Oxindole alkaloids in cat’s claw have immunostimulating properties in vitro, increasing phagocytotic activity and synthesis of WBCs ⁽⁵⁾ and enhancing T-helper cell function ⁽²⁾. Inhibition of TNFα production ^(3) (4) has been linked to observed anti-inflammatory activities. Mitraphylline isolated from cat’s claw was also identified as possessing anti-inflammatory effects by inhibiting release of IL1α, 1β, 4, 17, and TNFα ⁽²¹⁾.

In other preclinical studies, aqueous extracts enhanced DNA repair after chemically-induced damage ⁽²²⁾. Protection against oxidative DNA damage following UVB exposure may occur via enhanced base excision repair and inherent antioxidant effects ⁽²³⁾. The biphasic manner in which cat’s claw modulates anxiety, initially inducing and then reversing the effect after long-term administration, is attributed to the presence of alkaloids and flavonols ⁽¹⁸⁾.

The quinovic acid glycoside purified fraction of cat’s claw inhibited human bladder cancer cells via NF-κB modulation to induce apoptosis ⁽²⁰⁾. Cat’s claw also inhibited lactate dehydrogenase-A, an enzyme highly expressed in malignant and treatment-resistant tumors with poor clinical outcomes ⁽²⁴⁾. In vivo studies demonstrated antineoplastic effects against breast tumors due to modulation of oxidative stress and synergy among constituents with antioxidant properties, rather than alkaloid activity ⁽¹²⁾.