Production of a highly potent epoxide through the microbial metabolism of 3β-acetoxyurs-11-en-13β,28-olide by Aspergillus niger culture

Figures & data

Table 1. ¹H and ¹³C NMR chemical shift assignments of 3β-acetoxyurs-11,12-epoxy-13β, 28-olide (II) (600 and 150 MHz, respectively, CDCl₃).

C. no.	δC	Multiplicity	δH (J, Hz)
1	37.65	CH2	1.89, 1.72 m
2	22.67	CH2	1.27, 1.35 m
3	80.42	CH	4.5 dd (6)
4	41.39	C	–
5	54.72	CH	0.79 Overlap
6	17.44	CH2	1.19, 1.03 m
7	31.33	CH2	1.78, 1.15 m
8	41.22	C	–
9	51.25	CH	1.55 overlap
10	36.26	C	–
11	56.15	CH	2.93 d (6)
12	54.75	CH	3.09 s
13	89.03	C	–
14	41.39	C	–
15	26.75	CH2	1.64, 1.07m
16	23.12	CH2	0.89, 1.69 m
17	45.10	C	–
18	60.5	CH	1.74 overlap
19	40.14	CH	0.91 m
20	37.42	CH	1.72 m
21	30.49	CH2	1.25, 1.59 m
22	31.19	CH2	1.49, 1.79 m
23	27.69	CH3	0.83 s
24	16.19	CH3	1.14 s
25	17.22	CH3	0.84 s
26	17.3	CH3	1.14 s
27	20.22	CH3	1.03 s
28	179.29	C	–
29	19.51	CH3	0.96 d (6)
30	17.29	CH3	1.19 d (6)
1′	171.06	CO	–
2′	21.3	CH3	2.04 s

Scheme 1. Biotransformation of 3β-acetoxyurs-11-en-13β, 28-olide with Aspergillus niger.

Table 2. Inhibition potential of compounds I and II against α-glucosidase, β-glucosidase and glycation.

Compound	α-Glucosidase (IC50 μM ± SEM)	β-Glucosidase (% inhibition ± SEM)	Glycation (% inhibition ± SEM)
3β-Acetoxyurs-11-en-13 B, 28-olide (I)	14.7 ± 1.3	13.8	76.3 ± 6
3β-Acetoxyurs-11,12-epoxy-13 β, 28-olide (II)	3.56 ± 0.38	10.7	82.51 ± 1.2
Acarbose (α-glucosidase standard)	545 ± 7.9	–	–
Castanospermine (β-glucosidase standard)	–	59.98 (Verma et al. 2012)	–
Rutin (antiglycation standard)	–	–	80.5 ± 6.3

SEM, standard error mean of three experiments.

Verma N, Behera BC, Sharma BO. 2012. Glucosidase inhibitory and radical scavenging properties of lichen metabolites salazinic acid, sekikaic acid and usnic acid. Hacett J Biol Chem. 40:7–21.

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