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Gossypol (GP), a phenolic aldehyde isolated from cotton seed, exhibits various biological activities. Zn vitro effects include inhibition of sperm motility (1) inactivation of some parasites (2), and inhibition of the infectivity of HIV (3). GP is lipophilic and has a maximum attainable concentration in aqueous media of about 100 WM. Although an effective dose for the in vitro activities is around I10 pLM, 1 O-fold higher doses are required when 5% serum albumin is present in the medium. In some studies, high concentrations of GP are desired to establish dose-response relationships, and this proves difficult because of the limited aqueous solubility. This problem has hampered the development of potentially useful pharmaceutical preparations of GP, such as a protective vaginal cream (4). Water soluble gossypol (GP-S) was prepared at the Institute of Bioorganic Chemistry, Uzbek Academy of Science (Tashkent, USSR). The content of gossypol in GP-S was determined by optical absorption spectrophotometry. The spectrum was analyzed for its shape by log-normal curve fitting analysis, as described by Metzler et al. (5). GP-S contains 7.5% gossypol (w/ w), based upon its spectral analysis in 1 N NaOH and an apparent molar absorptivity of 22,000 cm-’ Mm’. We were able to prepare up to 6 mM GP-S solution in aqueous media (i.e., 0.1 M potassium phosphate buffer, pH 8.0). Spectra at different pHs (21 1) showed the identical shift, as observed with the GP standard. Arbacia and Spisula sperms were used, as described before (6), to examine the potency of GP-S to inhibit sperm motility. Figure 1 shows the effect of GP-S on the fertilizability of Arbaciu sperms. Fifty percent inhibition is observed at 10 PM of GP-S. Complete inhibition is observed at doses greater than 100 FLM. Identical results were obtained with Spisulu sperms (data not shown). The present results reveal that GP-S can inhibit sperm motility at concentrations equivalent to those of GP (7). Kanwar et al. (8) previously reported that gossypol (10 pA4) reduced the 45Ca++ uptake (25%) of isolated human spermatozoa1 plasma membrane vesicles. This effect of GP-S upon calcium uptake was further examined with whole sperms from Spisulu. Sperms were collected from clams, suspended, and washed in Ca”-free artificial seawater (MBL). Time-dependent incorporation of 45Ca++ into intact sperm was examined by: 1) incubating the sperm suspension with 45Ca+i (10 ji a steady state was then maintained during the subsequent 40 min, followed by a slight reduction. The effect of pre-treating intact sperm with GP-S was tested. Sperms were suspended in calcium-free seawater and preincubated with GP-S (0100 pA4) for 5 min prior to the addition of 45Ca++ (10 &I). After a 5-min incubation with 45Ca++, aliquots 100 |
