Rubus coreanus (Korean black raspberry) is a berry from the raspberry family yet contains such a large content of anthocyanins that it is seen as nutritionally comparable to blueberry and related berries. When looking at Korean black raspberries though, they seem to carry bioactives from the raspberry family as well as the anthocyanins making them (in all practical terms) some manner of naturally occurring hybrid.
The berries are a commerical product in Korea for the most part (hence the name) and are used to make jams, jellies, food products, and most notably a wine called bokbunja ju. The unripe berries (not so much the ripe, since whatever main bioactive is in there seems to decline during the aging process) are a medicinal product for blood flow and circulation as well as male sexuality (aphrodisia and erectile function).
When looking at the berries, they are for the most part comparable to blueberries or aronia melanocarpa due to being a good source of anthocyanins. There are some unique properties of these berries though, and they seem to be related to calcium metabolism. Specifically, the berries reduce calcium release from the sarcoplasmic reticulum of cells when it would otherwise be stimulated (in a manner that can drop below baseline levels if high enough in concentration) and due to this the contraction seen in vessels including the penis that would normally occur from calcium release is attenuated.
A rat study has noted abnormally high increases in testosterone (700%) but such an increase has failed in the pilot study on healthy men. We cannot fully conclude that a testosterone boost cannot occur in men (since there were difference in the sources of the berry, stage of ripening, and dosage) but at this moment it does not look too promising.
Also tied into the testosterone would be an increase in spermatogenesis and sperm motility seen in male rats fed the unripe berries, which oddly seems to occur without changes in testicular size. This has not yet been tested in humans.
