Anticancer effect of total annonaceous acetogenins on hepatocarcinoma.

OBJECTIVE: To confirm the anticancer effect of total annonaceous acetogenins (TAAs) abstracted from Annona squamosa Linn. on human hepatocarcinoma. METHODS: The inhibitory effect of TAAs was demonstrated in H22-bearing mice. The potency of TAAs was confirmed as its 50% inhibiting concentration (IC50) on Bel-7402 cell under Sulfur Rhodamine B staining. Both underlying mechanisms were explored as cellular apoptosis and cell cycle under flow cytometry. Mitochondrial and recipient apoptotic pathways were differentiated as mitochondrial membrane potential under flow cytometry and caspases activities under fluorescence analysis. RESULTS: The inhibitory rate of TAAs in mice was 50.98% at 4 mg/kg dose. The IC50 of TAAs on Bel-7402 was 20.06 µg/mL (15.13-26.61µg/mL). Effective mechanisms of TAAs were confirmed as both of arresting cell cycle at G1 phase and inducing apoptosis dose- and time-dependently. Mitochondrial and recipient pathways involved in apoptotic actions of TAAs. CONCLUSION: TAAs is effective for hepatocarcinoma, via inhibiting proliferation and inducing apoptosis.

Physiological and biochemical characterization of egg extract of black widow spiders to uncover molecular basis of egg toxicity.

BACKGROUND: Black widow spider (L. tredecimguttatus) has toxic components not only in the venomous glands, but also in other parts of the body and its eggs. It is biologically important to investigate the molecular basis of the egg toxicity. RESULTS: In the present work, an aqueous extract was prepared from the eggs of the spider and characterized using multiple physiological and biochemical strategies. Gel electrophoresis and mass spectrometry demonstrated that the eggs are rich in high-molecular-mass proteins and the peptides below 5 kDa. The lyophilized extract of the eggs had a protein content of 34.22% and was shown to have a strong toxicity towards mammals and insects. When applied at a concentration of 0.25 mg/mL, the extract could completely block the neuromuscular transmission in mouse isolated phrenic nerve-hemidiaphragm preparations within 12.0 ± 1.5 min. Using whole-cell patch-clamp technique, the egg extract was demonstrated to be able to inhibit the voltage-activated Na+, K+ and Ca2+ currents in rat DRG neurons. In addition, the extract displayed activities of multiple hydrolases. Finally, the molecular basis of the egg toxicity was discussed. CONCLUSIONS: The eggs of black widow spiders are rich in proteinous compounds particularly the high-molecular-mass proteins with different types of biological activity The neurotoxic and other active compounds in the eggs are believed to play important roles in the eggs' toxic actions.

Isolation and identification of a sodium channel-inhibiting protein from eggs of black widow spiders.

The eggs of black widow spider (L. tredecimguttatus) have been demonstrated to be rich in biologically active components that exhibit great research value and application foreground. In the present study, a protein toxin, named Latroeggtoxin-II, was isolated from the eggs using the combination of gel filtration, ion exchange chromatography and reversed-phase high performance liquid chromatography. Electrospray mass spectrometric analysis indicated that the molecular weight of the protein was 28.69 kDa, and Edman degradation revealed that its N-terminal sequence was ESIQT STYVP NTPNQ KFDYE VGKDY-. After being abdominally injected into mice and P. americana, the protein could make the animals especially P. americana display a series of poisoning symptoms. Electrophysiological experiments demonstrated that the protein could selectively inhibit tetrodotoxin-resistant Na(+) channel currents in rat dorsal root ganglion neurons, without significant effect on the tetrodotoxin-sensitive Na(+) channel currents. Using multiple proteomic strategies, the purified protein was shown to have only a few similarities to the existing proteins in the databases, suggesting that it was a novel protein isolated from the eggs of black widow spiders.

Physiological and biochemical characterization of egg extract of black widow spiders to uncover molecular basis of egg toxicity

BACKGROUND: Black widow spider (L. tredecimguttatus) has toxic components not only in the venomous glands, but also in other parts of the body and its eggs. It is biologically important to investigate the molecular basis of the egg toxicity. RESULTS: In the present work, an aqueous extract was prepared from the eggs of the spider and characterized using multiple physiological and biochemical strategies. Gel electrophoresis and mass spectrometry demonstrated that the eggs are rich in high-molecular-mass proteins and the peptides below 5 kDa. The lyophilized extract of the eggs had a protein content of 34.22% and was shown to have a strong toxicity towards mammals and insects. When applied at a concentration of 0.25 mg/mL, the extract could completely block the neuromuscular transmission in mouse isolated phrenic nerve-hemidiaphragm preparations within 12.0 ± 1.5 min. Using whole-cell patch-clamp technique, the egg extract was demonstrated to be able to inhibit the voltage-activated Na+, K+and Ca2+ currents in rat DRG neurons. In addition, the extract displayed activities of multiple hydrolases. Finally, the molecular basis of the egg toxicity was discussed. CONCLUSIONS: The eggs of black widow spiders are rich in proteinous compounds particularly the high-molecular-mass proteins with different types of biological activity The neurotoxic and other active compounds in the eggs are believed to play important roles in the eggs' toxic actions.

Purification and partial characterization of a novel neurotoxic protein from eggs of black widow spiders (Latrodectus tredecimguttatus).

Up to now, there have been a few reports on the toxic components purified from black widow spider (Latrodectus tredecimguttatus) eggs. In the present study, a novel neurotoxic protein was purified from the eggs by gel filtration combined with ion-exchange chromatography. Its molecular weight was 23.752 kDa determined by electrospray mass spectrometry. The protein could block the neuromuscular transmission in mouse-isolated phrenic nerve-hemidiaphragm preparations completely in a reversible manner and activate tetrodotoxin-sensitive sodium current in rat dorsal root ganglion cells. The N-terminal sequence of the protein was identified by the Edman degradation to be N-S-I-A-D-D-R-Y-R-W-P-G-Y-P-G-A-G-L-I-P-Y-I-I-D-S-. When the sequence was used to search against protein database with a sequence query in Mascot engine there was no matched sequence or protein whereas the Basic Local Alignment Search Tool (BLAST) analysis indicated that no significant similarity was found. These results demonstrated that the protein (named Latroeggtoxin-I) is a novel neurotoxic protein purified from the eggs of black widow spiders.

Solution structure and functional characterization of jingzhaotoxin-XI: a novel gating modifier of both potassium and sodium channels.

JZTX-XI is a peptide toxin isolated from the venom of the Chinese spider Chilobrachys jingzhao. It contains 34 residues including six cysteine residues with disulfide bridges linked in the pattern of I-IV, II-V, and III-VI. Using 3'- and 5'-RACE methods, the full-length cDNA was identified as encoding an 86-residue precursor of JZTX-XI. In the electrophysiological assay, JZTX-XI shows activity toward the Kv2.1 channel in a way similar to hanatoxin1 and SGTx1 that both the activation and the deactivation processes are affected, which is in accordance with the high sequence homology among them (over 60% identity). On the other hand, JZTX-XI also exhibits specific interaction against the Nav channels of rat cardiac myocytes with a significant reduction in the peak current and slowing of channel inactivation. The solution structure of native JZTX-XI was determined by 1H NMR methods to identify the structural basis of these specific activities. Structural comparison of JZTX-XI with other gating modifier toxins shows that they all adopt a similar surface profile, a hydrophobic patch surrounded by charged residues such as Arg or Lys, which might be a common structural factor responsible for toxin-channel interaction. JZTX-XI might be an ideal tool to further investigate how spider toxins recognize various ion channels as their targets.

Jingzhaotoxin-I, a novel spider neurotoxin preferentially inhibiting cardiac sodium channel inactivation.

Jingzhaotoxin-I (JZTX-I), a 33-residue polypeptide, is derived from the Chinese tarantula Chilobrachys jing-zhao venom based on its ability to evidently increase the strength and the rate of vertebrate heartbeats. The toxin has three disulfide bonds with the linkage of I-IV, II-V, and III-VI that is a typical pattern found in inhibitor cystine knot molecules. Its cDNA determined by rapid amplification of 3'- and 5'-cDNA ends encoded a 62-residue precursor with a small proregion of eight residues. Whole-cell configuration indicated that JZTX-I was a novel neurotoxin preferentially inhibiting cardiac sodium channel inactivation by binding to receptor site 3. Although JZTX-I also exhibits the interaction with channel isoforms expressing in mammalian and insect sensory neurons, its affinity for tetrodotoxin-resistant subtype in mammalian cardiac myocytes (IC50 = 31.6 nm) is approximately 30-fold higher than that for tetrodotoxin-sensitive subtypes in latter tissues. Not affecting outward delay-rectified potassium channels expressed in Xenopus laevis oocytes and tetrodotoxin-resistant sodium channels in mammal sensory neurons, JZTX-I hopefully represents a potent ligand to discriminate cardiac sodium channels from neuronal tetrodotoxin-resistant isoforms. Furthermore, different from any reported spider toxins, the toxin neither modifies the current-voltage relationships nor shifts the steady-state inactivation of sodium channels. Therefore, JZTX-I defines a new subclass of spider sodium channel toxins. JZTX-I is an alpha-like toxin first reported from spider venoms. The result provides an important witness for a convergent functional evolution between spider and other animal venoms.

Jingzhaotoxin-III, a novel spider toxin inhibiting activation of voltage-gated sodium channel in rat cardiac myocytes.

We have isolated a cardiotoxin, denoted jingzhaotoxin-III (JZTX-III), from the venom of the Chinese spider Chilobrachys jingzhao. The toxin contains 36 residues stabilized by three intracellular disulfide bridges (I-IV, II-V, and III-VI), assigned by a chemical strategy of partial reduction and sequence analysis. Cloned and sequenced using 3'-rapid amplification of cDNA ends and 5'-rapid amplification of cDNA ends, the full-length cDNA encoded a 63-residue precursor of JZTX-III. Different from other spider peptides, it contains an uncommon endoproteolytic site (-X-Ser-) anterior to mature protein and the intervening regions of 5 residues, which is the smallest in spider toxin cDNAs identified to date. Under whole cell recording, JZTX-III showed no effects on voltage-gated sodium channels (VGSCs) or calcium channels in dorsal root ganglion neurons, whereas it significantly inhibited tetrodotoxin-resistant VGSCs with an IC(50) value of 0.38 microm in rat cardiac myocytes. Different from scorpion beta-toxins, it caused a 10-mV depolarizing shift in the channel activation threshold. The binding site for JZTX-III on VGSCs is further suggested to be site 4 with a simple competitive assay, which at 10 microm eliminated the slowing currents induced by Buthus martensi Karsch I (BMK-I, scorpion alpha-like toxin) completely. JZTX-III shows higher selectivity for VGSC isoforms than other spider toxins affecting VGSCs, and the toxin hopefully represents an important ligand for discriminating cardiac VGSC subtype.