An object of the present invention is to provide a golf ball having a decreased spin rate on driver shots. The present invention provides a golf ball comprising a spherical core and at least one cover layer covering the spherical core, wherein the spherical core is formed from a rubber composition containing (a) a base rubber, (b) a compound represented by the formula (1) as a co-crosslinking agent, and (c) a crosslinking initiator,
(R
1
COO)M(OCOR
2
)
m
(1)
in the formula (1), M represents a metal atom, m represents 1 or 2, R
1
and R
2
are different from each other, represent an alkenyl group having 2 to 30 carbon atoms or an alkynyl group having 2 to 30 carbon atoms and have a carbon-carbon double bond or a carbon-carbon triple bond at an α-position carbon atom bonding to the carbonyl group, and when m is 2, two of R
2
may be identical to or different from each other.
Structure-antitumor Activity Relationship of Semi-synthetic Spicamycin Derivatives.
New derivatives of spicamycin modified at the fatty acid moieties of the molecule were synthesized and their structure-activity relationships were examined. The antitumor activity was greatly influenced by modification of the fatty acid moieties to tetradecadienoyl or dodecadienoyl analogues exhibiting better antitumor activity against COL-1 human colon cancer xenograft than SPM VIII.