The present disclosure relates to compounds of formula (AI), (I), (AII), and (II), or a pharmaceutically acceptable salt, solvate, stereoisomer, or tautomer thereof, a pharmaceutical composition comprising a compound of formula (AI), (I), (AII), and (II), and use thereof, wherein R2, R3, R4, R5, R6, R7, R10, R11a, R11b, R12, R16, R19a, R19b, and R20 are described herein. Such compounds are envisioned useful for the prevention and treatment of a variety of CNS-related conditions, for example, treatment of sleep disorders, mood disorders, movement disorders, convulsive disorders, schizophrenin spectrum disorders, disorders of memory and / or cognition, personality disorders, autism spectrum disorders, pain, traumatic brain injury, vascular diseases, substance abuse disorders and / or withdrawal syndromes, or tinnitus etc.