유사미소중력, 진동 그리고 저온과 같은 물리적 스트래스하에서 4일간 자란 약용식물인 스테비아(Stevia rebaudiana Bertoni)는 대조구에 비해 3.6%, 21% 그리고 8.7%의 생체 중량의 감소를 보였다. 합성 항산화물질인 AA(ascorbic acid)와 BHA(beta-hydroxyacetic acid)는 비교적 약한 22%와 27%의 항산화 활성을 보였다. 유사미소중력하에서 스테비아의 DPPH(2,2-diphenyl-1-picryl hydrazal)의 음이온 소거효과는 대조구보다 지속적으로 더 높게 나타났으나, 진동과 저온처리의 처리효과는 급히 증가했다가 진동의 경우는 6시간 후에 감소되고 저온처리의 경우는 24시간 후에 대조구 수준으로 감소되었다. 유사미소중력하에서 SOD활성은 대조구에 비해 147%, 진동과 저온처리는 각각 121%와 125%로 증가를 보였다. 이상의 결과로부터 유사미소중력스트레스는 다른 스트레스보다 스테비아의 항산화 활성에 더 효과적인 영향을 미치는 것이 분명해졌다.
A medicinal herb, Stevia rebaudiana Bertoni which is grown under physical stresses such as simulated microgravity, shaking, and low temperature for 4 days, showed fresh weight decrease of 3.6%, 21% and 8.7% compared with the respective control. On control plants, the radical scavenging value of DPPH represented 86% and 55%, respectively in the leaves and stems extracts. Relatively weak antioxidant activities of 22% and 27% were measured respectively in AA (ascorbic acid) and BHA (beta-hydroxyacetic acid) known as synthetic antioxidants. The radical scavenging effect of DPPH (2,2-diphenyl-1-picryl hydazal) in stevia plants under a simulated microgravity was observed to be consistently higher relative to the control, whereas those effects of shaking and low temperature treatments rapidly increased and then reduced after 6 hours in case of shaking process and 24 hours in case of low temperature treatment, which results had similar levels of scavenging effects to the control. The plants under simulated microgravity showed the highest level of activity with the value of 147% and the shaking and low temperature treatments showed the increases of SOD activity by 121% and 125%, respectively. From the above results, it is clarified that the simulated microgravity is more effective to the antioxidant activity than those of other abiotic stresses.
