In vitro modulatory effects of colonic microflora by olive oil iridoids

Figures & data

Table I.  Olive oils phenolic composition and raw olive oil phenolic extract composition characterized by HPLC analysis.

Iridoids	Original olive oil* (mg kg^−1oil)	Impoverished olive oil^† (mg kg^−1oil)	Raw phenolic extract (mg 100 mg^−1 extract)
Hydroxytyrosol (3,4-DHPEA)	4	−	0.10
Tyrosol (p-HPEA)	5	–	0.18
3,4-DHPEA-EDA	783	91	34.20
p-HPEA-EDA	71	17	18.20
p-HPEA-derivative	27	8	1.84
3,4-DHPEA-EA	247	63	16.90
Total	1137	179	71.42

3,4-DHPEA, 3,4 dihydroxyphenylethanol; p-HPEA, p-hydroxyphenylethanol; 3,4-DHPEA-EDA, 3,4-dihydroxyphenylethyl-3 formylmethyl-4-hexenoate; p-HPEA-EDA, p-hydroxyphenylethyl-3 formylmethyl-4-hexenoate; 3,4-DHPEA-EA, dihydroxyphenylethanol-elenolic acid.

*Extra virgin olive oil unmodified.

^†Extra virgin olive oil containing a reduced quantity of iridoids.

Table II.  Minimal inhibitory concentration (MIC) of hydroxytyrosol and raw phenolic extract from extra virgin olive oil, cultivar Moraiolo, against tested bacterial strains.

Bacterial strains	MIC values (µg ml^−1)
	Hydroxytyrosol	Raw phenolic extract
Bacteroides vulgatus	0.50	0.50
Bifidobacterium adolescentis	0.05	0.50
Clostridium clostridiiforme	NA	5000
Clostridium perfringens	NA	50
Enterococcus faecalis	NA	500
Lactobacillus salivarius	0.05	0.50

NA, not active at the highest concentration tested.

Table III.  Bacterial counts at 0, 24, 144, and 288 h of fermentation with daily addition of unmodified olive oil (original), with daily addition of the same olive oil impoverished of iridoids (impoverished), and with no addition of olive oil (control).

	Log CFU ml^−1
	Control				Impoverished olive oil				Original olive oil
Bacteria	0 h	24 h	144 h	288 h	0 h	24 h	144 h	288 h	0 h	24 h	144 h	288 h
Total aerobes	6.49±0.58*	8.66±0.40	8.36±0.49	7.75±0.44	6.49±0.58	9.41±0.30	8.53±0.44	8.20±0.37	6.49±0.58	8.02±0.63^†‡	8.84±0.60	8.69±0.62
Total anaerobes	9.44±1.02	9.22±1.15	8.57±1.08	8.79±1.12	9.44±1.02	9.80±0.53	9.65±0.77^‡	9.85±0.65	9.44±1.02	9.89±0.84	10.28±0.93^‡	10.06±0.88
Bifidobacteria	8.38±0.98	8.38±0.74	4.00±0.86	4.00±0.80	8.38±0.98	8.01±1.03	8.36±1.00^‡	7.01±1.02^‡	8.38±0.98	8.39±0.32	7.26±0.65^‡	6.83±0.48^‡
Clostridia	4.91±0.06	6.20±0.23	6.50±0.15	6.67±0.19	4.91±0.06	6.75±0.24^‡	6.84±0.15^‡	7.06±0.20^‡	4.91±0.06	6.55±0.31	7.52±0.19^†‡	7.43±0.25^†‡
Enterobacteria	8.90±1.27	8.05±0.23	8.06±0.54	7.54±0.42	8.90±1.27	8.80±0.45^‡	8.40±0.32^‡	8.29±0.66	8.90±1.27	9.23±0.34^‡	9.04±0.46^‡	8.63±0.23^‡
Lactobacilli	4.38±1.85	8.20±1.21	6.50±1.53	4.50±1.37	4.38±1.85	6.93±0.90	5.85±1.38	4.00±1.14	4.38±1.85	6.87±1.23	5.60±1.54	4.00±1.39

*Values are mean±standard deviation of two independent tests.

^†Significantly different from impoverished olive oil (p<0.05, t test).

^‡Significantly different from control (p<0.05, t-test).

Figure 1.  Concentration of acetic acid (A), propionic acid (B), butyric acid (C), and total SCFA (D) at 24, 72, 144, 192, and 288 h of fermentation with daily addition of unmodified extra virgin olive oil (original), with daily addition of the same olive oil impoverished of iridoids (impoverished), and with no addition of olive oil (control). (a) Significantly different from the impoverished olive oil (p<0.05, t test); (b) significantly different from the control (p<0.05, t test).