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Substance

Study Design

Results and Conclusions

Inhibition of enzymes

Saw palmetto, extract of fruit

5-α-reductase from human prostate (obtained from patients undergoing surgery for BPH)

Addition of any of 4 extracts inhibited 5-α-reductase. IC50 values: 5.6 μg/mL (Permixon), 7.0 μg/mL (Talso, presumed to be the same as Talso uno), 31 μg/mL (Strogen forte), 40 μg/mL (Prostagutt, presumed to be the same as Prostagutt uno)

For comparison, IC50 for finasteride: 1 μg/mL (Rhodes et al., 1993).

Saw palmetto, extract of fruit (Permixon)

Cells in culture: human foreskin fibroblasts (from healthy infants or adults)

Addition of extract inhibited steroid 5-α-reductase (conversion of testosterone to DHT) and 3-α-hydroxysteroid dehydrogenase (conversion of DHT to androstanediol) in assays using intact cells.

Addition of extract inhibited binding of [3H]-DHT to androgen receptor(s) in cytosolic, nuclear, and whole cell fractions.

Addition of extract inhibited binding of [3H]-methyltrienolone (R1881) to cytosolic components of rat prostate (Sultan et al., 1984).

Extract of fruit (Permixon)

Cells in primary culture:

Human prostate epithelial cells: from subjects with PBH (IC50 = 40 μg/mL); from subjects with prostate adenocarcinoma (IC50 = 90 μg/mL)

Human prostate fibroblasts: from subjects with PBH (IC50 = 200 μg/mL); from subjects with prostate adenocarcinoma (IC50 = 70 μg/mL)

Addition of extract inhibited metabolism of [3H]-testosterone (0.1 μM) to all metabolites (DHT, androst-4-ene-3,17-dione, 5-α-androstane-3,17-dione).

By comparison, finasteride inhibited metabolism of [3H]-testosterone (0.1 μM) to DHT and 5-α-androstane-3,17-dione (IC50 = 20–40 ηM for fibroblasts; IC50 = > 100 ηM for epithelial cells),



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