Melanogenesis-inhibitory activities of limonoids and tricyclic diterpenoids from Azadirachta indica

Botanical Briefs: Neem Oil (Azadirachta indica)

“…Western blot analysis of samples extracted and isolated from neem root and bark showed melanogenesis-inhibitory activities in B16 melanoma cells through the inhibition of microphthalmiaassociated transcription factor expression and decreased expression of tyrosinase, as well as tyrosinase-related proteins 1 and 2, which are largely responsible for melanin synthesis. 11 In another study, A indica flowers and their extracted constituents-6-deacetylnimbin and kaempferide-suggest melanogenesis-inhibitory activities in B16 melanoma cells with little to no toxicity to the cells (81.0%-111.7% cell viability). 1 In an evaluation of A indica seed extracts, some of the isolated limonoids and diterpenoids exhibited a marked melanogenesisinhibitory effect (74%-91% reduction of melanin content) with no toxicity to the cell.…”

Research progress of meliaceous limonoids from 2011 to 2021

“…Ring C-seco limonoids are found mainly in Melia and Azadirachta genera and are oen associated with signicant insecticidal activity (Table S1.6 †). However, in recent years, studies on the biological activity of ring C-seco limonoids (B143-B257) 81,89,95,108,116,117,119,[121][122][123][124]132,135,[137][138][139]141,143,[168][169][170][171][172][173][174][175][176][177][178][179][180][181][182] have mainly focused on the cytotoxicity, antiinammatory, antimalarial, etc., activities. More rarely, 1a,3a-dihydroxyl-7a-tigloyloxy-12aethoxylnimbolinin (B239) possess strong NGF-potentiating activities on PC12 cells at concentrations ranging from 0.1 to 50.0 mM.…”

“…Ring C- seco limonoids are found mainly in Melia and Azadirachta genera and are often associated with significant insecticidal activity (Table S1.6†). However, in recent years, studies on the biological activity of ring C- seco limonoids ( B143–B257 ) 81,89,95,108,116,117,119,121–124,132,135,137–139,141,143,168–182 have mainly focused on the cytotoxicity, antiinflammatory, antimalarial, etc. , activities.…”

Chemistry and Biology of Novel Meliaceae Limonoids

“…Toonaciliatone C ( 236) is C6 acetyl form of Walsuronoid I (235) and contain two α oriented acetyl groups at C6 and C7 as determined by NOE interactions between H7 and β-oriented methyl group at C8. The ∆ 1,2 double bond in compound (235) is reduced in compounds (237)(238)(239)(240)(241) and varies in substitutions at C1 and C11. The ∆ 12,13 olefinic double bond in compound ( 234) is shifted to ∆ 13,17 in Dysoxylumosin C and D (242 and 243) along with additional olefinic double bond at ∆ 11,12 .…”