Evaluation of Antimycobacterial Activity of Higenamine Using Galleria mellonella as an In Vivo Infection Model

Abstract

The Phytochemical investigation on MeOH extract on the bark of Aristolochia brasiliensis Mart. & Zucc (Aristolochiaceae) led to the isolation of major compound (1) as light brown grainy crystals. The compound was identified as 1-(4-hydroxybenzyl)-1,2,3,4-tetrahydroisoquinoline-6,7-diol (higenamine) on the basis of spectroscopic analysis, including 1D and 2D NMR spectroscopy. The compound was evaluated for its antimycobacterial activity against Mycobacterium indicus pranii (MIP), using Galleria mellonella larva as an in vivo infection model. The survival of MIP infected larvae after a single dose treatment of 100 mg/kg body weight of higenamine was 80% after 24 h. Quantitatively the compound exhibited a dose dependent activity, as evidenced by the reduction of colony density from 105 to 103 CFU for test concentrations of 50, 100, 150 and 200 mg/kg body weight respectively. The IC50 value for higenamine was 161.6 mg/kg body weight as calculated from a calibration curve. Further analysis showed that, a complete inhibition of MIP in the G. mellonella could be achieved at 334 mg/kg body weight. Despite the fact that MIP has been found to be highly resistant against isoniazid (INH) in an in vitro assay model, in this study the microbe was highly susceptible to this standard anti-TB drug. The isolation of higenamine from the genus Aristolochia and the method used to evaluate its in vivo antimycobacterial activity in G. mellonella are herein reported for the first time.

Synthesis and Antimicrobial Activity of Novel Piperidinyl Tetrahydrothieno[2,3-c]isoquinolines and Related Heterocycles

“…Fourier transform infrared (FT-IR) of 4a revealed bands at 3449 and 3271 cm −1 specific for NH 2 and at 1589 cm −1 characteristic for CO. 1 H NMR in CDCl 3 exhibited two singlets at δ 2.39 and 7.20 ppm attributed to CH 3 and NH 2 groups. 13 C NMR of 4a displayed signal at δ 192.32 ppm for CO unique for the acetyl group (Scheme 1).…”

“…1 H NMR of 5b affirmed the absence of the singlet signal attributed to NH 2 in 4b and the presence of multiplet signals at δ 6.20−6.33 and 7.15−7.46 particular for the pyrrolyl protons, in addition to triplet and quartet signals at δ 1.34−1.38 and 4.28−4.33 characteristic for CH 3 and CH 2 of the ethoxyl group, respectively. 13 C NMR in CDCl 3 exhibited signals at 14.55, 60.06, and 166.08 specific for CH 3 , CH 2 , and CO of the ethoxyl group. The pyrrolyl acetyl 5a was used as a basic intermediate for production of new heterocycles.…”

“…1 H NMR of compound 8 represented doublet and triplet signals at δ 3.63−3.70 and 5.03−5.18 attributed to CH 2 and CHPh of pyrazole. Also, 13 C NMR exhibited signals at δ 51.05 and 64.81 for CH 2 and CH pyrazole (Scheme 2).…”

“…1 H NMR in CDCl 3 represented two singlets at δ 3.89 and 6.26 accredited to NH 2 and NH. 13 C NMR emerged signal at δ 162.70 specific for the CONH group. Cyclocondensation of the carbohydrazide 10 with acetyl acetone 37 in ethanol produced first the corresponding pentylidene Schiff's base 11 followed by cyclization upon reflux in acetic acid to produce the dimethyl pyrazolyl derivative 12 in a moderate yield.…”

“…The 1 H NMR spectrum represented singlet signals at δ 1.27 and 1.65 ppm unique for the two pyrazolyl methyl groups. 13…”