Maxentra’s pitch is the nitric oxide pathway. The biology is real; the open question is whether this capsule contains enough to matter.
Arginine is an amino acid the body uses to make nitric oxide. Citrulline is converted into arginine in the kidneys, which is why it is often added. Malate and AKG are carrier forms.
Nitric oxide signals the smooth muscle in blood vessel walls to relax, widening vessels and easing blood flow. This is the same pathway that some prescription medicines act on, which is also why combining arginine with nitrates or ED drugs can drop blood pressure too far.
The marketing links better blood flow to gym endurance and vitality. Small studies of citrulline malate at multi-gram doses suggest a modest benefit for some exercise measures. Results for arginine are mixed.
The studies behind these claims generally use about 3,000–8,000 mg of citrulline or several grams of arginine per day. Maxentra lists 30 mg for the whole three-ingredient blend. Even if every milligram were citrulline, that is around one percent of a typical studied dose.
Regular exercise, a healthy weight, not smoking, moderate alcohol, good sleep, and managing blood pressure, cholesterol and blood sugar have far stronger evidence than any supplement.