A green chemical oligomerization of phloroglucinol induced by plasma as novel α-glucosidase inhibitors

Figures & data

Figure 1. Structures of newly generated phloroglucinol oligomers 2−5 induced by plasma treatment.

Figure 2. Selected HMBC correlations of 5 (a) and HPLC chromatogram of plasma treated phloroglucinol for 60 min (b).

Table 1. ¹H and ¹³C NMR shifts of compound 5.^a.

Position	δH (J in Hz)^b	δC, mult.	Position	δH (J in Hz)^b	δC, mult.
1	–	156.4	4′	6.05 (s)	97.2
2	5.92 (s)	96.5	5′	–	154.8
3	–	158.1	6′	–	108.0
4	5.92 (s)	96.5	6′a	3.67 (s)	17.9
5	–	156.5	7′	–	153.1
6	–	108.5	8′	–	108.2
6a	3.72 (s)	18.5	8′a	3.72 (s)	18.5
7	–	153.1	9′	–	154.7
8	–	107.0	10′	6.05 (s)	97.2
8a	3.67 (s)	17.9	11′	–	154.9
9	–	154.9	12′	–	107.0
10	6.05 (s)	97.2	1′′	–	156.4
11	–	154.7	2′′	–	108.5
12	–	108.2	3′′	–	156.5
1′	–	153.1	4′′	5.92 (s)	96.5
2′	–	108.0	5′′	–	158.1
3′	–	154.8	6′′	5.92 (s)	96.5

^{a 1}H NMR spectra were measured at 600 MHz, and ¹³C NMR spectra were measured at 150 MHz. Data obtained in CD₃OD. Assignments based on HMQC and HMBC NMR spectra.

^b J values (Hz) are given in parentheses.

Table 2. Inhibitory effects of isolated compounds 2 – 5 on α-glucosidase.

Reactant	IC50 value (μM)^a	Compound	IC50 value (μM)^a
Phloroglucinol (1)	> 500	Dimer (2)	178.8 ± 5.3
20 min^b	> 500	Trimer (3)	54.1 ± 2.9
40 min^b	275.6 ± 6.3	Tetramer (4)	7.4 ± 1.0
60 min^b	15.6 ± 1.7	Pentamer (5)	2.3 ± 0.4
		Acarbose^c	295.2 ± 5.3

^aAll compounds were examined in triplicate experiments.

^bResults are expressed as IC₅₀ value in μg/mL.

^cUsed as positive control.