The inappropriate or excessive use of antimicrobial agents caused an emerging public health problem due to the resulting resistance developed by microbes. Therefore, there is an urgent need to develop effective antimicrobial strategies relying on natural agents with different mechanisms of action. Nature has been known to offer many bioactive compounds, in the form of animal venoms, algae, and plant extracts that were used for decades in traditional medicine. Animal venoms and secretions have been deeply studied for their wealth in pharmaceutically promising molecules. As such, they were reported to exhibit many biological activities of interest, such as antibacterial, antiviral, anticancer, and anti-inflammatory activities. In this review, we summarize recent findings on the antimicrobial activities of crude animal venoms/secretions, and describe the peptides that are responsible of these activities.

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Iodine-125 HIPDM was evaluated as a screening agent for studying multiorgan toxicity due to Cyclosporine-A (CsA) and the results were compared to histopathological findings of the tissues. The rats were injected subcuta neously with 50 mg/kg (body weight) of CsA or with equal volume of the vehicle, Cremophor-EL, for 7 consecutive days. A dose of 10 μCi of I-125 HIPDM was injected intravenously at the end of the treatment period. The results indicated that there was a significant increase in the uptake of 1-125 HIPDM in the kidney, liver, heart and blood compared to control rats (P < 0.05). However, there was a significant decrease in the uptake of 1-125 HIPDM in the spleen compared to control animals (P < 0.001). The lung and brain of CsA treated rats showed no change in the uptake of I-125 HIPDM when compared to control rats. The change in the uptake of I-125 HIPDM in these organs was assumed to indicate tissue response to the toxic effects of CsA. The radiopharmaceutical results were compar able with the histopathological findings in which the organs showed varying degrees of tissue degeneration. It is concluded that the lipophilic radiopharmaceutical, 1-125 HIPDM, can be used as an effective screening agent to study multiorgan toxicity due to CsA.

The concept of altered biologic behavior of administered radiopharmaceuticals is used routinely in clinical nuclear medicine to increase the sensitivity of diagnosis, monitor the efficacy of chemotherapeutic drugs and radiation treatment, and determine injury caused by a drug whose effect has exceeded its therapeutic value. In this study, cyclosporine-A (CsA) an immunosuppressant drug known to cause nephrotoxicity due to tubular impairment and Tc- 99m MAG-3, a renal imaging radiopharmaceutical secreted by the tubules have been used in animal models to establish a method for investigating the nephrotoxicity of drugs. New Zealand rabbits and Wistar rats were used. The rabbits and rats were treated with 30 mg/kg of CsA for 4 and 28 consecutive days respectively. Plasma creatinine and urea were measured and renogram studies were performed in the rabbits prior to and on 1, 4, 8, 11 and 15 days after treatment with CsA. For the renogram, the rabbits were given an intravenous bolus injection of 44.4 MBq (1.5 mCi) of Tc-99m MAG-3. The Tmax, T1/2, TTHM and uptake slope of the Tc-99m MAG-3 were calculated. Each rat was injected intravenously with 185 MBq (5 mCi) of Tc-99m MAG-3, killed 3 min later, the kidneys removed and 20 mm frozen sections made. Autoradio-grams were generated from the frozen sections. Creatinine and urea levels were also measured in the rats. There was no consistent difference in creatinine and urea levels between control and CsA treated rabbits and rats. However, for the rabbit, on day 1 or 4 after treatment, there was significant increase in the values of Tmax, T1/2, TTHM and uptake slope between the control and CsA treated animals, indicating intrarenal vasoconstriction and delayed transit of Tc-99m MAG-3 from the parenchyma to the collecting system. This delay is dramatically shown in the tissue autoradiograms of the rats. The results are consistent with reported nephrotoxicity of CsA using other techniques. The results of this study, therefore, indicate that the concept of altered biologic behavior of Tc-99m MAG-3 can be used effectively as a toxicologic method for studying nephrotoxicity of drugs as exempli-fied by CsA.