There are lots of studies on saffron for depression, but this one shows it might also lower homocysteine:
Avicenna J Phytomed. 2018 Jan-Feb;8(1):43-50.
Saffron improved depression and reduced homocysteine level in patients with major depression: A Randomized, double-blind study.
Jelodar G, Javid Z, Sahraian A, Jelodar S.
PMID: 29387573
They used 30mg and it was not an extract:
"Saffron used in this study was of high quality collected from Khorasan province, Iran. The stigmas of C. sativus, which are being used as a food additive and also a herbal medicine, was powdered and packed into capsules in a hygienic manner. Each capsule contained 30 mg of the powder."
"Mean serum homocysteine concentration in experimental group was 9.31±0.9 μmol/l among women before treatment and 7.53±0.6 μmol/l after treatment which showed a significant decrease (p =0.040; Figure 2). Similarly, in men’s group there was a significant decrease in homocysteine level (10.14±1.45 μmol/l before vs. 7.83±0.94 μmol/l after treatment; p=0.049)."