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It has been reported that 4,16-Androstadien-3-one (androstadienone) affects subjects'mood, psychophysiological responses and brain activity. 4,16-Androstadien-3-one is a member of the family of odorous 16-androstenes and can be found in the peripheral blood plasma of men to the extent of 98 ng/100 ml blood and in their axillary secretion with a mean value of 228 pmol/total axillary hair weight. Androstadienone can also be found in women but at a much smaller concentration. Male axillae are said to be dominated by coryneform bacteria, while women's axillae microflora are said to be dominated by micrococcacea bacteria. Although examined in only a few subjects, it has been shown that there is a high correlation between coryneform bacteria and the amount of 5α-androst-16-en-3-one (androstenone)[1].

Androstadienone is a prominent androstene present on male human axillary hair and on the male axillary skin surface. Studies suggest that Androstadienone has a strong pheromone-like activities in hum ans. Androstadienone is a metabolite of Testosterone (T155000).

The main 16-androstenes occurring in humans are 5α-androst-16-en-3-one (5α-androstenone), 5α-androst-16-en-3α-ol (5α-androstenol), and 4,16-androstadien-3-one (androstadienone). Their metabolism has been extensively studied in pigs, and they are produced in the Leydig cells in the testes from the precursor pregnenolone. In humans, it is thought that these compounds are produced in the adrenal glands and the ovary and that their metabolism follows a common steroidogenic pathway. Androstenol has been detected in human urine; androstenone and androstadienone occur in plasma and saliva.

4,16-Androstadien-3-one (Androstadienone), a nonandrogenic derivative of gonadal progesterone, is the most prominent androstene present in male semen, axillary hair, and axillary skin surfaces. Its concentration in freshly produced apocrine sweat is about 440 μM on average, with large interindividual differences. Several studies from different labs have reported that 4,16-Androstadien-3-one heightens physiological arousal, maintains elevated levels of cortisol, and promotes positive mood states in female as opposed to male recipients, possibly in a context-dependent manner. In addition, it is found to modulate women's perception of men's attractiveness in a speed-dating event to increase the perceived dominance of men's faces and increase gaze avoidance in male observers with high social anxiety. There is some indication that androstadienone also modulates recipients' attention to and memory for emotional stimuli.

4,16-androstadien-3-one (Androstadienone) affects diverse aspects of psychological state, depending on the social and psychological context of the recipient. It improves women’s mood, particularly in laboratory settings that typically dampen mood (moreover, this improved mood is sustained after returning to everyday life outside the lab). These effects are obtained with exposure to less than 9 nmol of steroid passively inhaled and verified to be undetectable as an odour, even when also masked by the strong odour of clove. Simply waving a swab soaked in a 250 μM solution briefly below the nose is sufficient to produce enduring effects. Moreover, similar psychological effects are not produced either by a structurally similar 16-androstene steroid or muscone, which has a similar odour. Therefore, in minute amounts, androstadienone does not depend on odour properties for its functional effects on the mood of women. However, mood is not the only psychological state in which androstadienone modulates in women.

[1] Johan N Lundstrm, Mats J Olsson, Thomas Hummel. “Individual differences in sensitivity to the odor of 4,16-androstadien-3-one.” Chemical Senses 28 7 (2003): 643–50.