Table 2 Key compounds discriminating Korean and Brazilian propolis. The key compounds were selected from key molecular features with VIP > 4, and a fold change ≥ 2 or ≤ − 2 or observed only in each sample

1

16.79

161.060

C₁₀H₈O₂

0.118

5.69

6-Methylcoumarin

N/A

O

Benzopyrone (flavoring agent)

2

8.26

209.081

C₁₁H₁₂O₄

0.053

7.84

Dimethyl caffeic acid

N/A

O

Phenols, caffeic acid derivatives

3

16.75

263.128

C₁₅H₁₈O₄

0.236

4.13

Artemisin

N/A

O

Sesquiterpene lactone (drug for malaria)

4

15.48

315.087

C₁₇H₁₄O₆

1.098

11.64

Rosinidin

N/A

O

Anthocyanidins

5

12.89

317.066

C₁₆H₁₂O₇

0.091

4.79

Rhamnetin

N/A

O

Flavonoids (anti-inflammatory activity)

6

16.90

329.102

C₁₈H₁₆O₆

0.352

4.62

Ophiopogonanone A

N/A

O

Homoisoflavonoids (antioxidant activity) (Wang et al. 2017)

7

10.83

338.139

C₂₀H₁₉NO₄

0.053

4.02

Columbamine

N/A

O

Alkaloids (antidiabetic agent)

8

14.45

343.118

C₁₉H₁₈O₆

0.691

5.27

Tetramethoxyflavone

N/A

O

Flavonoid (anticancer activity)

9

15.49

285.112

C₁₇H₁₆O₄

0.039

5.03

CAPE

7.8

Phenols, caffeic acid derivatives

10

12.48

285.075

C₁₆H₁₂O₅

0.025

7.18

Genkwanin

7.3

Flavonoids (anti-inflammatory activity)

11

18.43

295.227

C₁₈H₃₀O₃

0.698

11.48

Kamlolenic acid

4.9

Fatty acids, Kamala oil's glyceride

12

14.43

255.065

C₁₅H₁₀O₄

0.020

17.12

Chrysin

4.6

Flavonoids

13

17.98

357.133

C₂₀H₂₀O₆

0.319

6.89

(2S)-5,7,3′,4′-tetrahydroxy-6-(1,1-dimethylallyl)flavanone

4.2

Flavonoids (anticancer activity)

14

10.66

269.081

C₁₆H₁₂O₄

0.033

4.11

Strobochrysin

3.9

Flavonoids (anticancer activity)

15

17.69

269.081

C₁₆H₁₂O₄

0.331

5.89

Tectochrysin

3.7

Flavonoids (antibacterial activity)

16

9.99

317.066

C₁₆H₁₂O₇

0.003

4.83

Quercetin 3-methyl ether

3.7

Flavonoids (antioxidant activity)

17

10.90

273.076

C₁₅H₁₂O₅

-0.029

4.70

Butein

2.8

Chalconoids (anti-inflammatory activity)

18

14.83

257.081

C₁₅H₁₂O₄

0.144

10.44

Pinocembrin

1.1

Flavonoids (anticancer activity)

19

19.30

268.264

C₁₇H₃₃NO

0.276

4.52

(5-heptyl-6-methyloctahydroindolizin-8-yl)methanol

-1.7

Semiochemicals

20

20.27

310.310

C₂₀H₃₉NO

0.045

5.89

N-Hexadecanoylpyrrolidine

-2.0

Alkaloids

21

15.25

301.071

C₁₆H₁₂O₆

0.086

8.27

Kaempferide

-3.4

Flavonoids (antibacterial activity)

22

15.75

331.081

C₁₇H₁₄O₇

0.103

7.87

Quercetin 3,7′-dimethyl ether

-3.5

Flavonoids (vasorelaxant activity)

23

18.26

215.107

C₁₄H₁₄O₂

0.558

4.60

Dihydropinosylvin

N/A

O

Phenols (antifungal activity)

24

16.24

231.102

C₁₄H₁₄O₃

0.169

4.25

Aucuparin

N/A

O

Benzenoid (phytoalexin)

25

13.18

233.117

C₁₄H₁₆O₃

0.133

7.79

Pterosin E

N/A

O

Indanones (anti-inflammatory activity)

26

12.39

249.112

C₁₄H₁₆O₄

0.072

4.08

Prenyl caffeate

N/A

O

Caffeic acid derivatives (flavoring agent)

27

16.96

271.097

C₁₆H₁₄O₄

0.181

4.68

Haginin B

N/A

O

Flavonoids

28

18.78

273.258

C₂₀H₃₂

0.285

9.26

Casbene

N/A

O

Diterpenoids (antifungal activity) (Sitton and West 1975)

29

17.59

301.180

C₁₉H₂₄O₃

0.000

17.75

Artepillin C

N/A

O

Cinnamic acid derivatives (anti-inflammatory activity)

30

12.48

311.128

C₁₉H₁₈O₄

0.077

5.04

Moracin N

N/A

O

Flavonoids

31

17.81

321.243

C₂₀H₃₂O₃

0.386

4.27

Hydroxyeicosatetraenoic acid (HETE)

N/A

O

Unsaturated fatty acids

32

9.86

363.180

C₂₀H₂₆O₆

0.080

4.51

Gibberellin A36

N/A

O

Diterpenoids (plant hormones) (Stowe and Yamaki 1959)

33

15.13

391.212

C₂₂H₃₀O₆

0.427

6.68

Neoquassin

N/A

O

Quassinoids (insecticidal activity) (Dou et al. 2008)

34

7.21

517.134

C₂₅H₂₄O₁₂

0.184

5.04

Apigenin 7-(2′′,3′′-diacetylglucoside)

N/A

O

Flavonoids (anti-cancer effect)

35

19.74

527.337

C₃₂H₄₆O₆

0.759

4.27

(24E)-3alpha-acetoxy-15alpha-hydroxy-23oxo-7,9(11),24-lanostatrien-26-oic acid

N/A

O

Triterpenes