CUCURBITACIN is any of a class of biochemical compounds that some plants — notably members of the family Cucurbitaceae , which includes the common pumpkins and gourds — produce and which function as a defence against herbivores . Cucurbitacins are chemically classified as steroids , formally derived from cucurbitane , a triterpene hydrocarbon —specifically, from the unsaturated variant cucurbita-5-ene , or 19-(10→9β)-abeo-10α-lanost-5-ene. They often occur as glycosides . They and their derivatives have been found in many plant families (including Brassicaceae , Cucurbitaceae , Scrophulariaceae , Begoniaceae , Elaeocarpaceae , Datiscaceae , Desfontainiaceae , Polemoniaceae , Primulaceae , Rubiaceae , Sterculiaceae , Rosaceae , and Thymelaeaceae ), in some mushrooms (including Russula and Hebeloma) and even in some marine mollusks.
Cucurbitacins may be a taste deterrent in plants foraged by some animals and in some edible plants preferred by humans, like cucumbers . In laboratory research , cucurbitacins have cytotoxic properties and are under study for their potential biological activities.
* 1 Biosynthesis
* 2 Variants
* 3 Occurrence and bitter taste * 4 Research and toxicity * 5 See also * 6 References
The biosynthesis of cucurbitacin C has been described. Zhang et al. (2014) identified nine cucumber genes in the pathway for biosynthesis of cucurbitacin C and elucidated four catalytic steps. These authors also discovered the transcription factors Bl (Bitter leaf) and Bt (Bitter fruit) that regulate this pathway in leaves and fruits, respectively. The Bi gene confers bitterness to the entire plant and is genetically associated with an operon -like gene cluster, similar to the gene cluster involved in thalianol biosynthesis in Arabidopsis . Fruit bitterness requires both Bi and the dominant Bt (Bitter fruit) gene. Nonbitterness of cultivated cucumber fruit is conferred by bt, an allele selected during domestication. Bi is a member of the oxidosqualene cyclase (OSC) gene family. Phylogenetic analysis showed that Bi is the ortholog of cucurbitadienol synthase gene CPQ in squash ( Cucurbita pepo )
The cucurbitacins include:
* Pentanorcucurbitacin A , or 22-hydroxy-23,24,25,26,27-pentanorcucurbit-5-en-3-one C 25H 40O 2, white powder :1
* Pentanorcucurbitacin B or 3,7-dioxo-23,24,25,26,27-pentanorcucurbit-5-en-22-oic acid, C 25H 36O 4, white powder :2
* 3-Epi-isocucurbitacin D , from species of Physocarpus :14 and Phormium tenax * 22-Deoxocucurbitacin D from Hemsleya endecaphylla, 14 mg/72 g :6 * 23,24-Dihydrocucurbitacin D from Trichosanthes kirilowii :13 also from H. endecaphylla, 80 mg/72 g :3 * 23,24-Dihydro-epi-isocucurbitacin D , from Acanthosicyos horridus :20 * 22-Deoxocucurbitacin D from Wilbrandia ebracteata :21 * Anhydro-22-deoxo-3-epi-isocucurbitacin D from Ecballium elaterium :22 * 25-O-Acetyl-2-deoxycucurbitacin D (amarinin) from Luffa amara :24 * 2-Deoxycucurbitacin D , from Sloanea zuliaensis :23
* 22,23-Dihydrocucurbitacin E from Hemsleya endecaphylla, 9 mg/72 g, :8 and from roots of Wilbrandia ebracteata :28 * 22,23-Dihydrocucurbitacin E 2-glucoside from roots of Wilbrandia ebracteata :29 * Isocucurbitacin E , from Cucumis prophetarum :30 * 23,24-Dihydroisocucurbitacin E , from Cucumis prophetarum :31
* Cucurbitacin F from Elaeocarpus dolichostylus :33
* Cucurbitacin F 25-acetate from Helmseya graciliﬂora :34 * 23,24-Dihydrocucurbitacin F from Helmseya amabilis :35 * 25-Acetoxy-23,24-dihydrocucurbitacin F from Helmseya amabilis (hemslecin A ) :36 * 23,24-Dihydrocucurbitacin F glucoside from Helmseya amabilis :40 * Cucurbitacin II glucoside from Helmseya amabilis :41 * Hexanorcucurbitacin F from Elaeocarpus dolichostylus :43 * Perseapicroside A from Persea mexicana :44 * Scandenoside R9 from Hemsleya panacis-scandens :45 * 15-Oxo-cucurbitacin F from Cowania mexicana :46 * 15-oxo-23,24-dihydrocucurbitacin F from Cowania mexicana :47 * Datiscosides B, D, and H , from Datisca glomerata :48–50
* Cucurbitacin G from roots of Wilbrandia ebracteata :52 * 3-Epi-isocucurbitacin G , from roots of Wilbrandia ebracteata :54
* Cucurbitacin H , stereoisomer of cucurbitacin G, from roots of Wilbrandia ebracteata :53
* Hexanorcucurbitacin I from Ecballium elaterium :56 * 23,24-Dihydrocucurbitacin I see Cucurbitacin L * Khekadaengosides D and K from the fruits of Trichosanthes tricuspidata :57,58 * 11-Deoxocucurbitacin I , from Desfontainia spinosa :59 * Spinosides A and B , from Desfontainia spinosa :61,62 * 23,24-dihydro-11-Deoxocucurbitacin I from Desfontainia spinosa :60
* Cucurbitacin J from Iberis amara :69
* Cucurbitacin J 2-O-β-glucopyranoside from Trichosanthes tricuspidata :71
* Cucurbitacin K , stereoisomer of cucurbitacin J, :2 from Iberis amara :70
* Cucurbitacin K 2-O-β-glucopyranoside from Trichosanthes tricuspidata :72
* Cucurbitacin L , or 23,24-dihydrocucurbitacin I, :63 :1
* Brydioside A from Bryonia dioica :64 * Bryoamaride from Bryonia dioica :65 * 25-O-Acetylbryoamaride from Trichosanthes tricuspidata :66 * Khekadaengosides A and B from Trichosanthes tricuspidata :67–68
* Picracin from Picrorhiza scrophulariaeﬂora :79 * Picracin 2-O-glucoside from Picrorhiza scrophulariaeﬂora :79
* Cucurbitacin R is actually 23,24-dihydrocucurbitacin D.
There are several substances that can be seen as derving from cucurbita-5-ene skeleton by loss of one of the methyl groups (28 or 29) attached to carbon 4; often with the adjacent ring (ring A) becoming aromatic . :87–130
Several other cucurbitacins have been found in plants. :152–156,164–165
OCCURRENCE AND BITTER TASTE
Fruit and flower of the Ecballium elaterium , also called the squirting cucumber or exploding cucumber containing cucurbitacin B
Constituents of the colocynth fruit and leaves (Citrullus colocynthis ) include cucurbitacins. The 2-O-β-D-glucopyranosides of cucurbitacins K and L can be extracted with ethanol from fruits of Cucurbita pepo cv dayangua. Pentanorcucurbitacins A and B can be extracted with methanol from the stems of Momordica charantia . Cucurbitacins B and I, and derivatives of cucurbitacins B, D and E, can be extracted with methanol from dried tubers of Hemsleya endecaphylla.
Cucurbitacins impart a bitter taste in plant foods such as cucumber , zucchini , melon and pumpkin .
RESEARCH AND TOXICITY
Cucurbitacins are under basic research for their biological properties, including toxicity and potential pharmacological uses in development of drugs for inflammation , cancer , cardiovascular diseases , and diabetes , among others.
* ^ A B C D E F G H I J K L M N O P Q R S T U V W X Y Z AA AB AC AD
AE AF AG AH AI AJ AK AL AM AN AO AP AQ AR AS AT AU AV AW AX AY AZ BA
BB BC BD BE BF BG BH BI BJ BK BL BM BN BO BP BQ BR BS BT BU BV BW
Jian Chao Chen, Ming Hua Chiu, Rui Lin Nie, Geoffrey A. Cordell and
Samuel X. Qiu (2005), "Cucurbitacins and cucurbitane glycosides:
structures and biological activities" Natural Product Reports, volume
22, pages 386-399 doi :10.1039/B418841C
* ^ A B Alghasham, AA (2013). "Cucurbitacins - a promising target
for cancer therapy" . International Journal of Health Sciences. 7 (1):
77–89. doi :10.12816/0006025 . PMC 3612419 . PMID 23559908 .
* ^ A B Kapoor, S (2013). "
* v * t * e
Cytokine receptor modulators
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