Whilst trials of CC have demonstrated efficacy in ovulation induction and resultant pregnancy, there are numerous side effects associated with the drug including multiple pregnancy risk, undesirable anti-oestrogenic effects in the endocervix, endometrium and ovary, vasomotor flushes, mood swings, visual disturbances, breast tenderness, pelvic discomfort and nausea.
Most of the phytooestrogens-based preparations freely available on the market are proposed as legal and non-toxic anti-oestrogenic compounds (to counterbalance the side effects of anabolic steroids, mainly based on methoxyflafones (Usui, 2006)), as fat lowering products or sexual enhancing compounds based mainly on plant extracts from Commiphora Mukul (Guggulsterone), Eurycoma Longifolia (methoxyflavone), Vitex Agnus Castus and Astragalus Root (isoflavones).
Where concentrations of endogenous oestrogens are relatively high, as in premenopausal women, they can exclude the more potent oestrogen from binding to the receptor and, therefore, the overall effect is anti-oestrogenic.
A recent Oxford University study found smokers take, on average, around two months longer to conceive because ciggies produce anti-oestrogenic chemicals which can affect egg quality and even suppress ovulation.
The centre, which is based at the Welsh School of Pharmacy at Cardiff University, is trying to identify the complex mechanisms that the cancer cells use to become resistant to these anti-oestrogenic drugs.
21) Rather than being targeted for phase 2 excretion, 16aOHE1 and 16[alpha]OHE2 have strong biological activity on uterine tissue, (21) whereas 2OHE1 and 2OHE2 are regarded as inactive and possibly anti-oestrogenic.
Conversely, when administered concurrently with the hormone, the DC seed extract significantly inhibited the uterotrophic effect of estradiol and thus exhibited anti-oestrogenic activity, likely via competitive inhibition at the oestrogen receptor.