The Bulgarian members of Chenopodiaceae are mainly ruderal and weed species; another part are halophytes. Over the last two decades, phylogenetic molecular studies have led to a number of taxonomic changes in the above mentioned family. Changes have also occurred in one of the largest genera – Chenopodium. The aim of the present study is to review the research on Bulgarian members of the Chenopodiaceae family. The data available in the literature on the taxonomic composition, chorology, morphological features and karyological variability of the species from their Bulgarian populations has been studied. A review of the phytochemical studies of Chenopodiaceae plants from their Bulgarian populations has been made. The systematized data is presented in chronological order, which allows for tracing the current level of study on the family in Bulgaria and opportunities for new research.

Bulgaria, Chenopodiaceae, chorology, karyology, morphology, phytochemical investigations

The family Chenopodiaceae is relatively large and worldwide it numbers about 1600 species belonging to more than 100 genera, spread more widely in the moderate and subtropical regions (Kühn et al. 1993; Kadereit et al. 2003).

The greater part of the Bulgarian members of the family belongs to the group of the highly movable ruderal plants and weeds with habitats in the central and southern part of the continent but having successfully spread in Bulgaria’s thermal zone and in the western parts of its territory (Stefanov 1943). Their wide distribution is related to the ability of most species to grow under extreme conditions such as high air and soil temperature (Ilyin 1936). Some of the species are North American, North African or Australian and have spread over the territory of the country due to human activity. The last part is the number of species belonging to the Mediterranean and Boreal floral element, as well as those distributed on most of the continents. Another part of the Bulgarian members of the family are halophytes inhabiting the periodically flooded, muddy and sandy terrains on the periphery of the hyperhaline and, less frequently, the brackish Black Sea lakes. They form the communities of the annual halophytes in the Black Sea salt lakes (Tzonev and Gussev 2015). The globalization we have witnessed over the last two decades has led to the penetration of many foreign species, and molecular research has led to new taxonomic changes and decisions in the family.

The objective of the present study is to review the chorological, morphological, karyological, and phytochemical studies regarding the Bulgarian members of the family Chenopodiaceae.

Detailed studies on the morphology of Chenopodiaceae in Bulgaria were conducted, mainly on Chenopodium s. lat. In particular, the following species were investigated: Chenopodium album and Dysphania botrys from 18 populations (Grozeva and Cvetanova 2008), Blitum bonus-henricus from 10 populations with ecological notes (Grozeva and Cvetanova 2011) and distribution in the country (Grozeva 2011), C. pratericola (Grozeva 2012a), the genus Dysphania (Grozeva and Cvetanova 2013), C. probstii and C. missouriense (Grozeva 2014), Blitum virgatum (Grozeva and Cvetanova 2016). Further taxa studies were Bassia hirsutа (Grozeva and Todorova 2014) and Petrosimonia brachiata (Grozeva et al. 2019a).

The first karyological data about Chenopodiaceae in Bulgaria was published by Markova (1968) on Dysphania multifida (population from the Danubian plain) resulting in a tetraploid chromosome number 2n = 36. These data was later confirmed by Grozeva and Stoeva (2006) on populations of the species from Sredna Gora Mountain, the Eastern Rhodopes and the Thracian lowland and by Grozeva and Cvetanova (2013) on populations from the Central Stara planina, the Danubian plain and the Thracian lowland.

Kožuharov and Kuzmanov (1969) specified for Suaeda altissima diploid chromosome number 2n = 18 for populations from the Southern Black Sea coast and these data were confirmed by Grozeva (2010a, 2015a, 2015b).

Cheshmedzhiev (1976) published for Beta trigyna populations from Eastern Stara planina hexaploid chromosome number 2n = 54.

Popova and Ceschmedjiev (1978) reported for Kochia scoparia population from the experimental field of Agricultural University of Plovdiv diploid chromosome number 2n = 18. These data were confirmed by Grozeva (2015a, 2015b) for a population of the species from the Thracian lowland.

Van Loon and Van Setten (1982) reported for Blitum bonus-henricus population from Rila mountain tetraploid chromosome number 2n = 36. These data were confirmed by Grozeva and Stoeva (2006) for populations from the Western Rhodopes, Pirin and Central Stara planina and by Grozeva and Cvetanova (2011) for populations from the Central Rhodopes, Western Stara planina, Rila, Slavyanka, and Vitosha mountains.

Van Loon and Van Setten (1982) reported for Blitum virgatum populations from Shipka, Central Stara planina diploid chromosome number 2n = 18. These data were confirmed by Grozeva and Stoeva (2006) for other populations of the species from Central Stara planina, Western Rhodopes and Tundzha hilly country by Grozeva and Cvetanova (2016) as well as for populations from Rila, Western and Central Rhodopes, Belasitsa, Tundzha hilly country.

Grozeva and Stoeva (2006) published for the first time chromosome numbers for 4 species from the family Chenopodiaceae, as follows: diploid chromosome number 2n = 18 for Bassia hirsuta and Corispermum nitidum for populations from the Southern Black Sea coast and for Dysphania botrys from the Danubian plain, North-Eastern Bulgaria and Central Stara planina; tetraploid chromosome number 2n = 32 for Dysphania ambrosioides populations from the Danubian plain and the Thracian lowland.

Grozeva (2007b) reported for the first time diploid chromosome number 2n = 18 from the Bulgarian populations of 8 species: Oxybasis chenopodioides from the Northern Black Sea coast; Chenopodiastrum hybridum from the Southern Black Sea coast; Danubian plain and the Eastern Rhodopes; O. glauca from the Northern Black Sea coast and the Danubian plain; C. murale from Central and Eastern Stara planina; O. rubra from North-Eastern Bulgaria; Lipandra polysperma from Eastern Sredna gora, Strandzha and Thracian lowland; C. ficifolium from the Northern Black Sea coast, North-Eastern Bulgaria and Thracian lowland; Atriplex tatarica from the Southern Black Sea coast (Grozeva 2007b). For the newly established species Dysphania pumilio diploid chromosome number 2n = 18 was published (Grozeva 2007b) and for the 2 new for the country North American species Chenopodium missouriense and C. probstii – hexaploid chromosome number 2n = 54 (Grozeva 2010a). The chromosome number for 3 species was reported for the first time: A. hastata 2n = 18 from the Danubian plain and the Thracian lowland, A. patula 2n = 36 from the Eastern Rhodopes and Eastern Sredna Gora, Suaeda maritima 2n = 36 from the Southern Black Sea coast (Grozeva 2010a).

Grozeva (2010b) published for the first time data about the chromosome number of 7 species from the genera: Atriplex (A. nitens, A. rosea, A. hortensis, A. oblongifolia), Chenopodium (C. opulifolium, C. urbicum, C. vulvaria) and Oxybaisis (O. urbica). Diploid chromosome number 2n = 18 was established for populations of: A. nitens from the Eastern Rhodopes; A. rosea from the Southern Black Sea coast and the Thracian lowland; A. hortensis from the Danubian plain and the Thracian lowland; O. urbica from North-East Bulgaria; C. vulvaria from the Eastern Rhodopes. Tetraploid chromosome number 2n = 36 was registered for populations of A. oblongifolia from the Thracian lowland and hexaploid chromosome number 2n = 54 for C. opulifolium populations from North-Eastern Bulgaria and the Thracian lowland.

For the newly established for the Bulgarian flora species Chenopodium pratericola diploid chromosome number 2n = 18 was reported (Grozeva 2012a).

Grozeva (2012b) reported for the first time data about the chromosome number of Chenopodium album subsp. album, C. album subsp. pedunculare, C. betaceum (sub. C. striatiforme and C. strictum), and Suaeda heterophylla. For C. album populations from the Northern Black Sea coast, Eastern Rhodopes and the Thracian lowland and for C. album subsp. pedunculare from the Northern Black Sea coast hexaploid chromosome number 2n = 54 was reported. For C. betauceum populations from the Southern Black Sea coast, Danubian plain and the Eastern Rhodopes tetraploid chromosome number 2n = 36 was established. For S. heterophylla population from the Southern Black Sea coast diploid chromosome number 2n = 18 was reported.

Grozeva and Cvetanova (2013) registered for the first time diploid chromosome number 2n = 18 for Dysphania schraderiana population from the Eastern Sredna gora mountain. Data about the karyotype of 27 populations of the species from genus Dysphania (D. ambrosioides, D. botrys, D. multifida, D. pumilio and D. schraderiana) was published. Polyploidy and disploidy are cited as basic evolutionary mechanisms in the genus.

Grozeva (2013) reported karyological data about 14 Chenopodiaceae species from their Bulgarian populations. For the first time the chromosome number of the species Bassia laniflora, Salsola tragus and Salicornia europaea subsp. europaea was reported for their populations from the Southern Black Sea coast. For S. tragus tetraploid chromosome number 2n = 36 was registered and for B. laniflora and S. europaea diploid chromosome number 2n = 18. The chromosome numbers known from literature data about 11 species (Atriplex oblongifolia, A. tatarica, Bassia hirsuta, Chenopodium album subsp. betaceum (sub. C. Strictum), Corispermum nitidum, Dysphania pumilio, Lipandra polysperma, Oxybasis chenopodioides, O. rubra, O. urbica) were confirmed (Grozeva 2013).

Grozeva (2015a) reported for the first time data about the chromosome number from the Bulgarian populations of 4 species (Atriplex heterosperma, Bassia prostrata, Salicornia perennans, and Salsola soda). For A. heterosperma population from the Southern Black Sea coast chromosome number 2n = 36 was registered. For B. prostrata population from the Thracian lowland and for the S. perennans and S. soda populations from the Southern Black Sea coast diploid chromosome number 2n = 18 was reported. The chromosome numbers known from literature data from the Bulgarian populations of two species (Suaeda heterophylla and S. maritima) were confirmed.

Grozeva (2015b) reported for the first time diploid chromosome number 2n = 16 for a Petrosimonia brachiata population from the Southern Black Sea coast and confirmed the chromosome number known from Bulgarian populations of Blitum virgatum, Chenopodium album subsp. pedunculare, C. probstii, C. pratericola, Salicornia europaea subsp. europaea, Suaeda altissima, S. maritima. Data about the karyotype of the species from genus Bassia (B. hirsuta, B. laniflora, B. prostrata, and B. scoparia) was published (Grozeva and Gospodinova 2016).

The karyological variability was traced and the karyotype of Blitum virgatum (Grozeva and Cvetanova 2016), of the species from genus Salsola (Grozeva et al. 2018) and genus Atriplex (Grozeva 2018a) was established.

Grozeva and Atanassova (2019) studied the karyotype of Chenopodiastrum murale and Ch. hybridum from their Bulgarian populations. Grozeva et al. (2019b) established diploid chromosome number 2n = 16 and described the karyotype of Petrosimonia brachiatа from populations of the species from the Southern Black Sea coast. Diploid chromosome number 2n = 18 and data about the karyotype of Oxybasis chenopodioides, O. glauca and O. urbica were reported (Grozeva et al. 2019b).

For the members of family Chenopodiaceae from their Bulgarian populations diploid (2n = 16, 18), tetraploid (2n = 32, 36) and hexaploid (2n = 54) chromosome numbers and two types of chromosomes – metacentric and submetacentric – were found (Grozeva 2018b). Basic chromosome numbers х = 9 and х = 8 were registered with the diploid ones being the dominant, followed by tetraploid and hexaploid species (Grozeva 2018b). According to data by Petrova and Vladimirov (2020), 80.4% of the Chenopodiaceae species have been studied karyologically. The data about the chromosome number of the studied species has been systematized in Chromosome atlas of the Bulgarian vascular plants (Petrova and Vladimirov 2020).

The karyological review showed that until 2021 data about the chromosome number and the karyotype of Beta vulgaris subsp. maritima, Camphorosma annua, C. monspeliaca, Ceratocarpus arenarius, Halimione pedunculata, H. portucaloides, Polycnemum arvense, P. heuffelii, P. majus, and Spinacia oleracea from their Bulgarian populations was lacking.

According to the Medicinal Plants Act (2000), 11 species of Chenopodiaceae are considered as medicinal plants: Atriplex rosea, Blitum bonus-henricus, B. virgatum, Camphorosma monspeliaca, Chenopodium album subsp. album, C. vulvaria, Dysphania botrys, Lipandra polysperma, Oxybasis rubra, Salicornia europaea, Salsola tragus.

Data on the phytochemical composition of medicinal plants of the family Chenopodiaceae so far are known from the Bulgarian populations of two species, i.e. B. bonus-henricus and B. virgatum.

The phytochemical investigations of genus Chenopodium revealed many compounds with a vast variety of structural patterns. The chenopods contained minerals, primary metabolites- carbohydrates, amino acids, nonpolar constituents, proteins, aromatic cytokinins, hormones and secondary metabolites – flavonoids, saponins, terpenes, sterols, alkaloids and vitamins (Nedialkov and Kokanova-Nedialkova 2020).

The aerial parts of Blitum. bonus-henricus are a rich source of bioactive compounds. Among them thirty-six compounds were distinguished including twenty-two saponins of eight sapogenins (phytolaccagenin, bayogenin, medicagenic acid, 2β-hydroxygypsogenin, 2β-hydroxyoleanoic acid, 2-hydroxy-30-nor-gypsogenin, 2-hydroxyakebonic acid and akebonic acid), twelve flavonoid glycosides of 6-methoxykaempferol, isorhamnetin, patuletin, spinacetin and two ecdysteroids (20-hydroxyecdysone and polypodine B). It was reported that glycosides of spinacetin and patulenin were the predominant compounds in the aerial parts of C. bonus-henricus (Kokanova-Nedialkova et al. 2020; Kokanova-Nedialkova and Nedialkov 2021). The occurrence of sapogenins 2-hydroxy-30-nor-gypsogenin, 2-hydroxyakebonic acid, and akebonic acids was also detected. The flavonoid and saponin-rich fractions showed in vitro hepatoprotective and antioxidant activity comparable to those of flavonoid complex silymarin (60 μg/mL) in a model of metabolic bioactivation, induced by CCl4. (Kokanova-Nedialkova et al. 2020). Nine flavonol glycosides of patuletin, 6-methoxykaempferol and spinacetin were reported to reduce lipid damage, showed antioxidant activity, neuroprotective, anti-α-glucosidase, and lipase activities and possessed no toxic on the HepG2 cell line (Kokanova-Nedialkova and Nedialkov 2021). B. bonus-henricus possessed emollient, laxative, anthelmintic, antianemic and vermifuge properties. It is used also as expectorant and for the treatment of inflammated wounds (Kokanova-Nedialkova et al. 2016; Kokanova-Nedialkova et al. 2009). The MeOH extract (60 µg/ml) of the aerial parts of C. bonus-henricus showed hepatoprotective and antioxidant activities comparable to those of flavonoid complex silymarin in an in vitro model of metabolic bioactivation, induced by tetrachloromethane. Along with the decreased MDA quantity and increased level of GSH, seven days pre-treatment of rats with the MeOH extract (100 mg/kg/daily) also prevented the tetrachloromethane-caused oxidative damage by increasing antioxidant enzyme activities (CAT, SOD, GPx, GR and GST) (Kokanova-Nedialkova et al. 2016). Extracts from roots of C. bonus-henricus L. radix showed radical scavenging activity evaluated by DPPH assay as IC50 was above 200 µg/ml (Nikolova et al. 2011).Moreover, ecdysteroids (especially 20-hydroxyecdysone, derivatives of makisterone A and polypodine B), triterpene saponins (3-O-β-D-glucopyranosyl-phytolaccagenin-28-α-L-arabinopyranosyl ester, 3-O-β-glucuronopyranosyl-bayogenin-28-O-β-glucopyranosyl ester, 3-O-β-glucopyranosyl-bayogenin-28-α-L-arabinopyranosyl ester, 3-O-β-glucuronopyranosyl-medicagenic acid-28-β-xylopyranosyl(1→4)-α-rhamnopyranosyl(1→2)-α-arabinopyranosyl ester), 6-methoxyflavonol glycosides(6-methoxykaempferol 3-O-[β-apiofuranosyl(1→2)]-β-glucopyranosyl(1→6)-β-glucopyranoside), flavonoid glycosides (spinacetin 3-O-[β-apiofuranosyl(1→2)]-β-glucopyranosyl(1→6)-β-glucopyranoside and spinacetin 3-O-gentiobioside) were found in the roots of B. bonus-henricus (Kokanova-Nedialkova et al. 2009; Kokanova-Nedialkova et al. 2013; Kokanova-Nedialkova et al. 2015). Spinacetin 3-O-gentiobioside possessed stronger DPPH and ABTS radical scavenging activity (IC₅₀ 0.44± 0.008 mM and 0.089 ± 0.002 mM) (Kokanova-Nedialkova et al. 2015). Fifteen saponins of six sapogenins were identified in roots of this plant, as saponins bonushenricoside A, 3-O-β-D-glucuronopyranosylbayogenin-28-O-β-D-glucopyranosyl ester, 3-O-β-Dglucuronopyranosyl-medicagenic acid-28-O-β-D-xylopyranosyl (1 → 4)-α-L-rhamnopyranosyl(1 → 2)- α-Larabinopyranosyl ester, 3-O-β-D-glucuronopyranosyl2β-hydroxygypsogenin-28-O-β-D-glucopyranosyl ester (4), 3-O-α-L-rabinopyranosyl-bayogenin-28-O-β-Dglucopyranosyl ester and bonushenricoside B deminstrateds possessed antioxidant and hepatoprotective effect (Kokanova-Nedialkova et al. 2019). Due to their root bioactive compounds infusions from them were used for the treatment of bronchitis, laryngitis, rheumatism, gout, constipation, dermatitis, eczema (Kokanova-Nedialkova et al. 2013). Moreover, the hepatoprotective activity of MeOH extracts from the roots of C. bonus-henricus as reported (Kokanova-Nedialkova et al. 2013). The glycosides of phytolaccagenin, bayogenin, medicagenic acid, 2β-hydroxygypsogenin, 2β-hydroxyoleanoic acid and oleanoic acid are a promising and safe class of hepatoprotective agents (Kokanova-Nedialkova et al. 2019). In plant material of B. bonus-henricus also sterols and vitamins were detected, especially vitamin C (Kokanova-Nedialkova et al. 2009).

Preliminary phytochemical screening of the aerial parts of Blitum virgatum shows the presence of carbohydrates, flavonoids, phytosterols, saponins and alkaloids/amins. Moisture content (6.05%) and total ash (12.19%) of aerial parts were also determined (Kokanova-Nedialkova et al. 2014a). The main secondary metabolites found in B. virgatum were terpenes (Kokanova-Nedialkova et al. 2009). This group of monocyclic hydrocarbon monoterpenoids includes limonene, α-terpinene and its γ-isomer, α-terpinоlen, β-phellandrene and three related derivatives that were found in this plant. It contains also aromatic monoterpenoid p-cymene, carvacrol, tymol, α-pinene and β-pinene, camphor and camphene, monocyclic sesquiterpenoids as β-caryophyllene (Kokanova-Nedialkova et al. 2009) and the oleanane triterpene 30-normedicagenic acid (Kokanova-Nedialkova et al. 2014b). The aerial parts of this plant also contain phenolic compounds. New flavonol glycosides were detected as 6-methoxy kaempferol-3-O-β-gentiobioside, gomphrenol-3-O-β-gentiobioside and gomphrenol-3-O-[6-O-(β-Dglucopyranosyl)-β-D-glucopyranoside], as well as the already known compounds patuletin-3-O-β-gentiobioside and spinacetin-3-O-β-gentiobioside. The decoction prepared from C. foliosum was evaluated as a potential source of flavonoids with a radical-scavenging activity. The highest radical-scavenging activity evaluated by DPPH and ABTS methods were patuletin-3-O-β-gentiobioside and 6-methoxykaempferol-3-O-βgentiobioside, which were comparable with those of classic antioxidant ascorbic acid (Kokanova-Nedialkova et al. 2014a). The new acylated flavonol triglycoside namely gomphrenol-3-O-(5’’’-O-E-feruloyl)-β-D-apiofuranosyl-(1→2)[β-D-glucopyranosyl-(1→6)]-β-D-glucopyranoside was also identified in the aerial parts of the plant collected from Beglika, Western Rhodopes, Bulgaria. This compound demonstrated low activity radical scavenging activity evaluated by DPPH and ABTS radicals and lack of antioxidant activity evaluated FRAP assay and inhibition of lipid peroxidation (LP) in the linoleic acid system by the ferric thiocyanate method. However, in combination with CCl4, gomphrenol-3-O-(5’’’-O-E-feruloyl)-β-D-apiofuranosyl-(1→2)[β-D-glucopyranosyl-(1→6)]-β-D-glucopyranoside reduced the damage caused by the hepatotoxic agent and preserved cell viability and GSH level, decreased LDH leakage and reduced lipid damage at the highest concentration (100 µg/mL) (Kokanova-Nedialkova et al. 2014b).