The present invention refers to compounds of the general formulae I as defined above, preferably .alpha.-mangostin, for use as/in a composition (especially foods and dietary supplements, cosmetic, as well as pharmaceutical compositions) for the prevention and improvement of muscular disorders and for the improvement of muscle function and endurance. Other fields of use are eating disorders such as bulimia and anorexia nervosa, use for accelerating wound healing, and/or use for the treatment/prevention of bone disorders such as osteoporosis and osteopenia. The present invention is also directed to dietary compositions such as (fortified) food, beverages, (fortified) feed, food additives, beverage additives, feed additives, clinical nutrition, dietary supplements, functional food, functional feed and nutraceuticals and to pharmaceutical compositions containing such compounds, to methods of preventing and/or treating the above mentioned disorders/diseases, as well as to methods of maintaining the healthy state and/or improving the baseline conditions in mammals including humans and to the compounds of the formula I themselves. Another object of the present invention is the use of such compounds for the manufacture of a composition for the prevention and/or treatment of such disorders/diseases as mentioned above.