A triterpene derivative of Formula ( Ia ) or a pharmaceutically acceptable salt or pharmaceutically acceptable solvate thereof, wherein independently, - A-B is selected from a single carbon-carbon bond or a double carbon-carbon bond; - B is selected from a methylene (-CH 2 -), an olefin methine (=CH-), a hydroxymethine [-CH(OH)-], or a hydroxylated olefin carbon [-C(OH)=]; - B-C is selected from a single carbon-carbon bond or a double carbon-carbon bond; or be part of a heterocyclic ring comprising one or more heteroatoms wherein at least one of said heteroatoms is nitrogen; and wherein said heterocyclic ring is a five-membered ring comprising one nitrogen and one oxygen; - C is selected from a hydroxymethine [-CH(OH)-], an acyloxymethine [-CH(OCOR')-], an olefin methine (=CH-), a carbonyl [-C(=O)-], an oxime [-C(=N-OH)-] or an hydrazone [-C(=N-NH 2 )-], wherein R' is methyl; - D-E is a single or a double carbon-carbon bond; - F is selected from F 1a , F 2a or F 3a ; - G is selected from a methylene (-CH 2 -) or a carbonyl [-C(=O)-]; and - R is a hydroxamate group (-CONHOH); and wherein, - when C is an acyloxymethine [-CH(OCOR')-], the triterpene derivative of Formula ( Ia ) is (3β) 3-Acetyloxy-11-oxo-olean-12-en- N -hydroxy-28-amide; - when B is a methylene (-CH 2 -), C is a hydroxymethine [-CH(OH)-], D-E is a double carbon-carbon bond, G is a methylene (-CH 2 -) and R is a hydroxamate (-CONHOH), F is F 3a ; - when B is a methylene (-CH 2 -), C is a hydroxymethine [-CH(OH)-], D-E is a single carbon-carbon bond, G is a methylene (-CH 2 -) and R is a hydroxamate (-CONHOH), F is selected from F 1a or F 2a ; - when B is a methylene (-CH 2 -), C is an oxime [-C(=N-OH)-], D-E is a double carbon-carbon bond, G is a methylene (-CH 2 -) and R is a hydroxamate (-CONHOH), F is selected from F 1a or F 3a . - A-B is selected from a single carbon-carbon bond or a double carbon-carbon bond; - B is selected from a methylene (-CH 2 -), an olefin methine (=CH-), a hydroxymethine [-CH(OH)-], or a hydroxylated olefin carbon [-C(OH)=]; - B-C is selected from a single carbon-carbon bond or a double carbon-carbon bond; or be part of a heterocyclic ring comprising one or more heteroatoms wherein at least one of said heteroatoms is nitrogen; and wherein said heterocyclic ring is a five-membered ring comprising one nitrogen and one oxygen; - C is selected from a hydroxymethine [-CH(OH)-], an acyloxymethine [-CH(OCOR')-], an olefin methine (=CH-), a carbonyl [-C(=O)-], an oxime [-C(=N-OH)-] or an hydrazone [-C(=N-NH 2 )-], wherein R' is methyl; - D-E is a single or a double carbon-carbon bond; - F is selected from F 1a , F 2a or F 3a ; - G is selected from a methylene (-CH 2 -) or a carbonyl [-C(=O)-]; and - R is a hydroxamate group (-CONHOH); and wherein, - G is selected from a methylene (-CH 2 -) or a carbonyl [-C(=O)-]; and - R is a hydroxamate group (-CONHOH); - when C is an acyloxymethine [-CH(OCOR')-], the triterpene derivative of Formula ( Ia ) is (3β) 3-Acetyloxy-11-oxo-olean-12-en- N -hydroxy-28-amide; - when B is a methylene (-CH 2 -), C is a hydroxymethine [-CH(OH)-], D-E is a double carbon-carbon bond, G is a methylene (-CH 2 -) and R is a hydroxamate (-CONHOH), F is F 3a ; - when B is a methylene (-CH 2 -), C is a hydroxymethine [-CH(OH)-], D-E is a single carbon-carbon bond, G is a methylene (-CH 2 -) and R is a hydroxamate (-CONHOH), F is selected from F 1a or F 2a ; - when B is a methylene (-CH 2 -), C is an oxime [-C(=N-OH)-], D-E is a double carbon-carbon bond, G is a methylene (-CH 2 -) and R is a hydroxamate (-CONHOH), F is selected from F 1a or F 3a . <EOS>