Xanthine oxidase/tyrosinase inhibiting, antioxidant, and antifungal oxindole alkaloids from Isatis costata

Figures & data

Figure 1.  Structures of compounds 1–6.

Table 1.  In vitro xanthine oxidase and tyrosinase inhibitory and antioxidative activity of compounds 1–6.

Compound	IC50 (µM)^a
	Xanthine oxidase	Tyrosinase	Antioxidative activity
1	90.3 ± 0.06	7.21 ± 0.05	226 ± 0.38
2	101.7 ± 0.02	9.40 ± 0.03	270 ± 0.42
3	117.5 ± 0.03	11.51 ± 0.07	300 ± 0.09
4	130.6 ± 0.05	12.53 ± 0.06	320 ± 0.50
5	170.5 ± 0.01	14.29 ± 0.09	401 ± 0.53
6	179.6 ± 0.04	17.34 ± 0.04	431 ± 0.09
Allopurinol^b	7.4 ± 0.07	—	—
l-Mimosine^c	—	3.70 ± 0.03	—
3-tert-Butyl-4-hydroxyanisole (BHA)^d	—	—	46 ± 0.22

^aStandard mean error of five determinations.

^bStandard inhibitor of xanthine oxidase enzyme.

^cStandard inhibitor of tyrosinase enzyme.

^dStandard antioxidant.

Table 2.  In vitro fungicidal bioassay of crude extract and compounds 1, 2, 5, and 6.

Name of fungus	Inhibition (%) of crude extract	Inhibition (%)				Standard drugs	Inhibition (%) of standard drugs
		1	2	5	6
Trichophyton schoen leinii	71.4	83.3	74.1	61.0	49.7	Miconazole Ketoconazole	90 90
Aspergillus niger	50.1	79.7	71.5	57.9	39.2	Amphotericin-B	100
Pseudallescheria boydii	39.4	60.8	59.7	45.3	31.8	Miconazole Ketoconazole	90 90
Candida albicans	48.0	73.2	69.2	49.9	30.5	Nystatin	90
Microsporum canis	34.0	27.5	21.9	11.9	8.1	Miconazole Ketoconazole	100 100
Trichophyton mentagrophytes	53.0	67.0	61.8	48.9	33.7	Miconazole Ketoconazole	100 100
Trichophyton simii	67.5	85.9	81.3	61.7	50.4	Miconazole	100
Fusarium solani var. lycopersici (tomato)	12.0	18.3	15.7	8.9	6.5	Benlate	100
Macrophomina phaseolina	56.0	79.1	74.9	59.6	48.6	Benlate Nabam	100
Rhizoctonia solani	60.2	57.4	52.8	39.7	22.1	Benlate	100