Abstract:

Objective To evaluate the antibacterial effect of sulfur heteroarotinoid A2 (SHetA2) on Mycobacterium tuberculosis (MTB) in vitro and in vivo.Methods (1) SHetA2 with different doses (2.5 μg/ml, 5.0 μg/ml, 10.0 μg/ml, and 20.0 μg/ml) was added to Sutong medium in test tube, followed by the addition of the equal volume of MTB standard strain H37RV solution (1 mg/ml, 0.1 ml/each inoculation, containing 10 ⁶ CFU). After cultured at 37℃ for 2 weeks, the minimum inhibitory concentration (MIC) of SHetA2 was determined. (2) Seventy-six specific pathogen free Kunming mice were inoculated with nebulizer inhalation device to establish tuberculosis infection model. Sixty mice were modeled successfully and randomly divided into control group, isoniazid group, and SHetA2 group in equal numbers (n=20), accordingly, the mice were treated with saline, isoniazid, and SHetA2, respectively, in different groups. After 45 days of treatment, the changes in physical signs, body weight, lung tissue bacterial load, and histopathology were observed. Results (1) In vitro results showed that MIC of SHetA2 against standard strain MTB H37RV was 10 μg/ml. (2) In vivo anti-tuberculosis experiments showed that after 45 days of treatment, the body weight of the control group was (27.21±2.85) g, which was significantly lower than those of isoniazid group ((37.98±3.09) g) and SHetA2 group ((38.28±3.43) g), with statistically significant difference (F=4.05, P=0.023). The difference of body weight between the isoniazid group and SHetA2 group (q=0.10, P=0.998) was not statistically significant. In the control group, the ratio of severe lung lesions (80.0%, 16/20) was significantly higher than those of isoniazid group (15.0%, 3/20) and SHetA2 group (10.0%, 2/20), with statistically significant difference (χ ²=32.18, P<0.01). Lung bacterial load (lg10 CFU/ml) of control group was 7.01±1.23, which was obviously higher than those of isoniazid group (2.59±0.87) and SHetA2 group (2.25±0.94), with statistically significant difference (F=6.71, P=0.002); while no statistically significant difference was found between the isoniazid group and SHetA2 group (q=0.33, P=0.970). Conclusion SHetA2 has a considerable antibacterial effect on MTB both in vivo and in vitro, which may be a candidate for new anti-tuberculosis drugs.

Key words: Mycobacterium tuberculosis, Tuberculosis, pulmonary, Drug evaluation, Animal experimentation, Sulfur heteroarotinoid