Evaluation of the chemical compositions, larvicidal and antimicrobial efficacies of Zingiber castaneum and Zingiber nitens essential oils
Authors: Huong Le T. , Huong Trinh T , Bich Nguyen T. , Viet Nguyen T. , Ogunwande Isiaka Ajani 
Published: November 2019

Abstract
In this paper, we report the chemical constituents, larvicidal and antimicrobial activities of essential oils from Zingiber castaneum Škorničk. & Q.B. Nguyễn and Zingiber nitens M.F. Newman growing in Vietnam. The main constituents of Z. castaneum leaf were bicyclogermacrene (24.8%), germacrene D (12.9%), cis -β-elemene (11.2%) and β-pinene (10.3%), while the pseudo-stem contained bicyclogermacrene (15.8%), cis -β-elemene (9.8%) and germacrene D (9.2%). The significant compound of the rhizome oil was sabinene (22.9%), along with α-pinene (7.8%), β-pinene (6.5%), bornyl acetate (6.1%) and γ-terpinene (5.5%). However, β-pinene (45.8%), α-pinene (10.7%) and bicyclogermacrene (7.8%) were the dominant compounds in the leaf oil of Z. nitens . Terpinen-4-ol (77.9%) occurred as the compound occurring in higher amount in the rhizome oil. The rhizome oil of Z. castaneum exhibited 100% mortality towards Ae. aegypti (concentration, 200 µg/mL; 24 h and 48 h) and Ae. albopictus (concentration, 100 µg/mL; 24 h and 48 h). However, mortality of 81.3% was observed against Cx. quinquefasciatus at 48 h (concentration 100 µg/mL). The leaf also exhibited 100% mortality against Ae. aegypti (concentration, 100 µg/mL; 24 h and 48 h) and Cx. quinquefasciatus (concentration, 150 µg/mL; 24 h and 48 h). The rhizome oil displayed a minimum lethal concentration LC 50 of 121.43 µg/mL and 110.31 µg/mL against Ae. aegypti respectively at 24 h and 48 h while values of 49.85 µg/mL and 43.93 µg/mL at 24 h and 48 h were observed against Ae. albopictus respectively. In addition, LC 50 values of 88.86 µg/mL and 48.08 µg/mL were recorded respectively against Cx. quinquefasciatus . Also, the leaf oil displayed significant larvicidal activity against Ae. aegypti with LC 50 of 39.30 µg/mL (24 h) and 31.78 µg/mL (48 h) while LC 50 values of 84.97 µg/mL (24 h) and 47.40 µg/mL (48 h) were recorded respectively against Cx. quinquefasciatus . The leaf oil of Z. nitens exhibited 100% mortality against Ae. aegypti at 24 h and 48 h period (concentration 50 µg/mL) while the rhizome oil displayed maximum mortality at concentration of 100 µg/mL. The rhizome oil attained only mortality of 93% against Cx. quinquefasciatus at test period. No significant mortality was recorded against Cx. quinquefasciatus by the leaf oil. The LC 50 values of 17.58 µg/mL (24 h) and 15.12 µg/mL (48 h) were displayed by the leaf oil against Ae. aegypti while values of 29.60 µg/mL (24 h) and 26.21 (48 h) were exhibited by the rhizome oil. Only the rhizome oil was toxic against Cx. quinquefasciatus with LC 50 of of 64.18 µg/mL (24 h) and 59.06 µg/mL (48 h). The pseudo-stem oil of Z. castaneum inhibited the growth of Pseudomonas aeruginosa (ATCC 25923) with minimum inhibitory concentration (MIC) of 12.5 µg/mL, while all other tested samples recorded MIC of 50 µg/mL. However, only the pseudo-stem oil of Z. castaneum displayed antimicrobial activity against Aspergillus niger (ATCC 9763) and Fusarium oxysporum (ATCC 48112) with MIC of 50 µg/mL.