Table 2.

Monoterpenes with anti-Helicobacter pylori activity.

Compound	Experimental Model: Treatment (Acute or Chronic), Route, and Doses	Effect(s)	Mechanism(s)
Carvacrol [42,63]	NSAID - Acute: 25 mg/kg (p.o) - ↓43.0% 50 mg/kg (p.o) - ↓42.0%	Gastroprotective and bactericidal effects	↑ Mucus, ↑ SH compounds,↑ NO, ↑catalase and ↑PGE2 level KATP channel
	Absolute Ethanol - Acute: 16.6 mM (p.o) - ↓48.0% 33.3 mM (p.o) - ↓41.0%
	Ethanol/HCl - Acute: 8.3 mM (p.o.) - ↓ 28.0% 16.6 mM (p.o) - ↓70.0% 33.3 mM (p.o) - ↓63.0%
	I/R - Acute: 16.6 mM (p.o) - ↓51.0% 33.3 mM (p.o) - ↓38.0%
	Acetic Acid (80%) – Chronic (14 days): 25 mg/kg (p.o) - ↓60.0% 50 mg/kg (p.o) - ↓91.0% 100 mg/kg (p.o) - ↓81.0%
	Minimal Bactericidal Concentration against H. pylori: 0.04 g/L
	Vehicle: Saline, Tween 80 -1%, saline, propylene glycol or distilled water
Citronellol [64]	Absolute Ethanol - Acute: 30 mg/kg (p.o) - ↓ 72.0% 100 mg/kg (p.o) - ↓89.0% Bactericidal activity in vivo against H. pylori - Chronic (7 days; 2 x day): 12.5 mg/kg (i.p.) - ↓ 87.0% 12.5 mg/kg (p.o.) - ↓53.0% 25 mg/kg (p.o.) - ↓ 80.0% 50 mg/kg (p.o) - ↓87.0% Vehicle: Tween 80 - 2%	Gastroprotective and bactericidal effects
Geraniol [65,66]	Absolute Ethanol - Acute: 3 mg/kg (p.o) - ↓ 55.7% 7.50 mg/kg (p.o) - ↓ 70.0%10 mg/kg (p.o) - ↓ 84.8% 200 mg/kg (p.o) - ↓ 99.0% Acetic Acid 10% - Chronic (5 days) 3 mg/kg (p.o) - ↓ 80.5% Bactericidal activity in vitro against H. pylori: 2 mg/L - ↓ 92.0% Vehicle: DMSO 10% or Tween 80 - 8%	Gastroprotective, bactericidal and healing effects	↑ Mucus (↑ mucin levels 88.5%) ↑ GSH ↓ MPO ↑ Compounds SH, NO, and PGE2 level ↑ CGRP and TRPV-1 activation
Limonene [43,44]	NSAID - Acute: 177 mg/kg (p.o) - ↓ 50.1% 245 mg/kg (p.o) - ↓ 99.0% Absolute Ethanol - Acute: 50 mg/kg (p.o) 100 mg/kg (p.o) 177 mg/kg (p.o) - ↓100.0% 245 mg/kg (p.o) - ↓ 99.2% Bactericidal activity in vitro against H. pylori: MIC 75 µg/mL Vehicle: Tween 80 - 8%	Gastroprotective and bactericidal effects	↑ Mucus Maintenance of high PGE2 levels ↑ GPx ↓ MPO ↓ IL-1β, IL-6 and TNF-α ↓ mRNA expression of Nf-κB, IL-1β and MPO ↑ mRNA expression of GPx
β-Myrcene [67]	NSAID – Acute 7.5 mg/kg (p.o) – 74.0%		↑ Mucus ↓ MDA ↑ GPx ↑ GR
	Absolute Ethanol - Acute 7.5 mg/kg (p.o)- 60.0%	Gastroprotective effect
	I/R - Acute 7.5 mg/kg (p.o) – 86.0%	Bacteriostatic effect against H. pylori
	Bactericidal activity in vitro against H. pylori: MIC = 500 µg/mL
	Vehicle: Tween 80 - 8%
β-pinene [43]	Absolute Ethanol - Acute: 33 mg/kg (p.o) - absent Bactericidal activity in vitro against H. pylori: MIC = 500 µg/mL Vehicle: Tween 80 - 8%	No gastroprotective and bactericidal effects
Safranal [68]	Bactericidal activity in vitro against H. pylori: MIC50 against H. pylori: 32 µg/mL Vehicle: not described	Bactericidal effect
Thymol [69,70]	Absolute Ethanol - acute: *10 mg/kg (p.o) - ~↓ 81.0% Vehicle: DMSO - 5%
	Absolute Ethanol - Acute: *10 mg/kg (p.o) - ~ 37.0% *30 mg/kg (p.o) - ~ 63.0% *100 mg/kg (p.o) - ~95.0%	Gastroprotective effect	↑SOD, ↑ GSH, ↓MPO, ↓LPO, ↓MMP-9
	NSAID - Acute 30 mg/kg (p.o) – 43.0% 100 mg/kg (p.o) – 49.0%	Gastroprotective effect Healing effect Bactericidal effect Absent	↑ Mucus PGE2 level KATP channel No involvement of NO No antisecretory action
	Acetic Acid 30% - Chronic (7 days) 30 mg/kg (p.o) – 91.8% 100 mg/kg (p.o) – 92.5%
	Bactericidal activity in vitro against H. pylori: 10,000 µg/mL (absent)
	Vehicle: Tween 80 - 0.2%

CGRP—calcitonin gene-related peptide; GPx—glutathione peroxidase; GR—glutathione reductase; GSH—reduced glutathione; IL-10—interleukin 10; IL-6—interleukin 6; i.p.—administered by intraperitoneal route; LPO—lipoperoxidation; MDA—malondialdehyde; MIC—minimal inhibitory concentration; MPO—myeloperoxidase; NO—nitric oxide; NSAID—non-steroidal anti-inflammatory drugs; PGE₂—prostaglandin E_2; p.o.—administered by oral route; SH—sulfhydryl compounds; SOD—superoxide dismutase; TNF-ɑ—tumor necrosis factor α; TRPV-1—transient receptor potential cation channel subfamily V member 1. * Data was estimated on the basis of the results presented in the article.