Basic phospholipase A₂ was identified from the venom of the eastern diamondback rattlesnake. The Crotalus adamanteus toxin-II (CaTx-II) induced bactericidal effects (7.8 µg/ml) on Staphylococcus aureus, while on Burkholderia pseudomallei (KHW), and Enterobacter aerogenes were killed at 15.6 µg/ml. CaTx-II caused pore formation and membrane damaging effects on the bacterial cell wall. CaTx-II was not cytotoxic on lung (MRC-5), skin fibroblast (HEPK) cells and in mice. CaTx-II-treated mice showed significant wound closure and complete healing by 16 days as compared to untreated controls (**P<0.01). Histological examination revealed enhanced collagen synthesis and neovascularization after treatment with CaTx-II versus 2% Fusidic Acid ointment (FAO) treated controls. Measurement of tissue cytokines revealed that interleukin-1 beta (IL-1β) expression in CaTx-II treated mice was significantly suppressed versus untreated controls. In contrast, cytokines involved in wound healing and cell migration i.e., monocyte chemotactic protein-1 (MCP-1), fibroblast growth factor-basic (FGF-b), chemokine (KC), granulocyte-macrophage colony-stimulating factor (GM-CSF) were significantly enhanced in CaTx-II treated mice, but not in the controls. CaTx-II also modulated nuclear factor-kappa B (NF-κB) activation during skin wound healing. The CaTx-II protein highlights distinct snake proteins as a potential source of novel antimicrobial agents with significant therapeutic application for bacterial skin infections.

Breast cancer is the most common cancer among women. To date, improvements in hormonal and cytotoxic therapies have not yet led to a sustained remission or cure. In the present study, we investigated the in vitro and in vivo antitumor activities of a novel Calotropis procera protein (CP-P) isolated from root bark. CP-P protein inhibited the proliferation and induced apoptosis of breast cancer cells through the suppression of nuclear factor kappaB (NF-kB) activation. CP-P, when administered individually or in combination with cyclophosphamide (CYC, 0.2 mg/kg) to rats with 7, 12-dimethyl benz(a)anthracene (DMBA)-induced breast cancer decreased tumor volume significantly without affecting the body weight. To elucidate the anticancer mechanism of CP-P, antioxidant activities such as superoxide dismutase (SOD), catalase (CAT), glutathione-s-transferase (GST) and non-enzymatic antioxidant - reduced glutathione (GSH), vitamin E and C generation in the breast were analyzed by various assays. SOD, CAT, GST, GSH, vitamin E and C levels were high in combination-treated groups (CP-P+CYC) versus the CYC alone-treated groups. Also, the combination was more effective in down-regulating the expression of NF-kB-regulated gene products (cyclin D1 and Bcl-2) in breast tumor tissues. Our findings indicate that CP-P possesses significant antitumor activity comparable to a commonly used anticancer drug, cyclophosphamide, and may form the basis of a novel therapy for breast cancer.

The majority of snake venom phospholipases A(2) (svPLA(2)s) are toxic and induce a wide spectrum of biological effects. They are cysteine-rich proteins that contain 119-134 amino acids and share similar structures and functions. About 50% of the residues are incorporated into α-helices, whereas only 10% are in β-sheets. Fourteen conserved cysteines form a network of seven disulfide bridges that stabilize the tertiary structure. They show a high degree of sequence and structural similarity, and are believed to have a common calcium- dependent catalytic mechanism. Additionally, svPLA(2)s display an array of biological actions that are either dependent or independent of catalysis. The PLA(2)s of mammalian origin also exert potent bactericidal activity by binding to anionic surfaces and enzymatic degradation of phospholipids in the target membranes, preferentially of Gram-positive species. The bactericidal activity against Gram-negatives by svPLA(2) requires a synergistic action with bactericidal/permeability-increasing protein (BPI), but is equally dependent on enzymatic- based membrane degradation. Several hypotheses account for the bactericidal properties of svPLA(2)s, which include "fatal depolarization" of the bacterial membrane, creation of physical holes in the membrane, scrambling of normal distribution of lipids between the bilayer leaflets, and damage of critical intracellular targets after internalization of the peptide. The present review discusses several svPLA(2)s and derived peptides that exhibit strong bactericidal activity. The reports demonstrate that svPLA(2)-derived peptides have the potential to counteract microbial infections. In fact, the C-terminal cationic/hydrophobic segment (residues 115-129) of svPLA(2)s is bactericidal. Thus identification of the bactericidal sites in svPLA(2)s has potential for developing novel antimicrobials.

Traditional medicine plays a vital role for primary health care in India, where it is widely practiced to treat various ailments. Among those obtained from the healers, 78 medicinal plants were scientifically evaluated for antibacterial activity. Methanol extract of plants (100 μg of residue) was tested against the multidrug resistant (MDR) Gram-negative and Gram-positive bacteria. Forty-seven plants showed strong activity againstBurkholderia pseudomallei(strain TES and KHW) andStaphylococcus aureus, of whichTragia involucrataL.,Citrus acidaRoxb. Hook.f., andAegle marmelos(L.) Correa ex Roxb. showed powerful inhibition of bacteria. Eighteen plants displayed only a moderate effect, while six plants failed to provide any evidence of inhibition against the tested bacteria. Purified compounds showed higher antimicrobial activity than crude extracts. The compounds showed less toxic effect to the human skin fibroblasts (HEPK) cells than their corresponding aromatic fractions. Phytochemical screening indicates that the presence of various secondary metabolites may be responsible for this activity. Most of the plant extracts contained high levels of phenolic or polyphenolic compounds and exhibited activity against MDR pathogens. In conclusion, plants are promising agents that deserve further exploration. Lead molecules available from such extracts may serve as potential antimicrobial agents for future drug development to combat diseases caused by the MDR bacterial strains as reported in this study.

We provide the scientific basis for the use ofCalotropis procerafor treating skin and wound infections in traditional medicine. The aqueous extract of stem-bark ofC. proceraexhibited more pronounced potent antimicrobial activity. Calo-protein was purified and identified from the most-active aqueous extracts ofC. proceraand showed broad-spectrum activity. Calo-protein inhibited the growth ofS. aureusandE. aerogeneseffectively at 25 μg/ml concentration. Mice topically treated with Calo-protein revealed significant wound healing after 14 days comparable to fusidic acid (FA) as positive control. This protein was devoid of cytolytic effect even at higher concentrations on skin cells after 24 h. Further investigation of this Calo-protein ofC. proceraon bacterial inhibition may provide a better understanding of the scientific basis and justification for its use in traditional medicine.