Ursane-type triterpenoids are a class of natural compounds commonly found in plants, such as ursolic acid from apple peels and holy basil. Recent scientific research has investigated their role in hair growth and the prevention of hair loss, particularly through their biological activities at the cellular level. Some in vitro and animal studies have shown that ursolic acid and related ursane-type triterpenoids can promote hair follicle proliferation, stimulate dermal papilla cells, and inhibit 5α-reductase (an enzyme involved in androgenic alopecia). Additionally, these compounds exhibit anti-inflammatory and antioxidant properties, which may help create a scalp environment more conducive to healthy hair growth.

However, despite these promising mechanisms, robust human clinical trials are lacking. Most of the supportive evidence comes from laboratory and animal research, with only a few small-scale or preliminary human studies. As such, while there is a scientific rationale and early evidence to suggest potential benefits for hair health, the level of clinical validation remains limited. Therefore, ursane-type triterpenoids are sometimes included in hair growth formulations based on these promising but not yet definitive findings.

In summary, while scientific research indicates potential for ursane-type triterpenoids to support hair health and possibly reduce hair loss, the current evidence in humans is weak, resulting in a moderate-low rating for scientific support.