Sunday, 2 July 2017

Cucurbitacin kháng Bel 7402

Cucurbitacin B induces apoptosis and S phase cell cycle arrest in BEL-7402 human hepatocellular carcinoma cells and is effective via oral administration

Cucurbitacin kháng Bel 7402

From Wikipedia, the free encyclopedia
  (Redirected from Cucurbitacin B)
Cucurbita-5-ene with standard carbon numbering.
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.[1] They and their derivatives have been found in many plant families (including BrassicaceaeCucurbitaceaeScrophulariaceaeBegoniaceaeElaeocarpaceaeDatiscaceaeDesfontainiaceaePolemoniaceaePrimulaceaeRubiaceaeSterculiaceaeRosaceae, 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.[2][3]

Biosynthesis[edit]

The biosynthesis of Cucurbitacin C has been described recently. Zhang et al. (2014) identified nine cucumber genes in the pathway for biosynthesis of cucurbitacin C and elucidated four catalytic steps.[4] 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[4]

Variants[edit]

The cucurbitacins include:

Cucurbitacin A[edit]

Cucurbitacin A

Cucurbitacin B[edit]

Cucurbitacin B

Cucurbitacin C[edit]

Cucurbitacin D[edit]

Cucurbitacin D

Cucurbitacin E[edit]

Cucurbitacin F[edit]

Cucurbitacin G[edit]

Cucurbitacin H[edit]

Cucurbitacin I[edit]

Cucurbitacin I

Cucurbitacin J[edit]

Cucurbitacin K[edit]

Cucurbitacin L[edit]

Cucurbitacin O[edit]

Cucurbitacin P[edit]

Cucurbitacin Q[edit]

Cucurbitacin Q

Cucurbitacin R[edit]

Cucurbitacin S[edit]

Cucurbitacin T[edit]

28/29 Norcucurbitacins[edit]

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.[1]:87–130

Other[edit]

Several other cucurbitacins have been found in plants.[1]:152–156,164–165

Occurrence[edit]

Constituents of the colocynth fruit and leaves (Citrullus colocynthis) include cucurbitacins.[10][11]
The 2-O-β-D-glucopyranosides of cucurbitacins K and L can be extracted with ethanol from fruits of Cucurbita pepo cv dayangua.[9]
Pentanorcucurbitacins A and B can be extracted with methanol from the stems of Momordica charantia.[5]
Cucurbitacins B and I, and derivatives of cucurbitacins B, D and E, can be extracted with methanol from dried tubers of Hemsleya endecaphylla.[6]

Bitter taste[edit]

Cucurbitacins impart a bitter taste in plant foods such as cucumber, melon and pumpkin.[12]

Deaths[edit]

Pathologists found cucurbitacin in the stomach of a 79-year-old man who died in BavariaGermany, shortly after eating a casserole containing zucchini he had received from a neighbor. The "Chemische- und Veterinäruntersuchungsamt Stuttgart" (chemical and veterinary research authority) found cucurbitacin in a sample of the casserole the man had eaten shortly before his death. Maria Roth of that agency said that recent hot weather had likely stressed the plant, causing more toxin than usual to be present.[13][14]

See also[edit]

Fruit and flower of the Ecballium elaterium, also called the squirting cucumber or exploding cucumber containing cucurbitacin B

Melittin kháng Bel 7402

Effects of melittin on growth and angiogenesis of human hepatocellular carcinoma BEL-7402 cell xenografts in nude mice

Melittin kháng Bel 7402

From Wikipedia, the free encyclopedia
Melittin
PDB 2mlt EBI.jpg
Melittin
Identifiers
SymbolMelittin
PfamPF01372
InterProIPR002116
SCOP2mlt
SUPERFAMILY2mlt
TCDB1.C.18
OPM superfamily160
OPM protein2mlt
Melittin[1]
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard100.157.496
MeSHMelitten
PubChem CID
UNII
Properties
C131H229N39O31
Molar mass2846.46266
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references
Melittin is the principal active component of apitoxin (bee venom) and is a powerful stimulator of phospholipase A2. Melittin is a peptide consisting of 26 amino acids with the sequence GIGAVLKVLTTGLPALISWIKRKRQQ.

Biological effects[edit]

Melittin inhibits protein kinase C, Ca2+/calmodulin-dependent protein kinase II, myosin light chain kinase and Na+/K+-ATPase (synaptosomal membrane) and is a cell membrane lytic factor. Melittin is a small peptide with no disulfide bridge; the N-terminal part of the molecule is predominantly hydrophobic and the C-terminal part is hydrophilic and strongly basic.
Extensive work with melittin has shown that the venom has multiple effects, probably, as a result of its interaction with negatively charged phospholipids. It inhibits well known transport pumps such as the Na+-K+-ATPase and the H+-K+-ATPase. Melittin increases the permeability of cell membranes to ions, particularly Na+ and indirectly Ca2+, because of the Na+-Ca2+-exchange. This effect results in marked morphological and functional changes, particularly in excitable tissuessuch as cardiac myocytes. In some other tissues, e.g., cornea, not only Na+ but Cl permeability is also increased by melittin. Similar effects to melittin on H+-K+-ATPase have been found with the synthetic amphipathic polypeptide Trp-3.[2]
Melittin also exhibits potent anti-microbial activity. For example, melittin has been shown to exert "profound inhibitory effects" on Borrelia burgdorferi, the bacteria that causes lyme disease.[3] Melittin has also been shown to kill the yeast Candida albicans[4] and to suppress Mycoplasma hominis and Chlamydia trachomatis infections.[5][6][7]

Potential therapeutic applications[edit]

At Washington University School of Medicine in St. Louis, very small nanobot "nanobee" devices are being developed to carefully deliver melittin (which is known to disrupt cell membranes, and thus, destroy cells) to tumor cells in animals.[8] In February 2013, it was reported that nanoparticles carrying melittin were effective in destroying HIV by eroding the double-layer viral envelope surrounding the virus. Possible applications include a vaginal gel that would target HIV intrusion prior to infection and as an intravenous treatment of extant HIV infections.[9]
It has been suggested that the regulation of S100B by melittin has potential for the treatment of epilepsy.[10]