Tribulus terrestris

Tribulus terrestris is a hardy, spiny herb native to Mediterranean and Asian regions, widely cultivated for its fruit and seed extracts. The supplement is primarily used for its saponin‑rich profile, which research suggests can modestly influence hormone‑related pathways, supporting athletic performance, sexual health, and metabolic function.

• Protodioscin: The most studied constituent is protodioscin (C₄₈H₇₈O₁₈), a spirostane‑type steroidal saponin. Its IUPAC name is: [(25R)-spirost-5-ene-3β,26-diol 3‑O‑β‑D‑glucopyranosyl-(1→2)-β‑D‑glucopyranosyl-(1→3)-β‑D‑xylopyranoside].
• Molecular Structure: The molecule comprises a spirostane aglycone (four‑ring steroid core) linked to a triple‑sugar chain (glucose‑glucose‑xylose) that confers amphiphilic properties, enabling interaction with membrane receptors and enhancing oral bio‑availability of the saponin fraction.
• Other Constituents: Other constituents include flavonoids (quercetin, kaempferol) and alkaloids, but the saponin fraction accounts for >90 % of the biological activity.

• Harvesting: Tribulus is harvested primarily in India, China, and Mediterranean countries (e.g., Greece, Turkey).
• Extraction: Commercial supplements typically use fruit or seed extracts obtained via ethanol‑water (70 % ethanol) extraction, followed by spray‑drying to yield a standardized powder.
• Standardization: High‑quality products are standardized to ≥40 % total saponins (often measured as protodioscin content).
• Quality Control: Good manufacturing practice (GMP) and third‑party testing (e.g., USP, NSF) are essential to ensure minimal heavy‑metal contamination and consistent phytochemical profiles.
• Sustainability: Organic and sustainably harvested sources are increasingly marketed, but the bio-active profile remains consistent across reputable suppliers.