In Vitro and In Silico Evaluations of Cardanol and Derivatives from Cashew Nut-Shell

Cardanol is a by-product of cashew nut shell liquids (CNSL); its combination of phenolic and a long alkyl side chain at meta position to the hydroxyl moiety makes it a remarkable starting material for several other useful bioactive compounds. One of the advantages of its unique structure is its antimicrobial activities among other important pathogenic properties. The study involved the isolation of Cardanol from CNSL, nitration of Cardanol to form nitrocardanol (NC₁) and the synthesis of Zn(II) complex of nitrocardanol (NC₁-Zn) from NC₁. The products were characterised using UV–visible spectrophotometer, FTIR and NMR. Cardanol (10% yield) was isolated as a dark pink liquid, NC₁ was synthesized as a yellow liquid (60% yield) and NC₁-Zn was synthesised as a black pellet (29% yield). Their antibacterial activities were tested against selected gram-positive and gram-negative bacteria. Cardanol, NC₁ and NC₁-Zn showed a high level of inhibition against all the organisms tested. NC₁ and NC₁-Zn gave better results than Cardanol for all the organisms except with Pedobacter mendelii. The antifungal resistance of Cardanol, NC₁ and NC₁-Zn were also evaluated against four organisms. Cardanol gave good results against all the organisms and its result of 12 ± 0 mm against Rhizopus stolonifar was better than that of clotrimazole (10.0 ± 0 mm) which was the standard drug used. NC₁-Zn has the best result overall against Rhizopus stolonifar (17.8 ± 1.06 mm). The molecular docking of Cardanol and NC₁ with selected enzymes showed C₁ as significantly better antifungal agent than an established drug. With C₁ and NC₁-Zn showing promising antimicrobial tendencies. Their results suggest that they are antibacterial and antifungal agents, while further work should be done to evaluate their other therapeutic uses.