9%, resp.) and Buglossoides purpureocaerulea (6.1, 16.6%, resp.). Alkanna species belonging to Boraginaceae had comparable amounts of ALA (37.3%) and GLA (11.4%) like Echium but lower SDA contents (3.7%). Different genera of Primulaceae (Dodecatheon and Primula) had varying ALA (14.8, 28.8%, resp.) and GLA portions (4.1, 1.5%, resp.), but similar amounts of SDA (4.9, 4.5%, resp.). Cannabis sativa cultivars (Cannabaceae) were rich in linoleic acid (57.1%), but poor in SDA and GLA (0.8, 2.7%, resp.). In conclusion, several of the presented plant seeds contain considerable amounts of n-3 PUFA and GLA, which could be relevant for nutritional purposes due to their biological function as precursors for eicosanoid synthesis.Practical applicationsN-3 PUFA are important for human health and nutrition. Unfortunately, due to the increasing world population, overfishing of the seas and generally low amounts of n-3 PUFA in major oil crops, there is a demand for new sources of n-3 PUFA. One approach involves searching for potential vegetable sources of n-3 PUFA; especially those rich in ALA and SDA. The conversion of ALA to SDA in humans is dependent on the rate-limiting Δ6-desaturation. Plant-derived SDA is therefore a promising precursor regarding the endogenous synthesis of n-3 long-chain PUFA in humans. The present study shows that, in addition to seed oil of Echium, other species of Boraginaceae (Cerinthe, Omphalodes, Lithospermum, Buglossoides) and Primulaceae (Dodecatheon, Primula), generally high in n-3 PUFA (30–50%), contain considerable amounts of SDA (5–10%). Therefore, these seed oils could be important for nutrition.

Characterization of fatty acids in different organs of some Iranian Echium plants

Seeds, leaves and stems of six populations of two Echium species (Family Boraginaceae) from Iran were surveyed for the first time in a search for new sources of γ-linolenic acid (GLA, C18:3ω6), stearidonic acid (SDA, 18:4ω3) and other unsaturated fatty acids. Oils from the corresponding organs were analyzed by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) for total oil content and fatty acid composition. The range of total oil content varied between 0.7% in stems of Echium amoenum, Behshahr population to 33.8% in seeds of E. amoenum, Ramsar population. The amounts of GLA ranged from 2.28% of total fatty acids in E. amoenum stems (Behshahr population) to 9.79% in Echium italicum seeds (Kaleybar population). In addition, considerable amounts of SDA were detected, with the highest values of 10.47 and 12.45% in seeds of E. italicumfrom Boumehen and Kaleybar populations, respectively. Other main unsaturated fatty acid components in the oils were α- linolenic acid (ALA, 18:3ω3) and linoleic acid (LA, C18:2ω6) with the highest amounts of 44.15 and 26.94% in E. amoenum seeds from Hezar Jarib and Behshahr populations, respectively. This data allows us to evaluate Iranian members ofEchium genus as alternative wild sources of valuable unsaturated fatty acids for commercial purposes. Key words: Boraginaceae, Echium, fatty acids, γ-linolenic acid, stearidonic acid, gas chromatography.

A new species of <i>Echium</i> (Boraginaceae) from the island of Porto Santo (Madeira Archipelago)

Carvalho, J.A., Pontes, T., Batista-Marques, M.I. & Jardim, R. 2010. A new species from the island of Porto Santo (Madeira Archipelago). Anales Jard. Bot. Madrid. 67(2): 87-96. A new species endemic from the island of Porto Santo (Madeira Archipelago) is described as Echium portosanctensis J.A. Carvalho, Pontes, Batista-Marques & R. Jardim. Morphological studies based on reproductive and vegetative traits revealed a set of diagnostic characters confirming separation of E. portosanctensis from other recognized species at sectional level. A taxonomic diagnosis, a morphological description and illustrations of the new species are provided. Images, distribution maps, ecological data and a key for Madeiran species of Echium are also provided. Diagnostic characters, conservation status, threats and speciation mechanisms are discussed. In addition, reports on the occurrence of E. candicans on the island of Porto Santo are also discussed.

Host‐plant finding and recognition by visual and olfactory floral cues in an oligolectic bee

Summary1. Bees use floral cues, such as odour, colour, size and shape, to discriminate and recognize flowers. The interplay between visual and olfactory cues in social as well as in solitary bee species is poorly understood.2. In this study we tested the host finding and recognition behaviour in a specialized (oligolectic) bee species,Hoplitis adunca(Megachilidae), which collects pollen exclusively on flowers ofEchium(Boraginaceae) species. We determined the importance of visual (especially floral colour) and olfactory cues ofEchium vulgareflowers in host‐plant finding and recognition, as well as in the discrimination of non‐host plants (Anchusa officinalis), by foraging‐naïve and ‐experiencedH. aduncafemales.3. Our investigations showed that the interplay between visual and olfactory cues ofE. vulgareflowers is essential for host‐plant finding and recognition byH. aduncafemales. The finding suggests that the blue colour of the flowers attracts the bees, while the olfactory cues, which areEchium‐specific, are used by the bees to recognize their host plant and discriminate it from non‐host plants.4. Our results show that different modalities of floral cues need to be studied in a combined approach in order to understand the communication in bee–flower interactions and the cues used by bees to find and recognize their host‐plants.

Sex ratio variation in gynodioecious species ofEchiumendemic to the Canary Islands

Species of Echium from the Canary Islands represent an adaptive radiation of plants involving evolutionary changes in habitat and life form. Alongside these changes, evolutionary transitions of the sexual system have occurred: approximately one quarter of Echium species from the Canary Islands are dimorphic for gender, paralleling other adaptive radiations of plants on oceanic islands, such as Schiedea in Hawaii. Here, I report on the variation in the frequency of female plants among eight gynodioecious populations representing four species of Echium on the island of Tenerife, and provide preliminary estimates of the seed fertility of females and hermaphrodites, which is an important determinant of the sex ratio for gynodioecious species. Across populations, female frequencies ranged between 6% and 54%, a much wider range than had previously been reported for gynodioecious species of Echium on the Canary Islands. Substantial frequencies of female plants occurred, even though no differences in the seed fertility of females and hermaphrodites were detected.

Stearidonic acid: A plant produced omega‐3 PUFA and a potential alternative for marine oil fatty acids

AbstractOmega‐3 (n‐3) fatty acids are widely recognized as being important in regulating many inflammatory disorders in man. However, metabolism of the parent n‐3 fatty acid α‐linolenic acid (ALA, 18:3n‐3) to the highly unsaturated bioactive fatty acids; eicosapentaenoic acid (EPA, 20:5n‐3) and docosahexaenoic acid (DHA, 22:6n‐3), in the body is limited. The first product in the pathway leading to EPA/DHA is the post‐Δ6 desaturase metabolite stearidonic acid (SDA, 18:4n‐3). The activity of the Δ6‐desaturase enzyme is low in man and can be adversely influenced by several environmental factors including dietary fat. SDA has been shown, in several studies, to be rapidly and efficiently converted to EPA which is a probable factor in its bio‐activity. The main source of EPA and DHA in diet is fish oil which, owing to over‐fishing and its extensive use in aquaculture feed, is becoming a scarce resource. There clearly exists a need for a renewable source of a lipid containing the highly unsaturated n‐3 fatty acids EPA, DHA or SDA. Although the highly unsaturated fatty acids (HUFA) have been commercially produced in micro‐organisms neither EPA nor DHA has been shown to exist in any quantity in land‐based plants. SDA is however found in several fungal and algal species and also in a small number of plant seed oils. Plants from the Boraginaceae family notably Echium species are particularly rich in SDA and Echium plantagineum has been grown commercially. Other plants from the Boraginaceae are being investigated and several have been identified that may offer benefits over Echium spp. Transgenic plants containing high levels of SDA have also been reported but engineering EPA or DHA into genetically modified higher plants is proving elusive. SDA‐containing lipids are of great interest in a number of areas such as fortified foods, dietary supplements, medicinal foods, pharmaceuticals and personal‐care products.

Study of embryotoxicity of Perovskia abrotanoides, an adulterant in folk-medicine, during organogenesis in mice

Aim of the study Perovskia abrotanoides is a medicinal herb which traditionally has been used as a topical application to treat leishmaniasis in Iran. Due to similarities of the flowers of Perovskia abrotanoides and Echium species, it is added as an adulterant to Echium preparations in Iran. Echium flowers have been used in Iranian traditional medicine as an “anti-stress”, tranquilizer, and energizer drink, fighting common cold and bronchitis particularly during pregnancy. In this study, the in vivo embryotoxicity of 0.125 and 0.25 g/kg of ethanolic and aqueous extracts of Perovskia abrotanoides during organogenesis in mice has been investigated. Materials and methods Maternal body weights were recorded and pregnant females were observed daily throughout gestation. After cesarean section, fetuses were weighed, lengthed and examined for gross external malformations. Others were fixed then stained with Alcian blue and Alizarin red to view any skeletal malformations. Results Our results indicated that this herb causes minimal maternal toxicity, while resorption, stillborn, fetal malformations including polydactyly, spina bifida, aglossia, tarsal extensor, gastroschisis, and numerous skeletal abnormalities were detected particularly in the ethanolic extract groups. Specific skeletal abnormalities based on type of extract were also observed. Conclusions Since Perovskia abrotanoides is widely used in traditional medicine intentionally or inadvertently, it is advisable its use during pregnancy should be avoided and strict regulations are imposed to prevent its addition to commercial preparations of other herbal products.

Taxonomy of Echium (Boraginaceae) species from Cape Verde Islands

The morphological variation of endemic species from the Macaronesian Islands has long attracted attention of many taxonomists. The taxonomy of the endemic Echium L. species (E. hypertropicum Webb, E. stenosiphon Webb and E. vulcanorum A.Chev.) from Cape Verde Islands was revised, on the basis of in situ collected material and on herbarium specimens. Our results revealed that the patterns of morphological variation correspond closely to the geographic localisation of the islands groups, and that habit and floral morphology are important for distinguishing the two southern taxa, E. hypertropicum and E. vulcanorum, from the northern species, E. stenosiphon. This species has the same ecological preferences (e.g. altitude; exposition; soil type) in São Nicolau, São Vicente and Santo Antão Islands. However, the differences in indumentum observed among E. stenosiphon specimens account for the occurrence of different taxonomic groups distributed in these Northern Islands. The two southern species, E. hypertropicum and E. vulcanorum, are morphologically similar, but have different ecological preferences, a pattern of variation similar to other Macaronesian Echium species. Furthermore, the morphological variation observed among the three Cape Verde species, discussed within the general context of Echium taxonomy and closely related genera (e.g. Lobostemon, Echiostachys and Pontechium), suggests that the systematic relationships are beyond the actual circumscription of these genera.

Stearidonic acid (18:4n‐3): Metabolism, nutritional importance, medical uses and natural sources

AbstractStearidonic acid (SA, 18:4n‐3) is a polyunsaturated fatty acid (PUFA) that constitutes the first metabolite of α‐linolenic acid (ALA, 18:3n‐3) in the metabolic pathway leading to C20–22 PUFA, such as eicosapentaenoic acid (EPA, 20:5n‐3), and docosahexaenoic acid (DHA, 22:6n‐3), which recently have received much attention because of their various physiological functions in the human body. Recently, several studies indicated that dietary SA increased EPA more efficiently than ALA. Thus, vegetable oils containing SA may become a dietary source of n‐3 fatty acids that is more effective in increasing tissue n‐3 PUFA concentrations than the current ALA‐containing vegetable oils. Nevertheless, few SA sources occur in nature, although there are still a large number of species untested to date. SA has been detected in variable amounts in several species of algae, fungi and animals tissues, but the seeds of some plant families seem to be better sources of SA, especially Echium (Boraginaceae) species. This work reviews the nutritional significance, medical uses and natural occurrence of SA.