Standardized to 45% Steroidal Sapogenins Promotes Healthy Testosterone Levels Supports Libido & Lean Muscle Mass Dietary SupplementTribest is a standardized extract of the tropical plant Tribulus terrestris, also known as "puncture vine". The extract is similar in composition to the material used in the Bulgarian study, which contains a minimum of 45% sapogenins including furostanol and protodioscin. Research performed at the Clinical Pharmaceutical Research Institute in Sofia demonstrated powerful effects on both Leutinizing Hormone and Testosterone. The study also indicated enhanced libido, sperm production and motility.